Hey folks going for a 2.5 CDB on my Hawk sti plans are just use oem 2.5 heads

2.5 CDB
Mahle race pistons
Carillo rods
2.5 heat treated crank
11mm rcm extreme head studs
Rcm head gaskets
Perrin fmic
Sc46 billet with 58mm intake
Perrin 58mm intake pipe
Perrin big man induction
Carl davey parallel fuel rails
800cc injectors
Fuelab fpr
Rcm unequal length headers
Act clutch capable of holding 565lbs ft
Cosworth baffle plate
Rcm 11mm oil pump
Syvecs ecu
Tgv delete
Air pump delete

I have seen a few 2.5's making above 460 on the sc46 on v power and over 500 with a 20%

My plan is to run this but up the boost to over 2bar to see what it will make

What are your guys thoughts?

I've read on some sites that the rcm head studs are only rated to 450 but others have run 11mm head studs to well beyond that

Would it be wiser to go with 14mm head studs or would the rcm head studs be sufficient

Cheers

Steve

 

go with the 14mm on a build like that why take the chance

 

I'd throw another grand at it and go 2.35, well proven to 650bhp and beyond.

 

£500 for studs and machining on 14mm head studs is well worth it if you wanna chuck a load of boost at it IMO

 

i went for 2.5cdb and sc46 but it never seemed that quick so am having a 2.35 now with gt35

 

Probably worth talking to a mapper to see if you'd actually ring much more out of a SC46 by just upping the boost. At the top end IIRC Bob said my 2.5 was actually producing more airflow than the turbo could handle. Mine got 472 @ 1.7. bar peak.

Might be worth going to a SC50. Depends what you want really. A well built 2.5 with an SC46 is lovely for the road. You'd loose some response with the SC50

Going to beefier head studs good advice if you plan on cranking up the boost. 11mm fine for the SC46 running the kind of boost they normally take to make the usual power, any more than that and why take the chance.

BTW would add a baffled sump and inlet manifold spacers to your build. Also consider you choice of clutch; you don't want something that is a pain in traffic.

Finally, Keep the rev limiter at the stock level; no point reving the nuts off of a 2.5 with the std valvetrain etc.... you'll only ending up taking the engine home in a hoover bag!!

 

Duuuuuuuuuuude. You must be used to a QUICK car.

My old 2.5 with an SC46 had a mate with a 996 91 turbo raising an eyebrow!!