Jump to content
SAU Community

Recommended Posts

Did a fair bit of searching and couldn't come up with anything about running two SR20 turbos on an RB26.

I know that the GTR uses a compact 5bolt pattern that is not compatible with the regular 5bolt pattern.

I'm assuming there would be clearance issues between the front dump and the rear inlet trying to use regular SR20 dumps?

I'm hoping that with all the aftermarket twin turbo kits getting around that there are GTR dumps designed to suit the regular 5 bolt pattern?

Anyone have any ideas? Otherwise I'll just get some GTR dumps and having the flanges changed over.

Link to comment
https://www.sau.com.au/forums/topic/284159-two-sr20-turbos-on-rb26/
Share on other sites

Send in your stock GTR turbos we can high flow GTRS CHRA into them and every thing bolts back. Lot better then SR20turbos. Also stock SR20 turbos are running off .64 rear and 270 degrees thrust. Plus nothing fits. But if you really want to run SR20 CHRAs we can machine your housings to suit it so every thing bolt on no fibrications required.

Not really keen on spending that much money for highflowed turbos.

What is wrong with .64 rear housings? I thought SR20 turbos were ball bearing (eliminating the need for thrust bearings). What else is there that will not fit?

Machining housings to suit sounds like a bit more work than perhaps 1 custom dump pipe?

only S15 Jap Spec SR20 enignes has Ball bearing T28 turbo. By the time you get the turbos, with customized dump and intake pipes made you probably be spending the same amount as highflowing. plus most of them are 10 years old and will be very laggy to run on standard Twin GTR setup.

Did a fair bit of searching and couldn't come up with anything about running two SR20 turbos on an RB26.

I know that the GTR uses a compact 5bolt pattern that is not compatible with the regular 5bolt pattern.

I'm assuming there would be clearance issues between the front dump and the rear inlet trying to use regular SR20 dumps?

I'm hoping that with all the aftermarket twin turbo kits getting around that there are GTR dumps designed to suit the regular 5 bolt pattern?

Anyone have any ideas? Otherwise I'll just get some GTR dumps and having the flanges changed over.

lot of other issues to contend with other than the dump flange. dont know why you would want to run such crap turbos to begin with (they are good for scrap metal only), gtr turbos second hand are the same price anyways.

Edited by URAS

Your call but not as easy as it first appears . Like people have said nothing fits - except the turbine housings mounting flange and even then I thought GTR GT28 turbine housings were threaded for either studs or through bolts .

The bottom line is that even the factory twin turbos and associated plumbing is all up close and cuddly - and that's with factory engineering .

SR20 GT28 turbos or rather their housings are not even close to what RB26 spec GT25 or GT28 turbos use , they won't position the turbos or their plumbing where everything needs to be - note the "eye" holes on the bottom of GTR spec turbos compressor housings , SR spec or generic comp housings don't have them .

As I said your call but the best minimalist approach (IMO) would be to fit fresh cartridges between the std housings even if that means machining them to suit .

No offense but I wouldn't go near a "budget" RB26 with GTRS/GT2871R cartridges , I would NOT machine the std 26's small comp covers to suit 71mm compressors - too small and defeats the whole purpose IMO .

May seem expensive but really bolt on turbos like the GT2859R's are good things , unfortunately I don't think their cartridges are available separately which is a shame .

You can't really cut corners with bastard twin turbos - way too much time and money involved proving that it doesn't work . Nissan didn't just throw a couple of generic dryers on RB26's , it's not as easy as designing a single system but does have advantages .

Over to you , cheers A .

Your call but not as easy as it first appears . Like people have said nothing fits - except the turbine housings mounting flange and even then I thought GTR GT28 turbine housings were threaded for either studs or through bolts .

The bottom line is that even the factory twin turbos and associated plumbing is all up close and cuddly - and that's with factory engineering .

SR20 GT28 turbos or rather their housings are not even close to what RB26 spec GT25 or GT28 turbos use , they won't position the turbos or their plumbing where everything needs to be - note the "eye" holes on the bottom of GTR spec turbos compressor housings , SR spec or generic comp housings don't have them .

As I said your call but the best minimalist approach (IMO) would be to fit fresh cartridges between the std housings even if that means machining them to suit .

No offense but I wouldn't go near a "budget" RB26 with GTRS/GT2871R cartridges , I would NOT machine the std 26's small comp covers to suit 71mm compressors - too small and defeats the whole purpose IMO .

May seem expensive but really bolt on turbos like the GT2859R's are good things , unfortunately I don't think their cartridges are available separately which is a shame .

You can't really cut corners with bastard twin turbos - way too much time and money involved proving that it doesn't work . Nissan didn't just throw a couple of generic dryers on RB26's , it's not as easy as designing a single system but does have advantages .

Over to you , cheers A .

Off topic but since you mentioned the whole twin v single thing... In your opinion is it worth going twin scroll single or twins...?

I was contemplating getting stock 26 turbos and getting them highflowed, really want about 330-350kw... (Want the maximum response for that power goal) other option i was considering was the gt3076?

PS: This is a 3ltr bottom end.

sorry to drag off topic a bit.

Put the .64 turbos on and see >_<

It's similar to runnning a 1.06 rear or larger - ie fken laggy.

If you are not chasing 450rwkw+ with twins, you do not put .64 rears on.

Wat u on about man? ALL of the aftermarket twins from GT-SS to GT2835 ALL have .64 housings and i think stock turbos do also.

Well originally I was going to go with R34 N1 turbos. Checked the specs on turbobygarrett.com and they come pretty close to the GT2560 (OEM SR20 turbo). Should've specified that they're going on a 25/30 engine but wasn't expecting this to turn into a turbo selection thread.

Stock GTR turbos have .48 rear housings which i think would be a bit restrictive on an RB30

I'd prefer a twinscroll single over the twins but you also have to factor in a twin scroll manifold.

"You can't really cut corners with bastard twin turbos - way too much time and money involved proving that it doesn't work . Nissan didn't just throw a couple of generic dryers on RB26's , it's not as easy as designing a single system but does have advantages" .

In a nut shell the big advantage of the twins is low exhaust manifold pressure and the pulse division of the engines front and rear three cylinders . It can be done with a larger single turbocharger but very few are available that achieve the same thing with integral waste gating .

Anyway the original poster seems to want to get his power ask from a quite low budget and I don't think that's possible with a GTR/RB26 .

The trouble with those engine , so I'm told , is that they don't have enough capacity to drag a GTR's bulk around especially if your trying to use boost for torque early in the engines rev range . Same basics apply , smallish turbos come on early for lets get going torque then run out of gas flow capacity and lose out up high .

You can have the power ask 300-350 (actually TORQUE ask) but don't cry if it won't be pulling at 8000 revs . You just can't have it both ways .

Maybe in a perfect world the GTR's would have come with 4WD RB30 bottom ends , you very probably could have got away with a far simpler single scroll single turbo and used the capacity to cover the lack of low down torque in the 2558cc RB"26" . But Nissan didn't , something to do with turbo multiplication effective capacity and the weight class they could run in with Grp A . Fine for a race car but race cars don't tool around at lowish revs like road cars do , history shows that they blitzed the field - on the race track . In this case the homologation factors bit the roadies on the bum .

There is nothing cheap and simple about GTR's , I think simplest and cheapest with them is to use good bolt on twin turbos because you keep 95% of the parts around them and look standard . The thing is to have a set goal and not change that part way through the build . Built something PRACTICLE that is USABLE and let the heroes live with the laggy intractable pig . Do it once do everything at the same time ie head /cams / manifold matching etc and live with the result .

A .

Well originally I was going to go with R34 N1 turbos. Checked the specs on turbobygarrett.com and they come pretty close to the GT2560 (OEM SR20 turbo). Should've specified that they're going on a 25/30 engine but wasn't expecting this to turn into a turbo selection thread.

Stock GTR turbos have .48 rear housings which i think would be a bit restrictive on an RB30

I'd prefer a twinscroll single over the twins but you also have to factor in a twin scroll manifold.

I'm looking at the same path as you. only difference being the head which is a 26. This car is primarily for drift so i'm not after too much top end. Origionally looked at highflow the stockers, twin r32 gtst highflows (as i have one and another one available for cheapo) and then started looking in to maybe just biting the bullet and going single; GT3076, 35r, t04z... quite a difference in power bands and after reading some conflicting things over the last two i was almost set.

What car is your motor going in? my whole car with the 2630 should weigh in around <1200kg (silvia) so i was inclined to go for a slightly larger turbo with maybe some diff gears off around 4.11 or 4.36 which is another ball park...

I'v never even had the chance to drive in a 26/30 which is why other peoples experiences are a big help!!! I think you should ditch the idea of sr20 twins and look for a proven combo (when i work out what that is....)

until then, suggestions people?

Edited by GT-RZ

If you are going to use twin R32 gtst highflows you'll need either to change the housing or the manifolds (or an adaptor) because they use different flanges.

I know that the easiest path would be use a standard RB25 manifold and a single turbo, but I've got my heart set on this idea. I figure worse case scenario I get it all together and it's a pile of crap I can always pull it off and change it to something else.

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

    • Thanks, I removed the fuse and the relay from the car and made my own circuit with them to test them with a test bulb.  I will look for the wiring diagram and go from there.
    • Jdm DC2R is also nice for a FF car compared to the regular hatches of the time.
    • Now that the break-in period for both clutch and transmission is nearly over I'd like to give some tips before I forget about everything that happened, also for anyone searching up how to do this job in the future: You will need at least 6 ton jack stands at full extension. I would go as far as to say maybe consider 12 ton jack stands because the height of the transmission + the Harbor Freight hydraulic platform-style transmission jack was enough that it was an absolute PITA getting the transmission out from under the car and back in. The top edge of the bellhousing wants to contact the subframe and oil pan and if you're doing this on the floor forget about trying to lift this transmission off the ground and onto a transmission jack from under the car. Also do not try to use a scissor jack transmission lift. You have to rotate the damn thing in-place on the transmission jack which is hard enough with an adjustable platform and a transmission cradle that will mostly keep the transmission from rolling off the jack but on a scissor lift with a tiny non-adjustable platform? Forget it. Use penetrating oil on the driveshaft bolts. I highly recommend getting a thin 6 point combination (box end + open end) wrench for both the rear driveshaft and front driveshaft and a wrench extension. These bolts are on tight with very little space to work with and those two things together made a massive difference. Even a high torque impact wrench is just the wrong tool for the job here and didn't do what I needed it to do. If your starter bolts aren't seized in place for whatever reason you can in fact snake in a 3/8 inch ratchet + 6 point standard chrome socket up in there and "just" remove the bolts for the starter. Or at least I could. It is entirely by feel, you can barely fit it in, you can barely turn the stupid ratchet, but it is possible. Pull the front pipe/downpipe before you attempt to remove the transmission. In theory you don't have to, in practice just do it.  When pulling the transmission on the way out you don't have to undo all the bolts holding the rear driveshaft to the chassis like the center support bearing and the rear tunnel reinforcement bar but putting the transmission back in I highly recommend doing this because it will let you raise the transmission without constantly dealing with the driveshaft interfering in one way or another. I undid the bottom of the engine mount but I honestly don't know that it helped anything. If you do this make sure you put a towel on the back of the valve cover to keep the engine from smashing all the pipes on the firewall. Once the transmission has been pulled back far enough to clear the dowels you need to twist it in place clockwise if you're sitting behind the transmission. This will rotate the starter down towards the ground. The starter bump seems like it might clear if you twist the transmission the other way but it definitely won't. I have scraped the shit out of my transmission tunnel trying so learn from my mistake. You will need a center punch and an appropriate size drill bit and screw to pull the rear main seal. Then use vice grips and preferably a slide hammer attachment for those vice grips to yank the seal out. Do not let the drill or screw contact any part of the crank and clean the engine carefully after removing the seal to avoid getting metal fragments into the engine. I used a Slide Hammer and Bearing Puller Set, 5 Piece from Harbor Freight to pull the old pilot bearing. The "wet paper towel" trick sucked and just got dirty clutch water everywhere. Buy the tool or borrow it from a friend and save yourself the pain. It comes right out. Mine was very worn compared to the new one and it was starting to show cracks. Soak it in engine oil for a day in case yours has lost all of the oil to the plastic bag it comes in. You may be tempted to get the Nismo aftermarket pilot bearing but local mechanics have told me that they fail prematurely and if they do fail they do far more damage than a failed OEM pilot bushing. I mentioned this before but the Super Coppermix Twin clutch friction disks are in fact directional. The subtle coning of the fingers in both cases should be facing towards the center of the hub. So the coning on the rearmost disk closest to the pressure plate should go towards the engine, and the one closest to the flywheel should be flipped the other way. Otherwise when you torque down the pressure plate it will be warped and if you attempt to drive it like this it will make a very nasty grinding noise. Also, there is in fact an orientation to the washers for the pressure plate if you don't want to damage the anodizing. Rounded side of the washer faces the pressure plate. The flat side faces the bolt head. Pulling the transmission from the transfer case you need to be extremely careful with the shift cover plate. This part is discontinued. Try your best to avoid damaging the mating surfaces or breaking the pry points. I used a dead blow rubber hammer after removing the bolts to smack it sideways to slide it off the RTV the previous mechanic applied. I recommend using gasket dressing on the OEM paper gasket to try and keep the ATF from leaking out of that surface which seems to be a perpetual problem. Undoing the shifter rod end is an absolute PITA. Get a set of roll pin punches. Those are mandatory for this. Also I strongly, strongly recommend getting a palm nailer that will fit your roll pin punch. Also, put a clean (emphasis on clean) towel wrapped around the back end of the roll pin to keep it from shooting into the transfer case so you can spend a good hour or two with a magnet on a stick getting it out. Do not damage the shifter rod end either because those are discontinued as well. Do not use aftermarket flywheel bolts. Or if you do, make sure they are exactly the same dimensions as OEM before you go to install them. I have seen people mention that they got the wrong bolts and it meant having to do the job again. High torque impact wrench makes removal easy. I used some combination of a pry bar and flathead screwdriver to keep the flywheel from turning but consider just buying a proper flywheel lock instead. Just buy the OS Giken clutch alignment tool from RHDJapan. I hated the plastic alignment tool and you will never be confident this thing will work as intended. Don't forget to install the Nismo provided clutch fork boot. Otherwise it will make unearthly noises when you press the clutch pedal as it says on the little installation sheet in Japanese. Also, on both initial disassembly and assembly you must follow torque sequence for the pressure plate bolts. For some reason the Nismo directions tell you to put in the smaller 3 bolts last. I would not do this. Fully insert and thread those bolts to the end first, then tighten the other larger pressure plate bolts according to torque sequence. Then at the end you can also torque these 3 smaller bolts. Doing it the other way can cause these bolts to bind and the whole thing won't fit as it should. Hope this helps someone out there.
×
×
  • Create New...