I would like my BB to redline around 7000 at the strip. I need to select a cam that peaks at the proper rpm, but what rpm am I looking for? How many rpm should the engine peak before shifting?

Sir, you won't need a 7000 redline with 4.10s unless you're running an unusually short tire. EX, with 25.5" slicks and a 4.33 I shift at 6750.

427L88, I don't have any particular need to shift at exactly 7K. I was really just putting an approximate number out there to help someone give me advice on the cam selection & to tell me where I should make peak TQ/HP relative to the shift point. If it helps, I'll probably be using 28 or 29" tires, so I could be shifting at a lower RPM. Thanks, Kirk.

Peak torque on a strong running (read not full-on race) 454 will usually fall between 4,500-5,000 and peak horsepower between 6,000-6,500. These numbers can naturally vary greatly with cam/head/intake selection, but those are typical of engines with strong hydraulics/solid cams and good flowing heads.

For an automatic car you want the RPM to be within a few hundred RPMs of peak torque after the shift. For example, if your engine makes peak torque at 4,500RPM a 4,200 stall would work nicely. As far as shift points, I always try to shift a few hundred RPMs above peak horsepower. My old hydraulic setup made peak horsepower at 6,200. I would shift at 6,500. I shift about the same place with the solid roller, too.

HTH.

Ideally you want to shift a few hundred(no more then 500) above peak hp and fall right to your peak torque thus letting your power band pull you up accelerating you fastest.

Thanks guys, that was exactly what I was looking for.

May I suggest that you buy a copy of D2K and play with a family of cams starting from say a smaller then stock, 250 and go up in 50 increments and watch the torque curve move over or up the rpm scale to the right. 300 is about as high as I ever went..

And note that as you get up to the 270/275 cams you generally need to bump up your compression b/c it's around this type cam that dynamic compression starts falling off and power goes down if static compression isn't raised accordingly..

I did this with I forget how many cams before I finally settled on one for my 496.

I ended up with a good old CC 282S solid b/c in my particular combination, D2K said it peaked hp at 5500 and torque at 4500rpm which to me is right in there where a powerful street motor should be!!

IMHO...

pdq67

Thanks pdq67, I have DD2K (19.99 on ebay!!) and I've seen what you're talking about. Although I've driven some real hot street cars, I have never been down the 1320, and am trying to get this combo to work right out of the box. I believe that I'll be going with a cam similar to the 502A4LUN that Harold was dicussing in an earlier post. Somewhere around 250/260 and 0.660" with a 110 LSA for my 10.5 CR BB. I may have to go a little smaller after some more investigation into DCR and playing with DD2K, but I hope not graemlins/thumbsup.gif Kirk

The best way to determine shift points for a given engine/trans combo is plot engine torque (if you have dyno results) in each of the gears versus driveshaft (or vehicle) speed. Where torque in a gear starts to fall below torque in the next higher gear (in other words, where the curves cross) is the optimum shift point.

I'm sure some computer literate guy could do this in an excel spreadsheet; torque and engine rpm in first 2 columns (would also be torque and driveshaft rpm in high gear), torque times first gear ratio and eng rpm divided by first gear ratio in the next 2 columns, etc. Then plot all on the same plot.

Good idea 70GS - I can't wait until I can get this thing built and on the dyno (and the track). Thanks