Quote:
Originally Posted by billjam
The standard ones looked pretty large to me!
I'd be interested in more info on the valves if you could steer me in the right direction. How much bigger are the RS valves?
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I believe your 964 has 49mm intake and 41.5 exhaust valves. The 993 VRam got 50 and 43.5 (where some of the extra power came from) and the RS valves were 51.5 and 43.5, light weight and sodium filled I believe. I'd figure maybe 10-15 hp over what you have? Pelican sells them here, I expect you may need to pocket the 964 pistons for clearance if you go with a cup solid lifter cam (which I would highly recommend).
As Steve mentioned when I did this I paired the with springs, ti retainers, etc to get to 7500 rpm, but the fact that you're on a tight budget sounds like it rules out reving the motor that high- I agree you'd need rods, bolts, etc. Probably not worth it given what you're saying.
Quote:
Originally Posted by billjam
Pete, I am more interested in acheiving good street performance rather than outright power.
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Given that statement and the fact you'll be limited on revs you might consider adding a Vram intake- when you say "good street performance" that's what the VRam is designed for. If you went that way I'd guess you'd probably be up 50 ft/lbs between 3500 and 4500 rpm over the ITBs, though of course you'd loose throttle response.
I love ITBs but unless you do the pistons (for a big cam needing more clearance) and rev the motor to higher RPM I'm not sure ITBs will pay off on the street. On the other hand I'm also interested to see what you come up with for an ITB solution...