Cam Duration Vs. Usable/Used RPM Range

[805moparkid]

So i have been thinking about duration in a slightly different way. I know you usually only want the minimum amount of duration to achieve a rpm shift or redline.

Now if your shifting at say 6500, when you shift it drops to:

1-2 shift 3850rpms
2-3 shift 4480rpms

Lets use a 500RB, 4.15 stroke motor as our model. So if your running a 240* @ .050 cam and (3000-6000, 6500 redline ( Crower 32309 cam) and say the Crower 32310 (3500-6500, 7000redline), which would go faster.

It seems to me if your shift point never dropped below your peak tq it would go faster, even if the cam was bigger. Im just looking at this and curious.

 

[70aarcuda]

you dont say if it is a 4 speed or automatic....if automatic..the rpm drop will not be less then the stall speed of the converter..

 

[805moparkid]

you dont say if it is a 4 speed or automatic....if automatic..the rpm drop will not be less then the stall speed of the converter..

auto

and a 4500 would be the stall

 

[flyfish]

auto

and a 4500 would be the stall

Then on your 1-2 and 2-3 shifts your RPM would drop to 4500 each time, not 3850 and 4480....just sayn.:coffee2:

 

[bOb shingler]

if you're shifting at 6500 and your rpm's drop that low you have some real problems. like your rear ratio is 1-1.

 

[805moparkid]

Then on your 1-2 and 2-3 shifts your RPM would drop to 4500 each time, not 3850 and 4480....just sayn.:coffee2:

thats why i posted the converter stall, i was just going off the math forgetting the converter slip

if you're shifting at 6500 and your rpm's drop that low you have some real problems. like your rear ratio is 1-1.

i got those using the wallace calculator

 

[moper]

I have some other questions back at you...
What info is Crower using to determine those power ranges?
Do you feel that the time to determine the cam is after the rest of the package is put together?
What determines the "minimum amount of duration to achieve a rpm shift or redline"?

I think I know what you're asking - but the way you're asking it doesn't make much sense to me... if that makes sense...lol.

 

[HawaiiDuster]

Which ever one makes the most power in the rpm range that you're running. That would be the faster one....providing everything else is the same.

 

[805moparkid]

I have some other questions back at you...
What info is Crower using to determine those power ranges?
Do you feel that the time to determine the cam is after the rest of the package is put together?
What determines the "minimum amount of duration to achieve a rpm shift or redline"?

I think I know what you're asking - but the way you're asking it doesn't make much sense to me... if that makes sense...lol.

I have a hard some getting thoughts onto paper, always have.

Basically the smaller cam would probably be the best "all around" cam because it would come in sooner, and not go past intended usage BUT if your rpm range was high enough and you are running a high stall (4500, relative I know) why not run a cam that would build more power in the mid to upper being its never going to see the low.

is that at all better?

Which ever one makes the most power in the rpm range that you're running. That would be the faster one....providing everything else is the same.

Well right, and in reality I guess that's what it all boils down to. The smaller cam would make more power at a lower rpm but the bigger cam might make the same power or better in the "usable" or intended range.

 

[HawaiiDuster]

I was just being a wise a$$, forgot to add one of those smileys at the end

 

[Abodybomber]

32310,sweet here. Ran a aggressive 242/252 circle track cam(lobes widened to 112) Crower lobes. (396 Chev rat)A heavy car,with a tight converter(3680 lbs.,tight Darrell Young 2800 stall,4:10's ,out back). The shift points 6000,recovery at 4300. Same cam,square ports: same damn thing. The shift recovery, is what counts here. (Add an 8082 Dominator, couldn't keep the tires from spinning). Hope this helps,lol.