Crazy Stealth Cam Idea
TECH Addict
Joined: Jul 2005
Posts: 2,153
Likes: 3
Okay, let's just take a look at the suggested 220/236 cam.
Start out with the CheaTR cam specs, which is 214/230-117. This cam has -7 deg overlap and closes the intake valve at 44 ABDC. You can pick just about any performance cam, even up to the race cams, and you will find that IVC is between 40 and 50 degrees. For example, a popular dirt track cam is 262/268-106. This cam is meant to make maximum hp with no regard for low-end or idle quality. Do the math and IVC is 50 deg ABDC (subtracting 6 deg for lash and 4 deg for advance). Even the TRex puts IVC at just under 50.
If you want to keep the same sound and idle quality, then the overlap would have to remain at -7. This means that the added duration would need to be on the EVO and IVC sides, rather than overlap (EVC/IVO). Doing this would make the spec's 220/236-120. IVC become 50 ABDC. The IVC becomes very late for this cam, which puts the dynamic compression pretty low and the rpm range very high.
It probably would produce a couple more hp up top, but most people who are looking for stock idle quality are willing to sacrifice 5 hp on top-end to gain 10 ft-lb down low.
Mike
Start out with the CheaTR cam specs, which is 214/230-117. This cam has -7 deg overlap and closes the intake valve at 44 ABDC. You can pick just about any performance cam, even up to the race cams, and you will find that IVC is between 40 and 50 degrees. For example, a popular dirt track cam is 262/268-106. This cam is meant to make maximum hp with no regard for low-end or idle quality. Do the math and IVC is 50 deg ABDC (subtracting 6 deg for lash and 4 deg for advance). Even the TRex puts IVC at just under 50.
If you want to keep the same sound and idle quality, then the overlap would have to remain at -7. This means that the added duration would need to be on the EVO and IVC sides, rather than overlap (EVC/IVO). Doing this would make the spec's 220/236-120. IVC become 50 ABDC. The IVC becomes very late for this cam, which puts the dynamic compression pretty low and the rpm range very high.
It probably would produce a couple more hp up top, but most people who are looking for stock idle quality are willing to sacrifice 5 hp on top-end to gain 10 ft-lb down low.
Mike
