Help Me Decide Which Turbos For A Street/track Setup Gtr

[BoostdR]

I am currently building an RB26/30 to replace my RB26.

My original plans were to use HKS GT-RS's(already purchased) which in theory should work reasonably well on a 3 ltr. I have just been advised not to follow this path due to the GT-RS's choking exhaust flow up top and restricting power to ~420rwkw @ 1.65bar. If a 0.7A/R turbine housing was available to bolt on, we would be set....

The Greddy t517Z and T618Z come in a 10.0cm2 turbine A/R which equates to 0.7A/R. I have seen these turbos make 40 odd kw more at the top end however they are 50 or so kw down in the mid range. I assume I won't have to much of a reasponse issue with the 3ltr but the GTRS will still be ahead in the mid range not matter what. I guess average power will end up similar.....I'm very undecided.

The other options I have considered was looking into abrasive porting of the HKS GTRS turbine housings or/and running an external gate setup to reduce to onset of exhaust gas choking...

Or if available running a 0.7A/R exhaust housing from another family and making custom dump pipes to suit.

Any thoughts would be appreciated

Matt

PS Cams will most likely be JUN 272 or less

[STATUS]

T618z's onli if your are definately 3l bottom end.... they are weay to big for your average 2.6l streeter... on a 2.6 liter they need big cams and headwork to work effectively... i have a few trust T618z recipies somewhere they gave me when we put together one a few years back.... all reccommend sitting them in their 1.5-1.7bar efficiency range.

im personally not a big fan.... even though some of the trust turbos i rate very highly

[R31Nismoid]

Who said the GT-RS will restrict you @ that level and why?

They are a stroker motor turbo really, not that good on stock capacity 26, same as the 618... designed for a bit more power than 420rwkw too!!!

[BoostdR]

Thanks for the reply,

It's definately a 3ltr, It's already prepped to go.

Do you have any power figures from your experience?

What twin setup would you run for 450rwkw with optimal response?

[Roy]

Be interesting to see how well a 450kwGTR copes with track work. It seems a 3L will make almost any turbo combination work, so go for whichever you can get for a good price. My guy feel is perhaps the GT-RS are the way to go

[BoostdR]

Who said the GT-RS will restrict you @ that level and why?

They are a stroker motor turbo really, not that good on stock capacity 26, same as the 618... designed for a bit more power than 420rwkw too!!!

I have the upright respect for my engine builder/tuner. So the "he said she said" is not and arguement I am interested to have. Suffice to say he has tried the combination of HKS GTRS's on std to 3ltr capacity and they have come up short of the compressor flow ability. The mismatch between the compressor and turbine.......proven by the signature compressor surge causes restriction of the topend capabilty but obviously gives stonking mid range. They are pushed hard to make over 420rwkw on pump fuel, to the point where the exhaust manifold pressure and associated gas temps are not a combo that I can reliably get more than a few laps out of.

just to confirm again..capacity IS 3ltrs

so is there anyone out there with experience on the Greddy 10cm GTR turbo's?

Matt

[XRATED]

I had a pair of T517Z 10cm's on a bone stock 2.6- made 393rwkw on pump 98 @ 22psi. Party was on at around 3600rpm and pulled hard all the way to 9000rpm (he he he). I ran mid 10's on them.

[BoostdR]

I had a pair of T517Z 10cm's on a bone stock 2.6- made 393rwkw on pump 98 @ 22psi. Party was on at around 3600rpm and pulled hard all the way to 9000rpm (he he he). I ran mid 10's on them.

do you have a copy of your dyno graph?

[XRATED]

Sorry... I'm in Italy atm. A looong way from home ( and my car ). They were great little turbs, pulled hard when they came on..... they were on the border for street driving though around the twisties in Tassie, so for a street car I'd definatly recomend the 8cm versions.

I'll be going a set of gtrs's on a 2.8kit with a big ported head and cams. I'm also considering custom exh mans whith small external gates and a garett non internal wastgate housings.....

But for a 3lt w_ big cams and head work I'd go a set of T618Z's on matched, tubular manifolds. And the matching set of trust dump pipes.... I picked up 22rwkw with them as opposed to a set of ported HKS copy dumps and down pipes.

Edited July 16, 2008 by XRATED

[Gav]

I had GT-RS terbs on my 2.8L and topped out at 600 rwkw on more than 1 dyno.

I dropped to smaller Garrett -5 for the sake of gaining time on the track. Sure, my rwhp dropped by 40 to 50hp, but my lap times improved HEAPS.

For dyno comps, bragging rights, drag racing.......go the larger/high hp terbs. For a good streeter/track car (as you titled the post), forget about top end and chase response with a healthy 500 to 550 hp.

[Snowman]

I originally advised Gav to change over to the -5's and I think he'll agree with me that it was the best thing to do. I still reckon they are the way to go even on a 3.0L.

Although hopefully Gav your car isnt TOO fast now since I have to race you next week

[Lithium]

What twin setup would you run for 450rwkw with optimal response?

Me personally, I'd go for HKS GT-RS twins interestingly. I'm not arguing with what your tuner says - but if I had not heard that and for some strange reason I wanted to go for twins at that power level, HKS GT-RS would be floating around the top of my list. Going for under 272deg duration is probably not something I'd do when going for turbos that size/power that high however.

I'd be looking at something along the lines of a single Garrett GT4088R with a decent twin scroll manifold for that power level, should have better response than the laggy GT-RSs (800hp turbo combination only capable of making 560hp @ wheels, what a fricken joke) and just be way cooler.

[R31Nismoid]

I have the upright respect for my engine builder/tuner. So the "he said she said" is not and arguement I am interested to have. Suffice to say he has tried the combination of HKS GTRS's on std to 3ltr capacity and they have come up short of the compressor flow ability. The mismatch between the compressor and turbine.......proven by the signature compressor surge causes restriction of the topend capabilty but obviously gives stonking mid range. They are pushed hard to make over 420rwkw on pump fuel, to the point where the exhaust manifold pressure and associated gas temps are not a combo that I can reliably get more than a few laps out of.

just to confirm again..capacity IS 3ltrs

so is there anyone out there with experience on the Greddy 10cm GTR turbo's?

Matt

Its not really an argument mate, just a point.

As lithium posted... your talking 800hp+ turbo setup, and your limited to 420rwkw?

A T04Z (800hp) rattles off 440rwkw like its a walk in the park, GT-RS's are not different far as i see it.

[BoostdR]

I had GT-RS terbs on my 2.8L and topped out at 600 rwkw on more than 1 dyno.

I dropped to smaller Garrett -5 for the sake of gaining time on the track. Sure, my rwhp dropped by 40 to 50hp, but my lap times improved HEAPS.

For dyno comps, bragging rights, drag racing.......go the larger/high hp terbs. For a good streeter/track car (as you titled the post), forget about top end and chase response with a healthy 500 to 550 hp.

Do you mean 600rwhp?

I am currently using GT2860R-5's on my 87mm bore 2.6, .5mm larger valves and tomei 260 9.15 poncams. Response is 1bar @4050rpm in 4th and positive pressure at anything after 1600rpm. My main goal obviously is not to go backwards in response. They make 350rwkw on std manifolds, 380rwkw on stainless manifolds and more on jungle juice. Peak power isn't my main concern however a usable power range is. From what I can see anything bigger than the GT-RS's will give a hole in the mid range... Just not a whole lot of info on twin Greddy turbo's on GTR's out there. We are building the same planned GTRS setup for John Munro's Track car so we will see how that goes on the engine dyno and go from there.

Matt

PS. on the subject of manifolds, we flow tested a chinese stainless manifold and std cast manifold and the stainless flowed 50% more! Then we spent 6 hours porting the std cast manifolds paying particular attention to the short turns and they flowed 46% more(4% less than the ebay ones). With the relability and heat retension properties of cast I know what I'll be using

[Gav]

Oops - typo. Meant 600 rwhp of course

Snowy - Relax, my motokhana skills are still crap lol Wanneroo and Collie will be interesting however

[unique1]

hey Gav when is your car pulling hard with the 2.8L capacity with the -5s? im building another engine (26/30) and unsure if i want single or twins yet, but if i go twins its out of the 2860 range of turbos, either -5s or -7s, im aiming for outright response and limit power to 450rwhp maximum, would u reccomend the -5s or stay with -7s if i dont plan on going over 500hp?

you dont happen to have a graph comparing your -5s with simons t04z setup to compare?

Edited July 17, 2008 by unique1

[Gav]

There's another GT-R in Perth with an RB26/30 with -5s fitted (Silver 32 driven by Matt). A very strong car and heaps of midrange as you would expect.

Don't a direct dyno graph with what I have now and Chooka's old setup, but his response was close to the GT-RS, but with another 50hp or so up top.

To give you an idea, however, have a look at this link of my old setup with GT-RS terbs and the -5s on a lower boost runin tune

http://www.skylinesaustralia.com/forums/up...05_63_75621.jpg

The power difference now is probably only 40hp or so lower now that I've raised the boost and dialed in a bit more timing

[Swiper the Fox]

our car easily made 450AWKW at all fours on BP98 @ 20psi with GT-RS's. 2.6ltr as well and was only ran in the day before this dyno run. Not as responsive as Racepace's much touted RB29 but with your extra capacity i think you would go the 'pepsi challenge' with it. Our car also made around 470AWKW at all fours on 25psi and over 500AWKW on Sunoco fuel. Look at the mid-range difference...thats where you RPM rage will be on the circuit. GT-RS's are a great turbo choice for your application...what tracks will you be racing on?

link to thread..

http://www.skylinesaustralia.com/forums/Rb....html&st=40

Edited July 17, 2008 by DiRTgarage

[R31Nismoid]

They make 350rwkw on std manifolds, 380rwkw on stainless manifolds

PS. on the subject of manifolds, we flow tested a chinese stainless manifold and std cast manifold and the stainless flowed 50% more! Then we spent 6 hours porting the std cast manifolds paying particular attention to the short turns and they flowed 46% more(4% less than the ebay ones). With the relability and heat retension properties of cast I know what I'll be using

Interesting again that one, many a car has made 380rwkw on stock manifolds here and for many years its been done, even more so on some setups (and fuel etc).

hmm.

unique1 - if 450rwhp is your goal, GT-SS/-7 will do it... but it'll virtually make boost on idle with the extra capacity as they spool early enough on my 2.6ltr thats choked up.

Gav - that graph still amazes me everytime i see it with the smaller puppies on there and a stroker - love it

[BoostdR]

There's another GT-R in Perth with an RB26/30 with -5s fitted (Silver 32 driven by Matt). A very strong car and heaps of midrange as you would expect.

Don't a direct dyno graph with what I have now and Chooka's old setup, but his response was close to the GT-RS, but with another 50hp or so up top.

To give you an idea, however, have a look at this link of my old setup with GT-RS terbs and the -5s on a lower boost runin tune

http://www.skylinesaustralia.com/forums/up...05_63_75621.jpg

The power difference now is probably only 40hp or so lower now that I've raised the boost and dialed in a bit more timing

Thanks for the info, what capacity engine was the dyno graph comlpeted on?

So you are currently making 534rwhp with the -5s on a 2.8ltr?