Jump to content
SAU Community

Recommended Posts

don't know to much about the rb motors but my wrx makes 320atw with a gt35.82 seeing full boost(25psi) at 4200rpm, I would have thought a 35r on 6 cylinder would be a good match and you would see full boost hitting alot earlier???

AGREED.

Pretty much the same situation with an 1992 VR4 RS.

320kw at the wheels, factory bottom end. GT3540, made 18psi at 4500rpm.

i think that a slightly bigger turbo or even the GT35.82 would be a near perfect matchup for the RB25

A GT3582R is definitely better than a GT3082R on an RB25 (or most things), one of my mates went from GT3082R to GT3582R on his EVO and the drive was much of a muchness - just made quite a bit more power. GT3076R is a fair bit of an improvement to drive, but a twin scroll GT3582R would be the dogs bollux I reckon.... if they were around when I was doing my turbo choosing I would have put a fair bit of consideration to one of those as an option.

Lasted 6 months... and the only reason it died was my laziness. Nothing else.

From my own experience, having a GT30 on my RB25, I think it is an excellent turbo. My car drives incredibly smoothe, power is incredible, delivery is excellent etc. But Mick at ovaboost would have to be the best RB tuner in WA. Tune is where its at! I'm sure any car would be a pig to drive with a poor tune.

From my own experience, having a GT30 on my RB25, I think it is an excellent turbo

Which GT30?

- Garrett GT3071R

- The GCG "GT3076R" with the .70a/r EC-1 compressor cover

- Garrett GT3076R with anti-surge compressor cover

- Garrett GT3082R

- some other combo?

They're all reasonably different beasts!

AGREED.

Pretty much the same situation with an 1992 VR4 RS.

320kw at the wheels, factory bottom end. GT3540, made 18psi at 4500rpm.

i think that a slightly bigger turbo or even the GT35.82 would be a near perfect matchup for the RB25

factory bottom end? thats a shipload of power for a standard bottom end, must of had some huge ass cams and only 18psi :D

don't know to much about the rb motors but my wrx makes 320atw with a gt35.82 seeing full boost(25psi) at 4200rpm, I would have thought a 35r on 6 cylinder would be a good match and you would see full boost hitting alot earlier???

EJ20?

Spool I very difficult one to compare as a result of gearing and how one tests where 'full boost' is.

My experience driving a few setups over the years...

GT35r .82 on an RB30DET top gear loaded up would see 17psi around 3100rpm.

Normal driving conditions in second gear leaving a corner it would punch hard around 3600rpm.

GT35r .82 on an RB25DET top gear loaded up would see 17-18psi around 3700-3800rpm.

Normal driving conditions in second gear leaving a corner it would punch hard around 4200rpm.

The biggest noticeable difference between the two setups was the 3ltr made more boost earlier providing a more linear power curve where as the 2.5ltr would go from what felt like nothing to everything.

your going to have to explain too restrictive to me. as in no top end?

It just limited the set-up overall.

Yes it'll bring on boost sooner, but the problem is the flow, you run into back-pressure in the turbine housing too soon when you take into account how much air the comp wheel flows.

It'll limit the amount of boost you can run so the turbo wont be making the most of what it possibly can.

If you wanted to go a .63, you are far better off with a hi-flow style R34/OP6 hi-flow of some description as the power output will be similar, response better.

This is all RB25/26 specific of course. Other motors, different dynamics

  • 4 months later...

Sorry to bring the post back up but I wanted to know if there was a difference in any aspect of the turbo if I get it with the S-style Anti-Surge compressor housing in/out is 4'' / 2''

Thanks for any info !!

Your calls but I would avoid the GT3082 like the plague - unless you can get the 50 trim compressor version which was the HKS spec one "GT3040" .

I cannot for the life of me see anything desirable about having a compressor wheel that's simply too big/much for the turbine to drive . The reason why they are lazy turbos is because they need a lot more exhaust gas energy (read higher WOT engine revs) to get them going .

I reckon if you need the sort of airflow that the 82mm GT40 compressor can pump then at least give it the GT35 turbine to drive it with .

I think its hard to go past a GT3076R on an RB25DET size wise , even these can be borderline laggy on the street but at least they are a reasonable wheel match and they are more than capable of frying road rubber .

There is no way I would accept a GT3082R for price reasons , I have and would not hesitate to pay more for the GT3076R knowing that it will give a better overall result and that's what makes you like driving your car on the street .

I know people think that HKS spec Garrett GT BB turbos have some sort of magic breathed into them but that's just garbage . What they did was have Garrett play around with wheel sizes and trims to optimize compressors to turbines so that they give good results on performance petrol engines . By good performance I mean a turbo that spools up and makes good engine torque over a reasonably wide range .

If you actually look at their spec turbos they often have a more minimalist approach particularly with compressor trims - look at these :

GT3071R - HKS 48/52/56T - Garrett 56T only . (HKS incorrectly called these GT2835 but they use a cropped GT30 turbine)

GT3076R - HKS 48/52/56T - Garrett 56T only .

GT3082R - HKS 50T - Garrett 56T only .

GT3540R - HKS 54T - Garrett 56T only . (HKS call their version GT3240 but the turbine is a cropped GT35 one)

Remember the pretty blue "Power and Response" tag ? Its because they aimed to make torque which is the thing that shoves you in the back .

I think GT3582R's are a real bitzer in that both ends don't use appropriate housings for their wheels , GT35 turbine in a GT30 turbine housing and GT40 compressor in a T04S compressor housing . I reckon it was all aimed at using biggish wheels in a small compact cartridge and ditto for the housings themselves .

I reckon its why you can sometimes achieve similar or better results using older T series BB turbos like the large frame BB T04 60-1 turbo . These use a T04 P trim turbine in a T04 turbine housing and a 76mm (3") T04 60-1 compressor in a T04S comp housing designed for a 76mm T04S compressor . Everything pretty much matches and you get 1001 T04 turbine housings in single/twin entry and T3/T4 mount flanges .

Years ago I saw someone that used a plain bearing P/60-1 turbo on a hotted up (head/cam/injectors) RB30ET Commode Door and he tore up the pavement everywhere on 10 pounds of boost . 1.00 AR TS T3 flanged T4 hsg BTW .

My bottom line for a street RB25 powered RWD car is a GT3076R , more than that equals more lag and you are beyond traction anyway .

A .

Edited by discopotato03

Well i am running a Garrett GT3071 By GCG . It runs the I/W Rear Housing with an A/R.82 Rear Housing and comes on full Boost at 3450 RPM and stays on the boost all the way to 7300 RPM . It's the only turbo i've put on my car but i would have to say its a very responsive street car and it does give you that big feeling when it comes on boost .

CHeck my post GT30RB for the dyno sheet

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now



  • Similar Content

  • Latest Posts

    • One thing I can tell you is, do it properly the first time. If you encounter unexpected problems just let the car sit for a week or two if you have to get some other parts or figure stuff out.  I'd have said go and use as many OEM parts as possible but since you want to change the turbo later on a custom kit is probably the better choice. Since I have no experience with RB25 just compare parts diagrams and images before buying a line kit and it should be easy to see if it has everything you need. Amayama has very good parts diagrams and part number lists, that is what I used a bunch to figure out what I might need. And don't forget to plan ahead and possibly renew other stuff that's easy to get to while you're in there doing the turbo lines. Happy wrenching
    • Update 4:   Hi all, good news. Engine is running and all the gaskets and seals seem to be working as intended. No leaks so far, even the JB Weld seems to hold. I flushed out the old coolant a few times and put in fresh coolant, not Nissan stuff, I decided to try the Ravenol Protect FL22, they claim it works for a wide variety of JDM cars and the opinions on it by some people were pretty good. And it has the nice poison green color! And man am I glad I bought a coolant system tester earlier this year, vacuum filling works wonders on this engine. I can definitely recommend this to anyone still doing it the old school way. All you need is compressed air supply. Will have to do a small test drive as soon as I can, I removed the gauge cluster again as the tacho needle was still bouncing around a bit but it was much better than before already.  I also found some cracks on all 4 tires inner and outer sidewalls. Apparently these tires should 't be parked on for extended periods or be kept under 0 degrees during storage, which I did not know. Clearly the previous owner didn't look into those details either, he probably bought them just cause they are cool semi-slicks. I'm just wondering how tf I am supposed to reach 30-80 degree tire temperatures on the public road consistenly, these tires were never going to work for my use case. I'll probably order Continental SportContact7 ones as these are the best allround summer tire available right now and I don't think I'll need anything crazier for now. Do let me know if you have experience with various tires and which ones you recommend.
    • You have no idea how many goddamn boxes I received these past three months haha Most have been put to use by now though, luckily
    • Not going to pretend I didn't do a bit of junky work this time around, but mostly due to the fact that some things I am not willing to spend days fixing right now, like wiring. I try to do most things properly the first time around.
    • Regardless of neglect or incompetence, fixing either is tedious and annoying. Most of the neglect on my car is definitely rust. I hope I can at least pass inspections later on and they won't fail the car due to slightly corroded hardlines. I was generous with rust converter and wax and it looks ok, most lines in the rear are hard to see properly anyways.  Definitely will test them though to make sure they don't rupture under pressure, in that case the car isn't going anywhere this year.
×
×
  • Create New...