R33 Sii - My Gt30 Upgrade Is Done. Lots Of Pics

[Cubes]

Mafia, as you are considering the 3ltr I would definitely consider a lower lower comp ratio than 8.3:1. 95RON sucks.

Static comp ratio doesn't make a huge difference to torque and spool as much as increasing displacement.

So... its a nice trade off, 3ltr but with a much lower comp ratio than you would dream of running in a 2.5ltr yet you can dial in the boost and still make more torque/power every where than the 2.5ltr.

At least you KNOW it will be suited to the fuel you are running and you could dial in 18-20psi without det.

A couple of options to running a lower comp is sticking with the stock pistons and using a thick headgasket, possibly an RB26 Tomei gasket that comes with the oil restrictors to prevent the head flooding at high rpm.

Doing the calcs the std 1mm headgasket will achieve a comp ratio of 8.25:1 (rounded up 8.3:1) comp ratio based on the head cc's being 62.2cc as mine was.

If you were to run 2mm tomei gasket the comp ratio would drop to a 95RON + high boost friendly 7.6:1.

OR if ripping the head of doesn't bother you go the std headgasket, see how the 8.3:1 compratio goes, if there's issues drop a 2mm headgaket under it.

[The Mafia]

ok, so what kind f boost would the standard slugs take at 8.3:1 comprssion?

also, is the Na \ turbo block the same, only provisions for oil water on the Turbo block being the only difference?

Edited February 12, 2006 by The Mafia

[Cubes]

Providing tuning and fuel is good the std slugs can easily take 20-25psi.

BUT thats in a perfect world.

Your not..

95RON fuel you want a low comp ratio in order to give you that little bit more head room to dial in more boost to get the airflow levels up without detonation.

N/A and turbo blocks are the same.

Some N/A blocks don't have provision for the turbo feed/returns but its nothing that can't be drilled and tapped.

The major issue is the blocks that don't have provision for (looking at the front of the block front on) the right side tensioner.

[The Mafia]

I'd like to keep the comp ratio at about 8.3:1 to keep the response nice and crisp.

Do you think my GT30 wit the RB25 groundout ass end will max out at some stage? Got a guess on when it would be?

I want about 250rwkw - 280rwkw somehow... punchy as f**k too, like REALLY torquey..

[Cubes]

Mafia... Its a 3ltr.. The response is going to be there...

You are going to have to slap the vg30 arse end back on the 3ltr if you want it to rev. Even then the vg30 turbine does restrict it a little.

With the 2.5ltr its a fine balancing act... With the 3ltr you want quite a bit more exhaust flow in order to have a nice wide power band.

For example.. Bl4ck32's rb20t bush t3/4 high flow. On the rb20det it lagged a bit, no where near as responsive as the stock rb20det turbo yet still made roughly the same power as the stocker.

Once it was dropped on the rb30det it spooled the same as the stock turbo.. Its appears to be hard to stuff up on a larger motor.

[The Mafia]

hhmmm. So to get me started, I need to find a RB30 block with Turbo provisions, and oil squirters, a crank, and some rods? Would it be worth replacing the old pistons? Or should I just get them re-rung?

[Cubes]

Don't worry about oil squirters.

A rb30e block comes with everything, rods, crank, pistons the majority are in perfect nick even though they have done high km's.

[The Mafia]

no oil squirters? Wouldn't that be bad for the pistons as they cool them and stuff?

[Cubes]

VL Turbo's have never run them..

But you are right it does help with high power levels... At what power level I have no idea as there's no reliability issues with 300rwkw's and no oil squirters.

[33SOM]

Ive got the same problems as the mafia only having access to 95 ron and was thinking about going the rb30 route aswell and I have a couple questions.

Would I be better of selling my rb25 complete and finding a new head to whack on the rb30?

Is a gcg hiflow to small for an rb30?

Will I have any trouble getting it registered with an rb30?

Also rb30ets do have oil squirters.

[Bl4cK32]

I remember it was a trade off though. No oil squirters, but we ran forged pistons (can tolerate a little more det. than a std piston. I can trust my tuner not to blow the motor also.Very important.) If i remeber SK gets the piston crowns ceramic coated to keep det. down. 2 different things to consider about pistons, but if you have a good tune, like any engine needs, thats all that matters

You seriously doont need to worry about the lower comp. My turbo (as cubes said) comes on so hard it just wheelspins on boost -any gear)

Im going to end up with a gt3037 on mine, simply cos i wanna keep the power around 300rwkw. Even though everyone says it may be too small, and the gt35r is a better match. It should come on hard around 2500(?) which is only like an extra 1000 rpm from now with the highflow.

It'll be a great turbo for the street, and with a lower 3.9 diff ratio, itll be better

[discopotato03]

My vote goes to keeping the 8.3 to 1 , a minimum really these days with fuel prices being what they are . Detonation should only be a problem if thermal issues are not sorted , choking the exhaust with improperly sized turbos promotes detonation .

Mafia it occured to me that there is one slight help for your turbo response probs but its not a ten cent option . Port shrouded compressor covers make the wheel cycle some of the inlet air so would tend to reduce the load on the turbine to a degree in the spool up phase . I have not seen the early HKS style covers with the centre insert removed but it should not be too difficult for a competent machinist to recreate .

My opinion only but the increased capacity of the 3L makes the turbo choice much easier , the engine has enough torque to get the thing moving in style without boost so the turbo can be sized to enhance power further up the rev range . Turbos to suit engines of this size are closer in specification to the aftermarket offerings so you can get away from the Garrett makes it but only HKS sell it price scenerio . Something in the GT30R - GT35R range should work well and the XR6 style GT35R is at least convienent with its integral gate and air in/out pipe dimensions . Its 1.06 turbine housing would help stave off detonation on a 8.3 - 8.5 CR engine and It should not need heaps of boost to steer it on the throttle . If the budget could stretch to a HKS cast manifild they're better and give the option of an external gate if you ever choose to go that way .

Cheers A .

[discopotato03]

Mafia long shot but there may be a compressor wheel that should help your turbo . Its from the plain bearing GT3776 shown on turbobygarrett/products/turbochargers in the large frame section . Its a GT37 BCI-18 family wheel like the real GT30R/GT3037 turbos use . It would make it very similar to a GT3037 52T though with your cropped turbine . You could ask Brett from GCG ifs its available here or o/s and what sort of machining mods are needed to make it fit your CHRA . The GT3776 turbo part no is 452159-1 CHRA no 436085-1 . The comp cover to use would be a Garrett TO4E .50 a/r .

Cheers A .

[The Mafia]

I checked how much it would be to get it changed to a 6 blade GT30r wheel and the changover cost is $700

New Turbo 0 $1300

....

so yeah....