Turbo Sizing Vs Response/spool Time.

[nicksamaniac]

Just to start with, yes I've searched

But have only found conflicting info.

As in gt3037? But it comes with the options of 3 different rear housings?

same as most Garrett units, hks, etc.

I'm shopping for a new/bigger turbo,

I have a RB30DET in a patrol wagon,

Currently makes 244hp atw, but with this nasty Chinese t04e (0.63ar rear)I'm running, it has to much back pressure and boost drops off over 6000rpm.

I'm not chasing power, just want good low down response that will flow enough for roughly 300-350hp?

My tuner said it will make more power at the same boost if the exhaust housing had less back pressure,

My setup is stock 30 block, 25de head non vct, hi-mount manifold, tial 44mm Gate, 3" mandrel exhaust all straight through except 3" metal cat.

Neo 25 injectors, stock (front facing- cut/shut) inlet, 2.5" cooler pipes, 600-300-75 fmic.

What I want to know is with what turbo, and especially what size trim and a/r rear are people's engines making boost?

As an example of what info I'm after -

RB30DET, t04e .50com .63rear, pos pressure @1850rpm, full 15psi @2600rpm .

So can people post?

Engine, turbo, rear housing size, rpm which you see boost, rpm you have full boost.

Cheers.

[KiwiRS4T]

I have VCT and a GT3540 with a .63 AR but you probably want a GT3076. My charts:

[wolverine]

So can people post?

Engine, turbo, rear housing size, rpm which you see boost, rpm you have full boost.

Cheers.

^^This is what the RB30 dyno results thread is all about.

[Cowboy1600]

^^This is what the RB30 dyno results thread is all about.

There isn't an RB30 dyno thread. There's a 25/26-30 thread, but results there are going to be quite different to a bog stock single cam 30DET head. Sure, he can get some ideas, but it's still a fair question.

To be honest a better response would have been to point him to a VL forum. They have way more experience with RB30s than the folks here.

[zebra]

I have a RB30DET in a patrol wagon,

[Cowboy1600]

Actually, I just re-read and caught the specs.

Wolv was in fact correct. My mistake. The OP has a 25de head on his 30.

[Ben C34]

The best bet would be to use a head with vct.

Then running out of puff doesn't matter so much as the curve will be heaps fatter, which would be best in a 4 wd.

[nicksamaniac]

I've read that thread over a few times, nearly all state a model of turbo, some state the rear ar, but those are always 1.06 or somethin massive =lag monster with a sledgehammer power curve, I'm after info on boost threshold.

Pretty much exactly what kiwiRS4t gave me!

Also recommendations are welcome.

[wolverine]

0.82 GT3076 or like from Hypergear. It should be providing reasonable boost just over 3000rpm.

[Blackkers]

do you know roughly where your compression is at?

[nicksamaniac]

I'm using an r31 block,pistons. Originally 9.0:1 static.

R32 rb25de head, 62cc chambers.

Slightly skimmed when it was freshened up.

1.3mm head gasket.

Cylinder pressure is 150psi exactly.

So maybe 8.5:1 (ish?)

[nicksamaniac]

How would a gt3076 0.63rear go?

Would it give positive pressure around 2000rpm and still flow enough to supply 15psi at 6-7000rpm?

[wolverine]

Awesome low down response followed by significant restriction as rpm increases.

[Cowboy1600]

The answer you seek is here:http://www.hypergearturbos.com/index.php?route=product/product&product_id=81

[nicksamaniac]

The ATR43-TX3 from hyper gear looks the part I need, rated 400-600hp.

G1 profile -400hp with .63 rear

Would this provide aggressive response and still be ok up to about 5500rpm?

Most of my driving is 1500-4500rpm

With the occasional 6900 overtaking and lights-lights drive maneuver!

[Cowboy1600]

It would be silly responsive on a 3l. You'll probably want the .82 rear on it. I reckon a .63 will struggle at 7k on a 3l.

Edited August 3, 2014 by Cowboy1600

[Dale FZ1]

The performance goals are achieveable with either the 3076 0.82 combination, or a Hypergear unit.

Begs the question of why muck around with a RB, when big cubes TB45/48 engines are made to run in the 1500-4500 bracket.

Best torque for an average 30DET should be in the 2500-6000 range, using budget gear as per the build spec notes from OP. Getting strong turbo-assisted torque below 2500 is likely to result in exactly what happened with the TO4E.

I'll throw in an unusual budget suggestion: Kinugawa TDO6H-20G 10cm.

[XKLABA]

I'll throw in an unusual budget suggestion: Kinugawa TDO6H-20G 10cm.

good idea

Though I'd look more at the TD06SL2-20G with the 9 blade rear wheel so it can still breath out at higher rpm

This one http://m.ebay.com.au/itm/291207219708?nav=SEARCH

The smaller exhaust wheel for faster spool

Also OP reading your post in the dyno thread I will guess from what you wrote you retarded the intake 2deg and advanced the exhaust 4 deg, this is wrong for what you want, advance intake 4 and retard exhaust 6, give that a go and report back

[Dale FZ1]

SL2 turbine probably should respond faster, due to less inertia

When building these 30DET you can't set cam timing from an unknown starting point. The cam timing markers don't line up to zero. Highly recommend paying the relatively small cost for an experienced builder to correctly set both cams using degree wheel and dial indicator. Then you've got a proper starting point if you wanted to play further on the dyno. Achieving low rpm gains will still come at a cost of higher rpm losses.

If bottom end grunt and instant response is the target, I wouldn't think the 30DET is the best spec. Small capacity engine in heavy truck can only do so much. These things still need to turn a few rpm to work well.

TB45/48 with a GT37 would be hard to beat, provided you could keep fuel and clutches/gearboxes up to it.

I'm certain that there would be some good info out on forums covering Patrols, Off Road racing etc.

[XKLABA]

That's a good point and something I should have added, the specs I give for cam timing should always be from a corrected zero

While the 4.8 patrol motor will give more from lower rpm, that is really only a benifit to rock crawlers, 4wding and off road racing use a wider rev range then the 4.8 will deliver, we race off road

This has a VQ35HR N/A

I think the RB30det set right with the right turbo will give more then enough power anywhere in the rev range