I think your getting carried away with the flow aspect, only one cylinder discarges at a time remember.
The problem or enhancement is sound waves, the same as how you hear in air. The cast item is like that for a reason, besides being cheap and repeatable to make, it acts like a damper with sound waves canceling each other out to a degree. A phrase I have heard mentioned is the 'constant pressure turbocharged system' which might well be how standard setups are orientated.

A badly thought out tubular header can only amplify the effects of the waves.

Yes I do belive the Grp. A delta used this cast manifold, likley unmodifyed as the regs of the class probably didn't admit it.

Nik, have you started a header yet ? or a long way from that yet .

Thanks Ricky - I had written a more full question, re the constraints OEM manufactures are under - ie cost, packing, easy to make in a mould

I hear what you are saying about constant pressure, designing mainly based on pressure differential - which will be high of course.

Given the grales Grp A history I thought Lancia would had looked at the design had it been considered a problem but perhaps their design parameters where different - as you say 'constant pressure turbocharged system'

Here is one with standard exhaust manifold

http://www.fiatklubben.nu/forum/sho...id=12845&perpage=20&pagenumber=1

same car

http://www.fiatforum.com/uno/246367-dynoed-uno-452hp-504nm.html

Standard intake and exhaust manifolds..

Thats just it saint, it wasn't a problem at the time also bear in mind the car had to homologated.

Good thread btw -

Suby dooby thread

It's subaru orientated, (if your familiar with that strange setup! ) It's long with a lot of arguments but bear with it, a good read. [/quote]

A proper brain strainer, sort the wheat from the chaff in that lot Joking aside, I've come across that Adrian guy before, one seriously clever dude, so clever I think it makes him ill. I've seen him jousting with some very clever people and not come unstuck though sometimes ultimate intellect can be a burden/hindrance IMO.

It's what I'm playing with ATM, when I can handle the cold. Shaping up pretty good so far, an area or two which I'm racking the brain for solution but I'll come through that given a little contemplation. It's an expensive way of doing it though, DIY, by the time I'm done I'll of spent as much (more actually) as just placing a commision but no fabricator will spend the time playing I'll do for free myself. End result, better than money can buy

little off topic but the uno in that link seems to be using same intake as standard 16vt? Obviously could be ported but i'm not gonna be worrying about mine being restrictive if it is same intake as mine?!

nick

The basic truth of the oe inlet manifold is that it's ok if the head is left untouched but work the head and it soon becomes a restrictive point.

I believe, that those are both ported ( head / intake )

and its very common to use that first part of intake and make a better plenum to it.

You are absolutely right - it seems I have as much trouble reading my calcs as you have proof reading!

For back pressures less than 1 psi/metre at EGTs of 750C, back pipe sizes need to be:
< 300 BHP 63mm
< 350 BHP 66mm
< 400 BHP 70mm
< 460 BHP 76mm

I'm sure 1NR0 will tell you what the 54mm dimension refers too....

Mail me some photo's sometime.

Thats what I like about you Nik , your not scared of much. Have you bought yourself a tig or is same guy doing the welding ?

The only trouble with pic's of the manifold will be cat getting out of the bag, it would tell folks a lot about what I'm up to which I'm not so keen to do these days.
I've a big old Hobart tig, a 400 amp beast which tomorrow if it arrives will be replaced with a Miller 375 amp syncrowave, mad eh, spend more than the cost of a manifold on a welder when what I really need is to get on with my engine.I love toys (tools) though
It's not a case of being scared really, the fundamental reason for my DIY is my fussiness, it's a rare service provider that can satisfy me, it's a burden.

Nope, I haven't a clue what your talking about, I lose you at "back pipe", WTF is a back pipe? It's possible to talk out of one, maybe thats what you mean
How can you make a statement like those pipe sizes? no bends in your exhausts and all engines are the same? I think not.
It's simple enough though, just put the biggest, most straight exhaust on you can fit, if you can shorten it better still, thats about as much effort as is needed.

It's a shame you feel that way, you may as well show me I'm gonna see sooner or later

I only have a DC tig inverter type, wish I had something to do alluminium got an inlet manifold that needs putting together.

Can't tell everything Richard, too many people who copy after I've done the brain straining and hands on. Shxt, I know.

I like an inlet manifold, any pictures you can send?

just a curious question ..

whats wrong if someone copy that ?

are you driving some asphalt serie, and cant show your engine bay ?

my opinion for people who has hobby for these coupes ; show and tell ..

thats at least what I do.

ps: and I am not gonna copy

Cheeky sod. - Yeah when it's underway, sure.

Hey, copy I don't do, unless I understand the reasons why it was made that way and it makes sense.

Some people flamed me for making that sump you've seen, saying I copied it from walkers. But the truth is I reaserched what makes a good one and as it turns out that was the way to do it. Anyway it's just a sump, what's the worst that could happen !

It's complex to explain, a long and boring story. It is very much against my usual ways, I like to share what I do but just sometimes I need to keep something to myself. I think generally I do a fair bit of sharing, here, other forums, via email and in person. The reason I do is because I hate the way some are who won't share, I've came across this many times. Over time I've come to realise that if they really know what they are on about they would share as they'd be safe in the knowledge that they couldn't possibly give everything away. A fine example of this is Guy Croft.

I'll look forward to that.

I'm sure you understand where I'm coming from Richard, I'd hope you could vouch for the way I usually am, other than being a grumpy sod

Pull yourselves together here people This forum is far too jocular for the likes of these shenanigans

Simple - do the math. Like the people at Garrett do...



mmm I guess you missed the lesson/didn't read up on discharge coefficients then.....

I would have thought that at least you would know that, as in many cases with engines/components, bigger isn't always better; sometimes 'big enough' is better.......

And if you can't work out where the 54mm diameter (or rather 23cm^2) fits into the exhaust design for the 16VT I'd be very surprised...... give it another go.

You are building a turbo based engine right?

School me and the others reading please, I can't be bothered to give it another go.

is the fight here something, that people underastand wrong..

I mean : 54mm work of course very powerful car, if..

the exhaust goes larger after the turbine .. you know . that is usually the best design, that its same size as turbo exhaust side hole, and goes larger right away in couple inch distance
54mm --> 76mm in 50mm distance for example.

but if using only 54mm exhaust , it wont work well in high performance turbo car.

Bigger is'nt always better, but not in this case. Not from the evidence I've seen.
This thread is about a GOOD 16v manifold .
were not discussing a crap one here, so pretty much max effort is the topic.
Please tell us how discharge coefficianty fit's in ?

Would fit the collectors outlet.

Right. I haven't looked at this thread much since it got hijacked somewhat! Although most of info in this thread was good, I posted this thread purely for anyone who actually wanted a manifold and downpipe made to register their interest - not for an in depth discussion on exhaust system design! If the thread had dropped off the page without a single post then that would have been fine, that's all it was for.
Anyway, the thread still managed to serve its original purpose.

So, to bring my thread to a close; a few people contacted me about it. Though unfortunately not nearly enough to outweigh the financial risk of designing it and getting a batch manufactured, sorry peeps! So instead I've put plan B in to action, which is to fabricate something for myself!

In reply to a couple of comments in at the beginning of this thread:
Through the on-going development of my own Coupe I've been through the steps of: building an uprated turbo, building a downpipe, then buying a tubular manifold (in that order). And since, of course, I do my own mapping I've been able to compare each step back-to-back.

With the both the turbo and downpipe there were compromises; both of them in the direction of more midrange to top-end power, but at the sacrifice of a small amount of low end torque and driveability. Not much, but noticeable and measureable.

The effect of adding a tubular manifold was marked. The boost threshold dropped by about 200 rpm, before mapping the AFR's were leaned out throughout the entire map, from idle to full load. After remapping to suit, drivability was improved all the way from practically off-idle; where before the car was sluggish to pull away from a standstill, it now pulled away with much more ease. the improvement in Off-boost performance was marked.

The particular tubular manifold I use is, to be blunt, really quite a poorly manufactured example; I had to do a fair amount of 'fettling' just to make it actually fit, let alone make it acceptable. But nonetheless, in my experience junking the stock manifold and downpipe were the best two modifications I made to my Coupe. The manifold especially; a marked improvement in all areas of performance, with no drawbacks. Unfortunately I think I've gotten rid of all my datalogs done with the stock manifold, but you could see the differences between the two were obvious. The stock manifold might be make power but there's much more to performance than peak bhp figures and, but, in my experience, the tubular manifold does it so much better. IMHO the tubular manifold wins hands down.

The exact performance characteristics of any one car will depend very much on the individual setup and manifold/downpipe design. But I'm sure you'd find they wouldn't be hugely different from what I described above.

I'm building a further improved setup right now, but more on that in the near future...

I've been keeping an inquisitive eye on this thread purely for selfish reasons & I wouldn't be commenting at all if it wasnt for the seemingly good patience of Kj16v. I would take my hat off to him if I was wearing one.

Fair play to him for putting up with the interference & others shoving in their two pence worth. Although nobody has been offencive, his thread was hijacked in a very extensive manor indeed. Maybe I'm doing a bit of hijacking here, but fair play to Kj16v for his patience.


OK wee rant over

"not for an in depth discussion on exhaust system design! "

Thats the good thing about forums, sharing knoledge between enthusiasts. Without them I bet you would'nt be mapping your own car now.

Hijacked or not, since this was posted in the tuning section and not the for sale one, I only assumed that the topic was open for discussion as to what would make a good manifold maybe leading to one actually being produced, hence my hopefully usefull input.

If you are having one made, fine I'm in the market for sure. I've got good money to spend, but not on the usual crap, so what are your design parameters ?

Jimboy

kj16v asked me a while back to close the thread but i said i would leave it open as it was getting a good discussion and it has, so would you have rather it been locked and not seen the information posted or left open and got some knowledge transfer from it?