Trouble Over 300rwkw With Rb25det

[muaythailuke]

Hi guys,

I was just wondering if anyone has experienced trouble once getting over 300wrkw with an RB25DET. The engine has enough mods under the sun to support it but once you start to run a fair whack of boost(~1.5)the power just drops off after 4500-500rpm thought it was spark so we put in a CDI and didnt seem to help. it seem to be pointing to weak valve springs springs but it has tomei springs, only standard cams though, runs approx. 8.7:1 compression and a 107 or 109 RON fuel. Anyone got any ideas?

Has anyone every had trounble with there VVT/VCT or whatever its called?

Any thoughts would be helpful thanks fella's

Cheers

Luke

[R31Nismoid]

Is the CDI working properly? What condition are the coil in or does CDI replace the coils?

personally i wouldnt have chosen the CDI route, the HKS ignitor box thingy is the way to go, keep the stock coils that way

What about the exhaust?

Care to list all the mods/specs etc? Might be something a miss in there

[James_03]

is it running splitfires? stock? wastedspark?

what plugs too.

[drag-on silvia]

prolly a stupid question but what turbo are you running??

[shanef]

sorta sounds like the turbo is running out of puff

[ULOOOK]

I am running 305Kw no worries at all, but i am running splitfire coils.

[MBS206]

I'm fairly new to the RB engines, but in alot of other engines, it'd either indicate turbo running out (Although this would equate to a pressure drop, which you haven't mentioned) or most likely the heads/cam aren't flowing enough.

[mad082]

could be the cams, since they are still stock. and if it is an r33 then the cams change at about 4500rpm.

[2BNVS]

im runnin 370rwkw no worries at all, with the autronic CDi ive kept my standard coils

ben...

[muaythailuke]

Coil have been replaced with the CDI system theres enough spark there to light half of tassie I think the turbo is a GT3540? So its not outta puff. Exhaust is 3.5" so that shouldnt be a problem. This is not my car, im just trying to find out some info for them. The head is also ported so that shouldnt be a problem.

On the dyno graph it heads straigh up looking like its gonna too 400kw but then get to 4500-5000rpm and just falls over, not a miss but just faids away and makes around 300-320rwkw

Edited October 13, 2006 by muaythailuke

[race_snooze]

kind of sounds like boost leak though wastegate or boost controler.

What is A/F doing at that rpm??

[Craved]

got a dyno sheet with some details? AFR's boost etc

[MBS206]

Drop a standard head on it. Seriously. Most likely who ever ported the head has stuffed it up. Either that, or get the head flow tested. Porting is a pure art.

[cameron]

MBS206,

Might be on the money...

Either that or you have serious boost drop, serious ign timing retard!

stock cams are capable of 300rwkws!

Perhaps its spinning the wheels on the dyno?

[RB30-POWER]

what intercooler do you have?

have you measured for any pressure drops across it at all?

[r33_racer]

you would think they would notice the wheelspin on the dyno.

[cameron]

you would think they would notice the wheelspin on the dyno.

I would hope so,

We dont exactually know how its strapped down?

A dyno graph would be of great help, with power/boost/afrs...

[James_03]

Edit: yeah not going to be cams.

Edited October 14, 2006 by James_03

[muaythailuke]

I cant see it being the head its not like it was hugly ported just cleaned up the dags etc. I dont think its the dyno either as they have had more powerful cars on there without trouble with wheelspin.

I will try and get the dyno graph scanned onto computer.

[infected flow]

this is like a hit and miss affair ...geez everyone is trying to help but your not giving any info...

How about u list your mods and post up the dyno graph...

cheers!