Cam, Engine and FI guys..need opinions...
 

I posted in another thread how I am seeing more boost with the new engine
setup. Any opinions on how,why? Only change is the cam and slightly higher CR(9:52.1 instead of stock 9:4.1) The cam is a comp cam 224/230 581/592 114lsa on X-ER lobes.
Any thoughts????????????????????

Thanks,
Randy

Could part of it simply be the colder outside temps? I am seeing a little more than an extra pound of boost due to the colder temps.

I know the colder weather helps, but it never saw 10psi last winter and it hit 10 the other day and I didnt stay in it long enough to rev out to high rpm's. I'm sure it would have gone higher than that if I had stayed in it :confused:

What were the old cam specs? How did the CR increase?

Not sure on the old cam specs. Engine was completely stock 2002 LQ4 6.0,Stock cam. THe CR increased because they had to deck the block slightly and the go over the bottom of the heads a bit.

Well my first vote would be for lower ambient temp., but you said you remember from last year it was not hitting that number. An increase of a pound and a half to two pounds is not uncommon at all.
Maybe this new cam has less dynamic compression??
form CranCam's website: "The cylinder pressure in an operating engine is closely related to the “effective” or “dynamic” compression ratio This dynamic pressure is affected more by the valve opening and closing events than the stroke length, cylinder bore, or combustion chamber volume. The single most important event is the intake valve closing point. The intake valve obviously must be open during the intake stroke, but most people don’t realize that the valve will remain open well past bottom dead center and into the compression stroke. In fact, with a high performance cam, the intake closing event can be more than 50° past BDC"!

I think this isn't the case either though. Your lobes are large enough to be letting a lot of air into the cylinders. (which would make a case for less boost) They would have to be closing that intake valve way early (or late after BDC) to not be filling the cylinders efficiently with more air.

Maybe your new engine is able to spin the compressor more easily from being more powerfull (less parasitic loss) No. I don't think so again, because it is a positive displacement supercharger.

...well I was thinking and typing at the same time :D Maybe it gives you some ideas, or I just took up some of your time by making you read this :D

What? It doesn't matter how powerful the engine is, the supercharger will always have the same parasitic loss unless modifications to the blower are performed. Also, maybe it's the way you worded it, but it seems your saying positive displacement superchargers don't have parasitic loss? :huh:

Keep the ideas coming...........

Ya just thinking while typing :D
Yes, belt driven = parasitic loss
Yes, there will be the same parasitic loss no matter what size engine.

i was kinda thinking the extra compression ration but that was not a big bump in the compression ratio only .12 :secret: is there something you not telling us :secret2: hehe no more ideas here when you figure it out post up though