Hi there i am currently in the middle or forging my 07 sti hawk. im going for cosworth pistons, rods, head gaskets and bearings.
im wondering whether to uprate the valve springs?


im looking for a safe 450 bhp but have read quite alot that the 2.5's dont like to be revved to the limiter much.

whats the reason for this and alotho i will not be increasing the rev limiter i was wondering if uprated valves springs will help, i was looking at the cosworth valve springs but keeping standard valves.

i do a little bit of drifting and was thinking while the engines apart may look at doing them

any ideas would be great

 

I would rather change the valves for one piece items, rather than the valve springs this is from a safety point of view

 

I'm not sure about on the scoob engines but when i built bike engines and wanted higher rev's i used, uprated springs, one piece stainless valves, titanium spring retainers and lighter followers. Be careful with the springs though. Go to strong and they will wear out your cams.

 

I would definately Go for supertech valves and uprated springs and retainers if the budget allows

 

It's cams you'll need if you want it to rev !

 

The right cams and turbo on a 2.5

 

That's an impressive graph, what's the full spec of that engine build as I thought 2.5 was best kept below 500 even if forged

 

whats the spec looks good, how much will the standard gearbox take got the standard 6 speed with dccd