Scruff

A guy I know has had his engine from his V5 type R rebuilt in the UK (can't remember who by) with cosworth pistons, steel gaskets, toughened crankshaft and a 2.2 litre stroker kit with a Motec ecu.There is loads of other bits like injectors, turbo, oil cooler etc... I just cant remember all the mods. He was told that it is peaking at 2.0 bar and then levelling off to 1.6/ 1.7 bar. I know he spent a huge amount of money getting it rebuilt, but is this just going to go down the drain as soon as he has it fitted in the car. In other words will it blow up again or is the 2.2 conversion that much stronger that it will take this much power. It has been on the dyno giving 351bhp and 394lbs torque.

Cheers

Scruff

Adam M

crankshaft is overkill, but apart from that, he seems to have strengthened the right things. so long as the block can take it, I see no reason why it should blow up.

rods are the weakest standard links and they have been seen survving at 350bhp, but then the torque is significantly higher.

1.6 bar at the top doesnt seem to be yiedling as much power as I would expect on a 2.2 though. perhaps they have dropped the compression a touch.

Scruff

Thanks Adam, I would hate to see problems after spending so much €€€€€€€€€.

ChristianR

iTrader: (1)

is the turbo meant to be running at 2bar? otherwise that could be the thing that will go

R19KET

Looks like the 394ftlbs is achieved by running 2bar overboost, but like Adam say's, I'd expect more than 351bhp, from 1.6~1.7bar held.

Sounds like either the turbo is too small, wrong cam profiles, or a mapping issue. It's also possible that the exhaust is creating too much back pressure.

Mark.

pob on the job

I'd be more worried about the transmission if he's running standard.

ustolemyname??stevieturbo

iTrader: (1)

Id like to think he has some sort of uprated intercooler. Surely any stroker kit is going to have an 'uprated' crank of some description??
But as they say, 351bhp aint too good for that boost and those mods....unless its at the wheels..

Just out of curiosity, what sort of power would be expected from a fairly well set up car, with ecu/injectors, cool air temps, suitable turbocharger etc, running around the 1.7/1.8bar mark?? on an EJ20, max rpm 8000 rev limit. Just a ballpark figure???


[Edited by ustolemyname??stevieturbo - 7/24/2002 5:28:49 PM]

Scruff

He also has a FMIC and equal length manifolds, the ECU has to be properly set up on the RR. I thought that the BHP was a bit low, would this be anything to do with the VF30? turbo. The power is definately not at the wheels as he only sent the engine over.

[Edited by Scruff - 7/24/2002 8:03:32 PM]

R19KET

VF30 2 bar .....brave man. Also explains why the bhp figure is so low, a VF30 won't be able to flow much air at high rpm. 2bar woulf be ragging the nuts off the poor little thing

You sure it hasn't been mapped on an "engine dyno", as against a RR ? Or was the engine put into a car, to go on the RR.

Mark.

Scruff

Yes Mark, I think it was an engine dyno, what turbo should he have used?

R19KET

Well the turbo would depend on what he was looking to achieve, ie top end power, or a good overall spread.

Either way, there are various bolt on hybrid options, or one of the Garrett GT series would work well, but would need some custom exhaust work done.

I suspect the smaller P18 exhaust housing, on the VF30 isn't helping either, although there is a lot of potential from the bigger RHF55 compressor cover the VF30 uses.

Regardless of this, 394ftlbs will make the car very drivable, but I think he may be replacing turbo's pretty often, running that level of boost.

Mark.

SoreHead

Scruff: sounds like the Celtic tiger bit his **** off

Is he knocking around on any of the mondello days? Wouldn't mind getting a goo at it.
Any idea what sort of money he spent getting that lot done?

fivepint

@Sore Head, the reason he's getting the work done is bcos he blew the doors off everyone at Mondello in Feb!!! then blew his engine, nice plume of smoke when he trundled into the pits AFAIK he will be there on the 1st but not running on track...

Cheers

Scruff

Yeah, he is a bit like myself, once bitten twice shy. After blowing up my gearbox the last time in Mondello I am a bit shy about putting my car on track again. I am looking around for a good track car so if the worst happens at least I will be able to drive home. The type R will be there but I doubt it if he will chance it.

Alan

submannz

That power from 2 bar boost seems way too low, we get 450BHP at the wheels at 20PSI.

ustolemyname??stevieturbo

iTrader: (1)

450bhp, at 20psi......, Is that ATW, or Flywheel...lol
I think I speak for most when I say.. ahem...b******t
Or are you using 3.0+ stroker kits?? There are certainly fast cars in australia etc, but c'mon now get realistic about it. Or are those horses the american variety, which are more like shetland ponies.
I think that if you had said 450bhp, at 30psi, I would have believed it, but 20??? Are we using the same pressure scale?
Or maybe its those "forged" pistons that help make the power

[Edited by ustolemyname??stevieturbo - 7/25/2002 9:31:04 PM]

ChristianR

iTrader: (1)

it all depends on the size of the turbo, and how much air it is flowing!

a big turbo running 1bar of boost, could be flowing much more air than a small turbo running 1.8bar of boost, and thus giving more power.

Pavlo

Hmm, I think those numbers are a bit extreme christian.

We have had quite a number of low boost high power threads recently, I seem to remember 1.25bar (18) on a big(ger) turbo giving 350hp at the flywheel, on Tim W's car.

But maybe I am missing some "oh so subtle" sarcasm somewhere relating to power claims about certain products....

for help, dial 8324-765423 (I'll let you work that one out!)

SoreHead

I believe christian is correct. The boost is only part of the equation. The bigger the turbo the lower the boost you need to be flowing the same air so 20psi on a big f**k off turbo will give loads more power than 20psi on a little turbo.

R19KET

The power you will get from an engine, will be based on just how much air you can get into the cylinders, at a given RPM, at a given boost pressure.

Now, 450bhp ATW's from a 2.lt running 20psi is possible, IF you were running to circa 9500rpm. It's NOT possible at 8000rpm.

There is some misconception about why a bigger turbo gives more power. A bigger turbo can produce more power for two reasons.

1) Because a smaller turbo simpley isn't big enough to flow enough air, to produce the required power.

2) Because even though a smaller turbo can flow enough air, it has to run very high boost, and is outside it's efficiency, working too hard, and super heating the air.

If you ran two turbo's, one big, and one small, at the same boost pressure, the only reason the big turbo would produce more power, is because the air charge temp would be much lower, and the air denser.

This means that you would need more fuel, resulting in more power. It would also mean that because the intake temps are lower, the ignition could also be advanced, also giving more power.

It's the same reason we get more power from a FMIC, running the same boost, and ignition, but can get even more from re-mapping.

Mark.

Andy.F

(In a never ending quest to join the techno police )

""If you ran two turbo's, one big, and one small, at the same boost pressure, the only reason the big turbo would produce more power, is because the air charge temp would be much lower, and the air denser.""

The reduced exhaust gas pressure on the big turbo would also increase the power output. There would be less pumping losses on the exhaust stroke and less contamination of the incoming charge.

R19KET

Andy,

"The reduced exhaust gas pressure on the big turbo would also increase the power output. There would be less pumping losses on the exhaust stroke and less contamination of the incoming charge."

True, assuming that back pressure is a problem in the first place.

On the engine dyno we measured EBP, and found it was on average, several psi lower than the boost I was running only slighty increasing where max power was achieved.

Mark.

Andy.F

Mark

Tell me more (if you dare ) As you seem fairly close to the turbo guru's, is there an ideal ratio between boost and exhaust gas back pressure ? Or should we strive to reduce it at all costs ?

I believe EGBP also has a considerable effect on the amount of ignition timing you can run.

Andy

dowser

Mark,

With what turbo did you measure the EBP though? Some people may assume it was a td04

Richard

R19KET

Andy,

My knowledge is limited to the basics, but the experts all say that EGBP, should be less than the boost pressure you are running.

I can't comment on the "ignition" side, since I wasn't in a position to try a more restrictive system, but not that one can really compare my engine to a stock version, as an example, IIRC, I'm running about the same ignition advance as Tim W, at 30psi, as he is, at 18psi. I'm also running higher compression.

Mark.

R19KET

Richard,

EGBP is not just based on the turbo, but the exhaust system, turbo, and boost pressure you run.

A TD04 would also run low EGBP, IF it was being used within it's limitations.

Mark

Andy.F

Cheers Mark

It was Pat that recently said that for 1 psi increase in boost he had 2 psi rise in EBP Perhaps this was as the compressor run off the efficient part of the map ??

R19KET

Andy,

You will get an increase in EBP as you increase boost, but it's also effected by rpm, or rather gas flow.

At 4000rpm running 28psi, my EBP is circa 16psi, but running the same boost at 7000rpm, the EBP rises to circa 25psi.

Mark.

ustolemyname??stevieturbo

iTrader: (1)

I had always thought, and read ( or mis-read it may seem ) that EGBP was normally higher than boost pressure, and it was when the presssure ratio between the two got closer to 1:1, then thats when the power really started to get released. It was using suitably sized ( special )turbos etc, with EGBP lower than boost pressure that allowed the old F1 cars to achieve the silly HP figures, eg 1500 bhp in qulifying trim, from a 1500cc engine. It even said that EGBP can be as much as twice boost pressure, although any higher than that is really going to lose power, and the difference should be kept to a minimum. Hence the short duration, minimum overlap cams for turbos, as with exhaust back pressure being so high, the inlet charge can be very easily contaminated. Having very low overlap, would reduce the contamination. If the boost pressure was higher than EGBP, then surely high lift, longer duration cams, with more overlap would be very good, as the inlet charge would be under more pressure, and there would be no risk of exhaust gasses remaining in the cylinder, during overlap. Generally, turbo cams are not long duration, they are short, with quite little overlap, maximizing flow, with more lift.
Does any of that make sense?? Another reason why Variable nozzle turbos are more efficient, because they can be matched to the engine much better, and allow more flow, with less restriction, ie less back pressure. ( I think the old F1 cars did use Variable nozzle technology )