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Maximum Response Setup For Rb25

colourclassic

By colourclassic,
in Engines & Forced Induction

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Dan_J Veteran

Dan_J

Posted
Posted

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

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Ryno
Ryno

My car has greater than 260 rwkw and has 100 rwkw by 3000rpm. This is on regular 98 octane, and I'm confident I could push the turbo harder to achieve closer to 300 rwkw - but it is really not neede

AngryRB
AngryRB

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

colourclassic
colourclassic

So I've decided to go ahead and put together a setup which offers similar response to a stock T28-turbo RB25, while maximising mid-range power and response. I think this is ideal for a mostly street-d

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owen1r Collaborator

owen1r

Posted
Posted (edited)

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 by owen1r
Chris32 Veteran

Chris32

Posted
Posted

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

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DoseVader Enthusiast

DoseVader

Posted
Posted (edited)

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 by DoseVader
  • Like 1
CEF33Y Experienced

CEF33Y

Posted
Posted

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

IMG_0013_zpsb44ba558.jpg

Modified

IMG_0065_zpsafhuqu6f.jpg

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

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DoseVader Enthusiast

DoseVader

Posted
Posted

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

Chris32 Veteran

Chris32

Posted
Posted

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 Mentor

colourclassic

Posted
  • Author
Posted

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.

colourclassic Mentor

colourclassic

Posted
  • Author
Posted

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 Veteran

Chris32

Posted
Posted

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

Dose Pipe Sutututu Grand Master

Dose Pipe Sutututu

Posted
Posted

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.

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