RB25DET Question from a newbie

[wowzers9930]

Well im about to aquire a rb25 swapped 240 with the follow mod list

3" turbo back exhaust
Some kind of intake
Spec stage 3 six puck race clutch
Spec lightweight flywheel
HKS wastegate
Tial BOV
Autometer boost/wideband

I was wondering if I were to pick up a manual boost controller, how far could I push the stock fuel/ignition too. I know the turbos on these things are only good for about 14psi max but I plan on replacing it soon. I just wanna know whats the max boost level that I could safely push every now and again. Thanks

[RRRRB]

my s14 with stock RB25 turbo on 12psi

stock everything besides the following
intake manifold
FMIC
3in downpipe ( but went back into stock s14 240 exhuast)

i had a manual boost controller set to about 11-12 psi car made 267 whp and the AFR was great right around 11.4- 11.8 ish

i still had OEM s14 fuel pump at the time.. i wouldnt push the rb25 turbo past 14psi period, due to the turbo being junk and risk of leaning it out.. without some type of injector fuel pressure regulator engine management past 13-14psi etc is just asking for engine damage.. my car responded very well to just a boost increase.. i think it only made like 230 something on the stock 7 psi and AFR wise was very safe still at the 11-12psi i ran..

[wowzers9930]

So with the mods currently done to the car, 14psi would be fine? And if I upgrade the turbo, fuel pump, and get a FPR I could run something like 16-18psi? Oh and another thing, the Speedo reads half of what your actually doing and the RPM tach doesnt even move what is the cheapest way to get them to read properly? Thanks

[Carl H]

you'll need to upgrade injectors/maf/management if you decide to go to a bigger turbo.
rising rate regulators are so 1999...and you'll need to have the speedo calibrated and the tach modified to work properly.

[wowzers9930]

Okay so, My plan of attack to run more boost should go as follows. Bigger turbo, injectors, maf which is what?, and tuning software? Do I not need to worry about a fuel pump and FPR? Also I would just like to run about 18lbs or so before I do a fully built motor which I plan to do, Would an hx35, 550cc injectors, and a tune get me my 18psi? And could I use Injectors,Fuel pump, FPR to achieve my 18lbs?

And on another note, how would I go about calibrating my speedo and getting my tach to work?


Heres some pics of the engine bay, Is that already a MAF on it?

[outlaw7]

i highly suggest you do lots and lots of reading so you can better understand whats involved with modifying a car

rule of thumb is if you change one thing, you must compensate the rest

yes thats the mAF but the question is, if you upgrade your turbo will that MAF be enough to keep up or will it act as a restriction? and on that note, if your going to change management is it even worth keeping a MAF at all?

[Carl H]

lol, that looks like one my harnesses.

[chad b.]

i thought for the speedo all you needed was to swap the rb to the ka VSS?

[Carl H]

using a 20 trans yes, 25 no.
20 trans will accept a ka vss from a s13 or 14, 25 is all on its own but generates the correct pulse for a 14 but half speed for a 13.

[StockAsFuhS14]

why do you want 18psi so bad?lol

[Rbee25]

Off subject but im digging your ic piping, looks clean!

[wowzers9930]

Okay so I just ordered my Hallman PRO RX Boost Controller. Currently my car is running about 8-10 lbs of boost and the AFR is right at 12-12.1 I want to run 13-14lbs where do you think my AFR would be at? Still in the safe range?

[Carl H]

proly rich and retard like all rb25's and somewhere in the mid 10's.

[wowzers9930]

Wouldn't 13-14 psi make it more lean then 12.2 afr at 10 psi

[91rb240c]

i highly suggest you do lots and lots of reading so you can better understand whats involved with modifying a car

rule of thumb is if you change one thing, you must compensate the rest

yes thats the mAF but the question is, if you upgrade your turbo will that MAF be enough to keep up or will it act as a restriction? and on that note, if your going to change management is it even worth keeping a MAF at all?

i just started on a rb25 swap and had a custom MAF fabricated, basically gutted OEM Z32 MAF that's now housed inside a custom segment of the FMIC intake side, looks very nice