Precision Billet Turbos

[Rolls]

bigmikespec, just want some advice from an expert.. wat are the pros n con of having and not having the surge cover for "my" application on this turbo?

i want to run about 25-30 psi on the street on e85 and keep winding it up for race til it tapers off the power/boost curve...

If you are running a 3L definitely go it to avoid surge issues. 2.5L I'm not sure, you might get away with it, anyone got any first hand advice?

[Ryan1200]

Sorry no expert or first hand experience here yet but when i purchased my 6765 i researched it and found some of the 2J crowd complained about surge so i got it just to be safe if i went 3.2/4+litres from the 2.6L...

[Ryan1200]

Originally Posted by KenHenderson

Craig, that made me laugh out loud, bud. Had some base timing map issues which we have gotten on top of. Then, we had a bit of surge to deal with. I was hoping I wouldn't have to purchase an anti-surge cover but I did. The first one was the wrong size, so I had to order a second one and I think they got it right this time. If these cars teach you anything, it's patience....

Every 6766 should have the anti surge cover!! The turbine wheel is too damn efficient. Put a back pressure guage on it and you will see.

THIS IS A POST FROM THE SUPRA FORUM BY SOUND PERFORMANCE WHO HAS TESTED A FEW ON SUPRA'S..

Edited September 24, 2011 by Ryan1200

[Rolls]

What do you mean back pressure gauge, as in exhaust side pressure?

[bigmikespec]

Exhaust manifold back pressure.

[Rolls]

Exhaust manifold back pressure.

Wouldn't having lower back pressure mean it is less likely to surge as it has a larger rear side?

[bigmikespec]

Not necessarily; if there is low exhaust manifold back pressure in relation to boost pressure then the turbine wheel is able to utilise more exhaust gases to spin rather than the gases just build up and create back pressure.

[Rolls]

True but if the wheel is just smaller then it is going to spin up faster anyway, so you could half the size, make back pressure ridiculous and it would spin up about 10x faster. That's why I don't really get why it is a factor in how much it is going to surge, surge is usually just too much compressor flow for the motor at x rpm.

[Ryan1200]

What do you mean back pressure gauge, as in exhaust side pressure?

I agree rolls it's a bit of unusual statement to make in that context.. Maybe they have done back to back testing of the exhaust wheels and found for a given boost pressure the back pressure is much lower and spools much faster.. Who knows..

[fujin]

Hey gentz,

Ive been meaning to pump my mods into my motor for a while now,

BUT I keep going around in circles

Ive got an R34 GTR with a standard motor (stock bottom end RB26) - GTR is currently equiped with a full exhaust (which I will need to change as current setup is @ 2.5inch dump and 3 inch outlet to catback) AND a ARC custom air filter (panel).

I was either going to put in 2860-9's (twins) or now considering putting in PT 6262 BB.

- With the -9's (ill hit anywhere b/w 330kwatw to 350kw on pump fuel, 380kw+ on E85) - with support mods ofcourse (refer below)

- With the 6262 (ill hit anywhere b/w 380kwatw on pump fuel, and 420+kwatw on E85) - with support mods ofcourse (refer below)

The question IS, is running massive amounts of boost on the 6262 to produce 400kwatw+ viable on a stock motor (Im trying to avoid building the motor which has approx 50K km on it - due to extra $ required for rods, pistons etc..)

Support mods:

- Need to change the exhaust anyway to open up top end (will get 3.5 to 4 inch turbo/dump back regardless of which option)

- Already got: Haltech Platinum Pro, Tomei Adjustable Cam Gears

- Need to get: 1000cc ID Injectors, twin fuel setup + regulator, fuel rail to match injector bore, Tomei 260 camshafts (single turbo option) + Manifold + Gate, e85 equipment (sensors)

Those are the rough mods, above figures have been confirmed by Powertune in Fairfield. Though I would like to get feedback from anyone who has previously ran MASSIVE amounts of boost on these PT's on stock motor and how they are holding up (preferably on RB26's).

Thanks.

Faiz-

[Rolls]

The question IS, is running massive amounts of boost on the 6262 to produce 400kwatw+ viable on a stock motor (Im trying to avoid building the motor which has approx 50K km on it - due to extra $ required for rods, pistons etc..)

If you want to run 400kw on a stock motor reliably you will almost certainly want to run exhaust temp sensors for tuning and trim each cylinder individually, or just run it massively rich and be conservative of timing. Any detonation at that level will kill it pretty quick smart.

How good is your tuner?

[fujin]

Thanks for your feedback Rolls,

The tuner would be PowerTune (who have posted up a few posts/comments in previous pages).

They are most likely going to tune feeding of the sensors currently in my GTR (i.e. no new sensors going in apart from increased boost rating sensor and ethanol sensor for e85).

[dori34]

Thanks for your feedback Rolls,

The tuner would be PowerTune (who have posted up a few posts/comments in previous pages).

They are most likely going to tune feeding of the sensors currently in my GTR (i.e. no new sensors going in apart from increased boost rating sensor and ethanol sensor for e85).

i would strongly advise you to get your tune checked out after to ensure everything is okay.

had my car done twice there only to find issues with the tune afterwards and ended up costing me more money in the end to fix up his mistakes.

[GTScotT]

I was either going to put in 2860-9's (twins) or now considering putting in PT 6262 BB.

- With the -9's (ill hit anywhere b/w 330kwatw to 350kw on pump fuel, 380kw+ on E85) - with support mods ofcourse (refer below)

- With the 6262 (ill hit anywhere b/w 380kwatw on pump fuel, and 420+kwatw on E85) - with support mods ofcourse (refer below)

Those are the rough mods, above figures have been confirmed by Powertune in Fairfield. Though I would like to get feedback from anyone who has previously ran MASSIVE amounts of boost on these PT's on stock motor and how they are holding up (preferably on RB26's).

You sound fairly switched on so I wont delve into massive detail regarding supporting mods, just search long and hard and make sure you have every supporting mod possible before chasing your power goals.

Two things I want to touch on and a recommendation:

2860 -9s will NOT make 330-350 on pump and 380+ on E85. They will make 300-330 on pump and anyones guess on E85 (quite possibly the 350 mark).

The precisions will want a lot of boost and you are risking your factory motor in the event of a minor fauxpas. For 400kw you will want to look at a 3788R, it is the replacement for 35Rish spool and more than T04Z power. You must run it in its twin scroll form.

Please read the 'who has 400kw' thread, it is the definitive answer to your questions.

[XRATED]

Hey gentz,

Ive been meaning to pump my mods into my motor for a while now,

BUT I keep going around in circles

Ive got an R34 GTR with a standard motor (stock bottom end RB26) - GTR is currently equiped with a full exhaust (which I will need to change as current setup is @ 2.5inch dump and 3 inch outlet to catback) AND a ARC custom air filter (panel).

I was either going to put in 2860-9's (twins) or now considering putting in PT 6262 BB.

- With the -9's (ill hit anywhere b/w 330kwatw to 350kw on pump fuel, 380kw+ on E85) - with support mods ofcourse (refer below)

- With the 6262 (ill hit anywhere b/w 380kwatw on pump fuel, and 420+kwatw on E85) - with support mods ofcourse (refer below)

The question IS, is running massive amounts of boost on the 6262 to produce 400kwatw+ viable on a stock motor (Im trying to avoid building the motor which has approx 50K km on it - due to extra $ required for rods, pistons etc..)

Support mods:

- Need to change the exhaust anyway to open up top end (will get 3.5 to 4 inch turbo/dump back regardless of which option)

- Already got: Haltech Platinum Pro, Tomei Adjustable Cam Gears

- Need to get: 1000cc ID Injectors, twin fuel setup + regulator, fuel rail to match injector bore, Tomei 260 camshafts (single turbo option) + Manifold + Gate, e85 equipment (sensors)

Those are the rough mods, above figures have been confirmed by Powertune in Fairfield. Though I would like to get feedback from anyone who has previously ran MASSIVE amounts of boost on these PT's on stock motor and how they are holding up (preferably on RB26's).

Thanks.

Faiz-

Stay away from the Precision turbo option...

Keep it twin low mounts, with good pipe work and exhaust. 400rwkw cam be had around 24psi with a set of 10cm t517z trust turbo's with good response for the power.

Cheers

Justin

[PJ.]

The precisions will want a lot of boost and you are risking your factory motor in the event of a minor fauxpas. For 400kw you will want to look at a 3788R, it is the replacement for 35Rish spool and more than T04Z power. You must run it in its twin scroll form.

Scott, a Precision will be no lazier than what you suggested with more power capability, so long as you have the correct sized turbine housing

[GTScotT]

Scott, a Precision will be no lazier than what you suggested with more power capability, so long as you have the correct sized turbine housing

At a lazy 20psi? Please show evidence to support.

The 3788 gets up and boogies long before 30psi

[PJ.]

PM Sent Scott

[GTScotT]

PM Sent Scott

Never received.. I'm sure there's nothing you could say I would not want to share with others, I give you full permission to add your PM to this thread

[PJ.]

At a lazy 20psi? Please show evidence to support.

By the way this is on a turbo slightly bigger than a 3788.

Satisfied?

Edited October 14, 2011 by PJ.