Two Sr20 Turbos On Rb26

[daisu]

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.

[hypergear]

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.

[daisu]

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?

[R31Nismoid]

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.

[kwickr33]

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.

[STATUS]

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 August 19, 2009 by URAS

[discopotato03]

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 .

[GT-RZ]

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.

[paulr33]

twin scroll on an sr20 properly setup would beat a pair of mangled twins on it

[bradsm87]

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.

[R31Nismoid]

hrm... nfi what i was thinking... mine do have .64's actually... oops

[STATUS]

twin scroll on an sr20 properly setup would beat a pair of mangled twins on it

haha now im confused... insert RB26 here.

[daisu]

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.

[discopotato03]

"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 .

[GT-RZ]

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 August 20, 2009 by GT-RZ

[daisu]

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.