Rb26 Turbo Comparision Graph (from Latest Hpi Mag)

[BOOSTD]

I am also running HKS 2530's.

My engine also has:

260 9.15 Poncams

88mm pistons

SS manifolds

ARC twin entry intercooler

twin 3" exhuast merging through collector to 3.5" at the rear seats. (2x4" magic Cats)

It made 360rwkw @12.5 psi on ADVAN's dyno ( later found my exhuast cam gear had slipped...car felt very laggy but huge top end.)

I recently ran a 11.5 @120Mph on BP98 and 16psi boost and no-name street tyres (1.9 60') Turbo response is very near stock. My datalogger shows AFR's were around 11.6-11.7 up to 6500rpm then into the 10's.

[9krpm]

nice 1/4 time boostd!

[SLY33]

Sometimes I find HPI stuff really annoying... I mean just going by their comparo graph, someone trying to choose a turbo setup could really get the wrong idea there. Especially when you look at examples like R32-GTS's graph, you see how good the T04 can perform.

Sorry i bring this up again, but from my understanding the TO4z HKS version only differs from the Garret version by having the extra holes in the compressor cover, supposedly to decrease spool time? Other than that the turbos are identical? Reason im asking is that ive decided to start with the tO4z on my rb28 instead of the T51R, and the HKS TO4Z kit prices are ridiculous at the moment!

Edited June 16, 2006 by SLY33

[discopotato03]

No it goes deeper than that . The compressor cover itself is of a higher AR ratio than Garretts and they have done a few sneaky mods (patiented) to the diffuser section of the housing itself . Notice how HKS don't have an AR ratio number cast into the covers on their TO4Z or T51R's . The drilled port shroud is probably bling factor though in small turbine housing form it may help a bit .

No doubt HKS have used any tricks they could think of in the turbine housing as well . You may have noticed that their custom TO4Z and T51R housings are circular cross section in the volute passage , their web site claims that circular rather than oval shape does something to boundary layer flow . More uniform acceleration into the nozzle ? At least the TO4Z housing has a T4/TA45 flange rather than the T51R's circular V band setup .

Damn you Cruiseliner , I really want to see the inside of the Z cover , still I'll have to rev up the spies OS .

Cheers A

PS I think I did see a pic of the HKS versions turbine with a slight back cut of the blades but unconfirmed . There were many conflicting claims that the HKS version used a slightly different or modded turbine . The fact that both versions use the same number cartridge would seem to prove otherwise .

Out of time cheers A .

[NXTIME]

I have heard and read many differing views on the power rating of turbo mnaufacturers, particularly HKS, in that they understate their HP ratings. At what PSI are these ratings? 15, 18, 20??? For eg, HKS T51R SPL is rated at 1000HP, but a few cars have made closer to 1200HP+ from them.

[Swiper the Fox]

No it goes deeper than that . The compressor cover itself is of a higher AR ratio than Garretts and they have done a few sneaky mods (patiented) to the diffuser section of the housing itself . Notice how HKS don't have an AR ratio number cast into the covers on their TO4Z or T51R's . The drilled port shroud is probably bling factor though in small turbine housing form it may help a bit .

No doubt HKS have used any tricks they could think of in the turbine housing as well . You may have noticed that their custom TO4Z and T51R housings are circular cross section in the volute passage , their web site claims that circular rather than oval shape does something to boundary layer flow . More uniform acceleration into the nozzle ? At least the TO4Z housing has a T4/TA45 flange rather than the T51R's circular V band setup .

Damn you Cruiseliner , I really want to see the inside of the Z cover , still I'll have to rev up the spies OS .

Cheers A

PS I think I did see a pic of the HKS versions turbine with a slight back cut of the blades but unconfirmed . There were many conflicting claims that the HKS version used a slightly different or modded turbine . The fact that both versions use the same number cartridge would seem to prove otherwise .

Out of time cheers A .

I have a brand new HKS TO4Z at the workshop...what parts do you want pics of??

[DoughBoy]

At a guess he wants pics of the HKS patented exh and comp covers, which Brett at GCG told him after being informed by Mark @ Hypertune.

It's nothing really, just shows the diffuser section being carried over to the scroll on the comp cover to improve high boost efficiency. The turbo cross section is similar to the TR race series of Garretts, again slightly more efficient.

As to the HKS stuff being worth double the price of Garrett shelf stock... maybe if you're racing for sheep stations but not many people are pusing the envelope with high boost to warrant the added expense.

[2rismo]

I have heard and read many differing views on the power rating of turbo mnaufacturers, particularly HKS, in that they understate their HP ratings. At what PSI are these ratings? 15, 18, 20???

PSI is irrelevant in this case as it's partly a measurement of resistance in a system and the systems can be different. If they listed absolute pressure it might help but not much. HP ratings of turbos mean next to nothing when we're comparing claimed and measured power output.

Adrian

[CruiseLiner]

the comp cover on my hks t04z looks a fair size bigger than the garrett t04z's for sure.

im sure when the garrett is running outta puff up top (2 bar) the hks will shine and show its true colours

[Beer Baron]

As to the HKS stuff being worth double the price of Garrett shelf stock... maybe if you're racing for sheep stations but not many people are pusing the envelope with high boost to warrant the added expense.

but it's also much more impressive to be able to say "I have an HKS turbo". hey it works for me! lol

[Roy]

I am also running HKS 2530's.

My engine also has:

260 9.15 Poncams

88mm pistons

SS manifolds

ARC twin entry intercooler

twin 3" exhuast merging through collector to 3.5" at the rear seats. (2x4" magic Cats)

It made 360rwkw @12.5 psi on ADVAN's dyno ( later found my exhuast cam gear had slipped...car felt very laggy but huge top end.)

I recently ran a 11.5 @120Mph on BP98 and 16psi boost and no-name street tyres (1.9 60') Turbo response is very near stock. My datalogger shows AFR's were around 11.6-11.7 up to 6500rpm then into the 10's.

Have you had the car on another dyno. I have now seen a few results from Advan that perhaps flatter the car.It has rana quick time at a good mph, and Advan obviously punch out nice cars, only i suspect their dyno reads higher then some

[mazgtr]

360RWKW at only 12.5PSI seem a little high compared to the other 2530 equipped GTR's ive seen. Either the boost is higher than 12.5PSI or the dyno reads a little high.

Ive seen several GTR's with the same mods and turbos register figures as high as 360RWKW but all of them needed closer to 20PSI.

Also if it made 360RWKW at 12.5PSI then at 16PSI it would be closer to 380RWKW-390RWKW and 120MPH doesnt support that.

Not in any way detracting from your results, just like Roy said, that dyno figure does seem a fair bit higher than most..

But a mid 11sec pass is a fecking great result, well done..

Cheers....

[mazgtr]

but it's also much more impressive to be able to say "I have an HKS turbo". hey it works for me! lol

LOL!!! Why not buy the Garret, then use the money you saved to buy several "HKS" stickers to put all over your car...

[mazgtr]

HKS turbo's have always had a reputation for being able to generate good numbers at very high boost pressures. Where others seem to run out of puff, most HKS turbo's seem to be right in the meat of their efficiency curve at levels up to and beyond 2.0Bar. Now unless your running C16/Avgas you might never need this ability to run such high boost, but if your after every last KW and are hunting for a Dyno-graph or Drag strip time to frame and put on your wall then HKS does seem to have that little bit more topend efficiency.

Me, id rather buy the Garret and use the money i saved on alcohol and hookers... But thats just me....

[CruiseLiner]

well i'd rather pump 2 bar in and see the gains

its like buying a watch from bali, it looks as good but it aint, and u get what u pay for in the end.

when u spend a small fortune on a bottom end and head then an extra $800 or so seems minimal when chasing big numbers anyway

the word "budget" and "big power" dont seem to go together very well

as they say, different horses for different courses

Edited June 18, 2006 by CruiseLiner

[R31Nismoid]

i dont think there is that much difference in the t04z's... slight yes. much, no

[CruiseLiner]

i dont think there is that much difference in the t04z's... slight yes. much, no

so how many garrett and hks t04z have u seen at 2 bar plus to compare?

i bet hks didnt do the comp cover bigger and different design for looks and going by other hks vs garrett stuff the garrett stuff always dies off around 2 bar.

i know most people dont want to run over 25psi or whatever so it wont matter but at the top end of pushing em im sure they will show their true characteristics

i see it as comparing a nissan rb26 stock to a gibson built rb26 for the group A cars.

Edited June 18, 2006 by CruiseLiner

[Sydneykid]

PSI is irrelevant in this case as it's partly a measurement of resistance in a system and the systems can be different. Adrian

The smartest post on this page.

The fixation with boost versus power is meaningless. A car with more boost does not necessarily make more power than a car with less boost. Airflow is what makes power, removing restrictions decreases boost, but increases airflow. So lower boost can actually mean more power.

When you apply that logic, the “HKS turbos make more boost” argument falls over. What if my power target is achieved at “low” boost because I have removed the restrictions? What if the Garrett turbo produces the airflow I need to make my power target at that “low” boost level? If I used a HKS turbo I would be using it “outside” its efficiency band. That would be pretty stupid wouldn’t it?

I have great fun with guys who brag “my car runs 2 bar boost”.

My response is “WOW, you haven’t removed many restrictions have you”.

cheers

[R31Nismoid]

so how many garrett and hks t04z have u seen at 2 bar plus to compare?

and how many have you seen to say there is a leaps and bounds difference?

when wheel trims are very similar, and housings mildly different... how can there be major differences?

I once believed yoo that the garrett gear was a "lower boost" turbo. Got the GT30 on there, screwed 24psi into it and its was amazing. Really woke up. 17psi was lazy, it felt lazy. Get to 24psi and it was feeling quite good.

admittadly that was no cams and everything else so i did need to run a bit more to get more out of it. But i honestly think the "HKS GT30" would really be worth the pricetag

Get the wheem maps maps (if possible) and compare between the both, i doubt large difference

[ferni]

The smartest post on this page.

The fixation with boost versus power is meaningless. A car with more boost does not necessarily make more power than a car with less boost. Airflow is what makes power, removing restrictions decreases boost, but increases airflow. So lower boost can actually mean more power.

When you apply that logic, the “HKS turbos make more boost” argument falls over. What if my power target is achieved at “low” boost because I have removed the restrictions? What if the Garrett turbo produces the airflow I need to make my power target at that “low” boost level? If I used a HKS turbo I would be using it “outside” its efficiency band. That would be pretty stupid wouldn’t it?

I have great fun with guys who brag “my car runs 2 bar boost”.

My response is “WOW, you haven’t removed many restrictions have you”.

cheers

Whats the major way to reduce restriction so you can flow more air, run less boost and get more power? I understand that if you remove restirction the engine can breath easier so it doesn't need as much pressure to force the same amount of air into it. I'd guess CAMS are the first/biggest difference? What else can you do? ... sorry if this is a dumb question, i really don't know.