Fiat Coupe Club UK

20vt Exhaust manifold

Posted By: Anonymous

20vt Exhaust manifold - 14/10/2010 20:38

I am making a manifold is there an optimum or maximum size for the primery tubes on the exhaust manifold, also i am putting the engine in a kit car is there a maximum distance the turbo can be from the exhaust ports any suggestions welcome.
Posted By: Nigel

Re: 20vt Exhaust manifold - 15/10/2010 08:05

Well done for having a go, but I fear you'll never get better results than stock - many professional tuning companies have tried and failed

As for the distance of the turbo from the exhaust ports, minimum is generally best as it makes best use of the gas speed - however you need to consider whether you're going purely for short header length, or whether you're going to attempt to get equal-length headers

As for primary tube diameter, you are again faced with a compromise - do you want to shift lots of gas, or do you want to shift the gas quickly?

A lot will depend on the intended turbo - some turbos need a high gas speed to prevent excessive lag, others will be less dependent.

You should probably make yourself a cup of tea and spend a couple of hours (or days shocked ) trawling through Guy Croft's excellent forum
Posted By: Anonymous

Re: 20vt Exhaust manifold - 17/10/2010 09:50

Hi, in another post i just said i might be making an 20v manifold also. But now i read that its impossible? What is the problem?, or is the stock manifold just very well made?.

Sorry for all the questions

regards remco
Posted By: Nigel

Re: 20vt Exhaust manifold - 17/10/2010 16:58

Originally Posted By: rmouthaan
now i read that its impossible? What is the problem?, or is the stock manifold just very well made?


It not impossible - there have been several versions over the years

However, the standard manifold has proven to be durable and capable of big power (lots of cars well over 400bhp with a standard manifold) It simply needs to be port-matched to the cylinder head and cleaned up a little around the collectors

I'm fairly convinced that the cause of the common cracking is because of a short heat/cool cycle - I'm still on the original manifold from my old Sprinty - its now done more than a quarter of a million miles
Posted By: Anonymous

Re: 20vt Exhaust manifold - 17/10/2010 20:06

Thanks for the reply i should have given you more info i am building a delta s4 replica and my engine of choice is a 20v turbo,the reasons for my questions is the turbo will not be in the original position it will sitt slightly forward of the front of the engine (ie cam belt end)back to questions is exual lenght pipes important on a turbo engine,i will now sit down for a night on the guy croft forum thanks mick.
Posted By: Anonymous

Re: 20vt Exhaust manifold - 18/10/2010 07:43

S4, very very nice. But yes equal length is important, but so it the pipesize, the numbers of bends(minimum), the degree of the bends,angle of collector, material etc. With trying to get an equal length manifold you are trying to avoid cilinder interference. But if the bends per runner differ to much then you will lose the gains you made with the equal lengths. For you, you might be lucky, as you move your turbo quite a bit, so you can make an nice manifold as you have all the room to play with. Dont go to large on the pipesize though, unless you are going to run big big power.

Regards and all the luck

remco
Posted By: Anonymous

Re: 20vt Exhaust manifold - 20/10/2010 09:58

Never mind bend radius and weld/joint quality and static back pressure, too short and too small a pipe diameter will be an absolute disaster and the enemy is, oddly enough, the sonic exhaust pressure waves whose speed varies directly with temperature. These waves interact and superpose and boucne all over the place cylinder to cylinder especially on short 4-1 systems with a poorly laid-out collector: they are a menace and functionally useless on your turbocharged engine. It is the exhaust port static pressure and heat energy that drives the turbine on your engine not the pressure waves.

Worse is to come: lagging to keep temperature up compounded with a short, small bore system with even minor deviations in flow characteristics generated by unequal length and poor exectution of bends and joints plus too much exhaust event or excessive boost will cause the most bizarre and damaging effects - local and very high port and cylinder temperature, turbine failure, erratic firing, distorted and burned valves, valve seat loosening and fracture, detonation with blown gasket and ruptured piston etc etc.

This is an issue of critical importance and I have devoted much time and thought to it in my new book which I urge you to buy if for no other reason than you will likely not find the answers to your questions anywhere else incl my website. I have seen more damage caused to engines of all kinds by infantile design of exhaust system than almost anything else. The standard plenum (damper) manifolds are OK up to a point and beyond that, frankly, you should expect to pay over £1000 for something effective enough to work consistently well on a tuned engine and if you choose unwisely you may be in for a real shock.

GC

Posted By: Nigel

Re: 20vt Exhaust manifold - 20/10/2010 10:11

Guy - looks like your name alert is still working well! I'd hoped you'd spot this thread when I mentioned your name earlier

When you worked on Matty's head did you flow-test the exhaust manifold as well?

As I said above, several people have tried tubular manifolds and I'm fairly sure that all of them have reverted back to a standard cast manifold

You commented when you worked on the 20VT head that it was a superb basic design, with pretty much everything in the right place and at the right angle. On the assumption that Fiat's engine designers seemed to know what they were doing, I can't believe that they would accept a crappy manifold design. We know the engine can suffer from piston failure that can be attributed to excessive backpressure, but we believe this is caused by a tiny turbo and a ridiculous 2" V band downpipe adapter. Good for midrange torque, we understand, but less useful at allowing decent top end breathing

Other than the unequal length headers (caused, I assume by a packaging restraint, rather than any performance issues), the only aspect that has always baffled me is that the ports in the manifold are significantly smaller then the ports from the head - there's a huge step (2mm all round) which can't be good for gas flow

Nice plug for the book wink Any discount for FCCUK forum members?
Posted By: Anonymous

Re: 20vt Exhaust manifold - 20/10/2010 11:08

Discount? When you've read it and told me it's not worth the price I'll think about it!


GC
Posted By: Anonymous

Re: 20vt Exhaust manifold - 20/10/2010 11:32

Who would have thought that the manifold was such an important factor. Had this discussion an long time ago, but without succes sadly enough. Actually i do try to take in account the pipesize/turbulance/temperatures/angles/collectors etc. But the biggest enemy is the room to make an sufficient manifold or atleast to make one that is a bit or a lot better then the std.version without having to reorganize the intire engineroom. That no single manifold will do, for all situations and enginesetups is very clear, but to make the best with the space there is, just pushes me to compromize a lot. For now i just let the manifolds flowtest staticly, its not much, but then i will have something to start with. What do you think about the sofware available at the moment, for example ricardo wave or simulair? Thanks for the reply, and hope to read your book soon.

Regards remco
Posted By: Anonymous

Re: 20vt Exhaust manifold - 20/10/2010 11:56

True.

As for Wave or any other software the annual licence is so expensive (I mean really expensive) that you'll never get access to it and if you did it would take weeks to put in all the parameters and process it even for one single installaion. And what it would tell you is what I've in essence already said and what you've referred to directly, that unless the architecture of the vehicle really does permit an optimised manifold setup you can't tune the engine with much hope of success at all.

I am going to 'stick my neck out' and say (perhaps for the 1st time) that tuning of turbo engines must begin with addressing this issue above all others.

GC
Posted By: Nigel

Re: 20vt Exhaust manifold - 20/10/2010 12:12

Guy Croft sticking his neck out? Whatever next wink

So, Guy - are you saying that our cast manifolds have significant room for improvement?

Clearly, the issue here is that the vast majority of Coupes are road cars, with rather tight engine bays that can't easily be extended to accommodate a "perfect" manifold. There's already a compromise in the downpipe design, as the exit from the turbo is very close to the aircon compressor - it has to take a fairly tight downward turn straight out of the turbo

Its interesting that you cite the manifold as a starting point for tuning turbo engines - is this in all cases, or does it only apply once the manifold is known to be a restricting factor?

As you have possibly read, there are many 20VTs with over 400bhp that are still running the stock manifold (although in all cases, it will have been port-matched to the head to get rid of the huge step I mentioned earlier)
Posted By: Anonymous

Re: 20vt Exhaust manifold - 20/10/2010 12:21

Guy - I'm happy to send you a standard (albeit cracked and now welded) manifold for you to have a play with).

I'll even chuck in a gasket and a spare head if you like.
Posted By: Anonymous

Re: 20vt Exhaust manifold - 20/10/2010 13:27

Indeed the software takes alot of time to programm,but i dont really mind as long as the results are positive. Will have a look next week at mentor graphics, they have some maybe interesting and faster to work with programm. Glad you sticked your neck out, now i can give my already overstretched neck some rest. Thanks again for your time and thoughts.

Regards remco
Posted By: Anonymous

Re: 20vt Exhaust manifold - 20/10/2010 13:52

The OE manifold will no doubt be good 'up to a point'. The Int 16v one (eg) is good for about 400bhp. Never seen a 20v one and don't care to.
Importantly there is a significant difference in mode of operation betw a cast item (designed to try and damp out the pressure waves) and a tubular one. If the tubular one is too short/small/hot it will have a very adverse effect on the firing and exhaust cycles - by comparison.

Selection of a SUITABLE exhaust manifold as a precursor to tuning is vital if you are aiming for much more than 1.5-2 x OE output and if you do bother to give precedence to that part you can get power gains per-se from a good system in itself with no_other_mods. Never believe, all that said, that because it's tubular - it's better than OE - it may well be a disaster whatever claims are made for them by the folk who produce them. To prove out a turbo header and sell it you have to do days of the most intensive calibration, run the engine flat out on full boost and power and then run it on a car for months to see it cracks.

GC
Posted By: Nigel

Re: 20vt Exhaust manifold - 20/10/2010 14:11

Hmmm - I'm running in your "1.5 to 2.0 x OE output" range and I still have nothing more than a port-matched OE manifold

However, I have no way of knowing whether the manifold is holding me back or not, so I accept that I might be giving better power with a better manifold (although I reckon my limiting factor is my turbo - I'm already at the upper reaches of what Garret say is possible)

I seem to recall that having tried and discarded a tubular manifold, JohnS reverted back to a lightly-ported OE item for his 2.4l Coupe - this was giving around 550bhp on pump fuel and over 600 on race fuel - surely this would suggest that the manifold is inherently capable?
Posted By: Anonymous

Re: 20vt Exhaust manifold - 20/10/2010 15:02

I will give it some serious thoughts, have some tubular versions also, but for sure you cannot use them for any race applications or 1,5 or 2.0 times the std.power. Cracking is often an problem indeed, 321 or inconel might prevent this a bit more, but still its difficult to prevent on an new product. Sometimes they try to solve with bracing, or just use an large wallthickness. Shifting problems you would think. May i ask who you normally use for these custom headers and manifolds?

Now preparing for an full boost run to italy smile

Regards remco
Posted By: Anonymous

Re: 20vt Exhaust manifold - 20/10/2010 15:09

if its going to cost £1000+ to make a manifold for the 20vt would it not make sense to buy a pre made manifold??
Posted By: Sedicivalvole

Re: 20vt Exhaust manifold - 20/10/2010 15:19

All dependant on your desired specification I believe.
Posted By: Anonymous

Re: 20vt Exhaust manifold - 20/10/2010 16:50

tongue
Posted By: Anonymous

Re: 20vt Exhaust manifold - 20/10/2010 16:59

its the 20vt manifold in marcos link
Posted By: Anonymous

Re: 20vt Exhaust manifold - 20/10/2010 21:30

All turbo manifolds wether they are 4 5 or 6 cylinder are usually into 1 collector dirctly at the turbo is this the best option or is it just down to space in the engine bay, as i have a lot of room in my engine bay is there any gain by having a longer single pipe from the collector to the turbo.
Posted By: Nigel

Re: 20vt Exhaust manifold - 21/10/2010 08:56

Originally Posted By: fialcia
is there any gain by having a longer single pipe from the collector to the turbo.


I don't want this to appear as though I'm putting your ideas down, but if you're asking a question such as that, you should really think hard about whether you are capable of designing and building a manifold

If you read Guy's comments above, you'll see that there are many critical aspects to manifold design that only a dedicated tuning specialist will ever be able to fathom out

By the time you've built half a dozen different designs and tested them thoroughly at all engine revs and loads, you would undoubtedly have been better off buying a proven design

And the answer to your question is that the turbo needs to be as close as possible to the exhaust ports in order to benefit from the high gas speeds - when the exhaust gasses cool, they contract, which slows it down and provides less drive to the turbine. This is a generalisation though - there are other things to consider.
Posted By: Anonymous

Re: 20vt Exhaust manifold - 21/10/2010 11:15

Sorry, nice if it were true but it's not so. The energy to drive the turbine comes from the enthalpy of the exhaust gas and the main components are pressure and heat not gas velocity. The nozzle region of the turbine housing is there to convert pressure to velocity to generate torque via the blades, the converse of how the compressor operates where velocity is converted to pressure through a diffuser.

For the most practical of reasons the turbo actually needs to be as far away as possible - quite simply in order to achieve as much separation of the (extremely high velocity) primary pressure waves as possible. These travel through the exhaust gas whose velocity is more a function of piston speed during the (upward) displacement phase.

There are some good examples of very long headers in Google images of old F1 engines:

http://www.google.co.uk/images?q=%22f1+turbo%22&hl=en&num=10&lr=&cr=&safe=images&um=1&ie=UTF-8&source=univ&ei=IgvATM6lJofQjAeFq_ydCg&sa=X&oi=image_result_group&ct=title&resnum=6&ved=0CD8QsAQwBQ

Separation and long pipes helps to achieve damping and attentuation of the primary waves and their reflections that would otherwise interfere hugely with the firing cycles of the other cylinders. The closer the turbo (ie the shorter the pipes) the more modest the exhaust event (in its entirety) has to be and the converse is also true.

As far as primary lengths go the magic number you are all looking for is a minimum of 15" and preferably 18" OR MORE. On n/a engine it is 27".

With a twin entry turbine a useful degree of separation can be achieved in practice and primary pipes can be oriented to take advantage of the gap between firing cycles. On a 4 cyl one would pair 1&4, 2&3 but irrespective of the net benefit one could achieve length is still utterly critical. On n/a engines pressure waves are vital to power - on turbo units they are a confounded nuisance. Except on real pulse turbocharging setups where the pipe length is so extraordinarily long the use is pretty-well confined to very big (ship & powergen) diesels.

GC
Posted By: Nigel

Re: 20vt Exhaust manifold - 21/10/2010 11:28

well - with an answer like that, I have no problem being wrong! However, if its pressure that's driving the turbine, there will still be an adverse effect of pressure drop caused by cooling of the gasses - the further away the turbo is from the exhaust ports, the cooler the gas and the lower the pressure - can this be overcome by careful sizing of the primaries?

So - why did Fiat fit the turbo so close to the head (which in turn left us with a horribly restrictive downpipe bend)?

Surely, they could have dropped the turbo location by a few inches and solved two major issues in one go

However, isn't there also a lag issue associated with longer primaries? - clearly not an issue on an F1 engine or even some race engines, but its not a desirable characteristic of a forced-induction road car
Posted By: Anonymous

Re: 20vt Exhaust manifold - 21/10/2010 11:56

...so close to the head to suit their own installation and they can get away with it because the ex overlap valve event is so modest as to be almost non-existent and a cast header acts as a damper which a tubular system does not and the boost is restrained. If you don't fully appreciate the meaning of 'event' it is the ex phase - governed by the valve lift, valve size, ex port flow characteristic, ex valve open and closure timing, extent of overlap and alteration of any one of those will impact on the behaviour of the turbocharger and engine as a whole. And I do mean as a whole because the turbine runs the compressor so the inlet event is indrectly affected too.

You're asking pertinent questions and that's fair enough but you can cite this-or-that issue as often as you like (lag eg) but it won't alter the savage reality that the marriage of a turbocharger to a gasoline engine is a 'match made in hell' and there are 'up' and 'downsides' to every conceiveable issue with no happy medium that is all things to all men. And I've not even remarked on the numerous degrading thermal and mechanical aspects that arise in these installations or even the survivability of the damned turbocharger itself. And I say that as a former turbocharger manufacturer Chief Engineer.

GC
Posted By: Anonymous

Re: 20vt Exhaust manifold - 21/10/2010 12:13

:), glad you have time to reply on this issue. Made me smile again, not so sure about others though.

Watch your neck.

Thanks and regards

remco
Posted By: Nigel

Re: 20vt Exhaust manifold - 21/10/2010 14:43

Guy - I'm pretty sure the answer to this will be "buy the book", but without giving too much away, what should we be doing to get reliable, usable extra power from our 20VTs? We can see from your answers above that you know what we shouldn't be doing, but what we really need to know is what we should be doing

I'm sure you've already seen the route that we have found to yield the bigger results, which tends to go something like this:-

Bigger turbo (GT28RS, GT2871, GT3071)
Cams (slight increase in duration and lift - nothing wild)
Exhaust (drop the V-Band and go for up to 3" from the turbo all the way back)
Forged pistons & rods to take the extra grunt
Head (usually a simple port cleanup and 3-angle valve seats for the intake)
Intake (decent filter, re-sited closer to the turbo)
Injectors (bigger, plus slightly increased fuel pressure)
Up the boost (1.2 - 1.4 bar is common, with the nutters amongst us running 1.5 - 1.7 bar)
And of course, some decent mapping

I'm sure you'll tell us that the majority of the above is simply making the best of an inherently bad job, but without spending barmy money, that's what we're stuck with, so we are looking for the most appropriate solution, not necessarily the very best solution.

I also accept that in your professional opinion, you may tell us that there's actually no point in ploughing serious sums of money into extracting more power from a turbo'd FWD car. However, that would be like telling the kids to keep their hands out of the open sweetie jar - it ain't going happen wink

Finally, thanks for taking the time to reply - we realise you're busy, but your input is valuable to us.
Posted By: Anonymous

Re: 20vt Exhaust manifold - 21/10/2010 15:11

There is nothing wrong with your tuning ideas per-se,that is the first thing I would say. The point about the book is this: for years and years I've been coaching folk about engines, not exclusively clients but prospects and others too. I know more than anyone how important it is to understand the engine as a whole before tuning it up and that is where I come in. Sadly more and more folk esp those with turbo installations are wrecking their engines because they have so little of this knowledge. The book tells you what I believe you_need_to_know. If you think (using the word 'you' in the general sense) you don't need to know all that, fine. I just happen to think you will enjoy the project a lot more (in every sense) if you find out first what makes the engine 'tick' - because there are so many more vital facets to tuning an engine and making it robust than our short list above covers. Most people who ring me about 'turbo projects' have never worked on anything more complicated than a bicycle in their lives. So often I've been asked 'why's that then?' as if I was trying to con them about something; they had no idea about many of the aspects yet still felt they wanted to argue about them. Thus another unhappy marriage in the making!

Anyhow I've put one on ebay if anyone wants to try for a 'discount' copy!

G
Posted By: Anonymous

Re: 20vt Exhaust manifold - 21/10/2010 16:51

Cant find it on ebay.co.uk, and no i am not in need for an discount smile.

Dont tell me its sold already now...

Regards remco
Posted By: Anonymous

Re: 20vt Exhaust manifold - 21/10/2010 17:01

Thanks for the good information Guy, this is the first time i have ever tuned a turbo engine so all correct information is valuable, i will get the book

regards Mick.
Posted By: Anonymous

Re: 20vt Exhaust manifold - 21/10/2010 17:02

Happy bidding. (note to Guy you will get more hits if you put your name in the listing title)

http://cgi.ebay.co.uk/MODIFYING-AND-TUNI...b#ht_500wt_1156
Posted By: Anonymous

Re: 20vt Exhaust manifold - 21/10/2010 17:49

Guy true or false, a five cylinder engine is more troublesome than a 4 pot or even a 6 cylinder where you can use a twin turbo setup. Because of the closer proximity from seperation of the exhaust valve events ? Even longer primarys than usual needed here ?
Posted By: Anonymous

Re: 20vt Exhaust manifold - 21/10/2010 18:45

Aha, many thanks sir.
Posted By: Anonymous

Re: 20vt Exhaust manifold - 21/10/2010 21:32

I just have to add as an off topic note that I have a sizeable amount of knowledge about engines and tuning, more then many - or so I thought until I got the new GC book. It covers subjects in an approach deviod in the numerous books I already own (streets ahead of the already good Forced induction Tuning by AG Bell).

Just for info Nigel I would say save yourself some fuel use in week and put that money on the book, its a real eye opener, I bet if you pick it up you wont put it down (its not good for marriages).

rich
Posted By: Anonymous

Re: 20vt Exhaust manifold - 21/10/2010 22:26

The five cylinder engine must be a can of worms for exhaust header design engineers. I can only imagine that dealing with the three phenomenas that occur when the primary wave ‘hits’ the collector must be a nightmare due to the extra (odd) cylinder compared to ANY other engine configuration known. Even cylinders can be paired off and the use of twin entry turbos can aid wave attenuation. But a five pot?!?. I have always said that getting the exhaust manifold design correct is key to unlocking this engine. I am yet to see proof of this. (Maybe we should ask Audi Motorsport laugh )

I have read many books including A G Bell but GC's new book is a serious read. It solves my insomnia problem quite well. smile
Posted By: Nigel

Re: 20vt Exhaust manifold - 22/10/2010 08:37

But the fifth cylinder isn't an "extra" as such - it doesn't just shove a pulse in at some random time

All that happens is that the normal 90 degrees pulse separation of a four pot is reduced to 72 degrees for the five

Admittedly, it would prove problematic for the implementation of parallel twin turbos, but that's pretty unlikely to be developed for the Coupe. Twin sequential would be interesting, but probably wouldn't provide enough gains for the investment

I'm sure that Audi Motorsport will have some good experience, but IIRC, even the hottest Quattro WRCs were 'only' putting out 500 - 600 bhp - we've already seen the lower end of this range from a 2L Coupe and our budget is rather less that Audi's was at the time, PLUS our engines aren't stripped and rebuilt every weekend
Posted By: Per

Re: 20vt Exhaust manifold - 22/10/2010 08:56

Originally Posted By: Nigel
I'm sure that Audi Motorsport will have some good experience, but IIRC, even the hottest Quattro WRCs were 'only' putting out 500 - 600 bhp - we've already seen the lower end of this range from a 2L Coupe and our budget is rather less that Audi's was at the time, PLUS our engines aren't stripped and rebuilt every weekend


cool
Posted By: Anonymous

Re: 20vt Exhaust manifold - 22/10/2010 09:37

"All that happens is that the normal 90 degrees pulse separation of a four pot is reduced to 72 degrees for the five"

Ooops. On a four stroke unit it takes 720 deg of crank rotation to complete the full cycle on all cylinders; the separation is 180deg and 144 deg resp.

G
Posted By: Anonymous

Re: 20vt Exhaust manifold - 22/10/2010 09:39

Nigel, there are two full revolutions to the 4 stroke cycle hence, a 4 cylinder will fire once every 180 deg.
Posted By: Nigel

Re: 20vt Exhaust manifold - 22/10/2010 09:39

I knew that.....


rolleyes wink
Posted By: Nigel

Re: 20vt Exhaust manifold - 22/10/2010 09:44

TBH, I was trying to remember the info about primary and secondary vibrations - I just didn't bother to think that there's only one firing stroke per two revolutions
Posted By: Anonymous

Re: 20vt Exhaust manifold - 22/10/2010 09:50

Thats what I was saying !
Posted By: Anonymous

Re: 20vt Exhaust manifold - 22/10/2010 09:57

OOPs. I think our posts overlapped!


G
Posted By: Anonymous

Re: 20vt Exhaust manifold - 22/10/2010 10:38

Originally Posted By: Marco20valveT
if its going to cost £1000+ to make a manifold for the 20vt would it not make sense to buy a pre made manifold??



I personally wouldn't spend my money on that, based on the advertisement.

The curves in that manifold are way too sharp and close to the exhaust port. Look at the #5 cylinder. How on earth is any super-hot exhaust gas going to get out of the cylinder there? Sod equal length here, you want equal (and high) flow and these ridiculous bends are not going to help at all. It sure look pretty, but the design has some obvious bottlenecks in it.

They stated that they used CFD design on this manifold, but I think that they merely went for the best possible flow with 36mm pipes and stock dimensions/locations of the flanges, plus equal length. If they would have dropped the equal length from the requirements and replaced it with equal flow, they would probably come up with something entirely different.

I know it's guessing based on just one advertisement, but this is exactly what they want you to do, decide to buy their product based on the ad.

If I'm wrong about this manifold, someone please educate me. I'd love to learn how this setup can work.
Posted By: Anonymous

Re: 20vt Exhaust manifold - 22/10/2010 11:02

Hi, i know something also, but know for sure its not enough, so hope my 100 bid will be enough. wink And i only have experience with turbocharged engines. But eager to learn ofcourse.
Posted By: Anonymous

Re: 20vt Exhaust manifold - 22/10/2010 11:06

Regarding the orientation of primaries on a 5 cyl the only sane way to to do it is 5-1. Attempts to 'pair' the pipes would only lead to rather bizarre variations in vol effy & firing pressure.


GC
Posted By: Anonymous

Re: 20vt Exhaust manifold - 22/10/2010 11:39

Surely they also work with the room there is, and not like guy likes it to be, or even better how it should be. One way might be an different castversion but this will still be an compromise and nothing more. Who has an spare head tongue
Posted By: Anonymous

Re: 20vt Exhaust manifold - 22/10/2010 18:28

Hi remco, this is what I was saying on delphi the other week if you remember about re-locating closer to, or over the gearbox.
Posted By: Anonymous

Re: 20vt Exhaust manifold - 22/10/2010 18:43

Hi,

Indeed i remember ofcourse wink.

Did you worked something out already, sizewise or something?

You can always contact me if you want to give it a go.

Regards remco
Posted By: Anonymous

Re: 20vt Exhaust manifold - 22/10/2010 23:44

Not yet, It's a while off (still no engine in the car). I need to think about a lot of other factors first.

Maybe we can come up with something very nice in the future, well for a 16v anyway.
Posted By: Anonymous

Re: 20vt Exhaust manifold - 23/10/2010 06:16

Most likely for your car only then;)
Posted By: Anonymous

Re: 20vt Exhaust manifold - 23/10/2010 15:41

Not especially just for me, the 5 cylinder unit does'nt interest me for starters, I would be more concentrated on a nice manifold for the delta specificaly. Once 1 is made and TESTED who knows what might happen, if there is a demand.
Posted By: Anonymous

Re: 20vt Exhaust manifold - 23/10/2010 18:40

Integrale specific, are you allowed to say that over here;). But no problem, just let me know when you are ready, dont think there will be much interest from others though.

All the luck with your build sir.

regards remco
Posted By: Anonymous

Re: 20vt Exhaust manifold - 25/10/2010 14:55

surely i was not even going to try to pair cilinders with the 5 cil.manifold , but maybe the reply was not ment for me tongue
Posted By: Anonymous

Re: 20vt Exhaust manifold - 26/10/2010 10:34

yes, 5 cyl header - it's my lack of familiarity with the reply procedure, sorry. Some folk no doubt wondering why I appear to be replying to them on er,'unrelated issues'..

G
Posted By: Anonymous

Re: 20vt Exhaust manifold - 26/10/2010 12:25

For sure no need to say sorry, i dont mind at all ofcourse. And i think in the end everybody is more then happy with any reply you will or can make on any forum.

Regards remco
Posted By: Anonymous

Re: 20vt Exhaust manifold - 26/10/2010 16:18

Thanks very much for buying my book Remco, I've emailed you for your address..

GC
Posted By: Anonymous

Re: 20vt Exhaust manifold - 26/10/2010 18:10

Just to add Nigels advice,the only thing i changed from getting near 500bhp was the manifold and now its running just over 400.
So i too will be reverting to the stock manifold with a few machining extras.

Would love to see a tried and tested solution though.
Posted By: Anonymous

Re: 20vt Exhaust manifold - 27/10/2010 10:33

Welcome sir, it will be an interesting read for sure smile.

Regards remco
Posted By: Anonymous

Re: 20vt Exhaust manifold - 27/10/2010 10:34

Thanks for your reply, question... do you have an picture of the manifold you used?

Thanks again and all the best.

remco
Posted By: Anonymous

Re: 20vt Exhaust manifold - 27/10/2010 11:19

I think Barbz is going for some rather fancy manifolds.
Might be worth droppiong him a pm.
Personally for the money i dont think the benefits are great.
Dont get me wrong a lot of little differences makes a big difference but theres not enough development and testing in my opinion for these to prove a worthy investment.
Posted By: Anonymous

Re: 20vt Exhaust manifold - 27/10/2010 12:01

Does not really matter to me about the investment etc. Just would like to see something that works. But if barbz is already working on them, surely there is no need for me to go on with them. Will pm him, and thanks for your reply again.

Regards remco
Posted By: Anonymous

Re: 20vt Exhaust manifold - 06/12/2010 18:50

Maybe I´m a bit late, but I will post something.

Here in Brazil we have some FIAT Marea 2.0 5cyl

The cars with more power(500+) here use this manifold.

http://i2.photobucket.com/albums/y39/TETEUS/INOX/ColetorInox.jpg

I don´t know the exact size. I think this one in the pic have 38mm diameter and 24" lenght.
Posted By: Freddan72

Re: 20vt Exhaust manifold - 07/12/2010 08:13

Originally Posted By: ponzio
Maybe I´m a bit late, but I will post something.

Here in Brazil we have some FIAT Marea 2.0 5cyl

The cars with more power(500+) here use this manifold.

http://i2.photobucket.com/albums/y39/TETEUS/INOX/ColetorInox.jpg

I don´t know the exact size. I think this one in the pic have 38mm diameter and 24" lenght.


Where can I buy it?
Posted By: Anonymous

Re: 20vt Exhaust manifold - 07/12/2010 13:52

Quick search revealed

http://todaoferta.uol.com.br/comprar/col...T1AHFXYGUG#rmcl

Approx £700 before tax delivery etc.

Steve
Posted By: Anonymous

Re: 20vt Exhaust manifold - 07/12/2010 15:53

It looks good but that is a THIN turbo flange, no?
Posted By: Anonymous

Re: 20vt Exhaust manifold - 07/12/2010 16:26

I would be interested to hear from anyone who has fitted this on a coupe, whether it clears the a/c and stock pipes or any other mods required to fit.
Posted By: Per

Re: 20vt Exhaust manifold - 08/12/2010 09:06

Originally Posted By: ponzio
Maybe I´m a bit late, but I will post something.

Here in Brazil we have some FIAT Marea 2.0 5cyl

The cars with more power(500+) here use this manifold.

http://i2.photobucket.com/albums/y39/TETEUS/INOX/ColetorInox.jpg

I don´t know the exact size. I think this one in the pic have 38mm diameter and 24" lenght.

You don't have one for internal wastegate..?
Posted By: Anonymous

Re: 20vt Exhaust manifold - 30/12/2010 22:10

Hi all this is my first attempt at a manifold the primary tubes are exual length to within around 20mm they are 40mm i/d and a wall thickness of 1.5mm from head to turbo the length is 640mm.

http://www.flickr.com/photos/fialcia/5307804288/


[imgpop]
www.flickr.com/photos/fialcia/5307804288/[/imgpop]
Posted By: Anonymous

Re: 20vt Exhaust manifold - 30/12/2010 23:41

I like it sofar for sure sir.

Like your car also btw wink.

Just some thoughts...

wall thickness might be a bit more to be safe, unless you have it welded by the best ever welder(maybe you wink.

Insted of the 2 time 90 degree bends after each other, use some 180 larger radius ones (if room allows it).

But for sure the layout is very nice indeed.

All the best in 2011

For all that is ofcourse;).

Remco
Posted By: Anonymous

Re: 20vt Exhaust manifold - 31/12/2010 00:53

Hi Remco it needs alot of work i take on your comments thanks Mick.
Posted By: Anonymous

Re: 20vt Exhaust manifold - 31/12/2010 19:40

A very good effort indeed, the only point I don't like is the angle of the pipes into the collector, hard to get it right with a five pot I know.

What method for measuring the pipe lengths are you using and how did you come to arrive at the length you did, or was it just a case of what fits ?
Posted By: Anonymous

Re: 20vt Exhaust manifold - 31/12/2010 21:16

Not happy with the collector myself instead of 45 bends i think stright pipes would be better as for measering the pipes i have measered them all at the same points when dismanteled, i decided on the primary lenght from what guy croft said in an earlyer post.
Posted By: Anonymous

Re: 20vt Exhaust manifold - 31/12/2010 21:34

Just buy one, do a google a few people make a 5 into 1. It'd finnish it off wink
Posted By: Anonymous

Re: 20vt Exhaust manifold - 31/12/2010 21:46

If you read the earlyer post the manufactured one's are made just to fit in the space provided in a coupe i have a lot more room and i want to try somthing different.
Posted By: Anonymous

Re: 20vt Exhaust manifold - 31/12/2010 21:59

I think you misunderstood, I meant buy a collector !

Main website

A page from the site ...

http://www.spdexhaust.com/pdfs/02-11_Merge_Collectors.pdf
Posted By: Anonymous

Re: 20vt Exhaust manifold - 31/12/2010 22:07

sorry thanks for the link
Posted By: Anonymous

Re: 20vt Exhaust manifold - 01/01/2011 04:35

I'm sorry but I have to disagree with a smooth converge at the collector. My method would be to use acute angles at the collector (as you have already done) in order to discourage primary pressure wave refraction thus reducing interference with adjacent cylinder firing order in an erratic way. In other words smooth flowing pipes towards the collector like the link above I consider as bad.

To be honest I am quite impressed with the current manifold you have built. Shame it can't be used for us coupé owners. Would be great if we could test it back to back with the OE manifold in an engine test cell.
Posted By: Anonymous

Re: 20vt Exhaust manifold - 01/01/2011 14:43

Thanks for that i see what you are getting at with the collector, this one so far has cost me £120.
Posted By: Anonymous

Re: 20vt Exhaust manifold - 19/01/2011 14:52

in italy, there are many producers that make T20 inox tubolar exhaust manifold.

one of them is mine friend, and he has tried lot of them.

in the photo, you can see the 36mm inside tbm, for Aircon equiped t20, and the 38mm tbm for non aircon t20. i think the 38 could be possible also for non aircon.

click to enlarge
click to enlarge
click to enlarge


http://dl.dropbox.com/u/13719348/coup%C3%A8/exhaust/e1.jpg

http://dl.dropbox.com/u/13719348/coup%C3%A8/exhaust/e2.jpg

http://dl.dropbox.com/u/13719348/coup%C3%A8/exhaust/e3.jpg

the price is very competitive, +- 675£ (not sure at all, but very less of 1K £..)

the quality very good.
lot of miles have done testing them on Monza circuit, so in very high&fatigue condition (like 80% of track in full trottle & pressure ) stress, with a 340hp gt2860 coupè.

if someone are interested, i can tell to my friend to make a GroupBuy.

In fact, i'm not a fan of Tubolar Manifold if other stuff aren't matched, like head exhaust port, or bending tubolar itself. The std manifold are short and more adiabathic than inox Tb, that are lighter but not necessary stronger.

it's a choice. now i want to try them, but i'm sure that my lag experience will be ruined by some hundred Rpms (with gt28rs 086), but final topend (now 344hp with 2,75" full exhaust and std manifold/injector @ 58psig) (hope) and EGT will be better.

stay tuned wink
Posted By: volumex

Re: 20vt Exhaust manifold - 19/01/2011 19:45

to me the manifold is not the problem... the turbo is the problem with its design... a donut .....exhaust gas enter's the housing spins round and round the gas compresess in the exhaust housing till it reaches the center were it exits the turbo so more back pressure ... the engine is trying to push gas into a centrafruge with a exit in the middle so more back pressure.. why not re-design a turbo so its like a spiral.... it would be a lot smaller ... but it would spin faster
Posted By: volumex

Re: 20vt Exhaust manifold - 19/01/2011 20:01

the turbo is a crap design ... to move high speed comressed gas through a 90 degree angle... its pants ... get a supercharger...a turbo charger needs re-desigening
big picture
i should paintent this...lol
more to think about
Posted By: Anonymous

Re: 20vt Exhaust manifold - 19/01/2011 20:39

It's a serious restriction, certainly not free power.
Posted By: Anonymous

Re: 20vt Exhaust manifold - 20/01/2011 17:21

Originally Posted By: volumex
to me the manifold is not the problem... the turbo is the problem with its design... a donut .....exhaust gas enter's the housing spins round and round the gas compresess in the exhaust housing till it reaches the center were it exits the turbo so more back pressure ... the engine is trying to push gas into a centrafruge with a exit in the middle so more back pressure.. why not re-design a turbo so its like a spiral.... it would be a lot smaller ... but it would spin faster


it is a spiral, the flow goes into a reducing diameter cone, like a snail around the turbine??
Posted By: Anonymous

Re: 20vt Exhaust manifold - 20/01/2011 18:39

as said,to see it watch this,at 30 seconds it shows the path of exhaust gasses really well.turbos are way more efficient than superchargers
http://www.youtube.com/watch?v=BXzQfKZczuw&feature=related
enjoy,especially if you speak german!
Posted By: Anonymous

Re: 20vt Exhaust manifold - 21/01/2011 06:35

So where do we seriously go if we want a performance manifold that isn't just shiney, but does all of the above then?????
Posted By: Anonymous

Re: 20vt Exhaust manifold - 21/01/2011 06:36

So where do we seriously go if we want a performance manifold that isn't just shiney, but does all of the above then?????
Posted By: Anonymous

Re: 20vt Exhaust manifold - 21/01/2011 09:00

There is on TIG-ART.com called superstock turbo manifold.
Trust me, it is the proper biz, by the look of it. equal lentgh.
The set back though is the price:Brace yourself, more than 1000Euro.
For what i heard, the flow is perfect
I just dont want to guess what noise it will make
Shake it out
Posted By: Anonymous

Re: 20vt Exhaust manifold - 21/01/2011 09:04

Unless you can make it yourself you need to find a perfectionist to do it for you. Brace yourself for the cost, just the materials and aftermarket collector touchs a grand. You will have to accept that the turbo will be moved away from its oe place and a knock on effect will be seen throughout the engine bay. Either that or just stick with the cast one.
Posted By: Begbie

Re: 20vt Exhaust manifold - 21/01/2011 09:18

Originally Posted By: Kenge_Romeo
The set back though is the price:Brace yourself, more than 1000Euro.

That's is not that much money. Trouble is people have been spoilt with cheap shiny looking manifolds, then baulk when a reasonable manifold appears with a high price tag.
Posted By: Anonymous

Re: 20vt Exhaust manifold - 21/01/2011 17:00

Already looked at the tig art one and it does look very well made. I don't think the price of that one is excessive either. I've just gave the go ahead on nearly £5k worth or gearbox and £1k worth of Brembo floating 2 piece discs so price doesn't put me off if it's the right thing. My whole car is pretty much tailor made for my own use and there isn't much on it that's OE so again i don't mind that. I might speak to Tig Art and see what they can do. It's the Israel thing and being so far away that kind of puts me off. I like to be able to speak to people and get some real information.
Posted By: Anonymous

Re: 20vt Exhaust manifold - 21/01/2011 18:11

In that case take your car to one of the UK exhaust specialists and let them loose on making the pipes to connect to the turbo. You get to call the shots and specify what you'd like.
Posted By: Anonymous

Re: 20vt Exhaust manifold - 21/01/2011 18:11

Doh!
Posted By: Anonymous

Re: 20vt Exhaust manifold - 21/01/2011 18:42

Yes I heard you the first time !
Posted By: Anonymous

Re: 20vt Exhaust manifold - 21/01/2011 18:44

Originally Posted By: Begbie

Trouble is people have been spoilt with cheap shiny looking manifolds, then baulk when a reasonable manifold appears with a high price tag.


On the nail matey.
Posted By: Anonymous

Re: 20vt Exhaust manifold - 22/01/2011 14:51

for decent exhausts in the uk,with no budget restrictions id go to OJZ engineering.quality craftsmanship
Posted By: Anonymous

Re: 20vt Exhaust manifold - 22/01/2011 15:03

Originally Posted By: sparco
Already looked at the tig art one and it does look very well made. I don't think the price of that one is excessive either. I've just gave the go ahead on nearly £5k worth or gearbox and £1k worth of Brembo floating 2 piece discs so price doesn't put me off if it's the right thing. My whole car is pretty much tailor made for my own use and there isn't much on it that's OE so again i don't mind that. I might speak to Tig Art and see what they can do. It's the Israel thing and being so far away that kind of puts me off. I like to be able to speak to people and get some real information.



dog gear kit marco?
Posted By: Anonymous

Re: 20vt Exhaust manifold - 24/01/2011 10:46

Rich yes a full custome dog gear kit with altered ratios and final drive, forged steel selector forks and a full race diff. Should help a bit.
Posted By: Anonymous

Re: 20vt Exhaust manifold - 09/05/2011 01:39

it seems this thread did not reach any conclusion about a manifold that would work better than stock...
it seems the john s one is the only one thats made better power
anyone know a custom manifold builder in uk or has anyone heard yet of a manifold known to make better power?

it seems that what will make good power on a 2.ol does not necessaraly do so on a 2.5!
Posted By: Begbie

Re: 20vt Exhaust manifold - 09/05/2011 08:40

Custom manifold builder = OJZ Engineering, but it won't be cheap and he is always fully booked so a couple of month lead time. Alternatively you could try Nortech, deal with a lot of Vauxhall's
Posted By: Anonymous

Re: 20vt Exhaust manifold - 09/05/2011 08:52

Try this company, they know a thing or two. cool

Click me

A UK firm originaly, Aylesbury iirc, you can bet your life it'l make the tig-art look cheap but if money really is no object you will be looking at design and quality foremost.

Problem is, the off the shelf manifolds cant be customised to suit your own cam, head and engine combinations. I've just had help designing my own with simulation from a US firm, it's suprising how many variables are involved and a thing like cubic capacity can change the primary length by a foot !
Posted By: Anonymous

Re: 20vt Exhaust manifold - 11/05/2011 16:11

Looking very nice indeed.

Do you know an price indication?

Regards

Remco
Posted By: Anonymous

Re: 20vt Exhaust manifold - 11/05/2011 20:45

Sorry chap I have no idea, but knowing how much the raw materials are and the time it would take to design and build a one off onto a car - probably £ 1500 to £ 2000 maybe more or less ?

Rich
Posted By: Anonymous

Re: 20vt Exhaust manifold - 12/05/2011 20:38


I was told £1200 to £1500 but got the impression that was loose and it'd possibly it could rise when actually there paying the bill. The most expensive 321 I've ever seen too so off to a bad start. There's no doubt they would do a first class job, it's quite a setup they have.
Posted By: Anonymous

Re: 20vt Exhaust manifold - 14/05/2011 14:36

Quite nicely priced then actually, given the work needed to make one and like said the costs of the 321. I wonder how much experience they have with the turbomanifolds though. You dont want to see cracks soon for this kind of money.

How far are you pro's (tricky,1nro) with yours now btw?, or still no time for progress yet?


Regards and all the best,

Remco
Posted By: Anonymous

Re: 20vt Exhaust manifold - 14/05/2011 23:06

Hi Remco, I think the cracking is down to a combination of bad fabrication technique and wrong material choice which usally seems to go hand in hand. I might drop by at goodfabs one day, there only 30 miles from where I live might be a good learner tongue

I'm staring on an exhaust mani within the next few weeks, finally ! This is what I've been so busy doing for the last few months . . .


http://s139.photobucket.com/albums/q305/oakleyintegrale/?action=view&current=IMG_2659.jpg

http://i139.photobucket.com/albums/q305/oakleyintegrale/DSC01408.jpg
Posted By: Begbie

Re: 20vt Exhaust manifold - 15/05/2011 08:59

Nice inlet manifold. First photo at GC's by any chance?
Posted By: Anonymous

Re: 20vt Exhaust manifold - 15/05/2011 09:03

No I've been going to see GC for a while now, he's been a great help.
Posted By: Anonymous

Re: 20vt Exhaust manifold - 15/05/2011 11:53

Hi,

Aha, indeed that must have taken quite some work to get it this far, really really nice sir.

Is that an scuderia comp. fuelrail by any chance?

The injectors seem to be a bit high?

Nomally i make the manifolds about 95% outside an jig, i wonder how they do it. Hopefully you can get some expert info and are willing to share. If they have enough turbomanifold experience that is ofcourse.

Material is always going to be an problem it seems, good things just come with an price.

Thanks for the pics, and keep the good work up.

Remco
Posted By: Anonymous

Re: 20vt Exhaust manifold - 15/05/2011 18:00


I believe the cracks that manifolds suffer from is a combination of the material choice and sub standard welding that most suffer from but the biggest reason IMO is the construction techniques which cause a lack of ability to absorb expansion. Everything bolted up rock solid and then there's suprise when it splits after some heat cycles, no wonder I say.
Posted By: Anonymous

Re: 20vt Exhaust manifold - 15/05/2011 19:31

It's just made from a blank -8 rail 11/16" ID.

What I found quite interesting about goodfabs is when tube supplies dry up, they make their own tube from sheet steel before mandreling it into bends. Quite a skill I think you'll agree !
Posted By: Anonymous

Re: 20vt Exhaust manifold - 15/05/2011 19:36

True indeed, 321 and inconel can an will crack easily when not " treated" properly. Especially the thin wall pipes are prone to work alot when welded, especially when the fitter part is done wrong, and the weldingtechnique that follows it.
As you know stainless has the tendency to go all over the place if you dont pay attention how you weld the pipes, and that includes the speed of the weld, and the power that is put into it.

I am no fan of the jig welded manifolds at all, ofcourse if everything is worked out perfectly then it might be no problem at all.

Expension solutions, like the slip or double slip joints like you use are very important to prevent these issues.
But on the other hand, money money money, haha.

Sadly enough, i still am using to much 304, but thankfully things seem to change a bit, and are people more willing to make it right the first time, so they dont have to worry about cracks of even complete turboflanges that seem to fall of just like that.

That also reminds me about the turbo support, tubular manifolds need one! You cant expect an turbo with all his weight and everything that is fitted on it to keep it hanging on an red or more glowing manifold. You dont want to know the forces that the piece of kit needs to cope with when there is no support at all. But you know all of this already ofcourse smile.

Regards, and show your progress whenever you have time.

Remco
Posted By: Anonymous

Re: 20vt Exhaust manifold - 15/05/2011 19:45

11/16th, sorry i have to calculate now, i am used to metrics only smile. But indeed if they have their own pipe making machine then for sure they are large, as normally these are quite big to start with.

I just asume that they have alot more speciality's then just exhausts then?

Remco
Posted By: Anonymous

Re: 20vt Exhaust manifold - 15/05/2011 22:17


It's true, the turbo support bracket is worth some care. It was the Mk 4 bracket before I was happy everything was were it best might be and suitably strong.

I see the double slip collector as cheap insurance that the manifold will survive use, not that expensive really considering all their merits. A manifold that needs repair or reworking soon become expensive, it's never cheap doing it twice.

I used 321 that was formed out of sheet and machine welded before being bent, couldn't find anything else in this country that was cost effective in that grade. Not sure what the likes of Burns sell but by the time it comes from the States with shipping and duties paid it's way expensive, they are good for some things but bends are available for less.

I stress cutting tube, so expensive and so fraught with potential mistake, practice helps a lot. Some mild steel bends to play with makes sense if you've a need to practice, a lot cheaper to mess that up than the precious 321.


Nik
Posted By: Anonymous

Re: 20vt Exhaust manifold - 16/05/2011 18:04

not sure why a low carbon steel manifold is used / made.

Stainless looks nice, but is crap at thermal fatigue, especially at those temps !

I'd personally have a decent manifold made from a good quality carbon steel & have the outside plated / passivated.

It won't rot & will be stiffer than a stainless jobbie. PLus they are tons easier to weld & are easier to get a better root.

I bet 90% of them manifolds would fail radiographic examination wink ( oh & I have access to that ! ).

why not try for a steel version, it'll be MORE durable ion the long-run, as after all, you'll want to heat wrap / put a heat shield over it to preserve your engine bay !

HTH smile
Posted By: Anonymous

Re: 20vt Exhaust manifold - 16/05/2011 19:39

no idea if these guys are any good, but they do Formula ford stuff....

http://www.jpexhausts.co.uk/gallery.asp?foldname=manifolds
Posted By: Anonymous

Re: 20vt Exhaust manifold - 16/05/2011 21:32

" Stainless looks nice, but is crap at thermal fatigue "

- Not if you pick the correct grade, mild steel is no good for turbos, full stop. EGT's get way higher than in can safley handle.
Posted By: Anonymous

Re: 20vt Exhaust manifold - 16/05/2011 21:57

I'll prob meet you about 30% of the way wink

Problem with most builders is that they don't prep, stainless is VERY hard to do right.

Just because the TIG weld looks nice, means nothing frown

A GOOD carbon steel will do better than most stainless. Less susceptible to cracking. Stainless is horrible for this.

And to be fair, I never said MILD steel, I'll let FIAT use that for bodyshells smile

I'm talking about a specific alloyed steel, the typical stainless grades used I don't think are up to it, hence they usually crack a while later, they just cannot take the thermal cycling... that I can assure you is a fact.

I will however agree that a GOOD weld prep, and I still believe post / pre heat is essential, as this is where the key to longevity lies.

Some have said post weld heat treatment is not worth it, however if you were to ask a heat treater, they'd probably recommend, as in reality you'd only achieve a high enough temp to solution treat the steel for a minute / so in road use, you need to do it for a specified time ( calcs done on material thickness etc.. ). Also a good time to get the bend out of the metal, then you could reface the mounting flanges correctly ( these always distort ).

I'm no expert & would love to see a good manifold, however for anything less than £2-3k, i would be cautious. Unforunately, this is a large outlay for what many may seem as a bling item perhaps ?

cheers smile
Posted By: Anonymous

Re: 20vt Exhaust manifold - 17/05/2011 21:09

Firstly all steel is made with carbon, iron + carbon = steel therefore mild steel is carbon steel. There are different amounts of carbon introduced according to which strength steel is being made more carbon % = a high carbon steel as opposed to a mild steel - low carbon content. Thats the first thing I learned at college some 14 years ago.

Incidently a lot of vehice manufactures use high carbon sheet to press the structual panels in a car these days because of it's better overall strength, this requires a special welding plant in vehicle body repair and training to use it.

Stainless is a great thermal barrier compared to steel and if you use the right grade needs no wrap or ceramic coating to help keep the heat in. Wrapping a manifold like you describe made from mild steel would cause it to fail very quickly due to it's inabillity to loose the heat it conducts away so easilly.

It's not heat on it's own that causes stainless headers to crack, common grades such 316 - 316l - 304 and 310 that are regulry used suffer from carbide precipitation at the sort of EGT's our turbo cars run at. Coupled to that, rarely is an aftermarket manifold designed with expansion of the tubes in mind and even rarer than that does anybody support the wheight of the turbo properly. In my experience aftermarket manifolds ALWAYS crack near the flange.

"I'm talking about a specific alloyed steel, the typical stainless grades used I don't think are up to it "
So what particular grade are you talking about ?
Posted By: Anonymous

Re: 20vt Exhaust manifold - 17/05/2011 21:46

Trick, don't confuse steel as Steel.

Alloyed may mean different types of alloys, Chrome, Vanadium, etc...

There are literally Thousands of grades. So NO I don't know, however I could find out VERY easily.

I have access to peeps who could bore you to tears ( literally ) in this subject area. I will ask, however you forget, exhaust gas is a complex mix of hydrocarbons, corrosive agents & god knows what else....

Steel is simply not steel, ignore the carbon content, that is about 1/50th of the makeup of a modern steel, grain structure, alloy components, the way the steel is formed, slag content etc...

Anyhow, 316 is way too soft, 316L is just a low carbon version.

All I'd say is that from what I've seen, al stainless ones crack quite readily ( YES< I do agree that the turbo mass needs supporting, bit obvious really, to me anyway ! ).

Lots of MILD steel manifolds as you put it, don't seem to suffer as much..

I'll ask about tomorrow. And as for structural steel, it's cobalt that is added, hence the reason why the fire brigade now need hydraulic equipment to cut people free.

HTH smile
Posted By: Anonymous

Re: 20vt Exhaust manifold - 19/05/2011 08:47

Originally Posted By: tricky
iron + carbon = steel therefore mild steel is carbon steel.


Not to be pedantic Tricky but if its was that simple then what's cast Iron in relation to your definition?
Posted By: Anonymous

Re: 20vt Exhaust manifold - 20/05/2011 21:16

Dunno I'm not a metalurgist, I just know what is the right thing to be used for a fabricated turbo header.
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