how big is too big?
03-18-2009, 10:13 PM
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how big is too big? hey guys i have started shopping for cams...i was just wondering about where should i cut off my duration at and still be not be sucking my vacume away and making other parts affected like brakes etc..and id wanna stay away from a external vacume tank if possible for now is 270 ish duration too much you think?
03-18-2009, 10:42 PM
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Come on now, we need more info than that......what cubic inch? What intake? Valve overlap will kill the power brakes (not just a big dur. #).And what, u think the biggest cam will make the most power? Remember, the biggest peak # does not always get u down the track faster.
03-19-2009, 02:03 AM
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lol no no no in no way was i saying that just the cam was going to give me my power...i was just wondering what would be too extreme sorry it was a bit vauge.. 383 stroker with my heads my compression ratio is roughly going to be 10.6:1 , bbk intake with 85mm throttle body 1.75 roller rockers
beehive valve springs AFR mongoose 225cc ported heads milled to 68cc pacesetter longtubes too LM1... the cam i am looking into is as follows 287/289 duration 238 @ .050 intake 240 duration @ .050 exhaust its a .605 lift cam the lobe seperation is 112 its powerband is between 2800-7200 rpms
beehive valve springs AFR mongoose 225cc ported heads milled to 68cc pacesetter longtubes too LM1... the cam i am looking into is as follows 287/289 duration 238 @ .050 intake 240 duration @ .050 exhaust its a .605 lift cam the lobe seperation is 112 its powerband is between 2800-7200 rpms
03-19-2009, 02:14 AM
#4
lol no no no in no way was i saying that just the cam was going to give me my power...i was just wondering what would be too extreme sorry it was a bit vauge.. 383 stroker with my heads my compression ratio is roughly going to be 10.6:1 , bbk intake with 85mm throttle body 1.75 roller rockers
beehive valve springs AFR mongoose 225cc ported heads milled to 68cc pacesetter longtubes too LM1... the cam i am looking into is as follows 287/289 duration 238 @ .050 intake 240 duration @ .050 exhaust its a .605 lift cam the lobe seperation is 112 its powerband is between 2800-7200 rpms
beehive valve springs AFR mongoose 225cc ported heads milled to 68cc pacesetter longtubes too LM1... the cam i am looking into is as follows 287/289 duration 238 @ .050 intake 240 duration @ .050 exhaust its a .605 lift cam the lobe seperation is 112 its powerband is between 2800-7200 rpms
Something in the 240's is as big as you want to go with a 383ci. Why such low compression?
03-19-2009, 02:39 PM
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"That's a 238/240 cam. His first numbers are just the advertised duration, not the duration @ .050."
soo then this cam would be right in the money zone then? being that it is rated at 238/240 @.50??
03-19-2009, 08:02 PM
#9
The problem with choosing a cam in this fashion is that you can't swing a dead cat around here without hitting a "cam expert". Find a knowledgable person with a good track record and pay them to design a cam for you based on the build and how you want to use the car. As many people are taking out BIG cams as are taking out smaller ones and putting in larger ones. Giant cams can get old pretty fast. A well designed cam can meet your HP wants and still leave you with a car that's fun to drive. That person can help you with compression, valve train setup, etc, etc, etc, so you end up with a nice package.
Just my $.02
Just my $.02
Last edited by WKMCD; 03-20-2009 at 12:53 PM.
03-19-2009, 10:17 PM
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The problem with choosing a cam in this fashion is that you can't swing a dead cat around here without hitting a "cam expert". Find a knowledgable person with a good track record and pay them to design a cam for you based on the build and how you want to use the car. As many people are taking out BIG cams as are taking out larger ones and putting in smaller ones. A well designed cam can meet your HP wants and still leave you with a car that's fun to drive. That person can help you with compression, valve train setup, etc, etc, etc, so you end up with a nice package.
Just my $.02
Just my $.02
03-20-2009, 07:00 AM
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The problem with choosing a cam in this fashion is that you can't swing a dead cat around here without hitting a "cam expert". Find a knowledgable person with a good track record and pay them to design a cam for you based on the build and how you want to use the car. As many people are taking out BIG cams as are taking out larger ones and putting in smaller ones. A well designed cam can meet your HP wants and still leave you with a car that's fun to drive. That person can help you with compression, valve train setup, etc, etc, etc, so you end up with a nice package.Just my $.02
I'd only add in response to your original Q; if you want it street-friendly stay below 50-55 degrees valve overlap (You will need the valve timing from the total or advertised duration figures to find this).
03-20-2009, 10:40 AM
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03-20-2009, 12:50 PM
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Just for a reference 10 degrees at .050 is 66 degees more or less at .003 depending on the lobes used. There are plenty of great running street cars with 13-14 degrees overlap. My cam is 11 degrees on a 111 LSA and it truly drives very close to stock. Todays tuning capabilities means you can get away with more cam than you could even 7-8 years ago and still have a great driving car.
03-20-2009, 01:52 PM
#20
Believe me. I can run my car down to 600 RPM in 6th and do it. Once on the highway I put the car in 6th and never shift for ramps etc. I can cruise through parking lots with no cam effect. 25MPH through the neighborhood in 3rd wit no cam effect.
It just takes a well done cam and a very good tuner.
