Rb28dett Turbo Choice.....

[Swiper the Fox]

Cheers for all the input guys.

I might look into GT-RS's then. I don't really fancy a big top mount. Even though they look sweeeet!

Mr DGarage, I remember reading somwhere that you run "modified" GT-RS's. Was that for response or for more top end??? who did them?

Do you have a dyno sheet posted up anywhere I can have a quiz at?

Cheers

Justin

Hi Justin,

The GT-RS's were just coated in ceramic...high temp black on the turbine side and ceramichrome on the compressor side. HKS 1.2bar actuators were swapped with the 0.8bar ones that come with them to stop boost creep. We set them to open at 17psi. min.

check in the 'dyno comparison tool', our pump fuel run-in tune for Newcastle Autosalon is posted in there. 20psi

any help you need just let me know

Paul

[Brockas]

we have a to4z on our circiut car...its laggier than the drag car and doesnt make the power, might be ok on a 2.8 ltr though.

Amazing the difference subtle changes in the setups make.

Simon's 2.6L + T04Z is on noise by 4k, makes 630rwhp.

Gav's 2.8L + GT-RS's was laggier and made 580rwhp.

Every 'big low mount twin' setup I've personally seen has been lazier than an equivalent big single setup (including my own).

Twins:

HKS GT-SS's (450-500rwhp ie. chris260's 2.6L)

Garrett 2860 -5's (500-550rwhp ie. Gav Beer's 2.8L)

Single:

GT35R (550-600rwhp ie. Jimmah's 2.6L)

T04Z (600-650rwhp ie. Simon's 2.6L)

IMO, these are the best setups for the desired power goals on a 26/28. Of course everyone is going to have a different opinion, but they're the only setups I've seen which have a reasonable trade off between response/power.

Edited July 7, 2008 by Brockaz

[XRATED]

Amazing the difference subtle changes in the setups make.

Simon's 2.6L + T04Z is on noise by 4k, makes 630rwhp.

Gav's 2.8L + GT-RS's was laggier and made 580rwhp.

Every 'big low mount twin' setup I've personally seen has been lazier than an equivalent big single setup (including my own).

Twins:

HKS GT-SS's (450-500rwhp ie. chris260's 2.6L)

Garrett 2860 -5's (500-550rwhp ie. Gav Beer's 2.8L)

Single:

GT35R (550-600rwhp ie. Jimmah's 2.6L)

T04Z (600-650rwhp ie. Simon's 2.6L)

IMO, these are the best setups for the desired power goals on a 26/28. Of course everyone is going to have a different opinion, but they're the only setups I've seen which have a reasonable trade off between response/power.

You do bring up some valid points.... There dose seem to be some comprimise for higher hp "standard position" turbo's. Exh and comp housings have size limitations, waste gate size limitation..

I don't see myself going to a single, however I'm now exploring mid size top mount, external gate options.

[Swiper the Fox]

You do bring up some valid points.... There dose seem to be some comprimise for higher hp "standard position" turbo's. Exh and comp housings have size limitations, waste gate size limitation..

I don't see myself going to a single, however I'm now exploring mid size top mount, external gate options.

ill bring up a valid point too...Justin your drag racing...why is it that no-one has got within cooee of my performance on the strip unless they have big single using anti-lag or launch control ignition cut to build boost. The RS's make plenty of power (500AWKW at only 25psi) you need to have the set-up right which is why some other cars fail to perform with them. The T04Z cars are where?? almost a second away. The RS's with a dogbox will see you possibly beat Mark Berry's low mount record. Go for it mate.

Edited October 8, 2009 by DiRTgarage

[XRATED]

Hey Paulie.... you are right. Results on the track speak louder than dyno sheets or opinion. It's hard to deny.

You'll have to pm me with your "secret recipie" for running good numbers with GT-RS's... ha ha ha

Has anyone seen/had any experience with twin TD06S L2 6cm turbos on a RB26/28??? I know it's a little far from "responsive" but it would be interesting.

J.

BTW. The origional post is inccorect, I have an HKS step 2 2.8 kit now... Not that it matters.

Edited October 10, 2009 by XRATED

[bradsm87]

Garrett GT4088R with a proper split pulse twin scroll manifold would win hands down for most responsive 450rwkw.

[XRATED]

Wow... I've been working on this turbo selection for a while "28 June 08- start of thread" ha ha ha.

It's still basically comming down to T618Z's Vs GT-RS's Vs 6cm TD06S L2 ...

Or an 8lt V10 Viper motor and twin 88mm turbo's...

[Strik3r]

Garrett GT4088R with a proper split pulse twin scroll manifold would win hands down for most responsive 450rwkw.

have you ever driven a car with a 4088? Or a car with 450rwkw? I dont understand why the hell you would recommend a 4088 for 450rwkw.

A t04z will make 450rwkw with room to spare and probably spool up nearly 1000rpm faster than a 4088.

[bradsm87]

have you ever driven a car with a 4088? Or a car with 450rwkw? I dont understand why the hell you would recommend a 4088 for 450rwkw.

A t04z will make 450rwkw with room to spare and probably spool up nearly 1000rpm faster than a 4088.

OK u keep ur turbo from the stone ages but a GT4088R with a proper sealed twin scroll manifold and twin wastegates will spool up faster than a T04Z and make more power. So many ppl follow the "proven" combos but times change and things improve but nobody wants to try because they've never seen a it and a dyno sheet on a forum.

Edited October 11, 2009 by bradsm87

[Lithium]

A t04z will make 450rwkw with room to spare and probably spool up nearly 1000rpm faster than a 4088.

Are you sure about spooling 1000rpm faster? Where did you get that idea? Admittedly I haven't been in a car running a GT4088R *YET* but everything I have seen and heard talking to people running them put them as a slightly quicker and smoother spool than a T04Z, and not too far dissimilar power.

[The Dan]

OK u keep ur turbo from the stone ages but a GT4088R with a proper sealed twin scroll manifold and twin wastegates will spool up faster than a T04Z and make more power. So many ppl follow the "proven" combos but times change and things improve but nobody wants to try because they've never seen a it and a dyno sheet on a forum.

Let's compare apples for apples and put the Z on a sealed twin scroll manifold with twin gates and see what differences there are. Or better still, I know of a stock 26 about to be tuned with a 4088 on a single pulse manifold and and we have the figures from the z's so it should be easy to compare right?

Wrong!

Different tuners, head work, manifold design, age of turbo, exhaust size will all change the result.

Have you done the comparison on equal grounds?

[Strik3r]

Are you sure about spooling 1000rpm faster? Where did you get that idea? Admittedly I haven't been in a car running a GT4088R *YET* but everything I have seen and heard talking to people running them put them as a slightly quicker and smoother spool than a T04Z, and not too far dissimilar power.

i was exaggerating.. the reality is probably more like 500-800rpm depending on what A/R you chose for the turbine. The 4088R is another frame size up from the t04z and will flow more HP.. at the cost of lag. There is no cheating the equation.

OK u keep ur turbo from the stone ages but a GT4088R with a proper sealed twin scroll manifold and twin wastegates will spool up faster than a T04Z and make more power. So many ppl follow the "proven" combos but times change and things improve but nobody wants to try because they've never seen a it and a dyno sheet on a forum.

Feel free to go prove me wrong chief. My dyno sheet is up in the 35r vs t04z discussion that you can dig up if you like. 620hp @ the wheels with 1 bar at 4000 rpm. Approx 500rpm laggier than a 35r, with about 100hp more than a 35r setup running similar boost.

[Lithium]

i was exaggerating.. the reality is probably more like 500-800rpm depending on what A/R you chose for the turbine. The 4088R is another frame size up from the t04z and will flow more HP.. at the cost of lag. There is no cheating the equation.

What I mean is do you have reference to numbers proving this or are you just assuming? Because of the physical frame size of GT4088Rs (and the somehow daunting sounding name) people seem to assume they are big laggy turbos. The T04Z's compressor is actually physically larger than the GT4088Rs, and of course an old T-series unit which if you believe the hype isn't as aerodynamically efficient - I know the GT4088Rs have been getting increasingly popular with Supra and RX7 owners Stateside for their nice power delivery.

RIPS is building a GTR with a GT4094R on an RB30 which should be interesting to compare with the T04Z RB30s he has built in the past, I expect the 94R to be a bit laggier as its a step in between the GT40R and GT42R but I would be surprised if it turns out 800rpm laggier than the T04Z setups. I wouldn't be too surprised if it isn't more than 500rpm laggier despite being the GT4088Rs big brother, it could be one to watch for big power with response RB fans - safe bet whatever it does a GT4088R will do with a bit less top end and a bit more response.

Edited October 11, 2009 by Lithium

[discopotato03]

In real terms most of what a GT4088R has is larger than a ball bearing T04R (T04Z) .

The actual center section is supposed to be the same size and the main difference bearing housing wise is that Garrett re machine the turbine end to take a T Series turbines housing with its crab plate mounting system . To mount GT Series turbine housing that bearing housing normally has four ears and bolts through them into the bearing housing .

Turbine wise the "Z" has a T04 P trim or I think 74 odd mm 76 trim .

The GT4088R is 77mm 78 trim GT wheel

Compressors , 84.4mm 63 trim R wheel vs 88mm 52 trim C117 . The trim of the 88's compressor is smaller than the smaller diameter R wheel but it has more blades to work with .

The other thing is that in non HKS form the T04Z uses a T04S sized compressor housing where the GT4088R goes up a backplate and housing size to GT40 .

I think what Garrett wanted from the GT4088R was good response and low restriction on the exhaust side . GT40 turbines and their matching housings are a size up from T04 P stuff and dimensionally more like TA45 gear only lighter and better aero wise . The 88's turbine is actually smaller at 78T than the diesel spec GT40 one which is 84T . It their native turbine housings (T4 international flanged twin scroll) they blow the doors off any T04 P trim system .

The real difference between the GT4088R and any other GT40 turbo is that C117 compressor wheel , you only have to look at its compressor map to see why .

So I'm told the secret to getting the most out of a GT4088R is to NOT use the smallest turbine housing made for it (0.84 A/R) , they seem to prefer the 1.06 A/R one and make good power at lower boost levels than they do with the 84 or 94 housings . They also seem to like a really well developed split pulsed exhaust manifold and a waste gate on each side .

The T04Z and plain bearing T04R are really just a T04 60-1 turbo with the R wheel substituted and the backplate/compressor housing machined to suit . Thats why thay have that iron backplate instead of a lighter aluminium one . HKS went to a bit more trouble with housings for their version of the Z turbo because they obviously thought it was a bit lacking with generic Garrett housings on it .

With the GT4094R Garrett used a 94mm GT compressor in an otherwise std GT4088R , again IMO too much compressor load for the turbine to drive and too much wheel size for a GT40's diffuser diameter and a GT40 compressor housing .

Rob must have his reasons for using one and its possibly that the 88R's compressor won't push as much air as he wants ATM . Possibly a GT4294R turbo with a turbine trim size like the 88R's 78T would have been better because from memory they are 84T and thats not the best thing for response in a turbo of that size on a three litre engine .

Garrett is a large group of companies world wide and the gears turn slowly with new developments - market driven . I think a lot of their turbos response issues could be solved if they offered a few trim sizes in the GT range , they have started with the GT4088R and the three GT37R diesel turbos but we need that 78T size in GT30/GT35/GT42 turbo ranges as well .

Some say that the GT4094R is a step backwards because they speced the 77mm GT40 78T turbine to drive that 88mm C117 compressor then go stick a 94mm compressor on the other end of it . A bit like having a diff ratio set up for a cars power and mass and then hooking up a loaded trailer to it .

Anyway I reckon a properly set up GT4088R is a better thing than a T04Z but they cost more to set up properly . The Z turbo tends to be a bit easier to get response from (for less money) but doesn't give the same overall result even if their maximums can be similar . It sounds like HKS housings get the most from the Z turbo but your'e spending big money again .

Super power with good response is rarely ever cheap , A .

[old mate]

wow u sure do know alot about turbos.

[Lithium]

Robs turbo choice may have actually been a customer's turbo choice. The catch with choosing turbos is also that sometimes the "optimal" combination of bits isn't always the major decider, given cost/options/preferred "drive" may have a weighting on it too.

If a GT4094R makes a reasonable amount more power than a GT4088R, with a fair amount better spool than a GT4294R when the user wants something that fits in between - what existing alternatives would you recommend DP, theoretical mismatch aside?

The difference in lag between a GT4088R and a GT4094R is a lot more trivial than that between a GT4294R and a GT4088R, that has been well proven. I always have often felt (though still trying to learn about the things) that given the GT4088R's turbine flows a fair bit more than the T67-BB's P-trim yet the compressor doesn't pump quite as aggressively, that the turbine could possibly take a bit more compressor when used on a smaller (than the diesels it would be used to) motor? The 94mm is "just" a 52trim, remember...

[discopotato03]

If I was trying to get between a GT4088R and a GT4294R (assuming there is room to fit the larger turbo) there is a few avenues to look in .

I don't remember off the top of my head the dimensions of the T51R's compressor and turbine but def worth a look . If you wanted to go inside and could get the bits maybe a GT4294R with the 52 trim compressor wheel .

You could also look at some of the emerging BW amnd Holset turbos because at times they are viable alternatives to Garrett units .

BTW the reason I don't like the idea of the 94mm GT compressor in the GT40 housing and backplate is because the set is designed to work with a set wheel diameter (88mm) and to machine it out for the 94mm wheel means reducing the effective diffuser area inside the comp housing . Same deal with the GT3540R (GT3582R)'s compressor in the T04S housing/backplate . These are bean counters decisions not engineers ones , I'm not saying they don't work at all but I am saying their performance is compromised . The real issue is pressure balance across the engine while the compromises involve try to spin the turbo up from low revs and light loads .

I did read that he was building 3.3L RB engines from RB30's and you'd think that if everything including the fuel and tune was spot on it would fire up a GT4294R ok .

BTW don't get sucked in by the American urban myth of that T04R compressor wheel being a "T67" , I think from memory its inducer measures ~ 66.7mm and the Americans truly love inducer size and don't seem overly worried about a compressors major diameter .

To put you in the picture these are some figures of inducer and major or "exducer" diameters .

GT3582R - 82mm 56T GT40 wheel - 61mm inducer .

T04Z® - 84mm 63T T04R wheel - 66.7mm inducer .

GT4088R - 88mm 52T C117 wheel - 63.5mm inducer .

GT4094R - 94mm 52T GT wheel ---- 67.8mm inducer .

GT4294R - 94mm 56T GT wheel ---- 70.3mm inducer .

I think I did search before and the T51R's may have a slight advantage over the GT42R's because of its turbine trim which from memory is 56T , older aero wheel design but supposedly better response through a smaller than 84T sized exducer diameter . Note what I mentioned before about the GT4088R's 78T turbine which is why its response is closer to a 76T P trim turbine in a T04Z . I think you can even buy T51BB turbos through Garrett these days but naturally without HKS's specialised housings .

Anyhow all this aside it does make a pair of GTRS's look easy especially with their integral waste gates and simplified twin manifolds . Possibly for a little more response and a bit less top end you could use the 48 compressor trim version of that cartridge - GT2871R 48T . Would all come back to engine size and how well it breathes I spose .

My money on GTRS's , cheers A .

[Swiper the Fox]

If I was trying to get between a GT4088R and a GT4294R (assuming there is room to fit the larger turbo) there is a few avenues to look in .

I don't remember off the top of my head the dimensions of the T51R's compressor and turbine but def worth a look . If you wanted to go inside and could get the bits maybe a GT4294R with the 52 trim compressor wheel .

You could also look at some of the emerging BW amnd Holset turbos because at times they are viable alternatives to Garrett units .

BTW the reason I don't like the idea of the 94mm GT compressor in the GT40 housing and backplate is because the set is designed to work with a set wheel diameter (88mm) and to machine it out for the 94mm wheel means reducing the effective diffuser area inside the comp housing . Same deal with the GT3540R (GT3582R)'s compressor in the T04S housing/backplate . These are bean counters decisions not engineers ones , I'm not saying they don't work at all but I am saying their performance is compromised . The real issue is pressure balance across the engine while the compromises involve try to spin the turbo up from low revs and light loads .

I did read that he was building 3.3L RB engines from RB30's and you'd think that if everything including the fuel and tune was spot on it would fire up a GT4294R ok .

BTW don't get sucked in by the American urban myth of that T04R compressor wheel being a "T67" , I think from memory its inducer measures ~ 66.7mm and the Americans truly love inducer size and don't seem overly worried about a compressors major diameter .

To put you in the picture these are some figures of inducer and major or "exducer" diameters .

GT3582R - 82mm 56T GT40 wheel - 61mm inducer .

T04Z® - 84mm 63T T04R wheel - 66.7mm inducer .

GT4088R - 88mm 52T C117 wheel - 63.5mm inducer .

GT4094R - 94mm 52T GT wheel ---- 67.8mm inducer .

GT4294R - 94mm 56T GT wheel ---- 70.3mm inducer .

I think I did search before and the T51R's may have a slight advantage over the GT42R's because of its turbine trim which from memory is 56T , older aero wheel design but supposedly better response through a smaller than 84T sized exducer diameter . Note what I mentioned before about the GT4088R's 78T turbine which is why its response is closer to a 76T P trim turbine in a T04Z . I think you can even buy T51BB turbos through Garrett these days but naturally without HKS's specialised housings .

Anyhow all this aside it does make a pair of GTRS's look easy especially with their integral waste gates and simplified twin manifolds . Possibly for a little more response and a bit less top end you could use the 48 compressor trim version of that cartridge - GT2871R 48T . Would all come back to engine size and how well it breathes I spose .

My money on GTRS's , cheers A .

Wow Adrian, you certainly are the turbo chronicle...or should that be oracle...the most important bit you left for last.

Edited October 12, 2009 by DiRTgarage

[9krpm]

discopotato03, how does the GTRS compare to the Greddy T618Z turbo?

On my rb26/30 the T618z starts to produce boost at around 2.2krpm and reached max torque at 4.7krpm.

I am still tinkering with the cams and the tune is not finished yet. I am hoping to shift the torque curve by 1000rpm earlier.

I would love to have a set of GTRS to test. Some people reckonds that they might be more responsive and produce more top end power, but I am not too sure looking at their specs. The only difficulty with these low mount turbos is that they will take a good day + evening to change them

[XRATED]

I'd like to see that test too....

T618Z V's GT-RS