High-lift cams?

[ozzie]

from where and what is the power gain on a 4.5lt? Cheers Lads.

[trefor]

Your request doesn't make sense to me. Do you mean fitting a higher lift cam to a 4.5 or the std cam? If a higher lift cam, then which one? as they will have different characteristics.

[ozzie]

Add higher lift cams to my 4.5lt to allow more air/fuel mixture into the cylinder, or the other option is to increase the compression ratio by getting longer crank arms or shaving the head (as a 4.5 has a compression ratro of 9.5:1 whereas the 5 and 4lt have 10:1)? Anyone any of these?

[GreenV8S]

I don't know what the CR is on the 450 or whether/why it is lower than the other engines, but if it is, there may be a good reason. For example different combinations of head volume and piston design have different resistance to pinking. A high lift cam works best in combination with gas flowed and/or ported heads, and the inlet manifold, trumpets, plenum, throttle etc are all marginal. There isn't much point doing a lot of work on any of them unless you consider all of them as a system. There's no easy answer to this question, I suggest you talk to the experts. Presumably you aren't proposing to wield the spanners yourself, so a chat with your mechanic is probably the best place to start. You could do a lot worse than talk to Tim Lamont and Mark Adams, the TVRCC members who helped me spec the extensive mods I'v got on the V8S (70 bhp up on standard). Contact numbers are in Sprint. Cheers, Peter Humphries (and a green V8S)

quote:Add higher lift cams to my 4.5lt to allow more air/fuel mixture into the cylinder, or the other option is to increase the compression ratio by getting longer crank arms or shaving the head (as a 4.5 has a compression ratro of 9.5:1 whereas the 5 and 4lt have 10:1)? Anyone any of these?