Torn between 2 cams
12-27-2008, 11:24 PM
#21
yeah you got it wrong. tighter (smaller #) brings the power band down in the rpm power band. at the sacrifice on idle quality and off idle quality. but as just stated, who cares about idle to 2500rpm. but if I can make 20HP more at 4K rpm and lose 20HP at 6500rpm, ofcourse that is alot more usuable. once in a great while you will hit WOT and actually rev it out to the limit. but you always hit 4K when goosing it for a few seconds right? plus it will help with keeping the engine alive longer too.
12-28-2008, 07:24 AM
#22
yeah you got it wrong. tighter (smaller #) brings the power band down in the rpm power band. at the sacrifice on idle quality and off idle quality. but as just stated, who cares about idle to 2500rpm. but if I can make 20HP more at 4K rpm and lose 20HP at 6500rpm, ofcourse that is alot more usuable. once in a great while you will hit WOT and actually rev it out to the limit. but you always hit 4K when goosing it for a few seconds right? plus it will help with keeping the engine alive longer too.
WHAT!?!?!
"
Lobe Separation: LSA is the number of degrees the intake and exhaust lobes are separated. The lower the LSA, the increased the overlap. Increasing overlap increases top-end power while reducing low-speed power and idle quality."
"cc305: (220/230 .544/.544 114lsa) w/ 1.6RR's
Very similar in size to the LT4 Hot Cam but with 2 more degrees of duration on the intake and exhaust side at .050 and a bit more lift. Comes in a 112lsa and 114lsa. The 114lsa will have increased bottom-end power over the 112lsa while that will have increased top-end power. The 114lsa is sometimes favored by cars running Nitrous or Blowers because it provides less overlap than a 112lsa which helps maximize the power coming from the Nitrous or Blower. Features Comp's Magnum lobes which are older but proven to not take a beating on the valvetrain."
I thought that was well known? Go look at ANY factory cam from GM. They are all on a 116-117 LSA or even higher sometimes. What does a stock LT1 rev to?
Last edited by joelster; 12-28-2008 at 07:41 AM.
12-28-2008, 08:24 AM
#23
http://www.babcox.com/editorial/ar/eb90252.htm
Said it a hundred times already 110 is still wide.
Factory cams are so mild they should not be used for comparison to aftermarket performance cams.
Look at the b-body cam, it is on a 111, not a lot of overlap because the lobes are so mild, roughly .030 less lift than the f-body cams and roughly 10 degrees less duration. Putting 1.6 rockers on it brings it up very close to f-body 1.5 lift numbers. We all agree it made more peak torque at a lower rpm than the f-body did and did it with 87 octane tuning and .4 less compression, heads generally agreed to flow slightly better.
Funny thing is that in bolton trim guys get this over 300rwhp, actually comes out pretty close to the f-body.
It is my opinion that the f-body cam was specifically compromised to limit lowend to save the POS axle they got, the LT1 b-body got the 8.5" axle. The lower advertised peak HP for the b-body was accruate but you get a LOT back as you open up the intake and exhaust, the airfilter box moves like 450cfm, the MAF is 3" and the exhaust while dual is severely crushed, the mufflers are 1.75" inside and it is all grandpa quiet, afterall that is who was buying these things right.
Said it a hundred times already 110 is still wide.
Factory cams are so mild they should not be used for comparison to aftermarket performance cams.
Look at the b-body cam, it is on a 111, not a lot of overlap because the lobes are so mild, roughly .030 less lift than the f-body cams and roughly 10 degrees less duration. Putting 1.6 rockers on it brings it up very close to f-body 1.5 lift numbers. We all agree it made more peak torque at a lower rpm than the f-body did and did it with 87 octane tuning and .4 less compression, heads generally agreed to flow slightly better.
Funny thing is that in bolton trim guys get this over 300rwhp, actually comes out pretty close to the f-body.
It is my opinion that the f-body cam was specifically compromised to limit lowend to save the POS axle they got, the LT1 b-body got the 8.5" axle. The lower advertised peak HP for the b-body was accruate but you get a LOT back as you open up the intake and exhaust, the airfilter box moves like 450cfm, the MAF is 3" and the exhaust while dual is severely crushed, the mufflers are 1.75" inside and it is all grandpa quiet, afterall that is who was buying these things right.
12-28-2008, 05:46 PM
#26
112 is a typical lsa, n20 or otherwise. 114 or 115 is for boost or really large n20 shots. 300and up.
also, I just realized. I kinda misspoke. what I should have said is narrower ICL will shift the power band down. (ADVANCING the cam is how you get a narrower ICL) narrower LSA will generally make more power across the board (w/n the normal range of LSA's) but at the expense of idle and off idle driveability. and longer durations (higher number) will lose power down low dramaticaly, and pick up some at the top.
all this is why you gotta know what you want the car to do, and how much are you willing to put up with in terms of driveability, and ease of tuning. but again Im not trying to act like I know everything. why I recomended you to at least talk to some experts to help guide you.
also, I just realized. I kinda misspoke. what I should have said is narrower ICL will shift the power band down. (ADVANCING the cam is how you get a narrower ICL) narrower LSA will generally make more power across the board (w/n the normal range of LSA's) but at the expense of idle and off idle driveability. and longer durations (higher number) will lose power down low dramaticaly, and pick up some at the top.
all this is why you gotta know what you want the car to do, and how much are you willing to put up with in terms of driveability, and ease of tuning. but again Im not trying to act like I know everything. why I recomended you to at least talk to some experts to help guide you.
Last edited by Irocss85; 12-28-2008 at 05:52 PM.
12-28-2008, 06:00 PM
#27
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It is not the LSA that effects it, it would be the Intake Center Line 9ICL) or the intake valve closing point.
224/230 112 LSA +4 (108 ICL)
224/230 109 LSA +1 (108 LSA)
Same Intake valve closing point and same intake lobe centerline but the 108 LSA cam will haev a lil less vacuum, a lil choppier idle, more mid range TQ and more top end power while pulling to the same RPM as the 112 LSA.
the LSA is not the deciding factor here.
If you have the same 224/230 109 LSA cam +4 and end up on a 105 ICL, it will peak sooner due to the earlier intake valve closing point and build a lil more TQ due to the higher clyder pressure but not as much peak HP due top the intake closing sooner and the exghaust being on a 113 ECL. This hurts the exhaust lobes efficiency at high RPM.
Lloyd
224/230 112 LSA +4 (108 ICL)
224/230 109 LSA +1 (108 LSA)
Same Intake valve closing point and same intake lobe centerline but the 108 LSA cam will haev a lil less vacuum, a lil choppier idle, more mid range TQ and more top end power while pulling to the same RPM as the 112 LSA.
the LSA is not the deciding factor here.
If you have the same 224/230 109 LSA cam +4 and end up on a 105 ICL, it will peak sooner due to the earlier intake valve closing point and build a lil more TQ due to the higher clyder pressure but not as much peak HP due top the intake closing sooner and the exghaust being on a 113 ECL. This hurts the exhaust lobes efficiency at high RPM.
Lloyd
12-28-2008, 06:07 PM
#28
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My Buddy and I put the Ai 226/234 cam in his stock shortblock car with the 200cc heads and ported intake. I don't know if this helps you much, but the car is a beast while being daily driveable. it also pulled down 28mpg on a road trip. the car has 373 gears and an m6
Hope this helps.
Kory
Hope this helps.
Kory
12-28-2008, 06:24 PM
#29
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It is not the LSA that effects it, it would be the Intake Center Line 9ICL) or the intake valve closing point.
224/230 112 LSA +4 (108 ICL)
224/230 109 LSA +1 (108 LSA)
Same Intake valve closing point and same intake lobe centerline but the 108 LSA cam will haev a lil less vacuum, a lil choppier idle, more mid range TQ and more top end power while pulling to the same RPM as the 112 LSA.
the LSA is not the deciding factor here.
If you have the same 224/230 109 LSA cam +4 and end up on a 105 ICL, it will peak sooner due to the earlier intake valve closing point and build a lil more TQ due to the higher clyder pressure but not as much peak HP due top the intake closing sooner and the exghaust being on a 113 ECL. This hurts the exhaust lobes efficiency at high RPM.
Lloyd
224/230 112 LSA +4 (108 ICL)
224/230 109 LSA +1 (108 LSA)
Same Intake valve closing point and same intake lobe centerline but the 108 LSA cam will haev a lil less vacuum, a lil choppier idle, more mid range TQ and more top end power while pulling to the same RPM as the 112 LSA.
the LSA is not the deciding factor here.
If you have the same 224/230 109 LSA cam +4 and end up on a 105 ICL, it will peak sooner due to the earlier intake valve closing point and build a lil more TQ due to the higher clyder pressure but not as much peak HP due top the intake closing sooner and the exghaust being on a 113 ECL. This hurts the exhaust lobes efficiency at high RPM.
Lloyd
