250rwkw At The Wheels Woohoo!

[bazr33]

Hey guys !

in the process of slowly doing mods to my car

currently have 170rwkw

fairly stock car ,

dump, FMIC, 8psi, AVCR , Exhaust

purchased power fc, gettin it installed and tune on the 19th of october

looking at turbo to get to get me around 250rwkw plus

knowing myself, i will want more later on ( you know how it is)

i know i will need upgrade on afm

injectors, fuel pump, and i know what im doing there

just getting an idea of what turbo to get as im goin round in circles .

thinking of the most efficient way , was trying to keep low mount standard manifold , but whateva is goin to cost me less, efficient and will get me there.

i was thinking the hks 2540 440hp

highflow gcg rb25 450hp ( just was a bit worried of being 2 grand though)

but if it was goin to save buying manifolds and external wastegate then

( Thats just how i was thinking )

Any ideas would be great guns!!

Thanks

Barret

[paulr33]

the hks 2540 is from the older hks turbocharger and is a proven laggy hoe for no reason, mismatched parts. for gtst around 250rwkw ish or a bit more i would look into

gcg hiflow with vg30 exhaust housing

hks gt-rs

garrett gt28rs

apexi ax53b70 (not sure on this one whats it rated at)

and a mid sized td05 could be good too

youll definetly need a heavy duty clutch as well. also make sure at least a 3" split dump pipe to take some exhaust restriction away. and dont look away from suspension or brake mods as youll be well over the stock rated power output of each. get the powerfc and boost controller kit instead of avcr.

[Trav33]

how much did your powerfc cost, and what model did you get? This is on my list of upgrades!!!

[paulr33]

powerfc, stock model should be fine, no need for d-jetro. $1050 delivered to melb from nengun.com

http://members.dodo.com.au/paul/docs/power...powerfc-faq.htm

everything you need to know

[R31Nismoid]

Please search guys, the "upgrade turbo" for my RB25 is such a common topic, and 250rwkw such a common goal.

[The Alchemist]

250rwkw is a lot of power to acheive and requires an investment in some major hardware and not just the turbo.

Selecting a turbo to acheive this power level is the easy part.....

As one of our customers found out, having a Garrett roller bearing turbo with an external gate capable of 500 to 550 hp at the engine and a RB30 bottom end/RB25 head with a Haltech running the show only produced 205rwkw with the torque disappearing after 5000rpm. 205rwkw is approx 400hp at the engine on pump gas (calculated using brake specific fuel consumption figures not just by applying a percent conversion, although it actually works out as a 30 to 32% drive train loss)

Further investigation revealed that the restriction lied in the standard RB25 head which although in good condition could only flow enough air to support 205 KW at the wheels or 400hp at the engine. Clearly the turbo was capable of flowing more air as it was rated at 550 hp but the head wasn't up to the task.

Boost creep was an issue with the 38mm waste gate struggling to control boost levels rising from 12psi up to 15 psi at 5000rpm. The run was stopped at 5000rpm as the torque and power disappeared.

The engine was removed at the head fully worked with the lifters replaced with solid buckets, larger valves with copper berilium seats, large cams similair to a "stage 2" cam spec (undisclosed specs), special valve springs, full port and polish job. Believe it or not over $4000.00 NZ worth of parts and labour went into that head!

Back on the engine with a larger 45mm gate fitted the car was dynoed this weekend at my work and the results were astounding!

At 12 psi moving up to 18psi at 6000rpm the engine made 282kw at the wheels or 564 hp at the engine right on the airflow limit of the turbo as rated by Garrett. The run was stopped at 6200rpm as the TURBO was now reaching its flow limit! B)

Thats a 75 kw gain from doing the head and gate although most of that gain would be from the head. Nothing else was changed on the engine. And remember this was on pump gas.

Point is this was a great learning curve and in sharing with you guys straight from the dyno operators mouth so to speak , will help you realise just what is required to reach those dream world power figures we all read about in the mags and on the net.

Take home points:

Std RB25 head seems to only flow enough air to support 205 rwkw, give or take a few kw.

It costs a lot of money to develop a RB25 head to flow enough air for 250rwkw plus.

Doesn't matter how big your turbo is or where it came from or who made it, if your head can't flow the air you won't make the rated power of your huge turbo.

At the very least CAMS DO MATTER as they will increase the air flow through the heads and therfore help the turbo make power up to its flow limit.

When going for big power figures fit the big 45mm gate don't muck around with smaller ones.

These are realistic real world results done in a controlled test environment on a dyno dynamics dyno in shoot out mode.

This customer is a competitive drifter here in NZ and now has a top rate engine, perhaps one of the gruntiest in the D1NZ.

[nitemare5]

mm unsure of that one, i know we shouldn't take dyno figures as gospel but there are just too many people on this forum with more then 200rwkw without touching the head (yes even on stock cams too) and alot around the 250rwkw goal too. But the cams do help a great deal when you are approaching the 250rwkw goal and want just that little bit extra flow (of course all pending on your turbo choice).

Edited September 6, 2005 by nitemare5

[paulr33]

what the? ive known a few stock head rb25's get over 250rwkw

what exactly was the restricition?

[mass_iv]

hey guys i went for a garrett gt30R ball bearing turbo, its big, but should get me to the 250rwkw, and my tuner seems to think i can reach it with my mods....

[bazr33]

THanks for the info alchemist

taking the information on board

my steps im taking , from all the information i have gained over time is

power fc install on the 19th october

next lot of stuff

looks more so a gcg highflow would work out better.

tomei poncams

550 injectors

040 bosch fuel pump ( intank )

Im going to speak to a person i know

that did my head work on my first car , And see if he can do work on the rb25 heads . if so that would work out good.

As he did work on some of the v8 supercars and got business from sydney and all over the shop.

Let yous know what happens !!

Thanks for all the information guys !

the car is comin along slowly!

Barret

[justin911]

do any of these larger turbos you've all mentioned still fit behind the factory heatshield ?

[Andi]

Stock head has only a max power rating of 205rwkw? I'd be inclinded to believe that your example was perhaps a 'one-off' Alchemist?

I'm sure plenty of other RB25 owners have had over 200rwkw running nicely, I mean even SR20's can take over 220rwkw before the head needs getting looked at.

Barret - sound like a plan man! 250rwkw on the road should be a monster if its a street car.

[Big Rizza]

I've been in silvias with 250+rwhp and Supras with 270+rwhp, and they are way faster than I would ever need/want to go. Given that, 250rwkw (=330+rwhp) will be insane - scary fast in fact. That's approaching double the stock car's power output there! Hope you've got some decent chassis, brakes, suspension etc. upgrades there!

At least you will never be designated driver - you're gonna scare off all the passengers! (unfortunately a stock 32 4 door turbo has enough appeal, enough space and low enough scare to make me a regular selection for a night out)

But you've caught the speed bug, and you've got it bad!

[Dee 33]

Meh. I have 240rwkw and you get used to it quickly.

Sure, 1st and 2nd gear are fast enough but you soon want the same results out of 3rd and then 4th.

[itbmils]

Meh. I have 240rwkw and you get used to it quickly.

Sure, 1st and 2nd gear are fast enough but you soon want the same results out of 3rd and then 4th.

<{POST_SNAPBACK}>

Agreed !!

I think it's a case of diminishing returns - I went from 210awkw up to 290awkw in my GTR - and it sure is quicker - no doubt

but it does not feel 80kw faster (that's a bigger difference than a corolla and a std wrx)

you get used to it quickly - and then you want more

and yes - it's a daily driven street car - and I typically have a queue at the passenger door

no shortage of volunteer drivers either - as long as we take MY car !!

[Maxx]

i have no idea what The Alchemist is talking about.

why after the head job, the boost will increase from 12 to 18psi??

as the head are now able to flow more air, shouldn't it make the same power at lower boost level??

i found myself facing a new defination of the word "boost"

Edited September 7, 2005 by Maxx

[The Alchemist]

hey, only sharing my experiences, tryin to help here....its not even my own car..thought you may just be interested thats all.

[BBQ]

Stock head has only a max power rating of 205rwkw? I'd be inclinded to believe that your example was perhaps a 'one-off' Alchemist?

I'm sure plenty of other RB25 owners have had over 200rwkw running nicely, I mean even SR20's can take over 220rwkw before the head needs getting looked at.

Barret - sound like a plan man! 250rwkw on the road should be a monster if its a street car.

<{POST_SNAPBACK}>

Skyline R33 - GTS-T Rb25Det Pushing: 303rwkw with Stock Head.

Nissan Silvia Sr20 Pushing: 290rwkw With yes again Stock Head.

[R31Nismoid]

Further investigation revealed that the restriction lied in the standard RB25 head which although in good condition could only flow enough air to support 205 KW at the wheels or 400hp at the engine.

It costs a lot of money to develop a RB25 head to flow enough air for 250rwkw plus.

dunno what you guys are doing over there... but thats some pretty misleading information

I made 369rwkw on my dead standard RB25 head with unknown km's on it, it wasnt rebuilt or fresh.

If you wanna talk RB25/30 cars then there are some just with a set of cams only raking out 350rwkw daily.

There was some other problem obviosuly with that car that isnt being mentioned.

There is no way it was the head

[RNS11Z]

myy r33 made over 420rwhp with dead standard head + cams on 21psi