More Power From My Rb25det

[eugen_syd]

Hi people,

I know this topic was covered few times but I am trying to seek some guidance from the RB25DET experts. Lots of people are asking how much power you can get from an RB25DET engine? Huh, I think is not quite clear for me yet. Maybe someone can tell me more.

I have an R33 Skyline series 1, 1993 model. I had it for more than 3 years now and I like to "play" with it. A few years back now I fitted to the car an HKS kit, turbo series 4+ mainfold+waste gate. This gave a power increase of 30kW with no tuning (still on standard computer). I managed to measure this at SAU dyna day, Unique Motorsport. Here is the recorded graph. After this I decided to get naughty, so I purchased:

- Power FC + Commander

- APEXI boost controller (power fc)

- SARD 550 Injectors

- Splitzfire ignition coils

- Z32 Air Flow Meter

- Cam Shaft Gears

Than I looked around for a tuner and I approched Unigroup (Yavuz). He fitted all my parts and had a series of problems with my HKS wastegate and intercooler piping (I have an Mick Metalcraft intercooler fitted by Hills Motorsport). After some work Yavuz managed to make the pipes stay together without popping, and shimmed my wastegate, he said is oppening too quick loosing boost. Huh, I was realy disapointed when after I spend more than 8000 I did not get too much. Only 220kW at the wheel...WHY???? Just an increase of 30kW with lots of dollars. I was expecting something like 270-280 kW to be honest. As you can see in my AFTER diagram car launches but power does not peak at high RPM???

What is going on? Yavuz said my wastegate does not hold pressure, openes to quick. I went out there and bought a spring for my wastegate 1 bar. I would like to run 1-1.1bar (14.6-16psi). After this he did not had much success. Did I hit his limitation?

now I decided to replace my intercooler with an HKS, better piping and install an GReddy plenum to simpifie piping. Also, I will rebuild head, with propper components (TOMEI cams and springs + valve cut).

My question to you is HOW MUCH POWER can be achieved on standard bottom (lower part) and what you think who is a good tuner in Sydney? Some point in time we need to "stop" the project and call it....DONE.

Thank you for your attention. Your comments are much appreciated.

Regards,

EUGEN

[paulr33]

there could be lots of things explaining why the power is lower than you expected. what turbo exactly? a plot of boost on the chart would be more useful. piping changes and plenum wont add any power so no need to worry about those. airflow makes power so work out whats going wrong with the airflow. what exhaust setup do you have. you should have 3" turbo back minimum

[eugen_syd]

there could be lots of things explaining why the power is lower than you expected. what turbo exactly? a plot of boost on the chart would be more useful. piping changes and plenum wont add any power so no need to worry about those. airflow makes power so work out whats going wrong with the airflow. what exhaust setup do you have. you should have 3" turbo back minimum

Hi Paul,

Thanks for reply. Exhaust has been upgraded to 3" all the way. Brand new cat converter 3" and Blitz exhaust. Turbo is T04E or something like that, Garrett, part of the HKS kit. Turbo works great. I drove the car hard in the weekend and I even reach 27 psi on my boost gauge. I think somthing is fishy there. Who the hell can sort my problems out????

Cheers,

EUG.

[MR331307]

Hi Paul,

Thanks for reply. Exhaust has been upgraded to 3" all the way. Brand new cat converter 3" and Blitz exhaust. Turbo is T04E or something like that, Garrett, part of the HKS kit. Turbo works great. I drove the car hard in the weekend and I even reach 27 psi on my boost gauge. I think somthing is fishy there. Who the hell can sort my problems out????

Cheers,

EUG.

Umm yeah you should be making more power

i dont think you will need to do the head

i think ur should get the manifold on and not worry about intercooler piping

Is the exhaust manifold top mount or side

[Al]

Not sure what type of HKS turbo you have, but what is it rated too?

Why are you only concerned about peak power? So what if you only made 30rwkw more at peak, were you spend 3% of the time while driving . LOOK AT YOUR MID-RANGE BUDDY , it is farkin awesome, compaired to your previous tune. At 4500rpm you make a wooping 60rwkw more!!! That is a PHAT increase .

How much boost are you running, on the final graph? If you have more than 18psi, you may have reached the limit of you current turbo, and to get more power requires an upgrade. But more power means more lag, do you really need it?

I am a little concerned with your a/f ratios b4 5500rpm, they seem too lean. My tune has been made to sit at about 11.7:1, from the moment it reaches 14psi@3200rpm til read line. Best to keep it a little rich on a std bottom end

Have you tried to drop your exhaust b4 the cat? This will show you if the exhaust system is a restriction. Do you have a full turbo-back 3" exhaust system?

Has you mechanic placed restricters in you boost line, to increase the boost?

[paulr33]

1.86 bar!!!!

get the car and tune checked by someone else

its going to go bang otherwise

[bazr33]

From what you have stated in your post

im led to believe you should be making 250rwkw plus

i have standard engine with hiflow r33 plain bearing turbo sitting on 12psi, power fc, split dump, walbro fuel pump, AVCR, FMIC

And im making 306hp at the treads (228rwkw roughly)

Im going to be getting my 555cc injectors, Arospeed ex cam gear, z32 afm and a nismo FPR put on hopefully soonish

and should make it close to 250rwkw

I would see if you can find a tuner that has the laptop software, to look at whats happenin through the whole rev range.

Im not very experienced with AFR's and specs pf what you have, but of what mods you have with a good tune, im sure you would make more.

Let ys know how you go

[Al]

Umm yeah you should be making more power

i dont think you will need to do the head

i think ur should get the manifold on and not worry about intercooler piping

Is the exhaust manifold top mount or side

NO NEED FOR A TOP MOUNT OR ANY OTHER MANIFOLD! I made 276rwkw, using a modified rb25 hi-flow, with the std manifold just match-ported to the head.

[MR331307]

1.86 bar!!!!

get the car and tune checked by someone else

its going to go bang otherwise

VERY VERY TRUE

but also

i think ur first graph is a little out

the IT is 42

while at uni group is 21 or so

half

watch out for these things

and yeah give us a little more information on what u have tried

[Al]

1.86 bar!!!!

get the car and tune checked by someone else

its going to go bang otherwise

Agreed!!!

There are plenty of good Pfc tunners in Sydney. It pays to pay more for a tune sometimes

[MR331307]

NO NEED FOR A TOP MOUNT OR ANY OTHER MANIFOLD! I made 276rwkw, using a modified rb25 hi-flow, with the std manifold just match-ported to the head.

ALL ABOUT THE FLOW

And the way the engine breaths

the more bolt ons the better

440 RWKW out of my one standard motor

[eugen_syd]

VERY VERY TRUE

but also

i think ur first graph is a little out

the IT is 42

while at uni group is 21 or so

half

watch out for these things

and yeah give us a little more information on what u have tried

HKS mainfold is with turbo underneath, wastegate on top. Anyone knows a reliable tuner in Sydney area? Should I go to Croydon?

[Color_Of_Green]

HKS or Tomei poncams and full 3" system + race cat dude

[Al]

ALL ABOUT THE FLOW

And the way the engine breaths

the more bolt ons the better

440 RWKW out of my one standard motor

At that power level yes, flow is very important, and i agree with you.

But we are talking about a mild turbo here and i beleive that the stock manifold (slightly ported) will easily cope with 330rwkw, and changing to a top-mount/aftermarket manifold below this power rating is almost useless.

Back on topic:

You mentioned a 3" cat, is it a hi-flow item? Drop the exhaust and do a test on the dyno, just to make sure the cat, etc is not restricting flow

[eugen_syd]

Hi people,

Thank you all for the generous comments. I made up my minds with my next step. I go trough a full rebuild of the head, TOMEI Procams, valve springs, service the head, valve cuts. bronze valve guides etc. Also a compression test before removing the head will tell me if I have to do ...more!!!!

I spoke with UNIQUE at Luke suggestion and I will purchase the PLAZMAN Plenum to simplify my piping and I will install the recent purchased HKS intercooler to fix my pipe "popping" problems.

Once all car back together I will take it to UNIQUE for fine tuning. I want to finish this project and I hope to get to 300 kW at wheels. Most of projects are abandoned due to cash problems... I wanna finish mine!!!!!!

Will be tuned for 14.6-16psi (1-1.1bar). Hopefuly UNIQUE will tell me what turbo I have on this car????

I hope you guys watch this when I will post the new DYNA sheet. You have to give me another 2-3 weeks.

Cheers,

EUG