Which Turbo For Rb20det

[Cubes]

Thats roughly what they go for at wreckers..

I've only seen them go cheap here in on the forums.

When JMS was open they wanted $800 for an R33 turbo and $600 for a VG30 turbo. :S

[Abo Bob]

$750 is ridiculous.

You guys should be aware that the difference between an R34 turbo and an R33 turbo is in the exhaust housing only so if you think the VG30 turbo is no good because of the size of the exhaust housing then the R34 trbo will be the same because the exhaust housings are the same.

As for the neo compressor wheel being known to fly apart when pushed... what the? It's the same as the R3 series 2 compressor wheel anyway. Is that known to fly apart?

[kenetic]

why not just go for a garrett gt28rs disco potatoe (bolt on turbo) great unit and spools up great you won't be dissapointed, and on the upside can be had for $1500, I can't see why you would really go for a VG30 turbo when you normally have 2 of them pushing 3 litres its not much of an upgrade with of the hassles of putting it on and so on I would go the extra distance and put something worth while on there even an S15 turbo GT28R both turbo's are roller bearing steel compressor turbo's that will have heaps of headroom for some upgrades down the track.

[Cubes]

Kinetic,

The VG30 turbo we are talking about isn't the twin turbo.. Its the single turbo VG30DET out of the latish model Cima/Leopards.. They made 190kw from factory at around 6000-6200rpm. 363NM torque at 3200rpm or there abouts.

You guys should be aware that the difference between an R34 turbo and an R33 turbo is in the exhaust housing only so if you think the VG30 turbo is no good because of the size of the exhaust housing then the R34 trbo will be the same because the exhaust housings are the same.

<{POST_SNAPBACK}>

Abo bob,

I'll say it again but better.

The VG30 turbo runs a small puny compressor wheel (rb20t), with a large turbine this makes for a lazy turbo that is suited to the larger 3ltr motor that is required to make 190kw at ~6000rpm. If it were to use the smaller turbine housing it would make this peak power much earlier in the rpm and nose over, resulting in a crap feeling diesel power band.

For example, peak power at maybe 4500rpm and peak torque at 2000rpm. Very much like what I saw with the rb20det turbo on my rb30det.

Should they have dropped a larger R33/R34 compressor wheel in to the VG30 setup it may have overshot the power level they were aiming for. To achieve the power level and boost they were after the rb20det turbo guts with slightly larger housings worked perfect.

The R34 runs a larger compressor wheel, every revolution it takes a larger bite out of the air and flows more air in to the motor, as a result there is more exhaust gas. Resulting in a less 'lazy' turbo compared to the VG30 that has been setup for higher exhaust flow.

Lets swap the turbine housing specs that one would use for a GT35R on a RB25DET and Ford 4ltr.

The RB25DET you would want the smaller .82 turbine housing, if not .64.

The Ford wants a 1.06 or greater.

Lets swap them...

Drop the 1.06 on the rb25det and it will make for a lazy peaky turbo with stuff all mid range.

Drop the .82 or .64 on the Ford 4ltr peak power made much earlier in the rpm as a result mid range and low end will be huge. Good for towing but not good for track work or acceleration.

I've now got a VG30DET turbo on my Rb30DET, it suits the motor much much better than the Rb20DET with its small quick spooling housings, I am now able to accelerate through first without boost snapping on hard and chirping the wheels, I can now have better throttle control. It now also rev's harder and makes power where I use it, it will now flick to 6k where as before it would only rev to 5k before power would nose over.

If you do engine airflow calcs you will see why the rb20det turbo only makes power to 5k. 5k airflow from the rb30det is roughly the same as the rb20det at 7000k. I don't remember exactly but its around the mark.

Its all about matching a turbo to the motor.

If that makes sense.

Edited November 30, 2005 by Cubes

[kenetic]

I stand corrected guys, sorry about that. But I still stand by the point of spending time money on a turbo thats fairly old, will properly need rebuilding down the track and has a ceramic wheel or worse.

[Cubes]

The VG30DET was used around the 94-95, so say the same as an R33.

If I had a VG30DET and was going to put it on my RB20DET again I would simply use the S2 RB20DET turbo and its smaller turbine housing but use the VG30's larger Compressor cover, this will help top end airflow some what but still retain the quick spool and mid range of the smaller turbine housing.

Then its basically a RB25DET turbo, bar the smaller compressor wheel.

It comes down to the fact of; for the amount of airflow the vg30 compressor generates the 2ltr doesn't need to breathe so well on the hotside, it only kills mid range and spool time.

Edited November 30, 2005 by Cubes

[gt-t_r34]

hey guys im wondering what kind of turbo to put on my rb20 too.. was thinking HKS GTRS or gt2530 (KAI???) or gt2835 pro s what not too much lag like around full boost under 4.5rpm and heaps of pull right to redline.

whats the go outta those what to keep it low mount and internal gated!

cheers simon

[QUIKBLADE]

Sorry, but if you're looking for BIG HP, minimal LAG and essentially a torque beast... drop me a line, because all of those goals conflict each other. So, if you find something that offers all these things... shoot me an email.

In ther meantime... get big turbo, add camshaft(s) and tuning to widen torque band and you should have a good goer... also, look at bigger injectors and possibly fuel pump to keep the fuel supply up. IMO, look at your support systems before the turbo is added.

Regards,

Grant

Edited November 30, 2005 by QUIKBLADE