alright, i have been doing my reading and research on new cams... i understand that a 114 lsa would be more emissions frignly than a 112 lsa and lsa is lobe separation angle...so i think its the number of degrees of rotation between another lobe but does LSA correspond to ramp rate? if so what exactly is ramp rate and how does it keep you from using a certain type of valve spring i.e. comp 918s? basicallly what does LSA have to do with the performance of a specific cam and how can it effect emissions....someone please explain ramp rate for me too

sincerely,
Sir Noob

 

in general the less LSA that is ground into a cam the more overlap that you will see between the intake and the exhaust valves open. a 112 LSA can create greater "suction" if you will because because both intake and exhuast valves are open at the same time. This is what makes an afternarket cam give you power is that greater amount of suction that is created by the lsa. But at the same time it is causing air to get sucked in (which is good for power, more air morepower) and just go out the exhaust because of the overlap specs that are ground into the cam. here is link that will help you out a little. I know that are guys that can explain better

http://www.chevyhiperformance.com/techarticles/95298/

 

Hey Kyle....Git your *** in here.

 

LSA is the angle between the intake center line and the exhaust center line. As Destrucktive said, LSA has a strong relationship to overlap -- generally speaking the smaller the LSA, the more overlap. What makes power in an aftermarket cam isn't the scavenging effect (although it helps on an NA cam) but the combination of more valve event duration and more valve lift.

Ramp rate is the "speed" that the lobe can get the valve to full open, and how long the valves are open wide. It has to do with the shape of the lobes. Faster ramp rates tend to be more abusive to springs because they compress the spring very abruptly and with more force.

LSA does a ton of stuff in a cam. It dictates how much lope (overlap), how much vacuum, drivability, etc. Here's a good thread: https://www.performancetrucks.net/fo...d.php?t=284128

 

so if i was looking at a VHP 218/224 .551 with LSA 115 and overlap of 53 would that be a decent step up from my current 204/218 LS6 cam now? i was a cam that will still move in the low rpms but note that when i swap it out i will have a tt3000. reading about LSA and stuff it seemed 115 was a little high.... but i dont know too much...

 

A lot of LSA tight vs. wide info out there on the net is SBC based instead of gen III. 115 is wide, but not ultra wide like it would be in an SBC. For an NA car, I would look a little tighter personally (like 110-112 range) but I really like nasty lope and can tune it myself. A 115 on that cam would be pretty decent in terms of drivability and idle, and that cam definitely has more go than the LS6 stick.

 

i was also thinkin about the crane cam 224/224 with 114 or a GM PP 219/228 .541 114 or i could even egt the same VHP 216/224 .551 with a LSA of 113 but overlap of 57* instead of just 53 with the 115 LSA...it's true im lookin for much stronger than the LS6, i want it to be pretty streetable i like the lope and will have any cam tuned by the people who installed my LS1 edit so tuning isnt the issue and next time i do the swap i will have a tt3000 so im not TOO worried about the low end but i still want to have some...whats your opinion turbo?

 

I'd do the VHP on a 113. I know Roger and Joe personally and they will be helping me design my next cam. They spend a lot of time designing and testing their cams for cars and trucks and have Crane engineers supporting them.

 

thanks a bunch turbo, i assume even though lift is only .551 i should invest in some comp918's?

 

I would.