Standard Neo Rb25det,

[Forged]

I've recently installed a Trust turbo kit on my GTT which can support up to 550PS (external gate), Im planning to retune the PFC to a "peace of mind" power figure. A full rebuild is on the card but due to financial reasons I don't want to destroy the engine just yet.

What's the maximum "safe power" level for stock RB25DET NEO running factory 9.0:1 compression?

Most people say 270rwkw is the "maximum optimum", but is 300rwkw doable? It would be nice to hear from experienced Gtt owners on this board.

The car has all supporting mods to produce 300rwkw (injectors, pump, fmic, etc) except the stock engine.

Cheers

Edited March 12, 2007 by Forged

[QRI05E]

Personally i dont think there is a definite “maximum” power level for any engine… there are many variables… it all comes down to:

- How well its tuned

- The driving style of the owner

- Service history

- Condition of the over all car

I have seen RB25’s pass the 300rw/kw mark and last for quite some time.. and have also seen RB25’s fail at 270rw/kw…

Cheers

[Forged]

Personally i dont think there is a definite “maximum” power level for any engine… there are many variables… it all comes down to:

- How well its tuned

- The driving style of the owner

- Service history

- Condition of the over all car

The car will be tuned at CRD mainly for street use and occasional drag and circuit work.

I dont rev the engine to the redline at every chance, a fairly sensible driver on the road I would say.

Have owned the car since imported from Japan and serviced regularly. Not sure of its history in Japan but has been treated with care for its life in Australia at least.

[QRI05E]

Im sure CRD will tune the car safely but even then they wont give you any warranty on the job. cause more power = more engine and component stress = higher risk of breaking something. As long as the AFR are fine and your not using excessive boost (20+psi) your car should be just fine...

Personally i would rather have slight less power but have greater reliability and economy.

Cheers

[R31Nismoid]

Im sure CRD will be able to sort you out.

Have a chat to them, get them to checkout the health of the motor etc etc.

Then let them do thier thing really

[Forged]

Yeah I know they would help me out but I also know there are people who have blown their engines on the dyno and when it happens the workshop is not liable for it. so its the owner's responsiblity to at least know what he is getting into.

Cheers

[Forged]

Personally i would rather have slight less power but have greater reliability and economy.

Cheers

One of the workshops I enquired reckons I should run no more than 0.8bar boost on the stock Neo. that would only give me around 230rwkw which you can easily achieve from the factory turbo. no much point for having a 500ps turbo then.

[paulr33]

forget boost as a guide

13psi on the stock turbo

and

13psi on a gt40

are two completely different power levels

[Forged]

forget boost as a guide

13psi on the stock turbo

and

13psi on a gt40

are two completely different power levels

are you saying that 13psi on a gt40 gives less stress on the pistons than 13psi on the stock turbo? what about 1.3bar of boost on a gt3037? wouldnt that kill the stock NEO for sure?

[paulr33]

13psi on a gt40 is exactly that, just a pressure rating, it means nothing. the compressor map will tell you how much airflow it will dial into the engine. again 1.3bar boost means nothing, 1.3bar on a gt3037 means nothing, look at the compresor map and find out how much airflow it will make.

run 4psi if you like or 4.2bar whatever you want, but boost shouldnt decide what power you make

the compressor map should dictate that for you. you may find "high boost" levels a problem if the compressor is out of effiency.

what happens is the compressor runs too fast and for every psi extra it just dials in more and more heat instead of useful air.

so for every psi extra over 1 bar say on XYZ turbocharger it adds in 15% more heat for each psi (bad example but still valid), more heat = more detonation likely.

boost doesnt kill an engine, heat and tuning will however. the more boost you run, the more likely you are to dial in heat, which is more likely to induce detonation.

ie: 5psi on a gt30 is better than 24 psi on a gt28

but thats purely a comparison based on pressure and heat. the gt30 combo will lag much more, and vice versa

[666DAN]

I know a few of the R34's are running 17psi on highflows..I'll be looking at around 15-16psi when I get my tune done (also a highflow)

With your extra power you could invest in one of my TCS stoppers (shameless plug, see my signature)

[paulr33]

yeah as my posted stated, its usually when they go beyond the compressors effiency that someone "kills an engine". you would never hear of somoene killing an engine on 7psi. its usually they make a certain figure and then keep trying more boost in the hope to make power, more boost = more heat, more heat = go bang.

the output from the hiflow probably looks like this;

7psi = 100 units of air

14psi = 250 units of air

15psi = 265 units of air

16psi = 272 uinits of air

17psi = 280 units of air

so as more pressure goes up, the compressor goes faster and faster and goes out of its effiency zone or "island" on the compressor map.

the faster it spins, more it moves out of the zone and starts dialing in heat, heat heat heat and heat.

[Forged]

the output from the hiflow probably looks like this;

7psi = 100 units of air

14psi = 250 units of air

15psi = 265 units of air

16psi = 272 uinits of air

17psi = 280 units of air

thanks paul are you able to calculate or estimate the "efficiency zone" for a trust t67-25g?

specs of my kit: t67 25g, 10cm exhaust housing, 44mm tial.

i just want to find out as much as possible before trialling high boost.

cheers

Edited April 2, 2007 by Forged

[paulr33]

no i couldnt sorry, the best somoene could do is an educated guess

without compressor maps you are somewhat in limbo.

trust probably dont release the compressor maps, like hks, apexi and others.

althought it is a mitsubishi turbocharger, you may get some luck there.

being a t67 variant its effeiency zone is probably quite high, past 1.3bar i would expect, but remember a t67 @ 1bar is flowing a massive amount of air vs a gt28 at 1bar so keep that in mind. youll need suitable fuel and drivetrain upgrades to support whatever power it dishes out.

[paulr33]

actually i think the t67 series is from the canter trucks? like the t78 and t88

well they are mitusbishi too im pretty sure

[Forged]

being a t67 variant its effeiency zone is probably quite high, past 1.3bar i would expect, but remember a t67 @ 1bar is flowing a massive amount of air vs a gt28 at 1bar so keep that in mind. youll need suitable fuel and drivetrain upgrades to support whatever power it dishes out.

no worries mate i understand these are only "educated guesses"

so in theory if the effciency zone is past 1.3 bar then it would be safe to run 1.3 bar boost on the standard engine? for there will be no excessive heat built up despite the massive amount of air generated?

i do have 600cc injectors and tomei pump to support increased fuel.

[Abo Bob]

One of the workshops I enquired reckons I should run no more than 0.8bar boost on the stock Neo. that would only give me around 230rwkw which you can easily achieve from the factory turbo. no much point for having a 500ps turbo then.

I think I can guess who told you that. You certainly can't get 230rwkw from a stock turbo, let alone easily.

Also I don't see why you should have to wear a blown engine if you give it to a workshop to tune and they blow it while tuning it. They should know what they're doing and not blow it. That's as long as they are doing it their way. If they are doing something you told them to do, like put more boost than they recommend, then that's different.

That said. Whack the turbo and other bits on and give it to CRD. Tell them you don't want to blow it up and they will look after you.

[Forged]

I think I can guess who told you that. You certainly can't get 230rwkw from a stock turbo, let alone easily.

Also I don't see why you should have to wear a blown engine if you give it to a workshop to tune and they blow it while tuning it. They should know what they're doing and not blow it. That's as long as they are doing it their way. If they are doing something you told them to do, like put more boost than they recommend, then that's different.

sorry i meant high-flowed turbo, but my car did make 220kw at the wheels before i changed it to the trust turbo.

I know a reputable company like croydon would take good care of it and all. but everyone has different opinions on this matter. i just want a bit more assurance to see what other R34 owners experience were with aftermarket turbos. how does neo engine coping with high boost? if Neo RB25s can handle more than R33s (stock for stock) and etc.

Cheers

Edited January 18, 2007 by Forged

[Abo Bob]

If anything it has appeared to me that they can handle less boost. There's not enough hipo NEO's to be sure though. All the ones I can think of have cams as well.

[Forged]

yeah cams and headgasket will be fitted in later stages as it will be expensive to open up the head, thats another reason im trying to find out a safe boost figure for the mean time.