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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

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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 :(

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.

Coil have been replaced with the CDI system theres enough spark there to light half of tassie :dry: 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 by 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.

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