"Stroker" on not "Stroker"........

[Mihnea]

That engine you are talking about was tuned by someone I call a "tinkerer", not a tuner and it gave up the ghost after 10.000 miles. Burnt pistons and valves. That motor was running 1200 degrees C EGTs before the turbine, i.e. it was meant to be destroyed. It was also running a T04E 57 trim cold side at 32 psi of boost (merely 2.3 Bar relative), which is off the compressor map, nevermind things like efficiency and stuff like that. That engine is not an example to be given to people who want to build motors with some hint of reliability and I personally would never "tune" a motor to run such high EGTs...

HTH,

Mihnea

Very interresting reading, indeed. For your modeling and mathemathical analysis you have used a set of constants, like VE and several others. Stroking an enginge might hurt VE because the other parts (head, intake manifold) might not work as good with the new stroke.

Question is, what can be done in order to optimize the stroker, in therms of head work, IM, boring, valves or other details?

I like the idea of the stroker, especially since I've seen som tourque curves (think it was on the cruemmer list) showing a 2584 ccm engine with 500 nm at 2500 rpm, increasing to almost 800 nm at 4000 rpm. The problem was loss of torque and hp at high revs. Still the engine had 485 hk at 5000 rpm. That kind of bottom end power would be worth having!

[AudiS4]

That engine is not an example to be given to people who want to build motors with some hint of reliability and I personally would never "tune" a motor to run such high EGTs...


Well, what you are telling doesn't sound too good, but an othervise sound engine can be destroyed quite easily by using the wrong software. Still it show the potential to spin up a fairly large turbo at low rpm's which is what I think many are after in a stroker. Mihnea

The high EGT I quess is a result of turbo working in a low efficiency area, improper IC and/or engine running lean. Sounds like you know some details from the enginge, what was the main cause of the high Egt?

I guess they did not use the motronic system ither, but some aftermarket system.

J


HTH,

[Pisobiker]

You're right. I of course had to assume some variables "as constants" not to mess things up too much.
Any stroke option of the ones in my examples (including the "stock" one) will need plenty of optimization over almost all of the mechanical parts once sensibly mooving off working conditions they where engeneered for. So any of the options will need head ports, valve diameters, IM and EM to be tuned accordingly to the different volume of flow they require.

But since my examples took into consideration the longer stroke options would have run at lower rpm (at same peak rpm, superiority of the bigger displacement would have been obvious), I think the results are likely to match the decresing in "breathing capabilityes" of long strokes at high rpm:
I did not assume all of the engines with same VE and other parameters "AT SAME RPM", I've assumed "SAME VE AT EACH PEAK RPM", which in the case, for the "stroker" is some 550 rpm less then the 86.4mm one.
Of course it is an approx. But seems to me could be close enaugh.



Marco

Very interresting reading, indeed. For your modeling and mathemathical analysis you have used a set of constants, like VE and several others. Stroking an enginge might hurt VE because the other parts (head, intake manifold) might not work as good with the new stroke.

Question is, what can be done in order to optimize the stroker, in therms of head work, IM, boring, valves or other details?

I like the idea of the stroker, especially since I've seen som tourque curves (think it was on the cruemmer list) showing a 2584 ccm engine with 500 nm at 2500 rpm, increasing to almost 800 nm at 4000 rpm. The problem was loss of torque and hp at high revs. Still the engine had 485 hk at 5000 rpm. That kind of bottom end power would be worth having!

[Audi_CQ]

Report from a stroker engine :

I've got a newly built 2.5 stroker (2.5 block and cranck, AAN head) in my -89 CQ. It's not been to a rolling road yet and just mapped by myself using a wideband meter (on the road and one trackday) so max pressure is just 1 bar. The engine feels very strong even off boost and really flies on boost. Friday night a friend and I tested it with a G-tech. The result was very promising: 400hk @wheels (tested in second gear w/1bar boost) Max rpm was ~6500. Strokers rules...

[Pisobiker]

Can't wait to have mine finished!!
Still a lot to do, though....


Marco

Report from a stroker engine :

I've got a newly built 2.5 stroker (2.5 block and cranck, AAN head) in my -89 CQ. It's not been to a rolling road yet and just mapped by myself using a wideband meter (on the road and one trackday) so max pressure is just 1 bar. The engine feels very strong even off boost and really flies on boost. Friday night a friend and I tested it with a G-tech. The result was very promising: 400hk @wheels (tested in second gear w/1bar boost) Max rpm was ~6500. Strokers rules...

[Audi_CQ]

Can't wait to have mine finished!!
Still a lot to do, though....


Marco

What's the current state of your project?

Cheers,
Roger

[caterpillar]

i think "jonus" have 7800 max rev,and the injektnossles are 1600ccm eatch with 3bar pressure.
i'cant wait for my engine......8-)

[Pisobiker]

Waiting for the pistons to come...
Then ready for balancing and reassembly.

Still have to make up my mind on which turbocharger to use, but I'm really tempted by the GT30R....

At the beginning I could run the stroker with my actual RS2 setup, while getting ready with EM, exhaust, IM and other auxillary stuff ....

Time and money will slow down the project a bit



Marco

What's the current state of your project?

Cheers,
Roger

[mbcouple]

Hey marco. As you may know, i am a mercedes guy at heart. I bought a 190e-16v to part out for some quick cash, and started looking up some of the specs. You will be happy to know that it uses a 95.5 stroke with 80.5mm pistons. Thats darn close to what our strokers wiill use. If you look it up, it won many awards and broke tons of recors. They drove the car, if i remeber correctly, about 130mph for 50,000 mi without engine trouble on the nardo track without breakes save refuelling and switching drivers. This maked me much more confident in my choice.
Hans

[Audi_CQ]

Time and money will slow down the project a bit

Marco

Welcome to the club....

[Pisobiker]

I really hope the long stroke engine will be a very healty and long lasting engine.
My heart couldn't survive a major engine failure (neider could my wallet ).

I actually am very impressed and fashinated by the numbers someone obtained with Audi's IL5 engines, but my car will be a road toy, therefore needing some kind of all around driveability and reliability so I won't go for an extreme tuning. The "stroker" looked at me like the only solution for having satisfactory top performances (in the range of 480-500 hp, enaugh to blow away almost everything I could find around.... ) with a smooth pull from low down in the rpm.

Only problem I can see is in Italy it still isn't possible to change wheels and tyres dimensions (....and anything mechanical as well, actually.....), so untill I'll find a way to legally fit at least some 225/40-17 wheels, I'll have to deal with the OEM 205/55-16

.....Will need some "northern Europe driving skills" for managing the "beast", expecially in the wet !!!

Luckily Italy is a very sunny Country



Marco

[Audi_CQ]

Only problem I can see is in Italy it still isn't possible to change wheels and tyres dimensions (....and anything mechanical as well, actually.....), so untill I'll find a way to legally fit at least some 225/40-17 wheels, I'll have to deal with the OEM 205/55-16

Marco

What about OEM option wheels for S2? A friend of mine (the late OzzzT ) had 245/40x17 as option on his. It was written on a sticker somewhere on the car (can't remember where). And 17x8 is a dimension the later S2's had as an option if I remember right.

Roger

[AudiS4]

I'm so looking forward to the final result, sorry I had to leave so quickly at Rudskogen, you were just getting into the mapping explanation when I had to go.

What compression ratio do you have, just curious. If you can get that sort of power at low boost, you should be able to keep a high compression ratio and keep a powerful off boost performance as well.

Pisobiker, I think a 500 hp target and the GT30R would be a good selection for the stroker for day to day driving. But even the RS2 turbo should benefit from improved spool up and low lag, almost as stock turbo I would guess.

Report from a stroker engine :

I've got a newly built 2.5 stroker (2.5 block and cranck, AAN head) in my -89 CQ. It's not been to a rolling road yet and just mapped by myself using a wideband meter (on the road and one trackday) so max pressure is just 1 bar. The engine feels very strong even off boost and really flies on boost. Friday night a friend and I tested it with a G-tech. The result was very promising: 400hk @wheels (tested in second gear w/1bar boost) Max rpm was ~6500. Strokers rules...

[Audi_CQ]

What compression ratio do you have, just curious. If you can get that sort of power at low boost, you should be able to keep a high compression ratio and keep a powerful off boost performance as well.

I've got ~8,5 in compression ratio. Seems to work very well
One thing about compression ratio : The engines breathing capabilities incl. camshafts and cam timing is much more important then compression ratio in getting good off boost performance. Take two identical 2.2 20v Turbo engines, one with 8:1 comp and the other with 9.3:1 and I don't think you're gonna notice much difference. Take two engines with same comp and modify one with porting, high lift short duration cams, good exhaust system +++, and you're gonna get a much bigger difference then with just a compression change.
Just my 2 cents

[porkkis]

CQ, what rod leghts, what pistons are you using?

I put in a query to Finnish dealer about that 92.8 stroke crank number found at eurospec (034 105 101 J) and they end up nothing. They say it's not in any European list. So probably brazil or states.

Has VW/Audi made industrial (or marine) 5cyl engines that could have used that crank?!