Exactly, compromises have to be made tuning the 20VT without going into uncharted terroritory and potentially spending huge sums of money. For example nobody has a rev limiter past 8000rpm, no aftermarket LSD and the only custom gearset costs 5k+.

If the manifold is unneccesary then so is the 2.4 conversion, at the end of the day you set a target and develop the best yo can to that point, if you wanted there is no reason why 900 bhp would not be possible with the right amount of development to the 2.0 litre setup, tue argument here is what's going to be best or cheapest


This is a pointless discussion if we don't have a target to aim for and discuss the best options to get there

I agree with Trickymex - if F1 turbo cars can get well over 1000 bhp from 1.5 litres, then a 2 litre Coupe must be capable of roughly the same

However, it would require massive investment and huge development resource - for example, the gearbox would be custom, the chassis would need to be re-engineered, the block would be strengthened, the crank would be a one-off, as would the rods and pistons. The head would have to be a complete work of art, with lots of hyper-expensive materials used for valves, guides, cams etc

And after a easy 30-50 grand, you'd be left with what? A stupendously fast Fiat Coupe that would probably be close to undriveable on the road

Personally, I reckon a 500bhp Coupe is the limit of what is achievable for remotely sensible money (ie sub £10k). After that, its telephone numbers on the invoices

That is not the point I am making I know JohnS makes the power. But is it optimum? no. To optimise the pulses the tubes will need to be modified and turbo location will likely have to be moved to achieve true optimization. I am talking on the fact of proper development with a decent budget and nothing else. Plus you cannot compare a four cylinder engine setup to a five it’s a complete different ball game. That extra cylinder causes a major issue for manifold design. The point I said and I will say it again “If I was given a serious budget to develop an item on the coupe it would be the manifold.”

one mans optimum is anothers so obviously not

It's not that expensive really, if your buying a custom manifold like Begbie did your mostly there. All that needs to be done first is to forget about the oe location and come up with one that assists in allowing much straighter pipes the length that would put you in a tuned length ballpark area and to them manufacture the bracketry that will hold the turbo in its new location before lashing the cash with a suitable craftsman.

To nail down an exact length is impossible, application dependant and to dail it in on a desired rpm would require two manifolds with different length to test and evalutae before further manifold lengths could be made to get closer still. Not really a concern unless your competing at a high level, somewhere in the relevent region would do just great.

Now I have to ask:
What do you want???
You want to have a reliable Fiat Coupe doing 500HP...

My thoughts
1. Existing manifolds do this without any problems. I read a lot of book about manifolds. Every specialist tells another story:

For example MacInnes suggests that turbo exhaust manifolds should use small diameter runners with about the same internal area as the ports and that in turbo engines, the use of "smooth flowing exhaust headers with beautiful swerving bends.... is more aesthetic than power-increasing"

Allard (from 1982) suggests the use of a log-type manifold pipe of not more than
2.5 times, and not less that double, the area of one exhaust port. The log is joined to the individual exhaust ports with stubs with the same inside diameter as the exhaust ports, each as short as possible and of equal length. The stubs can enter the log at right-angles or be angled towards the turbo.

Book "Supercharging und Turbocharging"

In a pulse-type manifold, Humphries suggests that the pipe runners should have a "cross-sectional area....not significantly greater than

the geometric valve area at full lift [and] these connections should be kept short and free of sharp bends".

He says the reflection of pulses within the system will be determined by pipe length, exhaust temperature and the status (ie open, closed or partially open) of the exhaust valves.

In order to take advantage of this pulse flow, "narrow pipes from several cylinders can be connected through a single branched manifold to one turbine....a four stroke engine which can have its cylinders grouped into threes is particularly attractive." This is because "the opening periods of the exhaust valves follow successively every 240 degrees with very little overlap between them.... thus a sequence of pressure pulses arrives at the turbine..."

Humphries suggests that the use of twin turbos on a six cylinder engine allows for efficient pulse operation, and where cylinder multiples are not in threes, a single turbo entry can be linked to multiple cylinders through "pulse converters". Pulse converters are suitably shaped junctions which prevent reverse pulse flow. Humphries shows a four cylinder exhaust manifold with cylinders 1 and 2, and cylinders 3 and 4, paired and then coming together through a pulse converter junction.

My conclusion:
You will get the best manifold by try and error. To claim that it will need longer tubes is no proven experience.
With existing manifolds you will get much more than 500HP - this with a very good power band...
Why should I design a complete new manifold and play guinea pig...
You will invest a lot of money for perhaps 100rpm earlier boost (or later, if wrong designed?)
Another topic: It is proven that the gear box is the weakest part in 500HP region?!
Nobody talks about this?!
There is no solution on market (for 6gear box)...
Thus - to develop a new manifold is useless in my opinion...
If your engine (because of your special designed manifold) would do 600NM in 3000rpm your gearbox will get killed after a short time...

Juergen

I personally think that to rework/ increase the strenght of the 20VT gearbox will be far more expensive than developing a stroker kit or a reliable efficient exhaust manifold.

How much benefit in terms of horsepower gain will be achieved with any project is relative depending on the total package and specifically what turbo is used in the build.

Maybe we must ask the question as to which upgrade will make more power on the 20VT more affordable.

Unfortunately it is a case of not being able to satisfy everybody in respoect of what they expect from a specific component. FE Some are very pro equal length and others want more pulse etc, you will never satisfy everybody.

I have also noticed that stainless steel is almost always a pre requisite for an after market exhaust manifold, but most writers on the matter recommend using Buttweld Fittings as mentioned here http://autospeed.com/cms/title_Making-Turbo-Manifolds-Part-1/A_2604/article.html

The above artcale and part two get quoted quite often on this forum and it makes for interesting reading.

Juergen,

This is a thread about optimum effort engine not what is possible with standard parts. It's wandered all over with different areas under discussion, such things as squeezing more capacity, what a proper exhaust manifold consists of and now gearboxes. The level we are discussing is only the best possible, not to dismiss excellent effort by people to date but rather what is possible.

With regard to capcity I stand in the camp that says it's really not an area worth changing. Much could be written about it but an example if you like from the real world. Titan Mototsport in the US compete in a class that includes some big V8 stuff like the Americans love, capacities over 600ci. Titan lead the way currently with a miserable 190 ci. http://www.youtube.com/watch?v=sTaPp9vLYe0&feature=channel

Quite simply a high spec exhaust manifold that is going to make an attempt on harnessing wave/pulse action won't be a log manifold, they work as you say but not to the full potential possible. Another extreme example maybe, look at the manifolds used by the F1 teams from back in the turbo era, no short runners seen there, pretty picture of an italian attempt http://i3.photobucket.com/albums/y85/1NRO/f1turbo3nh6.jpg
This trait is seen over and over in high end turbo engines used to this day, not by accident I'm sure.

Ah yes, the bloody transmission. Hard to discuss properly on here with some guys FWD and some like yourself AWD, I'd be of the opinion that there's always a solution. You yourself have seen the gearbox do fine at strong power, by the time you've fitted the spectacle plates my hunch is you'll do well to kill the gearbox. The FWD guys face the prospect of re engineering the transmission, wait maybe for someone to offer better internals or take the matter into their own hands? thats up to the individual but I'll bet anyone wh gets to that stage would be better of getting stuck in, they might wait some time before someone else wipes their backside. How might it be pursued? Hand a wedge over to a gearbox company of good reputation and get them to make a bespoke set of gears and engineer them into the oe caseing, do the work required to mate a gearbox from another car which has the potential to cater for requirments (some excellent products out there to fit Honda and Mitsubishi FWD gearboxes) or if they are taking their search of optimal seriously turn the engine and mate one of the many gearboxes available for RWD. One thing for sure is there is always a solution.

Nik

Here's a good example of a car with an optimal exhaust manifold.
http://i3.photobucket.com/albums/y85/1NRO/manifoldlength.jpg

For sure this is no good solution from my view.
It's a very bad solution!
You will need the exhaust impulses from your engine to get the turbine wheel spinning (means kinetic energy)
You will loose this energy, because the volume from outlet to turbine is too big!
Moreover the turbo lives from exhaust temperature - you will loose a lot of it because of such a length.
A formula one has installation place problems – therefore I am sure they would have chosen another solution, if they would have more space!
Juergen

I think the fact he gets his heavy nearly complete road car into the 8's is testament to the fact it does work. There are a ton of examples I could give you but sometimes the horse just won't drink. I could go on and examine all your points with evidence to back up my claims and try my best to show you the reality but I don't think it's worth my effort. Carry on as you are, makes no odds to me.

ditto

Personaly I'd leave flea and the other big boys to it, in 5 years time we'l have the knowlege or at lest a man that does! to build 500bhp coupes, but I really think you lot should stop and think where the hell can you find a cheap, not so common, turbo charged out the factory monster and modifiy with the complete help of this site and the members come and gone to produce power upto 350-400bhp without striping the engine down and forging and lightening and balancing fly wheels, cranks ect.

Other then a Audi s4 and the alroad I don't know of any other cars where you can get 350bhp just like that! Granted you need a decent turbo but if your a good spanner monkey you can do it

with regards to the gearbox issue, a lot of the internals of the alfa, lancia gearboxes can be swapped to give different ratio's,

i currently have a mix of alfa, fiat and lancia internals in my gearbox to give me the ratios i want

whether they would stand up to the big power that is being discussed here is a different issue

from a personal point of view going back to the idea of a stroker kit for the 20vt, i am sure if you offered a complete package that wasn't that much more than the known forged pistons and rods that are currently available for the 20vt i am sure lots would be interested

if you were aiming for 400bhp say with the aid of a gt2871r for instance, rather than going forged and having the power come in at 3700rpm if you could fit this kit and have power come in at around 2500rpm it would make the car massively more driveable with the power available at far more useable speeds

rob40's 2.4/5 is just that, no lag.

that must be a fantastic car to drive with that set up, massively quick at everyday speeds without having the rev the nuts off it

"You will loose this energy, because the volume from outlet to turbine is too big!"

This statment is nonsense, these primarys are full of gas flowing all the time even at idle. Soon as the throttle is touched the flow volumes become huge.
A turbine does'nt care for temprature, it works by way of a pressure differential accross the turbine wheel. High temprature is what kills a turbo not to mention exhaust valves when the pressure backs up and can't get away at the higher rpm. By virtue of having a turbo placed in the exhaust stream LOOSES bhp and there is not much that can be done about it.

This shows me, what knowledge you have from thermodynamics…
For you as information: I am a engineer and studied these topics amongst other things on an university in Germany. Up to now I am test / quality engineer in a big automotive company. From October I will go back to university and I will teach students regarding measurement technology and combustion engines – for this I will be the officer for the 3 engine test benches in this university.
Therefore: please do not talk about nonsense – I am no idiot! I also programmed the ECU of my Fiat Coupe myself.
Back to topic:
My problem is to tell this topic in English, but I will try. Also I will try to do this not in a scientific way - The turbo lives from two main factors:
- Pressure charging by accumulation (in German “Stauaufladung”): This is the topic, you mentioned. The pressure, coming from the cylinders, fills the collector and this pressurized air then flows through the turbine and get’s it to rotate. This is the simpliest method to get a manifold. Advantage of a manifold, constructed in this way: lots of maximum power.
now consider: when do you have most difference in pressure?! – YES – if the exhaust temperature is really hot – now he have reached the carnot cycle of a heat engine – means very hot exhaust temperature brings most pressure, which can be used for the turbocharger.
The turbo engine with best efficiency in my now older books (from ~2000) was the Opel Calibra Turbo – why – he has a very very short manifold (it’s part of the turbo itself) – therefore you won’t lose any energy regarding temperature. Porsche does another way with their turbo engines: they use ceramic inlines, to avoid temperature drops of the air before turbo.
Try to take a turbocharger and build it to your exhaust. You still have the same amount of pressure… or NOT??? In your theory you should have. But you won’t – you won’t get a good running turbo engine – no efficiency any more, because you exhaust temperature is much too low meanwhile!
Therefore: hotter is better – only problem is the material of the charger – it won’t do much more than 1050°C for a longer time. If you want a better response in low revs, it theoretically helps to insulate your manifold…
- Now to the second (much more effective) method in lower revs: using Kinetic energy, resulting from opening valves – an impulse is coming from the cylinder which has a lot of energy. In Germany this is called “Stoßaufladung” – in English translated impulse charging. To use this energy, all primaries have to be the same length to avoid a backflow of exhaust in other cylinders. You get separate impulses coming from each single cylinder – each cylinder does a impulse which get’s the turbine to rotation. Now you have to secure that you summarize cylinders which do their impulse to the same time. If you don’t do this then one cylinder pushes, the other pulls – no efficiency any more. To avoid this you take the cylinders with same working cycle and collect them. This is simple at four cyclinders, not so simple at 5 cylinders. For this also new chargers have been developed with divided turbine housings. At a 4cylinder you use your common pulses coming from cylinder 1 and 3 and lead it to first part of the divided housing. The same can be done with cylinder 2 and 4. You collect their common impulses and lead it to part 2 of the divided housing. -> result is much better response in lower revs because of this kinetic energy. But now back to our theory very very long primaries to get a wonderful manifold (which is trash – this may be good for very big engines with >5000cc, but not for our Fiat Coupe!).
Try to blow into a little wind turbine from a short distance. You will do an impulse if you empty your lungs – like a cylinder. Now - Take this wind turbine, take a tube, blow into this tube and beyond this tube you place your little wind turbine. Your wind turbine will be much slower – why??? You will lose your impulse during the way through your tube…
- Little (or bigger) Problem of impulse charged manifolds – to let the impulse alive, the diameter of the tubes is restricted – it may not get too big. This will be bad for maximum power in high revs.
- Therefore best is to develop a good combination from German “Stoßaufladung” for low revs and “Stauaufladung” for high revs…
- And now it is enough – believe me or don’t believe me. I know for myself who tells the truth.

I’m not getting into an argument as to who is right or wrong because I will be performing all sorts of tests involving turbocharged engines with exhaust manifold pulse tuning later this year. So I will be commenting on actual world testing rather that spewing stuff out of books I have read.

What I will ask is when the primary pulse wave from cylinder one leaves at the speed of sound ie 350m/s the gasses leave at a somewhat slower i.e 50/ms. What happens to the pulse wave when it hits the turbine blade?

Also consider the earlier you open the exhaust valve the greater the cylinder pressure. (Bit of a broad statement but still cam timing is all important to manifold design)

Sorry, but I myself stop this discussion now regarding manifold etc.
You will not have the possibility to build all sorts of manifolds with different diameters, different lengths and so on. But some people who wrote books did it. Therefore I believe them.
Johns and Barbz, two persons, who I value very much, did some test regarding manifold. Their result was, that the best power output they gained with 34mm ID, not really much - but it helps the impulse to survive till the blade of the charger which is constructed to do this implulse without defect.
TurboJ - I do not "attack" you - it is ok to do tests - they often show that theory and reality is not the same.
Thus I was the guinea pig in Germany for a GT28R, 2004!
After this I was the first (I think also in England there was no car with it), who had installed a GT2871R and original internals! Nobody knew at this moment, if the engine would keep this power without damage.
Now I am the first and only in Germany with GT3082R and 4x4.

I attack other people in this forum who do claims without any knowledge...
Unfortunately a lot of good members have left this forum, because the Coupe is not interesting any more... (too old, a cheap car for people, who buy this car, invest little money for a big charger only and later on wonder, why they got a engine failure).
Good tuning topics are rare meanwhile.
Before investing in a new manifold - it is better (from my opinion), to do some research regarding:
- prepare the valve train for higher revs - thus I am doing some research regarding this - this would be interesting for 2l engines - reving up to 9000rpm would be good for the power band...else you could reduce torque and save the gearbox
- block guard: important for engines >500HP
- strengthening the gear box (old topic)

But let's stop it now...

Juergen,

Obviously we've a translation issue and I much admire how you write in English but in your writing there is an ever increasing aggression, such writings as "I attack other people in this forum who do claims without any knowledge..." will do nothing for proper discussion, please keep your cool. Number one rule in discussion (argument if thats how you feel) is to keep your temper.

I've read through what you have written and forsure I'm not an expert but I know enough on some of these areas to know you are still someway from understanding the mass volumes a combustion engine exhausts and the way that pulses work in an manifold before the turbo. I'm not about to start writing again what I've covered enough in another thread (look through my previous posts if interested , it's not far back) but I will say that the pulses from my point of view (and you can be 100% sure I've had good advice and readings on this) don't have any influence when they hit the turbine. Pulses function off changes in area. If you write of pulses but are refering to a single exhaust charge I would see more truth in what you write.
Volume of gases in the exhaust are huge, even from a 2 litre engine at little more than idle. The exhaust volume is different to intake volume I understand but for simplicity think in the same terms for a moment. At 2000 rpm (no boost)with 100% Ve a 2 litre engine intakes (or exhausts but for some differences I am aware of) 2000 litres per minute which is equal to 33.3 litres per second. All if it is moving constantly looking for that pressure differential (which Tricky is correct on) but imagine if you can a snapshot where this volume had to be in a pipe at atmospheric pressure. Lets use a 1 3/4 i/d pipe as an example. 33.3 litres of air will fill a pipe 2144 cm long, so thats over 20 meters of pipe which in a 4 cyl (like I prefer) thats 5 meters of pipe for each runner. Nobody in their right mind is going to use runners 5 meters long (though I'll show you later something not far off) so it would be fair to asume some nutter that doesn't know what he's talking about who builds a manifold with 1 meter (no I don't mean we need 1 meter runner, it's an example) long runners would in fact have gases in the runners under pressure which as I understand it will be trying to get out into atmo, through the turbo in our case. I'll leave the example at that and let you calculate/imagine/see for yourself what actually is the case in those runners at higher rpm or even when it all gets exciting with improved mass/pressure as boost climbs.

Forgive my liking for examples of other people work but here's another good one for you, real world and not unusual and certainly not talking rubbish.

This is mounted in the back of a truck. http://i3.photobucket.com/albums/y85/1NRO/truckrearmount.jpg
Can you see the length the exhaust gases travel?
http://i3.photobucket.com/albums/y85/1NRO/truckrearmount3.jpg
Goes on forever wouldn't you say?
http://i3.photobucket.com/albums/y85/1NRO/truckrearmount2.jpg
Now don't go telling me he's using a big cube engine because thats a hell of a turbo he's spooling no matter the engine size.
http://i3.photobucket.com/albums/y85/1NRO/truckrearmount4.jpg
So it's bound to be a slug off the line, no secret assistance you'll notice but again here's someone telling us that you don't just know everything you think.
http://www.youtube.com/watch?v=pYVqtCWPUbk&feature=related
He's brave though don't you think, wouldn't fancy that intake backfireing and bursting that intake pipe right next to him! and yeah, that is an aluminium exhaust which is another of those talking rubbish won't ever work kind of topics.

For your students sake my advice is to open up to what IS done and not be stuck in past theory, open minded is how to learn, nothing is ever final.

Nik (not looking to argue but only share opinion, it's hard to write anything of persuasion without sounding harsh, I honestly don't want it to sound like that)

Is it possible to manipulate the flow of exhaust gas as it enters the exhaust housing and it hits exhaust wheel.

We are attempting to build a pulse based manifold that will allow exhaust gasses to enter the exhaust housing from the collector in their respective firing orders in a configuration that will ensure a anti clockwise flow of exhaust gas into the exhaust wheel since the spent exhaust gasses exiting the exhaust housing of the turbo is expelled in a anti clockwise fashion.

The exhaust wheel needs to turn anti clockwise to generate boost on the compressor side and if the exhaust gasses hit the exhaust wheel in a clockwise fashion you get inefficiency.

This is pure theory and comments are welcome, I have my burn suit on

Like a natural pre-swirl ? I can see the theory in there, but I beleive that because the gas is approaching the side of the wheel the effects will be minimal. Still, every little helps.

My idea was to build a housing that changes it's area ratio using an actuator (not in the same way as VNT). It would be extremely difficult to make though and I am yet to put pen to paper.

Costing info on stroker kit posted under Group buys.