Maximum Response Setup For Rb25

[Dan_J]

That's certainly surprising, is that including the swap to external gate?

Currently deciding if I should bother with 6boob and gate for 280kw

hypergear has done the tests him self, larger ID exhaust manifold pipe will lead to more lag but better top end power, but not a huge amount mind you

[owen1r]

hypergear has done the tests him self, larger ID exhaust manifold pipe will lead to more lag but better top end power, but not a huge amount mind you

Just had a read, the difference in response is only a couple of hundred rpm. Doesn't seem to be worth the $1000++ at 300kw power level for an extra 10-20kw on top of the stock mani.

Edited February 4, 2015 by owen1r

[Chris32]

Cool thread, kinda along the lines of what I'm doing - subscribed and will share my results along the way

Hoping for a close to stock response 230-240kw, which will be exactly what I'm after

My setup will be -

HKS 2535 turbo, hoping to run around 18psi (have turbo but not installed yet)

Split dump pipe - installed on stock turbo at the moment, quite a decent length split section

Nistune - installed

Autobahn88 intake pipe - installed

Injector wise, im either going to use a set of R35 GTR injectors, from what I've been able to work out they are 560cc and direct drop in, or a set of larger injectors if I wanted to go E85

I'm guessing the stock AFM will need to be upgraded to a Z32 or R35 GTR unit

Look forward to seeing the OP's results

[DoseVader]

Larger manifold/runners would reduce exhaust velocity/pressure. Good for high hp, not so much for response.

I'm now starting to consider the HyperGear 21U highflow as an option. I had the OP6 highflow previously and it was lacking slightly in response. Maybe the 21U will be a sweet middle ground.

This is 100% correct the OP6 highflow will cause a fair bit of lag, I myself just got a 21U highflow and am taking out my OP6 highflow as i want response. You will only lose about 10rwkw of top end power. Another member on here helped me make my mind up he said he had owned a skyline with a OP6 highflow and one with a 21U, on a dyno the OP6 made more power but on the street the 21U felt alot faster. Will have more info once I get mine installed and retuned

Edited February 5, 2015 by DoseVader

[CEF33Y]

If you use the JJR dump, it might need some work with a die grinder to match the turbo, there is a few threads on grinding to suit.

Or do what I did and cut the lower half away and open it up.

As purchased

Modified

Unmodified, there was a 10mm step at the bottom of the flange, die ground as much as I could but still wasnt happy, so started cutting! lol

I have a hypergear op6 highflow, and the highflow machining eats into the flange area, possibly more than a 21u highflow

[Chris32]

Cool, I'm guessing I'll need to mod mine a touch to suit the 2535

Can anyone confirm is 230kw is possible using stock Neo injectors and air flow meter?

[DoseVader]

Cool, I'm guessing I'll need to mod mine a touch to suit the 2535

Can anyone confirm is 230kw is possible using stock Neo injectors and air flow meter?

Pretty sure both max out at around 220-230rwkw

[GTSBoy]

Yeah, you'll likely be over the top of both by the time you get to 220rwkW. Not wise to try to run past the max, so you're kind of forced to upgrade. Sucks having to upgrade for +10rwkW, so that's probably why most prefer to aim for 240+.

[Chris32]

Yeah, you'll likely be over the top of both by the time you get to 220rwkW. Not wise to try to run past the max, so you're kind of forced to upgrade. Sucks having to upgrade for +10rwkW, so that's probably why most prefer to aim for 240+.

Yeah figured as much, I'll see how it goes

[colourclassic]

This is 100% correct the OP6 highflow will cause a fair bit of lag, I myself just got a 21U highflow and am taking out my OP6 highflow as i want response. You will only lose about 10rwkw of top end power. Another member on here helped me make my mind up he said he had owned a skyline with a OP6 highflow and one with a 21U, on a dyno the OP6 made more power but on the street the 21U felt alot faster. Will have more info once I get mine installed and retuned

Good feedback. ~500rpm response difference on a dyno graph doesn't look like much, but I think real-world driving response will be greatly improved.

Will be taking my 21U to HyperGear in the coming weeks, and will post back to back results compared to the OP6 unit.

[DoseVader]

If you already have a hypergear op6 highflow you might be able to get the rear housing changed over to the 21u just a thought would have to ask hypergear.

[colourclassic]

Nah sold it last year so I've gotta start fresh with another turbo. But you're right, the CHRA is identical in both versions, only the turbine housing is different.

[DoseVader]

Well there you go, I am aiming for 250-260rwkw so if your happy with that sort of power the 21u should be fine

[colourclassic]

Injector wise, im either going to use a set of R35 GTR injectors, from what I've been able to work out they are 560cc and direct drop in, or a set of larger injectors if I wanted to go E85

560cc should be able to support 240rwkw on e85.

[Chris32]

560cc should be able to support 240rwkw on e85.

Yeah, however I'm not sure if the VR38 injectors would cope well with E85 overtime?

It's a bit of a dilemma really!

Nistune have the flex fuel upgrade also, so I think for now I'll stick with the stock stuff and see what they can do, then do the injectors and the Nistune flex fuel setup in one hit and have it tuned for 98 and E85

[AngryRB]

why would you bother ? 1000cc bosch injectors are cheap, ask scotty

[Prutataaa]

Would cams be good upgrade for response, considering price and in a similar power range (240-270 killerwasps)

[Dose Pipe Sutututu]

Would cams be good upgrade for response, considering price and in a similar power range (240-270 killerwasps)

Stock cams are the best for that, longer duration cams will shift the power/torque towards the higher end of the RPM range.

[scotty nm35]

why would you bother ? 1000cc bosch injectors are cheap, ask scotty

Changing them now so you don't have to tune twice is the smart choice.

[DoseVader]

I wish there was a united near me so I could run pump e85