What cam to hit 400rwhp for 383...

[imported_admin]

...with fully ported stock LT1 heads?

Mine flow 273/192 @ .600. I think this is on the low side for the breathing requirements of a 383. Ported LT4's would be nice, but a new short block is going to be budget-central, LOL.

I have more flexibility in cam choice now too that the car is an M6

236/242 112+4 LSA? (108 ICL)

Or 233/239 112+2 LSA (110 ICL)

I don't personally care for cams so large they cause PITA driveability...

[CamTom12]

Why would you want advance in the cam in a stroker?

[imported_admin]

Why would you want advance in the cam in a stroker?


Smaller duration and higher ICL will make same peak power as larger cam with lower ICL. I would bet the two examples above would make similar peak power, but the 2nd would make a tad less total power under the curve.

So I guess with that being said maybe 236/242 112+0 :o

[madmax]

Have you looked at the comp XFI cams? Lots of lift, short durations. 113LSA.

[imported_admin]

Have you looked at the comp XFI cams? Lots of lift, short durations. 113LSA.


No, but I will. Hmmm....

[CamTom12]

Why would you want advance in the cam in a stroker?


Smaller duration and higher ICL will make same peak power as larger cam with lower ICL. I would bet the two examples above would make similar peak power, but the 2nd would make a tad less total power under the curve.

So I guess with that being said maybe 236/242 112+0 :o


I thought you wanted to retard a cam to pull its peak numbers higher (though peak torque would be slightly lower, it would be higher in the rpm range and make more power)... And advancing made more torque at a lower rpm..

Did I get backwards again?

[imported_admin]

Why would you want advance in the cam in a stroker?


Smaller duration and higher ICL will make same peak power as larger cam with lower ICL. I would bet the two examples above would make similar peak power, but the 2nd would make a tad less total power under the curve.

So I guess with that being said maybe 236/242 112+0 :o


I thought you wanted to retard a cam to pull its peak numbers higher (though peak torque would be slightly lower, it would be higher in the rpm range and make more power)... And advancing made more torque at a lower rpm..

Did I get backwards again?


Yeah, you've got it backwards. Higher ICL moves the peak up in the RPM range. Reason is simply that as RPM increases, actual time for valve events is less per rotation, so you open the valves earlier to get the gasses in faster.

[CamTom12]

Not flaming, I just don't see how it makes sense... Opening the valve early also closes it early (when velocity is the highest) but it opens the exhaust early and closes it early which helps low-end breathing on bigger cams with more overlap...

I did a quick google (keywords: cam advancing retarding powerband) and saw this: "Advancing the cam 4 degrees always moves the torque curve down a few hundred RPM..just as retarding it moves it up a few. Just MAKE SURE your cam is ground to a 0 timing. Comp Cams for instance are ground with a 4 deg advance in the cam profile, so you would be advancing it 8 degree's on the chain." here: http://www.442.com/oldsfaq/ofcam.htm

[imported_admin]

Not flaming, I just don't see how it makes sense... Opening the valve early also closes it early (when velocity is the highest) but it opens the exhaust early and closes it early which helps low-end breathing on bigger cams with more overlap...

I did a quick google (keywords: cam advancing retarding powerband) and saw this: "Advancing the cam 4 degrees always moves the torque curve down a few hundred RPM..just as retarding it moves it up a few. Just MAKE SURE your cam is ground to a 0 timing. Comp Cams for instance are ground with a 4 deg advance in the cam profile, so you would be advancing it 8 degree's on the chain." here: http://www.442.com/oldsfaq/ofcam.htm


OK, you and I are just saying the same thing but saying it differently. if your lobe sep is 114, then 114 ICL would be "straight up". Advancing the cam is anything less than 114. So a 112 LSA and 108 ICL is 4 degrees advanced. But its called a 112+4 because its 4 advanced. So 112+4 in cam math = 108.

You are right, advancing helps low end, but advancing is the lower ICL, not the higher.

112+

[CamTom12]

AAAaaaaaahhhhhhhh

Makes much more sense now, hahaha. Thanks!

[Fenster]

230/236 or maybe a 236/242 IMO...

[madmax]

230/236 (more like 232/238) .576/.570
Thats what I have now. Pretty mean cam, cant tell where it really starts to run hard the tach moves too fast no matter where its at.