Good cam article
Discussion
stigmundfreud said:
yep been looking at that a while back or similar as I was worried or rather concerned about the huge lsa's. The question is with a smaller LSA would it be possible to have a fruity cam and control emissions better?
The wide LSA is typically going to offer less overlap for any given set of profiles. Yes Martin is trying to distance the two and talk about actual valve events, but inevitably they will be linked for the majority of profilesThis reduced overlap helps emissions, and largely they can get away with cams like that because relatively speaking the heads flow very well.
Tighter LSA's will in most cases offer better power...but they will become harder for emissions
As for actual installed ICL...again in general there isnt a huge variation for most profiles.
stevieturbo said:
stigmundfreud said:
yep been looking at that a while back or similar as I was worried or rather concerned about the huge lsa's. The question is with a smaller LSA would it be possible to have a fruity cam and control emissions better?
The wide LSA is typically going to offer less overlap for any given set of profiles. Yes Martin is trying to distance the two and talk about actual valve events, but inevitably they will be linked for the majority of profilesThis reduced overlap helps emissions, and largely they can get away with cams like that because relatively speaking the heads flow very well.
Tighter LSA's will in most cases offer better power...but they will become harder for emissions
As for actual installed ICL...again in general there isnt a huge variation for most profiles.
stigmundfreud said:
its also where do you want the power, the wider lsa is more but higher and the graphs for the smaller LSA looks promising for street power so to speak it just seems everyone is hellbent on 114s 15s etc
Yes and no.115 LSA compared to some engines is still a pretty high number.
And whilst the wide LSA should ( and likely will ) push the power higher up the rpm....it's also relative to other timings.
If you look at almost all n/a builds with biggish cams that pull high rpm's and make damn good power doing so. Almost all will be in the low 110 range, some maybe even 108/9.
So that would almost throw the wide LSA for high rpm theory.
But they wont be particularly nice at low rpm's. There are always compromises and tradeoffs everywhere with cams and there are literally thousands of options which make it all the harder.
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