Rb26 Turbo Comparision Graph (from Latest Hpi Mag)

[Gav]

But are you using a 3ltr engine? Not sure if i did metion it or not, but my engine consist's of an rb26 head with rb30 bottom end

No - I've got an HKS stroker crank fitted giving just on 2.8L displacement (87mm bore). The hardware should permit the engine to venture north of 9000 rpm, so I imagine overall airflow should not be too dissimilar.

Good luck and keep us informed.

[Beer Baron]

found it (post #96)

http://www.skylinesaustralia.com/forums/in...ic=72151&st=80#

dont know what he was talking about there? twin HKS 2530s for GTR are most definately ball bearing. i have never seen one that wasn't or even heard of one. i guess it's possible that there was one, but i dont think so.

[paulr33]

could be right, anyone else have any supporting material they are ball bearing? anyone know the CHRA no#'s

[Beer Baron]

My guess is the trust turbos on the dyno graph are 518z with the 0.72 rear housing. I am not sure whether that is the 8cm or 10cm (or neither) which is how trust measure the rear housing but that would be my guess.

Maybe someone could convert the 8cm and 10cm to a/r.

i dont think there is such a thing as 518z in twin form for a GTR. it's either 517Z or 618Z.

[shanef]

If you basing the GT-RS vs T04Z on the graph comparo here... im not too sure.

Im still un-convinced by one dyno graph comparo with unknown spec'd motors.

Its too hard to make a call without the detail of every car used, and the subsequent modifications.

As you said, give you 704rwhp... thats 704awhp

So i dont see how it isnt what you are looking for.

gotta allow for front drivetrain loss on top of that 704rwhp to get awhp

gave matty spry a ring today but he's not to 'in the know' with set-ups so he couldnt offer me adivce. anyone know who else is a 'turbo professor'?

[mazgtr]

could be right, anyone else have any supporting material they are ball bearing? anyone know the CHRA no#'s

HKS 2530'S AND HKS 2540'S are both Ball-Bearing Turbo's.

Period.

[paulr33]

i wont rest till i get a chra #

really only for curiosity sake

i dont care if they are or arent

[CruiseLiner]

ill put $50 on them being ball bearing, why would they be bush bearing??? they aint Trust turbos

Edited June 9, 2006 by CruiseLiner

[R31Nismoid]

gotta allow for front drivetrain loss on top of that 704rwhp to get awhp

Far as im concered there is no loss at all.

There is a super recent thread on it aswell if you wanna take a look

http://www.skylinesaustralia.com/forums/in...howtopic=119673

I've seen a number of GTR's back that up aswell going from two different mods

[R31Nismoid]

Paul, the old HKS T3G, basically what the 2530 replaced, is Bush bearing... 2530 is all ball bearing for the GTR twins

[R31Nismoid]

paul my MSN is on now lol... harras me if you wanna know more about the old bucket HKS stuff

[paulr33]

haha nah its all good

what u doing tomorrw night

[NXTIME]

twin high mount 2835 would give ya that extra kick in the guts

but form my experience on a 2.6 litre gtr motor twin 2835's dont hit full boost till 6k rpm

but on a 3.1 litre im thinking 4k rpm

2.6L 2835 combo is quite laggy but could be made to come onto boost earlier depending upon cam choice and tuning. With the RB30, they would spool up substantially quicker and would be a great combination. However, when switching from low mounts to high mounts the cost goes up considerably. The GTRS's and the 2835's are rated similarly, and therefore should make similar power.

I would stick with the GTRS's in a track car and enjoy the ride.

Also, there is little drivetrain loss difference between rwhp and awhp in GTR's due to the ECU-controlled torque split of the ATTESA system.

[rb26s13]

i dont think there is such a thing as 518z in twin form for a GTR. it's either 517Z or 618Z.

nowadays there is a 517z and a 618z.. how ever if my memory is still working there use to be a twin 518z kit you could buy for gtr's how ever the 618z's replaced them soo maybe thats wat they are?

[Dale FZ1]

I would stick with the GTRS's in a track car and enjoy the ride.

Looking at the ski-jump profile of the graphs, I reckon all the chosen turbos are track refugees. And straight-line tracks at that. Willall Racing are into dragging as far as I can tell.

The shape of the torque curves would be interesting - nearly vertical I would think. It would make for some interesting driving if you come on/off boost rolling on/off throttle on the road. Even on a drag strip they would need to look at very tightly stacked gearbox ratios to factor in the effective speed range(s) of the chosen turbo(s).

I do find it interesting to see their results from an academic viewpoint, as it highlights the ability of one setup to generate significantly more power across the range, if not the biggest outright number. GT-RS looks the best in that regard.

Also, comments made beg the question for the HPI exercise - do you match the turbo to engine, or choose a turbo and then work out what spec the engine needs to be?

cheers

Dale

[Sydneykid]

Far as im concered there is no loss at all.

There is a super recent thread on it aswell if you wanna take a look

http://www.skylinesaustralia.com/forums/in...howtopic=119673

I've seen a number of GTR's back that up aswell going from two different mods

I read that thread at the time and I had a couple of difficulties. The main one being switching/pulling the ATTESSA fuse doesn't remove all of the 4wd train losses. You really would have to remove the transfer case completely to achieve a 100% result. Secondly there is loss in the rollers themselves, so no matter how hard you tie the car down, there is always some slip. The slip differences between 2wd and 4wd can mask other factors. For example you may have more slip in 2wd hence the power reading is lower than it really should be.

As posted many times we have done a couple of engine dyno versus roller dyno versus hub dyno power runs. The % loss method is (as many have pointed out) totally illogical. Newtons law (fire up that high school physics) says energy is transformed not lost. So the kinetic energy (torque if you like) has to be transformed into some other type of energy. In the case of cars, most commonly, that is heat.

If you are using the % method, doubling the horsepower of an engine should results in doubling the heat (in the gearbox, the diff, the drive shafts, the CV joints etc). But a quick check with the pyrometer shows that to be complete rubbish.

What we have found in the engine dyno versus roller dyno is a 2wd Skyline loses (transforms actually) around 60 kw and a 4wd around 80 kw. A hub dyno is around 20 kw less, as they have no rollers.

Totaly off subject, so let's get back to the turbo comparison............

As far as I ma concerned all the aftermarket turbos in that comparison are too big for a 2.6 litre engine. So it's not a matter of which turbo is good and which turbo is bad. They are all bad as far I am concerned.

Stick Paul's 450 rwkw 2530's on the graph and you will see what I mean.

cheers

Edited June 9, 2006 by Sydneykid

[T04GTR]

hmmm. my to4z on a ebay manifold is at 1.2 bar by 4100.

[rb26s13]

that sounds a alot better t04gtr always thought that t04z result in the comparision was a bit of bullshit

[Swiper the Fox]

Stick Paul's 450 rwkw 2530's on the graph and you will see what I mean.

cheers

ill post a few up

BTW 2530's are ballbearing...when my rear one failed, guess what i found in my sump??....ballbearings.

[Sydneykid]

ill post a few up

BTW 2530's are ballbearing...when my rear one failed, guess what i found in my sump??....ballbearings.

When we say "MORE BALLS" we mean larger ones, not a greater number of little ones

cheers