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Gt35 40 Big Lag?

xxx_25L

By xxx_25L,
in Engines & Forced Induction

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32GTRB Proficient

32GTRB

Posted
Posted

my xr6 turbo has a stock gt35/40 turbo. even though its running only 5.6psi of boost, and has a 4l 6 cylinder engine, and it doesn't lag one bit.

however on an r33 with only basic mods i think you will find there to be quite alot of lag if you want to run higher boost levels.

Cubes Grand Master

Cubes

Posted
Posted
"The GT3540R core swap is about a 6 hour job, where adaptors plates need to be welded and machined and tapped to the turbine housing, and some extensive machining and modification is required.

The GT35R Conversion - Rated between 600 & 650 using customers housings.

Well thank you for clearing it up.

Now please extrapolate on how it spools..........

A 'real' GT35r .7 comp .63 turbine I would expect to be all in by 4000 on an rb25. How does yours compare?

FSTR32 Rising Star

FSTR32

Posted
Posted (edited)
Well thank you for clearing it up.

Now please extrapolate on how it spools..........

A 'real' GT35r .7 comp .63 turbine I would expect to be all in by 4000 on an rb25. How does yours compare?

Yeh i would say u be just about spot on with all hell breaking lose at 4000rpm. Needs to have full tune in 1000km's time and then i will be increasing boost to see what it can pull. Yeh guys that built motor were quite surprised at its response. They thought it would be much laggier (pulled 187rwkw's @ 3-4psi on a dyno run done while they were giving it a mild tune and bedding rings - running stock injectors and gtr pump + fuel reg)

Will post up a dyno chart for sure once its been fully tuned and boosted.

Edited by FSTR32
R31Nismoid Grand Master

R31Nismoid

Posted
Posted

So its 3-4psi @ 4000rpm?

Dont know how hell breaks loose when its really not even doing anything

I think once more boost is put in you'll find that it wont actually be the same as 3-4psi that you have now

FSTR32 Rising Star

FSTR32

Posted
Posted
So its 3-4psi @ 4000rpm?

Dont know how hell breaks loose when its really not even doing anything

I think once more boost is put in you'll find that it wont actually be the same as 3-4psi that you have now

No its running 8psi at the moment and yeh its doing plently...doesnt throw you back in ur seat but its more of a consistant build up which is why it feels like it has no lag at all We'll see how it goes with a bit more boost but want to change injectors and fuel pump before that.

garage-tuner Rookie

garage-tuner

Posted
Posted

Consider the GT3540 .63? I'm sure SAU needs a guineepig. ;)

Looks like it has already been done....

http://www.skylinesaustralia.com/forums/in...110&hl=gt35

~ 450 hp @ 17psi

~ 480 hp @ 19psi

Not sure about response as no graphs as yet.

Cheers.

discopotato03 Grand Master

discopotato03

Posted
Posted

I'd be looking real close at the GT35R/GT3582R turbine map and note the total mass flow .

There are some GT35R "Hi Flows" getting around but not my whissle to blow . Search GCG or Full Race Motorsport in US under GT3567R . HKS is supposed to have an experimental version of the GT35R as well .

Just as food for thought , I've been told that even std GT35R's can bend turbine shafts if pushed really hard . Using greater capacity (and diametre) compressors is not going to improve reliability . The TO4Z uses the larger shaft (and bearing pack) which survives pretty well and is the same effective guts as larger GT37R/40R/42R/T51R etc . People need to realise that the GT35R is as large in the wheels department as the basic GT25BB centre section gets , in fact the compressor end part of the shaft is a little larger than most GT25BB turbine shafts .

My ideas only but the GT35R would have been better with a smaller trim compressor like the HKS only GT3040R or GT3240R uses . Better to give the turbine less load to push against than to speed up the exhaust gasses (via smaller AR housing passages) which limits total exhaust flow .

Someone else mentioned a TO4 Hi Flowed with a GT35R cartridge . This has been done in the US and gets you a TO4 exhaust housing instead of Garretts native GT35 housings . Possibly reprofiled TO4 "O" trim housings . Depending on what comp cover the "TO4" had it could be profile machined to suit the 82mm GT40 compressor . There is a cover that suits the TO4E backplate already so machined .

Someone mentioned the GT3071R , this med sized animal can churn on paper ~ 440Hp worth of air - provided the engine is modified and tuned to do it properly . At least its turbine and compressor are large trim (84 and 56) and the wheel diametre ratio is good . You could look at it as a GT2835 with a smidge more turbine because thats what it is .

Cheers A .

180bfj20det Community Regular

180bfj20det

Posted
Posted

My guess is not tuned properly or non genuine turbo or screwed engine. I run 0.82 on my stock fj20 at it sees 10psi at about 2500rpm and full boost at ~4500 as mentioned before. Ive seen an rb25 on the same dyno as mine (pits matt spry) with 3540 0.82 and by 4000rpm on had 14 psi adn was beautiful to drive, though not a gcg highflow...but much more powerful.

had a GT3540 0.82 on a standard RB25 with fuel support mods only and Link ECU.

12psi boost by 4900 rpm. Very laggy on the road. Horrible to drive with on/off power extremes.

yuch

Mike

R31Nismoid Grand Master

R31Nismoid

Posted
Posted

Is the numbers your quoting on a dyno or on the street?

There is a massive difference between loading a car up on a dyno and getting boost to come in super early in 4th...

As opposed to 60-140km/h say on the street which see's an un-loaded 2nd and semi-3rd.

On the street a .82 GT35 i would fully expect to be in around 4700-5000rpm

rob82 Mentor

rob82

Posted
Posted

Shit me, I find the 3540's laggy on xr6T with all the mods and remember they have indepandant cam timing (on the BF's). Thats not including the nizpro intake manifold casue its awesome for response. Its going to be laggy as hell on a 25. I would think 12psi by 5000rpm at the earliest.

Cubes Grand Master

Cubes

Posted
Posted
My guess is not tuned properly or non genuine turbo or screwed engine. I run 0.82 on my stock fj20 at it sees 10psi at about 2500rpm and full boost at ~4500 as mentioned before. Ive seen an rb25 on the same dyno as mine (pits matt spry) with 3540 0.82 and by 4000rpm on had 14 psi adn was beautiful to drive, though not a gcg highflow...but much more powerful.

Thats pretty awesome response, almost unbelievable as a mates S15 I drove didn't even spool that well on the stock turbo. :P

Even on the RB30DET's you only see 5psi by 3000rpm and then ~3600rpm or so what ever boost you throw at it.

But then again boost is a measure of inlet restriction.

HypeR33 Mentor

HypeR33

Posted
Posted
Shit me, I find the 3540's laggy on xr6T with all the mods and remember they have indepandant cam timing (on the BF's). Thats not including the nizpro intake manifold casue its awesome for response. Its going to be laggy as hell on a 25. I would think 12psi by 5000rpm at the earliest.

its no where near that...as I said before my 3540 hits 15psi at 4600rpm. 12psi at 4250rpm, and thats with the .82exh housing.

180bfj20det Community Regular

180bfj20det

Posted
Posted

On dyno and street in 4th . To tell you the truth, I dont really know when it comes in by on the street in the first 3 gears, i dont have time to see as it just flies through the revs so thats why i only know in 4th gear. Apologies to those who were confused. I will mention quoted figures are in fourth :D

But the person wants to know whether its big lag, I dont think so. Its laggy, but not big laggy and its nice* to drive on the street bt 2-3000rpm.

*Nice may not be nice to you :)

Is the numbers your quoting on a dyno or on the street?

There is a massive difference between loading a car up on a dyno and getting boost to come in super early in 4th...

As opposed to 60-140km/h say on the street which see's an un-loaded 2nd and semi-3rd.

On the street a .82 GT35 i would fully expect to be in around 4700-5000rpm

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