Twin Or Single? Please Help..!

[LaurelPWR]

I have an IHI twin turbo set off two different WRX engines for an rb25/30 build im doing for my drift car. I was told by the guy who was running it he was making just shy of 300rwkw on an rb25 with fairly good response. He also told me they would in theory be even more responsive on an rb25/30 because of the 3L bottom end and because I’m using a 6 throttle RB26 inlet manifold. The manifolds that came with the head and turbos are way too high and so I asked 6boost to make me some new ones. He then told me -

Do you want to do this to be different?? Or to make power, or think it'll spool earlier?? As my best advise would be to sell it and go single, GT35 will make more power and out spool it, look neater and be less hassle, however if you must have twin manifolds, they would be $1400inc and take 1 week to build for you.

And I said -

hi mate,

I was told these came off a built rb25 and made just shy of 300rwkw. I was also told, because I’m putting them on a RB25/30 they will spool faster then on the RB25. I’m only after a solid 300rwkw. I’ve always liked the idea of twins, (not trying to be different) but it was always too much hassle and money to go that way. I was going to go the GT35 and then I found the head on eBay for real cheap. The turbo's are in immaculate condition (almost new). I’m also putting a 6-throttle RB26 inlet manifold on the NEO head to improve response.

Do you think these ideas and info sound plausible?

And he said -

The twins will definitely spool slower than a single GT35. Even on an RB26, a GT35 with .82 spool FASTER than the STOCK twins, and makes more power than the biggest bolt on style turbo's the HKS 25/40's, which it out spools these by 1500rpm. The old myth that twins spool earlier is from 10 years ago when single turbo technology was in the 70's still, yet smaller style T28 stuff had been vastly improved. If you’re after response, IMO, the worst thing you could do it fit twins.

Same goes for the 6 throttle intake manifold. They lose about 500rpm of spool; Zoom back to back tested it years ago and found they lost massive midrange. I have found the same thing comparing a GReddy style RB25 intake to a stock intake with top half style plenum. The short runners of either a GReddy or RB26 manifold is what kills the bottom end torque and hence spool. The best possible spool combination you could possibly fit to this engine is the stock lower runners, a Plazmaman top half plenum, and a GT35 with .82 rear. With the VCT connected, you should have 20psi by 3400rpm, and make 300rwkw on 16-18psi, if the engine is built with rods and pistons, you'll make 350-380rwkw on 20-22psi pump fuel no stress at all.

So can some one pleas clarify this for me?? And please tell me what is true.

[atta

chment=237597:5.jpg]

[R31Nismoid]

If it was making '300rwkw' on a RB25 it would have been on around 3500rpm mark give/take (IMO possibly close to the 4000rpm marker)

Now add in two of them, and only another 500cc - you are not going to see it any better than at least 4500-5000rpm IMO.

Its all pretty much guess work of course because of the unknown spec of the turbos (you other thread said they were hi-flowed?)

Basically forget whatever he was telling you, most of what you have posted above is wrong mate.

2540's are NOT the biggest bolt on's, in fact they are a horrid horrid turbo that HKS should never have sold.

Also im not really sure where you say a 6 T/B setup hurts spool and performance... first i've heard of it.

At the end of the day - two simple questions for you.

How much power do you want?

What is the budget for new turbos?

Answer that - the rest is easy for everyone.

[joeyjoejoejuniorshabadoo]

[NYTSKY]

GT35R will make an easy 300rwkw and be somewhat responsive with the 30 bottom end.

Also cheaper:

1x Set of lines

1x Oil drain

1x Dump pipe

1x Intake

Id say go single.

[MrStabby]

If it was making '300rwkw' on a RB25 it would have been on around 3500rpm mark give/take (IMO possibly close to the 4000rpm marker)

Now add in two of them, and only another 500cc - you are not going to see it any better than at least 4500-5000rpm

The way i read what he said the twin system was making the 300, not a single.

Extra capacity will make the thing spool faster no doubt, but since you dont know how they spool now this doesnt tell you much.

If it were me and my money;

- I sort of like the idea of being a bit different but i'd only try this setup IF

1. you can verify that the turbos are a sensible size

2. you use the manifold you have. I dont see that buying this setup is worth it if you just going to throw the manifold away

- the 26 manifold/throttles probably arent worth the extra cost for only 300kw

- single vs twin is largely a wank - as long as you get something that's sized correctly for your power goal you'll be happy.

That guys style of discussion sets off alarms for me.

[discopotato03]

I dread to think what that er collection would weigh let alone how it would fit in an engine bay - sheesh .

Firstly WRX turbos are designed to work on a 2L four with a badly screwed up firing order in relation to the exhaust headers layout . The boxershi - er pistons motor fires the adjacent cylinders in each bank before going to the other bank and because the headers go two into one just down stream of each head the exhaust pulsing is all wrong . This is why Rexes make that stupid off cadence "Boxer Burble" especially when Roger Racer pinches the stink pipe off thye side of the house and makes a automotive farter out of it ...

People here are getting 300 Kw out of a GT3076R on - wait for it - the factory RB25 exhaust manifold .

I don't agree with the less torque / "spool" with the GTR inlet system . What they do is let pressure rise very quickly in the cylinders when you bang them open and if there is enough fuel hosed it to keep the AFR's about right then theres a bit more exhaust being produced to help drive the turbo/s into boost . Throttle response and turbine response are not the same thing but they can be better match with a bit of thought put into it .

I find it hard to be objective about the drift world and I wouldn't waste a Skyline or an RB doing it .

Better I think with an AE86 Sprinter or even an old T18 because they are lighter in the bum as well as overall , sort of narrow track to wheelbase ratio and maybe better to steer with the throttle .

I'm sure 6Boost will take your money if you want him to but I reckon it's good money after bad .

Start again , cheers A .

[R31Nismoid]

The way i read what he said the twin system was making the 300, not a single.

Extra capacity will make the thing spool faster no doubt, but since you dont know how they spool now this doesnt tell you much.

If it were me and my money;

- I sort of like the idea of being a bit different but i'd only try this setup IF

1. you can verify that the turbos are a sensible size

2. you use the manifold you have. I dont see that buying this setup is worth it if you just going to throw the manifold away

- the 26 manifold/throttles probably arent worth the extra cost for only 300kw

- single vs twin is largely a wank - as long as you get something that's sized correctly for your power goal you'll be happy.

That guys style of discussion sets off alarms for me.

hrm true - if he was though, just looking @ the sheer size of the comp housing and wheels... i can't see how its going to be all that responsive

Everyone gauges 'response' differently. Some are fine with power coming on @ 5000rpm as it makes them feel like they have a fast car

[STATUS]

totally useless setup for drift.

[Cjmartz2k]

Just one thing about the GTR intake/ITB's set up. It's a short runner intake design and is better at high end flow than low end torque. The ITB's produce better throttle response, not better low end power. Their is a world of difference between those two and most people mistakenly consider them one and the same.

[STATUS]

I have an IHI twin turbo set off two different WRX engines for an rb25/30 build im doing for my drift car. I was told by the guy who was running it he was making just shy of 300rwkw on an rb25 with fairly good response. He also told me they would in theory be even more responsive on an rb25/30 because of the 3L bottom end and because I’m using a 6 throttle RB26 inlet manifold. The manifolds that came with the head and turbos are way too high and so I asked 6boost to make me some new ones. He then told me -

Do you want to do this to be different?? Or to make power, or think it'll spool earlier?? As my best advise would be to sell it and go single, GT35 will make more power and out spool it, look neater and be less hassle, however if you must have twin manifolds, they would be $1400inc and take 1 week to build for you.

And I said -

hi mate,

I was told these came off a built rb25 and made just shy of 300rwkw. I was also told, because I’m putting them on a RB25/30 they will spool faster then on the RB25. I’m only after a solid 300rwkw. I’ve always liked the idea of twins, (not trying to be different) but it was always too much hassle and money to go that way. I was going to go the GT35 and then I found the head on eBay for real cheap. The turbo's are in immaculate condition (almost new). I’m also putting a 6-throttle RB26 inlet manifold on the NEO head to improve response.

Do you think these ideas and info sound plausible?

And he said -

The twins will definitely spool slower than a single GT35. Even on an RB26, a GT35 with .82 spool FASTER than the STOCK twins, and makes more power than the biggest bolt on style turbo's the HKS 25/40's, which it out spools these by 1500rpm. The old myth that twins spool earlier is from 10 years ago when single turbo technology was in the 70's still, yet smaller style T28 stuff had been vastly improved. If you’re after response, IMO, the worst thing you could do it fit twins.

Same goes for the 6 throttle intake manifold. They lose about 500rpm of spool; Zoom back to back tested it years ago and found they lost massive midrange. I have found the same thing comparing a GReddy style RB25 intake to a stock intake with top half style plenum. The short runners of either a GReddy or RB26 manifold is what kills the bottom end torque and hence spool. The best possible spool combination you could possibly fit to this engine is the stock lower runners, a Plazmaman top half plenum, and a GT35 with .82 rear. With the VCT connected, you should have 20psiby 3400rpm, and make 300rwkw on 16-18psi, if the engine is built with rods and pistons, you'll make 350-380rwkw on 20-22psi pump fuel no stress at all.

So can some one pleas clarify this for me?? And please tell me what is true.

Hmmmm... not likely

lets pluck some numbers

Edited August 1, 2009 by URAS

[zebra]

I would personally just go a ext Gate 3076, Nytsky's dyno results prove that they are capable of 35R type power with way better response.

URAS - Check your Pms too btw

[LaurelPWR]

Thanks for the info and criticism guys.

[Strik3r]

The best possible spool combination you could possibly fit to this engine is the stock lower runners, a Plazmaman top half plenum, and a GT35 with .82 rear. With the VCT connected, you should have 20psiby 3400rpm, and make 300rwkw on 16-18psi, if the engine is built with rods and pistons, you'll make 350-380rwkw on 20-22psi pump fuel no stress at all.

Hmmmm... not likely

lets pluck some numbers

errm.. on a 25/30 with VCT i think 20psi by 3400 isn't too far off the mark..... the power figures he is quoting are also pretty consistant with the other results I have seen on 35r's....

I think that someone who designs and builds manifolds every day might know what he is talking about.

[mico]

i was told the exact same by kyle, and he is right 4 sure. with 1 of HIS manifolds u will see the figures he has stated.

[LaurelPWR]

so because i already have all the parts mentioned above, if i kept this set up and still went with this style of build, would i uase a RB26 or RB25 ecu??

[zebra]

what ECU? PFC, Haltech, micro guess, Link etc etc??????

[LaurelPWR]

what ECU? PFC, Haltech, micro guess, Link etc etc??????

i was looking at a D-Jetor POWER FC +Hand Set for about 1250

[zebra]

well if you want that, then there is no other option than the rb26 one

[LaurelPWR]

well if you want that, then there is no other option than the rb26 one

yeah thats what i thought ay. so will the rb26 one still run okay a rb25/30 engine?

[LaurelPWR]

done a little research and found that the turbos are - Make=IHI, Model=RHB52, Compressor trim=VF10

these turbos came off two differant subaru liberty/legacy 1989-1994 models.