what to look for in a cam?
06-20-2008, 09:41 PM
#1
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Car: 89 IrocZ/17 LS 1LE
Engine: 383/LGX
Transmission: 400/TR-3160
Axle/Gears: 3.08/3.27
what to look for in a cam?
what kinda of lift/duration #'s should I be looking for? motor is 8:1 350 stockish heads/TPI with a P600b @ 10-12lbs. more of a street/daily driver, but will see some track time.
06-20-2008, 09:48 PM
#2
Re: what to look for in a cam?
possibly something like comp's 276nx blower/nitrous grind. 224/236... its abit bigger than i'd like for that setup but i do hear blowers tame cams down abit. could go custom grind, but basically you dont want alot of overlap like optimal n/a cams have. generally a wider exhaust duration split and slightly wider lsa dependign on duration
with stockish L98 heads, i would keep lift no more than .500's-.520's. no point in going too much higher. Boost may make the flow numbers peak at a higher lift than a n/a motor but i dont think its gonna make much difference in power
with stockish L98 heads, i would keep lift no more than .500's-.520's. no point in going too much higher. Boost may make the flow numbers peak at a higher lift than a n/a motor but i dont think its gonna make much difference in power
06-21-2008, 08:03 AM
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Car: 1991 Corvette
Engine: Bottle fed L98
Transmission: ZF 6 speed
Axle/Gears: D44 IRS/3.92
Re: what to look for in a cam?
Be careful with spring retainer to valve guide seal clearance with the stock L98 heads. If your heads are cast iron they might be different than the aluminum ones on my Corvette, but I would think they would be the same. On my car, anything over about a .520 lift would cause the keepers to contact the valve seals.
06-21-2008, 09:04 AM
#4
Re: what to look for in a cam?
Overlap is not necessarily bad in a forced induction applications. It does increase fuel consumption.
Since overlap increases scavenging, more fresh mixture can be compressed since the intake pressure helps to remove the residual exhaust gases with results similar to an increase in compression ratio.
Here's an interesting experiment on the subject:
http://www.not2fast.com/NACA/naca-tn-405.pdf
Since overlap increases scavenging, more fresh mixture can be compressed since the intake pressure helps to remove the residual exhaust gases with results similar to an increase in compression ratio.
Here's an interesting experiment on the subject:
http://www.not2fast.com/NACA/naca-tn-405.pdf
06-23-2008, 10:38 AM
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Car: 1982 Trans-Am
Engine: 355 w/ ported 416s
Transmission: T10, hurst shifter
Axle/Gears: 10 bolt, true-trac, 3.73
Re: what to look for in a cam?
Orr hit the nail on the head. Wider LSA, longer exhaust. I'd keep the intake short, since you have such a small CR, that you'll want your low end back.
You have a centrifugal blower right? Therefore you'll have a bit of a soft bottom end until the blower comes on.
You don't really need a big cam (duration wise), just like Orr said (although he was referring to lift), since the blower will make up for it. ie even if the cam says 1200-5200RPM, the blower will make it a wider range.
You have a centrifugal blower right? Therefore you'll have a bit of a soft bottom end until the blower comes on.
You don't really need a big cam (duration wise), just like Orr said (although he was referring to lift), since the blower will make up for it. ie even if the cam says 1200-5200RPM, the blower will make it a wider range.
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