Andy.F

I don't think the headers are that bad as std. My car made 432 bhp at Well Lane on slightly ported std headers. Then 440bhp on Gruppe-s headers but that was on a different rolling road (Star Performance)which normally gives a lower output than Well Lane.
John Banks also made 406 bhp at Star on Std ported headers.


Andy

The Fixer

All Classics though Andy.....

Andy.F

True I'll swap you engines anyday though !!

[Edited by Andy.F - 11/18/2003 11:40:48 AM]

P20SPD

iTrader: (1)

Tink Scotts did 382 on standard headers at PE.

The Fixer

You wouldn't want mine, trust me Any suggestions please

Conrad

Updated Spec:

RCM - Intake System as on (Gadget Daz's car)
SX - Fuel Pressure Reg
MRT - Billet Parallel Fuel Rails
MD321 - Turbo With P20 Housing
APS - DR500 FMIC
APS - Cast High Flow Turbo Outlet
APS - Cast Tapered Upipe * Flexi Coupling
APS - 3" Exhaust System
650cc Injectors
Forge - MY98 BRD Modded Recirc Valve
GEMS ECU
Standard Headers

Currently 362 HP @1.5 ish bar.

Seems a lot to expect to get 40+ HP from some headers LOL

Andy.F

I've never worked on a Sti8, do they have the TGV's on the intake manifold ? If so are they a potential restriction ?

Andy

The Fixer

TGV? Please enlighten me? Acronym for...

Andy.F

Tumble Generator Valves. They improve atomisation and reduce emmissions at low engine speeds. Not sure if they are only fitted to US cars or not ?

Andy

The Fixer

Andy, TGV housings are there but there are no butterflies in them on the STi models, only WRX models. Path through them is not a fill diameter as there is a deflector type plate that the injector sprays at to get better atomisation. i have noticed on the APS replacements that they are full bore and hence less restrictive.

Conrad

The Fixer

On the subject of ignition...

Interstingly the car as a warm start issue, apparently the newer cars can have a weak cam signal which is why the car appears to put the spark in at the wrong time when trying to start it?? Pop, bangs etc I wonder if this is having an effect during normal running?? Apparently Subaru released a bulletin about these sensors and have written a software frig in the OEM ECU to get round this....The GEMS does not however cope very well with this problem at the moment. (Things are in hand I believe, GEMS to address it)

Conrad

[Edited by RSVR Racer - 11/18/2003 12:41:24 PM]

SPEN555

Conrad,

'software frig in the OEM ECU' lol!

Who's wrote the map? Microsoft

Damian.

The Fixer

You may laugh but it happens all the time! I know because I'm a programmer! lol

David_Wallis

In that case Id wonder if its down to to you using a aftermarket ecu?

Try a timing light on it?

David

marcin@klubsubaru.pl

Can it be the AVCS (or generally heads) on the new age STi that is the source of trouble?
We have recently prepared an MY'01 STi with Greddy FMIC and Greddy TZ518 turbo, Gruppe-S headers and 3" decat. Mapped with Unichip, 1.4 bar boost. Not really satisfied with the results.
353bhp and 450Nm.
http://www.majer-tech.com.pl/hamownia/sti1.gif
We plan to build a bigger engine (probably based on US STi) but still look for proper heads solution.
Marcin

The Fixer

Very Similar results to the rest of us, albeit you even have headers, don't know about the greddy turbo though, whats the spec of that LB/Min Air Flow? What Induction kit / ECU?

Conrad

hades

Steven - Scott did get over 380 (IIRC on two different rollers) on standard headers, but I'm sure he'd had them ported ages ago. That was with standard WRX internals and heads. Seems likely he was running over 400 with the Gruppe-S headers before the unfortunate demise of his #4 piston. I'll leave any further comments on his car to him

dowser

A restriction in the exhaust path? Have you measured pressure levels in the headers? Or EGT's? Could be a burned out/melted cat?

Richard

marcin@klubsubaru.pl

Conrad,
US guys say that TZ518 it is a slightly modified TD05 18G and claim that theoretically it should be very close to SR40 or PE1820. But their results are also usually 350-370 bhp.
The car has a standard ECU piggybacked by Unichip, but it was not mapped very aggressivly in terms of timing and for safety reasons it also runs quite reach.
Marcin

The Fixer

A few things left to eliminate, I will try a different down pipe / up pipe rather than the APS Items and see what happens.

Conrad

Pavlo

But what is the difference i up-pipe down pipe?

Did I mention Rob's 400hp result was with a standard up-pipe?

Have you seen a standard up-pipe inside?

To be honest, I think you are closer to the problem with the inlet between the throttle body and inlet valve. The new age inlet manifold is rather different, plus you still have the deflector plate in the TGV body. What are you doing to the AVCS? If disconnected it remains in max retard, which means max peak power rather than low down torque.

I just can't see one 2" uppipe being different to another 2" uppipe.

Paul

David_Wallis

paul, have you seen the aps ones??

ODD..

David

aus73

A standard STi 7 or 8 with 3" exhaust, DR500 FMIC, induction kit, fuel pump and GEMS ECU will achieve 355-360bhp (using standard headers).

We change the standard headers for HKS headers, upgraded to 650cc injectors, and replace the standard turbo with an SR40 turbo. This package produced 385bhp. The debate regarding equal and un-equal length headers on turbo cars is a waste of time. We replaced the headers as I was not happy with the internal flow path - not the length of the pipes.

By replacing the 3" exhaust with the 3.5" exhaust this package now runs 402-405 bhp. The 3" exhaust system has 2.5psi back pressure - the 3.5" system has 0. We could have used an SR50 turbocharger to overcome the exhaust backpressure issue, but wanted a turbo that would spool up similar to the standard item. This package reaches 1 bar of boost at 3700rpm. Power figures and performance is quoted on Optimax. If people want to compare cars on race fuel or additives add at least 10% to these figures - and drop turbo spool up time by 3-400rpm.

The reason that the car did not make 400bhp with the SR40 and 3" exhaust system is that the SR40 is a 40ib/min turbocharger. Turbocharger flow maps are produced on a turbocharger dyno with no inlet or outlet pressure drop. As the SR40 is on the limit at 40ib/min - the inlet and outlet has to be perfect to produce the numbers. A quicker alternative would have been to run a larger turbocharger, such as the SR50, in order to overcome the 2.5psi back-pressure in the exhaust - but at the expense of bottom-end response. Inlet or exhaust back-pressure in the system will limit how far along the compressor map the turbocharger will reach.

The spool-up of the turbo-charger in question comes in 400-500 rpm later - which would indicate a larger exhaust housing simlar to an SR50. However the compressor side of the turbocharger appears to flow less than the SR40 when in reality it needs to be closer to 50ib/min to vercome minimal exhaust back-pressure.

For those who are unaware - the chief Technical Engineer at APS spent 10 years at Garret Research in the US, mostly on their m'sport development program - read Indycar. APS design and manufacture their own housings, and use Garret internals. The compressor maps you normally see are produced by one particular compressor wheel inside one particular compressor housing. Its a tricky business matching turbocharger performance, and un-believably difficult to determine flow maps on hybrid turbos. If the turbo combination in this instance were tested on a turbocharger dyno I'm sure it would answer a lot of questions.

Inlet manifolds do become a restriction - but not at these power levels - and for different reasons than most people would guess.

I'm quite interested to see what difference modifying the headers will produce - as we did not have time to do a before and after comparison on the headers alone.

Interesting point regarding APS up-pipes David. I'm sure someone like you with a deep understanding of fluid dynamics will know why they are made like that. Anyone would think the real reason you don't like it is because it has APS stamped on it.

Cheers,

Chris

carlos_hiraoka

http://www.airpowersystems.com.au/wrx/my01/up_pipe/up_pipe.htm





Carlos H.

carlos_hiraoka

would rather go for this type of uppipe :


Zero Sports Turbine Support Venturi (60mm-50mm-60mm)

Carlos H.

The Fixer

Guys, very informative, i'm not trying to start a slanging match between people just trying to resolve a problem But I think we are definitely onto something here.

I have spoken to the few guys who are running New Age Cars (STi's) and looking at there specifications, which are near as damit all identical, Jonno, Gadget Daz etc They are all having to run headers and / or lots more boost than 1.5 bar / & NF to get to 400 BHP. Even G-Forces car as Chris pointed out above has to run headers and a 3.5" downpipe / exhaust system to achieve 404 BHP. They just don't seem to respond to mods like classics do.

What could it be

In simple terms there is something very different between classics & the new age STi! I am not including new age WRX's in here because they don't seem to be having a problem, example RB5 Scott with his WRX @380 ish BHP or Over 400 with his new Gruppe S Headers.

Main Differences : New Age STi AVCS, Tumbler Housing But No Butterflies

WRX's No AVCS, Tumbler Housing and Buterflies

Anybody any ideas, We can rule out ECU's because 1 car is on ECUtek, another on Motec and 2 on Gems????

Conrad

Ref APS Up pipe - Cast Item, full bore at the bottom and tapered to a slot type configuration at the top (turbo entry) to speed gas up I assume (having not studied fluid dynamics its a guess )

carlos_hiraoka

if you try a set of headers and gain 40bhp we will have the answer .....

Carlos H.

john banks

No finger pointing here either, just a few points....

The only way to tell if the engine is the problem is to change everything to a known easy 400 BHP classic configuration and then test that? Assumption and theory probably have to go out the window until you can achieve this simple baseline with known components with proven results. By this I mean....

Which turbos used on 2.0s beat 400 BHP by at least 10% (ie easily) on anyone's dyno (including the miserable ones where the figures are 10% down on the ones typically quoted)? This allows some leeway for the funny fuel/booster brigades, of which I am a fully paid up member myself

Bob's Garrett/P20 hybrid
Harvey's Ion Turbo
Andy's TD05/06-20G
Any others to add to the list with consistent 400+ results on 2.0s across a few dynos? (include a low reading dyno like Star or Powerstation - I would eat my hat if someone made a VF35 do 360 BHP on one of those repeatably) Not saying others might not join this, but do any of the others have these sorts of results already?

If you change too many things at once from a known good configuration you won't know where you are. Some compressor maps look stunning, but they don't deliver the goods in a given housing.

Pavlo

I think the package that G-force have put together is quite an and effective one. More significantly (to me) is that it's simple.

Paul

john banks

Why not just go for that then and then you are sorted?

R19KET

John,

Does Jonno's circa 400bhp at G-Force, and Alan McRae's 406bhp at PE count ?

IIRC, Harvey got marginally less power at PE, than he did at G-Force.

Like Chris says, it's nigh on impossible to produce a flow map for a hybrid turbo. It has to be based on experience, and results.

The "original" flow map for the compressor wheel/cover used in the MD321 is 55lbs, but the cover used on the MD321 is smaller, and the best estimate in this configuration is 45>48lbs, based on similar combinations.

Out of interest, all the engines we've run on the bench dyno, have used 3" d/p's. I was curious to know if the 3" was restrictive, so as a test, we fitted a length of 2.5" pipe to the D/P. It made no difference, but that may be due to running external WG's.

I must be honest, I'm not certain how changing the turbo would effect the EBP "after" the exhaust side,

I'd be very interested to see the WGDC's on Conrads car, to see if the WG was being blown open ?

Mark.