Garrett 2860/rb30 Question

[James_03]

Hey guys,

I am after some guesstimates on the following.

When should I see boost with the following setup:

rb30dett low CR 8:1

Standard rb26 head & plennum

Garrett 2860-10 twin turbos

HKS Dumps

3.5" with hi-flow cat

70mm GTR FMIC

At the moment there coming on at 4500rpm. I am trying to establish if I have a problem elsewhere, or if it's the low CR and -10's that are just making it a "oink oink".

I know it's not an ideal setup, but that's just how it's ended up unfortunately. My reasoning is that with the rb30, it should still be coming on way earlier than that despite the low CR.

Cheers.

Edited January 7, 2010 by James_03

[9krpm]

What cams are in the engine and what ecu?

[James_03]

Sorry forgot to mention that.

Standard rb26 cams

Apexi PFC

[R31Nismoid]

Well the -5's come on around the same on a 2.6ltr.

You've now gone to the big daddy's, but on a bit more capacity. Virtually cancelling out each other. So sounds "around" about right.

Perhaps they might/should be coming on ~300-400rpm earlier but at the end of the day that's what you would assume.

I take it by info thus far you've not played with the cam gears?

There are always gains there which would see it closer to 4000rpm one would assume.

[James_03]

Yeah haven't played with gears yet, that's probably our very next point of call but.

I think I really made a bad choice by going the -10's. The whole reason I did the 30 was for response, it had N1's on before and started to ramp at like 2000 which was a dream to drive.

Ah well, might have to get some half decent cam's for it now.

[R31Nismoid]

I wouldn't expect cam's to change the response terribly much

I was hoping when i clicked the thread, it was going to have -5's & 26/30

That would be similar to GT-SS on a 2.6ltr... super responsive and 400rwkw... ye baby!

[N1GTR]

I wouldnt change the cams, if you must, only go to 260's

The low compression will make it feel like a p!g to drive. If you could get CR up to around 9:1 it would feel a lot nicer to drive.

Ash, there's 2 people up here doing that combo currently

[N1GTR]

Also, ive got GTRS's on a 3L and 270 cams, the power delivery is great - but not 2000rpm great

[James_03]

Hey guys,

I will be changing the turbo's and chucking some cams in. Even if the cams help a little I will be happy.

CR is actually 7:1

So what cam's would you guys go for? You reckon nothing over 260's so I was thinking a set of tomei poncams type B.

Also should I go the -5, or the -7 2860's?

Cheers.

[N1GTR]

7:1?

Are you sure?

If that's correct, do what you can to change that instead of cam and turbo changes

[R31Nismoid]

-5's would be on say ~3500-3800 with a bit of an educated guess.

Hold till 8000rpm, fairly tasty range of power you'd have

[James_03]

7:1?

Are you sure?

If that's correct, do what you can to change that instead of cam and turbo changes

Yeah it pulled up 125psi/cylinder, which is around there. Made shit power on the dyno, tuner did his best with it but. Top end is reasonable, but the 30 doesn't like being up there like the 26 which makes for a real shitter of a motor. I pretty much lost the one thing that didn't make it such a p1g, which was the smaller housings of the nismos I had before.

I just don't know if I have the strength to pull it all down again just to change the pistons over. It's a massive fkn job. It's running a tomei MLS HG too which just seals the deal as far as low CR is concerned.

Any other ways of upping the CR without doing slugs guys?

Or just bite the bullet and strip it down again?

Open to suggestions. Ill probably still go the -5's as you said Ash regardless of what happens with CR.

[N1GTR]

Pull it down and build it to between 8.5 and 9.0:1

everything else you've got is fine and does not need to be changed.

I know it's an effort, but it's the solution to your problem.

Also, don't believe a 30 won't rev. There's plenty doing 9000rpm without issue, but stick to 8000 cause allthat revving is just extra wear and tear

[R31Nismoid]

thinner head gasket

shave the head

would get you some of the CR back - how much, NFI, i dont build motors

[R31Nismoid]

and unless you want 450rwkw+

you might as well put -5's on there and be happy with a super easy 380-400rwkw.

So combined with the stuff above - could fix the problems where you feel the setup is lacking. Not perfect, but certainly much cheaper.

[James_03]

Ok thanks guys.

Yeah I am going to strip it down again and change the pistons over. I just got it back together again with the -10's too after some crank work lol.

I am going to sell the -10's and put -5's on too. When I built the block which was a while back now, they didn't have rb30det specific pistons, I must have used homo rb30et slugs.

Lesson learnt anyway.

Cheers.

[TiTAN]

if you use 30e slugs its ok. but the 30et slugs just kill the Compression, throw some CP 9:1 pistons in there when you pull the others out and with -5's it should be an animal.

[R32 Driver]

I wouldnt change the cams, if you must, only go to 260's

The low compression will make it feel like a p!g to drive. If you could get CR up to around 9:1 it would feel a lot nicer to drive.

Ash, there's 2 people up here doing that combo currently

You dont recommend changing cams? are the 270s to big?

How are your 270s with the -10s in terms of driverbility/boost

Thanks

[N1GTR]

You dont recommend changing cams? are the 270s to big?

How are your 270s with the -10s in terms of driverbility/boost

Thanks

It was a huge choice between 260 270 and 280s.

Doing it again I'd go 260s, the 270s are great but if the power was a tad earlier that would be nice. Reving it to 9000rpm feels great with nice even power and torque delivery which means it's easy to drive quickly. The closest car I've driven power delivery wise is a 997 GT3, there is no big boost hit like a laggy single for example. Yep, i'm very happy with it, 260 cams would just finish it off

Also, it's GTRS's not -10's