Whenever you take a cams power range and lower the LSA, it moves the powerband up or down or has nothing to do with the range?

 

Narrower LSA usually lowers the RPM range of the camshaft.

 

Lower LSA= More power down low!!!

 

Awesome, wanted to make sure my research taught me something. So if I took a MS4 donkey dick cam and lowered the LSA from the standard 111 to something a 110, it would lower the range of the RPMs like maybe 3-500?

 

As I understand it lowering the lsa will also make the power and torque curve more "peaky" but that is a very generalized statement. It will also increase ovelap and make the engine lope more

 

As far as lowering the powerband of the ms4, without cutting another cam is add cubes. The long duration of the ms4 moves the powerband way up high. I dont think changing to a lower lsa will help.

 

That is relative ICL used.
In general let us take a 224/224 cam and set the advance at +4* for exemple's sake.

A 114 +4 LSA would have a IVO of 2 BTDC and IVC of 42 ABDC
A 112 +4 LSA would have a IVO of 4 BTDC and IVC of 40 ABDC
A 110 +4 LSA would have a IVO of 6 BTDC and IVC of 38 ABDC

What does this mean?
It means that the tighter the LSA, the Intake valve opens sooner and closes earlier. basicaly, power will come on sooner and peak will occur sooner.
A product of LSA is overlap, by tightening the LSA you are increasing overlap. increasing overlap increases power.
All together (this is general to so you can understand, there are many other factors involved and it is a bit more complicated than that)
Tightening the LSA would basical bring the power on sooner, peak sooner and make more of it.

 

with an in general, rougher idle.

Any real downsides to lowering the LSA? I do not mind the choppy idle, so 110 or 109 is OK by me, just want to make sure there really arent problems.

 

I understand that valve events play a large role in where the powerband sits in the rev range but when you increase overlap too much, cylinder pressure will decrease as well as dcr which will hurt power production at low rpm correct? Just trying to learn here.

 

Yes, you are learning correctly.

More overlap = the camshaft bleeding off pressure and compression which is not good when using a big cam and not upping the compression.

Theres probably MANY threads of people putting in big *** cams in their cars just b/c "such and such made X amount of power" and power/nasty idle is cool. Then come back a few weeks later to complain how the car is soft down low. Thats b/c the wild duration and valve overlap KILLED the dynamic compression and made it soft...which sucks especially on a DD or mostly a street car.

The other thing with a tight LSA is that it makes it more difficult to tune that I have heard/read. Not a big deal to me as I dont tune my own **** so I havent read too much into it and am not 100% sure if thats still a problem or not.

I like picking combo's right the FIRST time by knowing my goals and what I want/expect from the motor. Pick out a set of heads, get them milled/ported and then pick a camshaft to compliment the heads in the RPM range you want to work with.

Just be careful is using milled heads to make sure the valves will clear the pistons and they dont need to be flycut b/c that gets into a pain in the ***.

Sorry for the long post.

 

good post, so tightening the overlap will cut out down low a little