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| overlaping cam https://slantsix.org/forum/viewtopic.php?t=46927 |
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| Author: | USAJon [ Wed Nov 09, 2011 5:05 am ] |
| Post subject: | overlaping cam |
back in the day on big inch/high comp harleys we sold a lot overlapping cams so they were a tad easy to start... do you think this would apply to high comp/pinging slant six's? as in to reduce ping from street high octane gas?. any thoughts? |
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| Author: | sandy in BC [ Wed Nov 09, 2011 5:49 am ] |
| Post subject: | |
Dynamic compression ratio. Read more. |
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| Author: | DusterIdiot [ Wed Nov 09, 2011 5:50 am ] |
| Post subject: | They already do... |
Pretty much all cams for car engines have overlap...smaller cams have a tighter overlap and all the race cams have lots (the cam i just ordered has 76 degrees of it)...this can be changed a bit by changing the lobe separation...and yes the more you have the more the cylinder pressure bleeds down during the scavenging event. Which does help in cases of higher compression as you mention. -D.Idiot |
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| Author: | Doc [ Wed Nov 09, 2011 8:48 am ] |
| Post subject: | |
Cam, compression and fuel quality are all closly related... that where doing a accurate DCR calculation comes in. Set the DCR to the fuel you will be running and the engine will respond with "ping free" performance. DD |
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| Author: | USAJon [ Wed Nov 09, 2011 9:43 am ] |
| Post subject: | |
when you ran 11 to one in your 210 stroker cuda what fuel/cam did you run? |
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| Author: | Doc [ Wed Nov 09, 2011 9:55 am ] |
| Post subject: | |
Pump Premium spiked with race gas, a roller cam w/ a late intake closing event and reduced ignition timing.' Basically... a race engine "de-tuned" for street use. I would build that combo differently for "street performance" use. DD |
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| Author: | DusterIdiot [ Wed Nov 09, 2011 6:21 pm ] |
| Post subject: | Yep... |
Currently I have a mill that is running 10.3:1 SCR, DCR is low 8's...engine runs fine on 87 regular with a little timing yarded out of it...I can add about 4 degrees (twist of the wrist...check with timing light) and run it fine on 89-92...cam is the 280/270 erson 4 degrees advanced with a 111LSA (overlap in the low 50's). DCR calculator is one of the best engine building tools you can use. -D.Idiot PS-My next mill is going to be low 12:1 SCR...calcs show with the cam I'll be in the mid-high 8's DCR...expect the mill to strictly be a premium/race gas engine... |
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