Opinions On Hks Gtrs On A Rb26

[gmchaser]

I have both turbos. The t04z on 25psi in an rb25 and and -5 on an rb26 28psi. Both standard head and cams. The -5 are more useable in 2 gear and it feels it has more torque from 4500-7000rpm. But the z from 5000rpm is alto more aggressive. I can't comment on gtrs but even getting the -5 set up properly on the gtr is abit of a pain.

[jet_r31]

Old Z with a newer style billet compressor with a bit of cleaning up comes on 300 or so earlier. Pretty much what a GTW does, yet people always claim more response, like 500 rpm, yet to see it though.

you talking about the 11 blade gtx style t04z wheel that every man and his dog is throwing into 3582's?

cheers

darren

[XGTRX]

you talking about the 11 blade gtx style t04z wheel that every man and his dog is throwing into 3582's?

cheers

darren

That's the one.66mm I think. Mate with a Barra has one with a bigger flapper and making 350 on 14 pounds. Response is nothing to get excited about for a 35, will see how it behaves with a valve spring change and more boost.

[mr skidz]

Dual Ball Bearing Garrett To4Z . 700-750HP flow potential.

Compressor wheel diameter is 84mm exd. / 66.7mm ind. (63trim) Compressor housing is .70 A/R has a 4" inlet and 2.5" outlet slip on connection.

T4 Turbine housing divided A/R .84 entry, all with standard 3" V-band discharge.

Turbine

-Wheel: 74.2mm w/ 76 trim

-T4 Divided Housing A/R .84

Compressor

-Wheel: 84.0mm exd./66.7mm ind w/ 63 trim

-Housing: 0.70 A/R

(707160-5) dash 5's stack up nicely against that compressor map maxing out at virtually the same numbers.

Lower half of the -5 Map looks better as it moves more air at a given pressure which helps with response but tapers off a bit earlier.

Edited March 22, 2016 by mr skidz

[s2d4]

70% vs 65% efficiency at the top end makes some difference.

It actually looks like it's better down low as well. Look at the 1.5 pressure ratio and 20lb/min for the z vs 10lb/min for the twins.

[XGTRX]

(707160-5) dash 5's stack up nicely against that compressor map maxing out at virtually the same numbers.

Lower half of the -5 Map looks better as it moves more air at a given pressure which helps with response but tapers off a bit earlier.

Don't know mate, I just went for a drive in a few, liked it, bolted one up and thrash the fk out of it and drive it daily.

I am sure there are better set ups out there but I love the power delivery and the fact I drive around under boost all day in traffic and am just a gear change away from shits and giggles.

Once this one goes I might bolt up an old Borg Warner s300 -66, apparently they're good value with similar characteristics.

[mr skidz]

70% vs 65% efficiency at the top end makes some difference.

It actually looks like it's better down low as well. Look at the 1.5 pressure ratio and 20lb/min for the z vs 10lb/min for the twins.

*Regarding the to4z map if that's what it is. it seems a bit hard to read but it looks like it says 65% efficiency at the top island of the compressor map, which also requires more pressure to get there.

Just doesn't seem as energy efficient is all I was saying.

but not bad it actually looks really good for an old school single, I like em.

*regarding the 10lb's/min -5 vs T04z 20lb's/min which is essentially 7psi boost and neither have cracked the wastegate at that pressure and they are both identical as the dash 5's are used as twins so it's 10lbs of air from each -5 totaling 20lbs/min.

Look at the popular wastegate pressure ratio of 2bar which is (1bar boost)

it shows the -5's out flowing the T04z by 10lbs/min.

I have had the pleasure of going in a fully built stroked ca18 180sx imported from Japan which had one on it and it was mega still one of the loudest n quickest cars I'd been in.

Edited March 22, 2016 by mr skidz

[s2d4]

*Regarding the to4z map if that's what it is. it seems a bit hard to read but it looks like it says 65% efficiency at the top island of the compressor map, which also requires more pressure to get there.

Just doesn't seem as energy efficient is all I was saying.

but not bad it actually looks really good for an old school single, I like em.

*regarding the 10lb's/min -5 vs T04z 20lb's/min which is essentially 7psi boost and neither have cracked the wastegate at that pressure and they are both identical as the dash 5's are used as twins so it's 10lbs of air from each -5 totaling 20lbs/min.

Look at the popular wastegate pressure ratio of 2bar which is (1bar boost)

it shows the -5's out flowing the T04z by 10lbs/min.

I have had the pleasure of going in a fully built stroked ca18 180sx imported from Japan which had one on it and it was mega still one of the loudest n quickest cars I'd been in.

Have a look at the 70lb/min vs the 35lb/min.

At the 20lb/min to10lb/m vs 10lb/min to 5lb/min mark, there's definitely more "area" on the z.

Running 1 bar on either of turbos is a waste of time really.

Edited March 22, 2016 by s2d4

[mr skidz]

Your doubling the the potential lbs/min flow of the -5 Map aren't you?

So when I see 35lbs it's theoretically 70lbs.

Was just pointing out similarities in flow vs pressure ratios.

Edited March 22, 2016 by mr skidz

[s2d4]

Your doubling the the potential lbs/min flow of the -5 Map aren't you?

So when I see 35lbs it's theoretically 70lbs.

Was just pointing out similarities in flow vs pressure ratios.

Yeah, which is why I was referencing 70lb/min vs 35lb/min.

[Dose Pipe Sutututu]

In theory, then in practise it's not when you've got two turbos pushing against each other and twin restrictions on the motor.

Like I said, for those flow values to be anywhere near true in practise you'll need twin cooler, twin plenum to fully separate everything.

[Greekos]

question is a little off topic, GTRS bolt up on sr20's reason im asking is I have a set I want to sell to the sr20 guys

GTR'S are old, they will make 500kw but to do it right cost more than going single and your not getting anywhere near as a good result!

[r32-25t]

The Gtr versions only fit on rb26s

[reaper]

Off topic but the HKS T04Z is a good looking turbo even now. Far better than my ugly little EFR.

[XGTRX]

Just a few plots I did a while back just for the fun of it more than anything.

Might not be precise but its in the ball park.

Might be of some value to someone.

Edited March 23, 2016 by XGTRX

[bigmikespec]

Off topic but the HKS T04Z is a good looking turbo even now. Far better than my ugly little EFR.

Yes. But I will wait for someone to say "oh they are old tech" without even quantifying (or perhaps understanding) what that means.

[Dose Pipe Sutututu]

Yes. But I will wait for someone to say "oh they are old tech" without even quantifying (or perhaps understanding) what that means.

it is though... but it's solid tech that works better than any modern tech that runs in pairs.

[gmchaser]

I don't think this turbo in twin form will perform well on any engine unless upwards of 3500cc as you are not able to cheat and run more boost to make the claimed 850-900 hp because it runs out of compressor at 2bar boost. On a 2.6 with let's say big cams revving to 8500rpm the -5 should make the same power as them at around 1.8 bar. A single turbo on the other hand like a t04z, gtx4088 or even gt4294r I think you are able to cheat because if you don't have massive cams or oversize valves to improve the Ve of the engine( which are essential to make the gtrs work well in an rb26/28/30) you can just run more boost to make the power.

[gmchaser]

These days with e85 and billet compressors less rpm and heaps of boost seems to be all rage.

[jet_r31]

That's the one.66mm I think. Mate with a Barra has one with a bigger flapper and making 350 on 14 pounds. Response is nothing to get excited about for a 35, will see how it behaves with a valve spring change and more boost.

Yeh.its a little turbine driving a big comp wheel.\

My mate has a 3582 on a vl in a 1.06 housing with that wheel. Makes 450rwkw through a loose converter on 30psi. Ran over 140mph.\

But his gate is plumbed back into restrictive 3 inch exhaust aswell.

On 30psi it made no more boost..unplugged gate and went straight to 40psi and maxed fuel pumps out coming on

Another has gone 145mph on 30-32psi with gates vented to atmo with that turbo

The comp wheels a decent thing..needs a gt37 turbine ot similiar. Peformanz turbos in perth selll a turbo with that comp wheel in a 3582 core and gt37 turbine..

cheers

darren

Edited March 23, 2016 by jet_r31