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Engine Mechanical TopicsDiscussion for motor builds, cams, head work, stripped bolts and other engine related issues. The good and the bad. If it goes round and around or up and down, post it here.
I've been reading a few of the top engine builders have been getting good results from the comp cams TC-3103.
they have been using compression ratio of 10.7 or so.
I'm doing a 96" - 106" build and wanting to use this cam, but can't see how to getting it to work at 10.7 compression...
This is what I get from big boyz calculator. Can't get ccp below 200?
Low 40s close makes my mind jump to ~10.5 static. If pistons are only 5 thou in the hole then quench is pretty ideal at .035. Combine that with 93 pump Id be ok with it unless its a touring bike (assuming it will be tuned right). APE has said good things about the Comp grinds, if they are one of the builders recommending that cam at 10.7 just remember they run different fuel out there. I like to push CCP but not everyone does so to each their own.
Was just on HTT and saw the thread you started there. I see you’re down under, not familiar with the fuel used there so cannot comment on the appropriate CCP now. The results I see from APE and some others using that fuel type are more generous than what I’ve seen here in the US even when converting to SAE. Makes me wonder if the fuel enables the use of more timing or is more forgiving with cranking pressure vs what we use here.
Based off your other thread I’d put a Comp 3102 in there instead (if wanting a Comp grind) at lower 10s static. Your friend seems to ride perhaps a bit conservatively and he has an exhaust system that’s likely not super ideal. Wouldn’t want a lot of overlap in the cam or too much exhaust duration as that mixes like oil and water with a eh pipe.
As a general comment, I am seeing a trend to run higher CCPs lately. I am running a CR595, 46*IVC in a 98" motor at 212psi with no issues, even in south Texas summer heat of 100+ with no issues. I believe if the motor is tuned by a real "tuner", higher CCPs are possible.
Providing a good tune and access to decent fuel, I wouldn't run a CCP less than 200psi.
I'm running 212 myself. 11.0:1 CR with the Tman 590 and 43° IVC.
No.issues with detonation on the hottest of days..
Low 40s close makes my mind jump to ~10.5 static. If pistons are only 5 thou in the hole then quench is pretty ideal at .035. Combine that with 93 pump Id be ok with it unless its a touring bike (assuming it will be tuned right). APE has said good things about the Comp grinds, if they are one of the builders recommending that cam at 10.7 just remember they run different fuel out there. I like to push CCP but not everyone does so to each their own.
Yeah, I would have thought 10.5 static is the maximum, but APE and some of the very reputable builders in the US are having good results at 10.7.... just wondered if it can be pushed that high?
Assuming decent fuel is availale, it will depend on the quality of the tune. I 10.5? 10.7? static is just a number; CCP is the guide for me.
Yeah, I agreed that dynamic compression / ccp is more important.
With 10.7 static and the TC-3130 I end up with over 206ccp and 9.8 corrected compression agriculture
which I always thought was too high, even with a good tune?
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Getting compression right for Comp cams TC-3103
