Cam Motion cams
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I run a Cam Motion. My only recommendation would be to not let them spec out your cam. I was running a hotcam and decided to upgrade several years back. I didn't know how to spec a cam and thought it would be best to let them tell me whats best based upon my combo, flow sheet, etc. After replacing the cam and getting a new tune, I have not yet been able to run better NA times than what I did with the hotcam. I also dyno less than I did with the hotcam (360 vs 340 rwhp) on the same dyno. I have had a few others that do know cams take a look at the specs and all of them agree that it was done incorrectly. Once of the recurring statements is that a single pattern cam is probably the worst choice for an LT1. I dunno, just have not been happy with it.
I was looking for a step up and got what seems to be a step down
Duration:
Intake: 227
Exhaust: 227
Lift:
Intake: 556
Exhaust: 556
Lobe Center: 112
Centerline: 108
And my head flow numbers are below.
I was looking for a step up and got what seems to be a step down
Duration:
Intake: 227
Exhaust: 227
Lift:
Intake: 556
Exhaust: 556
Lobe Center: 112
Centerline: 108
And my head flow numbers are below.
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Joined: Oct 2007
Posts: 2,630
Likes: 28
I run a Cam Motion. My only recommendation would be to not let them spec out your cam. I was running a hotcam and decided to upgrade several years back. I didn't know how to spec a cam and thought it would be best to let them tell me whats best based upon my combo, flow sheet, etc. After replacing the cam and getting a new tune, I have not yet been able to run better NA times than what I did with the hotcam. I also dyno less than I did with the hotcam (360 vs 340 rwhp) on the same dyno. I have had a few others that do know cams take a look at the specs and all of them agree that it was done incorrectly. Once of the recurring statements is that a single pattern cam is probably the worst choice for an LT1. I dunno, just have not been happy with it.
I was looking for a step up and got what seems to be a step down
Duration:
Intake: 227
Exhaust: 227
Lift:
Intake: 556
Exhaust: 556
Lobe Center: 112
Centerline: 108
And my head flow numbers are below.
I was looking for a step up and got what seems to be a step down
Duration:
Intake: 227
Exhaust: 227
Lift:
Intake: 556
Exhaust: 556
Lobe Center: 112
Centerline: 108
And my head flow numbers are below.
I would question whether or not the install was done correctly before bashing the cam maker. That cam should mop up a hotcam. A single pattern camshaft is perfectly fine. Most cams are ground with more duration on the exhaust side because typically exhaust flow numbers are WAY behind intake flow numbers. In your case your exhaust flows over 80% of what your intake flows which is excellent. No need for additional exhaust duration if the valve and port work are getting the job done. I would have a second set of eyes go over the lash, check the install height on the springs, check the pushrod length, etc, etc...
On that subject...
http://www.iskycams.com/techtips.html#2003
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Joined: Oct 2007
Posts: 2,630
Likes: 28
You also have to take into account the ENTIRE intake portion of the car and the ENTIRE exhaust. Just because the heads flow unevenly doesn't mean the rest does.
On that subject...
http://www.iskycams.com/techtips.html#2003
On that subject...
http://www.iskycams.com/techtips.html#2003
You didn't. I did. 80% is uneven. 100% is even. It's not bad like our stock heads are (though that's still 78%ish @.600), but it's still not "even." Our aftermarket exhaust typically makes it closer to even than heads alone will show. Most don't take that into account.
Last edited by LSWHO; Oct 6, 2010 at 01:40 PM.
I would question whether or not the install was done correctly before bashing the cam maker. That cam should mop up a hotcam. A single pattern camshaft is perfectly fine. Most cams are ground with more duration on the exhaust side because typically exhaust flow numbers are WAY behind intake flow numbers. In your case your exhaust flows over 80% of what your intake flows which is excellent. No need for additional exhaust duration if the valve and port work are getting the job done. I would have a second set of eyes go over the lash, check the install height on the springs, check the pushrod length, etc, etc...
Not really trying to bash them, just stating my experience and opinion as the OP asked for. The cam is installed correctly, straight up, as recommended by Cam Motion using springs spec'd by Cam Motion as well. Push rods align perfectly. In contrast to my NA numbers, I have run better n2o times with their cam. I just don't run it NA anymore.
Last edited by LSWHO; Oct 6, 2010 at 01:40 PM.
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Joined: Oct 2007
Posts: 2,630
Likes: 28
It doesn't need to be even as in, intake flow= exhaust flow. That is why EVERY 4- cycle engine built has a larger intake valve/port than exhaust valve/port. There is a reason for this. An engine has gas (air) and fuel (liquid) going in one end, but just burned gas (hopefully) coming out. If the intake port can flow 250cfm, the exhaust port doesn't need to flow 250cfm. The combustion turns the air/fuel into heat energy and the overall volume of stuff going out is less than what went in.
Light a match
Place a 500cc glass over it
watch the match go out
What happened to the 500cc of air? Gone, poof!
Combustion is a chemical reaction that alters things.
I'm heading down the split ratio rocker track. I have plenty of room and a set of 1.7s on the shelf in the garage. Just need to measure the pushrod size for the 1.7s
I'd like to see the difference in using all the 1.7s vs split ratio with 1.6/1.7
I'd like to see the difference in using all the 1.7s vs split ratio with 1.6/1.7
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Joined: Oct 2007
Posts: 2,630
Likes: 28
Did you dyno your car on the same dyno when you did the hotcam vs the Cam Motion cam?