Cam Dynamics Question....
11-18-2003, 02:56 PM
#1
Cam Dynamics Question....
Cam Dynamics Question…..
I purchased a cam from Ultradyne prior to their demise and ran it in my boat for 2 seasons.
At the time, I ordered a cam from them with the following requirements; A mild cam for a 540 c.i. naturally aspirated motor with 9.2:1 CR that spun about 5300 rpm and was run 85% of the time at altitudes of 4500+ feet meaning I needed to retain cylinder pressure.
The cam they supplied me was a 232/240 114 .600/.600. The cam card instructs to degree the intake at 108’ ATDC which I believe is 6’ advanced. I’m thinking that this was done to make the cam a little milder and bring the peak rpm down to 5300. Kind of making an existing grind fit I suppose.
The cam is in perfect shape and I think I would like to use it again with my now blown 540.
Question is, by degreeing the cam at 112-114 rather than 108, would it make the cam a little more aggressive and bring the peak to say 5500 rpm?
Some side notes:
Cam card reads:
Duration at .006 is 284/292
Degree intake lobe to 108’ ATDC
Seat timing INT-32 BTDC 72 ABDC 108’
Seat timing EXH-85 BBDC 27 ATDC 120’
compression is now 8.75:1 with 5-7 lbs of boost.
Thanks in advance,
Dave
I purchased a cam from Ultradyne prior to their demise and ran it in my boat for 2 seasons.
At the time, I ordered a cam from them with the following requirements; A mild cam for a 540 c.i. naturally aspirated motor with 9.2:1 CR that spun about 5300 rpm and was run 85% of the time at altitudes of 4500+ feet meaning I needed to retain cylinder pressure.
The cam they supplied me was a 232/240 114 .600/.600. The cam card instructs to degree the intake at 108’ ATDC which I believe is 6’ advanced. I’m thinking that this was done to make the cam a little milder and bring the peak rpm down to 5300. Kind of making an existing grind fit I suppose.
The cam is in perfect shape and I think I would like to use it again with my now blown 540.
Question is, by degreeing the cam at 112-114 rather than 108, would it make the cam a little more aggressive and bring the peak to say 5500 rpm?
Some side notes:
Cam card reads:
Duration at .006 is 284/292
Degree intake lobe to 108’ ATDC
Seat timing INT-32 BTDC 72 ABDC 108’
Seat timing EXH-85 BBDC 27 ATDC 120’
compression is now 8.75:1 with 5-7 lbs of boost.
Thanks in advance,
Dave
11-18-2003, 09:08 PM
#3
Platinum Member
Platinum Member
4 degrees advanced is pretty common for a normally aspirated motor. The two or so more degrees they advised would have rocked the torque peak down a few revs.
A supercharged motor typically doesn't "need" the same amount of advance that benefits an NA motor. In fact, the additional advance tends to cause the first bit of intake charge to be wasted into the exhaust stream. In most cases, a couple less degrees of cam advance is helpful from both an economy and power production standpoint.
You had 6 degrees of advance. 4 degrees would have been "standard", and 2 degrees would be standard for a supercharged app.
There's your "guidelines". Feel free to experiment, as long as you make sure your valve to piston clearance remains safe.
A supercharged motor typically doesn't "need" the same amount of advance that benefits an NA motor. In fact, the additional advance tends to cause the first bit of intake charge to be wasted into the exhaust stream. In most cases, a couple less degrees of cam advance is helpful from both an economy and power production standpoint.
You had 6 degrees of advance. 4 degrees would have been "standard", and 2 degrees would be standard for a supercharged app.
There's your "guidelines". Feel free to experiment, as long as you make sure your valve to piston clearance remains safe.
