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.
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