Thread: another cam question

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I had a similar problem when obtaining cam recommendations from manufacturers. They generally recommended me a cam that seemed to have too much duration for my needs. I would explain that I wanted low end similar to that of the original 1971 smogger L42 350 engine that was generously rated at 270 crank Hp. I explained that I wanted something to just drive around town and would NOT be drag racing. I am keeping the 3.31:1 gears for fuel mileage and comfortable driving. I had the 350 bored 0.030 over with pocket ported S/R Torquer heads, Edelbrock performer Intake, 9.4:1 CR, balanced engine and headers. I had cam recommendations that were over 240 degrees duration at 0.050 and over 0.500 lift at the valve. Comp cams recommended the XE268H as a minimum. I am still undecided between the XE262 and XE268. With the original engine, I could easily shift into 4th gear at 35 mph and car would react fine. If I was making an acceleration run, I would shift at 5000 rpm. Now I am looking to shift at 5500-5700 rpm for a high speed run and yet still retain the ability to comfortably drive around town and shift at 1800-2000 rpm. Maybe this is impossible and I need a smaller cam. Comp cams says either cam will allow me to do this as they will make approx the same torque as stock BELOW 2000 rpm and more torque above it, especially with better heads. However they recommend cams that have rpm ranges that extend beyond 6000 rpm. The XE262 has a range of 1300-5600 and the XE268 1600-5800 rpm.

I remain confused with some of the factory recommendations

I'll pose this question again: For a high acceleration run such as drag racing, when is the best time to shift gears? Slightly before max Hp? That is, if max HP was realized at 5600 rpm, shift at 5500 while the car is still pulling? Comments?

Originally posted by Richard Quattro
I'll pose this question again: For a high acceleration run such as drag racing, when is the best time to shift gears? Slightly before max Hp? That is, if max HP was realized at 5600 rpm, shift at 5500 while the car is still pulling? Comments?

I aint no pro but, I have had my best luck when shifting at HP peak. Ideally, I believe the goal (for the most acceleration) is to shift at the HP peak and have it "land" right at the Torque Peak. Make as much of the run as possible in that band between the two.

Like I said though, I aint no pro.

Dutch

check out the lunati voodoo series i did ...look at my post,bigger isnt always bigger that voodoo 268 looks like a awsome cam imo

Im still looking at the Voodoo 268 (60102). LSA is 112 instead of 110 like comp cams which means a broader rpm range, maybe lower peak. Usually a tighter LSA gives more low end power and a little more cam sound. Intake and exhaust valve openings are very close to the Comp Cams XE262H. The Voodoo has a little more lift and duration.
XE262H range is 1300-5600 rpm
Voodoo 60102 is 1400-5800 rpm

I havent been able to find any dyno charts or magizine articles on the Voodoo. Comp cam has a lot more info available. I still cant get straight answers from the Lunati tech line.

i have a power max crane it's 272 In a 355 it's like a 216- 228 dur i have it in a 84 S10 it 's very fast u'll hate the vac carb i've tried one it sucks.