The Quest for 450hp on the RB25DET

[geno8r]

Hi

I'm just about to get my tax return & am thinking this will be good money to do the next stage of mods to my car, or atleast a stash for when i have enough to do a whole lot at once.

My car is currently putting out 309 rwhp (230 rwkw) @ 12psi which im guessing is around 370 hp (275kw) @ the engine.... My goal is to get my engine towards 450 hp (335 kw), by the time its at the wheels, maybe 260 - 270 rwkw? Please correct me if you have better estimations.

This is my car & current performance mods:

r33 GTS25T 95' Series 1.5

GTR Front Mount Intercooler

GTR Fuel Pump

T3/T4 HighFlow VL Turbo *internal wastegate

Apexi S-AFCII

GReddy Profec B Boost Controller

Blitz Dual Turbo Timer

Blitz Open-Atmosphere BOV

3" Exhaust Turbo Back

HighFlow Cat

MegaFlow Twin 2" Tip Muffler

K & N Pod Filter

Iridium Spark Plugs

Brass Button Clutch

Locked Diff

Works Rims

10" Wide Rear Tires

Aftermarket shocks

Front Strut Brace

Always run 98 Octane BP Ultimate

Stock RB25DET engine.

Stock Headgasket, Injectors, Cams, ECU.

Stock AFM, Throttle body, Plenum.

Current Max Power

309 rwhp (230 rwkw) @ 12 psi

This is all I can think off, might be another 1 or 2 small things… Anyway.

So i've been thinking a bit about my next mods & would really like some information & prices about the following mod subjects

Total mod prices are estimations / guesses, could be 2nd hand or brand new, prices should include installation.

Next Mod 1: Power FC

Total Mod Price: estimated $1600

Now I'm not sure whether to get a 2nd hand one or brand new, im thinking i'd like to get a 2nd hand one with hand controller for around $900 - $1000.

Once i have this i'll need a full on tune which will cost around $500 i believe, but! i wont get a power FC installed or tuned before i get the next mods installed @ the same time i think.

Next Mod 2: 550 cc Injectors or 440 cc GTR Injectors?

Total Mod Price: Anywhere from $400 - $1000

Ok so to make 450 hp im going to need some better injectors, i'm planning to run max boost of 18 - 19 Psi. What injectors could do this for me, could the GTR ones cut it? & are 2nd hand injectors acceptable after being cleaned.

Next Mod 3: z32 AFM

Total Mod Price: $300 - $500

From what i've read the stock AFM is getting maxed out at around 230 - 240 rwkw. I know im going to need one of these.

Next mod 4: Misc parts, Fuel Rail?,Oil Catch can, any suggestions what else i'll need?

Total Mod Price: $200 - $500?

Depenind on what injectors i'll need, might need certain fuel rail, with this power *450hp* do i need a oil catch can... please suggest other parts i should get.

Ok so whats the plan?? I think i'll save & buy all these parts @ once & get them all installed at the same time, get everything set up & done once. With all the part installed I'll get a full dyno tune & see how much power we can make @ 18 - 19 psi. Posibly might need new Headgaskets too. another $800 right there. I'd really like to see how much power my turbo can make & a good tune from the Power FC. In good time it'll all happen.

Now this is my simple understanding of what to do next, Any feedback with people who have went through this stage of modding, "Stage 2, Stage 3?" your feed back would be greatly appreciated, & for all the people who simply know what parts work well with what, your suggestions / comments would be great too!

Cheers!

[Robo's]

So what is the limiting factor to your 230rwkw now??? Injectors???? SAFC2??

Sounds like your turbo will push out more than 12psi to get 230rwkw.

[geno8r]

Yep, my first limit is the stock ECU cutting off fuel @ over 12 psi. So Power FC to fix that.

Then up the boost to around 15 psi, this is when the stock injectors are being maxed out i believe. So get the bigger injectors.

Up to boost some more to 18psi, making some high power now will need new AFM. *z32 AFM*

Then i'm not sure, maybe a few other things to help handle that power best.

I think i'll do it all @ once, just making sure im going the right way about it. I'm wanting some people with experience doing this to suggest the best parts to the job i require with my current set up.

Cheers,

[abcent]

Hey GENO8R,

I'm basically running the same set-up as yourself except I have a Microtec ECU an adjustable fuel reg (malpassi) running 18psi to achieve 248kw (bout 320-325hp?). Microtech runs well an that bypasses the need for Z32 upgrade because no AFM needed, uses MAP sensors....I believe Wolf 3D ECU's have the same setup.

My next step is injectors....cant use GTR injectors unless you modify your fuelrail to suit topfeed injectors, as RB25's are side fed. Best price ive found them is around $990 a set from Japan (not installed, doing that myself). Here the same injectors range between around $220-$300 PER INJECTOR depending on brand/size.

Could customise your fuelrail to suit top fed, but in the end it'll cost about the same, maybe more than a set of direct fit items from Japan (Neugun or PerfectRun). With bigger injectors your stock fuel rail will be fine to suit your power needs, you probably need to more look at strengthening the internals of you motor to suit big HP before you'll need a bigger fuel rail....

hope i've been of some help?

Berin

[Trust33]

Next Mod 2: 550 cc Injectors or 440 cc GTR Injectors?

Total Mod Price: Anywhere from $400 - $1000

Ok so to make 450 hp im going to need some better injectors, i'm planning to run max boost of 18 - 19 Psi.  What injectors could do this for me, could the GTR ones cut it? & are 2nd hand injectors acceptable after being cleaned.

Sure they are.Make sure when you get them cleaned that they are flow tested and you have a sheet to proove it..

Next mod 4: Misc parts, Fuel Rail?,Oil Catch can, any suggestions what else i'll need?

Total Mod Price: $200 - $500?

Depenind on what injectors i'll need, might need certain fuel rail, with this power *450hp* do i need a oil catch can... please suggest other parts i should get.

My thinking on that question is no i wouldnt worry about it but too much cause there are inj's that flow enough for your needs and they drop straight in..Just get an adj fpr..Correct me if you know any better.

Conclusion:

yes injectors indeed.I belive there to be some 550cc for sale on the forums atm for $650...Plus i heard that the injectors run out of puff at 370hp@ the flywheel.Definently go for a ecu+z32,adj fpr.The stock fuel rail should be fine but it never hurts.And a tune..

The skys the limit......

Ecu:$800 up.

Z32:$250 up.

Adj Fpr:Cheap ones $150.Brands like sard,nismo $300 up.

Oil catch can:Also depends on where/what u buy.$100 uppppp

[R31Nismoid]

dont get adjustable fuel reg. there is simply no need for one and you save money right there.

I'd then suggest buying a GT30 500-550HP (no bigger required), get an external gate and run a bleed valve

but then, thats just me. Others could suggest cheaper options... but my setup i feel is awesome with only 16psi running @ 270rwkw with plenty more room to move should i feel like it. Response is amazing. It absolutely kills my old T04 Hybrid that i had.

Thats running the 600HP GT30 though.

So if you dont want anymore than 270, get the 500-550, and it'd be even better.

personally id stay away from microtechs as the fuel economy suffers greatly.

PowerFC with 550's... I'd probably get Nismo 740cc's ($940 from nengun) as they only cost about $10 more and are a straight fit to the RB25, the sard 550 are a bit of an effort to fit.

[Sydneykid]

Since your target is 450 bhp, the standard SR20 side feed 480cc injectors would be my choice. Pleanty of SR20's being upgraded so there are quite a few sets around. I think someone on the forum bought 2 sets of 4 and has 2 for sale, if you get those you would only need one set of 4.

Definitely Power FC would be my choice anda set of Tomei 256 Poncams.

As long as the turbo can keep up, I reckon that will get you to 265 rwkw (265 + 65 X 1.34 = 445 bhp).

[N I B]

Ask GTS-tvspec as he has 450rwhp and was a walk in the park. Send him a PM

[Trust33]

Sk when would geno8r's style of turbo run out of puff with a set of tomei poncams.And would a high flow stock unit be anywhere near his turbos capabilities with the same seutp and cams.Cheers sk....

[geno8r]

Thanks for the replys guys, i do have some options there... I need to choose whether i get bigger injectors for more modding in the future or some cheaper SR20 ones. I know some new Nismo ones will cost me $1000 all up pretty much, have to see how much cheaper the SR20s are. Im thinking maybe going some nismo ones simply because im starting to hear people are running 450 rwhp & not 450 bhp *bhp is engine hp right Sydneykid ?*

So i read the RB25DET is good for 450hp, i thought this was at the engine and not rwhp? Some people seem to be running around this @ the wheels. If they were running 450 rwhp what kind of internals would they need?

PowerFC with 550's...  I'd probably get Nismo 740cc's ($940 from nengun) as they only cost about $10 more and are a straight fit to the RB25, the sard 550 are a bit of an effort to fit.

Wouldnt the 740cc's be a little big for little old gtst.... I remember reading something about what happens when you run too large injectors. 550cc seems to be the go.

Just checked out some new cam shafts too *whats the 'pon' mean in tomei pon cam shafts*, bout $700 new. I think i'll want to be going for 2nd hand for this whole operation.

Oww & one last question, where do you place the priority on these cams Sydneykid? They're not absolutely necessary are they. How much extra hp do you think you might get out of them after having the z32 AFM, Power FC & Injectors all installed & tuned.

[R31Nismoid]

Wouldnt the 740cc's be a little big for little old gtst....  I remember reading something about what happens when you run too large injectors.  550cc seems to be the go.

PowerFC controls them fine.

Mine idles better now than when it had the stock injectors.

So all that about bigger injectors is just rumour and :bs!:

[geno8r]

PowerFC controls them fine.

Mine idles better now than when it had the stock injectors.

So all that about bigger injectors is just rumour and  :bs!:

Some1 to 2nd this mans words? Sk?

[Pandaemonaeon]

Sorry guys. It's been a bad day, and brain has just started working again. I'll correct myself. It helps if you square your answer to get the total area. :dump:

[geno8r]

Anyone running these injectors? 740cc? Would the 740cc's be too big for around 450 bhp. Most of the time i'd only be running around on stock-O 7 pound boost.

[tang0]

I bought 8 of the sr20 injectors ...

they are shortly to be fully cleaned and flow tested etc ... so yes, will have 2 sr20 side feed injectors for sale ...

will post up in the for sale section when they are cleaned etc

cheers

Anyone running these injectors? 740cc? Would the 740cc's be too big for around 450 bhp.  Most of the time i'd only be running around on stock-O 7 pound boost.

[morlock]

hey tango,

Are the sr20 side feeds a direct fit or do you have to stuff around to fit them?

Cheers

[tang0]

hey

afaik, they are a straight swap, they are side feed, same as rb25 ...

physically they do look the same ... but i guess we'll see when i come to fit them !

will post up results when they are fitted ...

cheers

hey tango,

Are the sr20 side feeds a direct fit or do you have to stuff around to fit them?

Cheers

[geno8r]

740cc ... Anyone?

[GIGOLO]

The closer rated injectors you can get for your desired power output, the better metering you will have for emissions and fine tuning take off and idle.

I was going to get the Nismo 740cc's, but decided on 555cc's as I won't be going past 550bhp.

I was also advised to get 550's by CRD who will be tuning the car. Check with your engine tuner who may also want the adjustable fuel pressure reg. Advan won't tune a car without one and CRD highly recommend one.

[geno8r]

Cheers thats all the info i needed.