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Boost - How Much? (rb25det Standard Internals And Big Turbo)

The Mafia

By The Mafia,
in Engines & Forced Induction

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The Mafia Grand Master

The Mafia

Posted
Posted (edited)

Hi guys, I have a fairly simple question. I want to run a little more boost into my RB25DET. Turbo is a Garret GT30r (With the T04S 7 blade wheel) Its currently running a standard RB25DET turbo exhaust housing ground out to fit. Full boost comes on at 3200rpm in 2nd, and the car is fairly spastic by 4,000rpm - 5,000rpm. (oh, and power fc, datalogit, fuel pump, 555cc injectors, full exhaust, 600x300x75 fmic)

Here's the catch - I'm running water methanol injection 50\50 mix and 2 nozzles (175ml minute). One pre Intercooler, and one pre throttle body.

The kit is set to start 0% pressure at 5 psi and 100% pressure at 15psi. Its a high pressure kit (Boost Cooler by Snow performance)

Someone told me that the water methanol will keep the pistons cooler than normal, and that I should be able to run a little more boost.

I'm currently running 18psi, and yeah, 2 psi extra on this turbo is going to make a BIG difference.

Compression test showed all cylinders above 160psi, and 3% leakdown.

Anybody got some suggestions?

ok, to sum it up -

1. Is that going to be too much boost for my Cast pistons even though the water meth is keeping them cool?

2. is my exhaust housing too small for this kind of boost?

3. Power Figure - No idea, haven't had it dyno'd yet. Runs 110mph - 112mph down the strip though.

4. Anything else I need to be aware of?

Edited by The Mafia
paulr33 Grand Master

paulr33

Posted
Posted

how failsafe is the meth injection system?

ie, if it fails for whatever reason, i would expect instant detonation as the intake temps would have a massive change, instant-gib like in unreal tournament.

fEkuaR Experienced

fEkuaR

Posted
Posted

Runs 110mph - 112mph down the strip though. What times it running on those mph. Were you going to get it tuned again on the higher boost did you dyno tune it the 1st time or it hasnt been on a dyno period?

Robo's Mentor

Robo's

Posted
Posted

What petrol are you running???

110-112mph, your not making huge power, i think your motor should be able to take a heap more boost. Im running 20psi out of a HKS 2535, everything stock and running 116mph.

The Mafia Grand Master

The Mafia

Posted
  • Author
Posted (edited)
how failsafe is the meth injection system?

ie, if it fails for whatever reason, i would expect instant detonation as the intake temps would have a massive change, instant-gib like in unreal tournament.

Water meth system is fairly fault proof at the moment. I haven't got a saftey system yet, but there is one that measures pressure and opens th wastegate when the water runs out or drops in pressure

Runs 110mph - 112mph down the strip though. What times it running on those mph. Were you going to get it tuned again on the higher boost did you dyno tune it the 1st time or it hasnt been on a dyno period?

I managed a 12.9, but that was with a crappy launch (bogged down) 60 foots aren't anything to be excited about, I don't think I got below 2 secs for the 60 foot.

Was having syncro problems too, they didn't help..

What petrol are you running???

110-112mph, your not making huge power, i think your motor should be able to take a heap more boost. Im running 20psi out of a HKS 2535, everything stock and running 116mph.

Running BP ultimate (98 ron), and water methanol on top of that. The water methanol makes a f**kING HUGE difference. 2 x 175ml \ min jets = 350ml minute being sprayed in. The jets are awesome too, when they are spraying, the mist is so fine it looks like steam.

116mph? Is your turo bigger than mine? what sized exhaust housing do you have on it?

Edited by The Mafia
grigor Rising Star

grigor

Posted
Posted

350L per minute? No wonder you go through so much methanol. Do you need so much?

Glen's only uses a fraction of that and recorded a max knock of 9.

Haven't altered the maps either and prior to the meth kit install, I had a yellow flash pulling hard up the same big test hill at Cooroy.

discopotato03 Grand Master

discopotato03

Posted
Posted

Detonation is the greatest enemy , water injection is one way to keep combustion temperatures down to a level that the end gasses wont spontaneously ignite before the spark initiated burn gets to them .

There is no guarantee that more boost will make more power . More airflow helps but greater exhaust restriction just creates more reversion . The unknown factor with that kind of water injection is equal water distribution between all six cylinders . It only takes one not getting enough water to detonate its piston to death . Also I would be a bit concerned about that injector before the intercooler because there's no way to tell if its filling up with water . When water vapor cools it condenses and could be winding up in the foot of the IC .

Cheers A .

R31Nismoid Grand Master

R31Nismoid

Posted
Posted

If you are using 98 i cant see a reason for the meth...

If your using meth and you only have 110-112 MPH then im guessing no more than approx 220-230rwkw.

I ran a 12.9 @ 109 with a 2.0 60ft with 220rwkw

If you require 98 and meth additive then your tune IMO is sus, or you have a restriction elsewhere thats causing issues with detonation

Husky33 Veteran

Husky33

Posted
Posted
If you are using 98 i cant see a reason for the meth...

If your using meth and you only have 110-112 MPH then im guessing no more than approx 220-230rwkw.

I ran a 12.9 @ 109 with a 2.0 60ft with 220rwkw

If you require 98 and meth additive then your tune IMO is sus, or you have a restriction elsewhere thats causing issues with detonation

I dont believe he can access 98 octane where he is, hence the meth inj

R31Nismoid Grand Master

R31Nismoid

Posted
Posted
I dont believe he can access 98 octane where he is, hence the meth inj
Running BP ultimate (98 ron), and water methanol on top of that.

I win... you owe me a beer :sorcerer:

The Mafia Grand Master

The Mafia

Posted
  • Author
Posted (edited)

heh yeah we have 98 ron now.

The water doesn't make that much difference.. I'm not really sure hey. I can't add anything more to it because it loves detonation.

I'm running the stock ex housing ground to fit the GT30r core, do you think that is choking the exhaust flow?

Edited by The Mafia
R31Nismoid Grand Master

R31Nismoid

Posted
Posted

haha, no beers for me :(

Mafia, i think your making about the limit of what its going to make.

Maybe a tad more in it but i doubt it.

Its the T04S wheel, in conjunction with a small housing.

Its two things that dont work with each other that well

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