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Yeah, but you don't get a rumpety-rump idle and can't brag about horsepower if building for "best average power".groberts101 wrote: Most of us have raced and beaten much higher powered cars than our own because the other driver was in the wrong gear or put a too big a cam in front of too tall a gear. Peak power means almost squat for a street car where AVERAGE POWER RULES.
MikeB wrote:Yeah, but you don't get a rumpety-rump idle and can't brag about horsepower if building for "best average power".groberts101 wrote: Most of us have raced and beaten much higher powered cars than our own because the other driver was in the wrong gear or put a too big a cam in front of too tall a gear. Peak power means almost squat for a street car where AVERAGE POWER RULES.
The correct stall would cover up some of the sins. If the owner of the car, in his youth, mis-identified his (presumably) Muncie as a close ratio M21; and it was actually an M20...it would be much more lively feeling in 1st, 2nd and 3rd.MikeB wrote:Thanks for all the comments.
Looking at the bicycle, it might be geared OK for an easy getaway by a big kid, but a little kid would need more teeth on the rear sprocket to get it moving!
Also, that's an interesting comment by cpmotors about gearing for just past peak hp RPM at end of 1/4 mile. The guy I'm arguing with says back in the day he raced two 57 Chevys, each with a 6500-7000 RPM 327 and 3.36 axle. Yes, 3.36. One had auto trans, the other a manual. Presumably they had 1:1 top gears. Is there any way the 3.36 axle ratio could have been optimal? Might it have worked OK with high T/C stall?
That was a tongue-in-cheek comment on my part. Please don't put me in that club!groberts101 wrote:MikeB wrote:Yeah, but you don't get a rumpety-rump idle and can't brag about horsepower if building for "best average power".groberts101 wrote: Most of us have raced and beaten much higher powered cars than our own because the other driver was in the wrong gear or put a too big a cam in front of too tall a gear. Peak power means almost squat for a street car where AVERAGE POWER RULES.
Then IMO, you're not building them right, Mike. Want the idle to rumpity rump a bit more? Turn it down to about 600 rpm with a 230°+ @.050" cam. It'll start to lope liker a much bigger cam. Problem solved.
My first drag car was a 60 Bel Air with a 365 HP 327 crate engine. It had a 59 Pontiac rear with 4.56 gears and 28" M&H cheater slicks. It weighed 4000 with me in it. Trans was a wide ratio Muncie. I launched the car at 6000, power shifted at 7000, crossed the 1/8th at 7000 in 3rd, and nose dived to 4700 when I shifted into high. It was barely recovering from the shift at the stripe. The 1/8th performance was pretty good, but it gave up over 3 tenths because of the rpm drop into high gear. Wrong cam, wrong gears, wrong intake, etc. These days, overdrives, lockup converters, and 5 speeds can get you closer to ideal, but in the end you have to know just how fast you need to be going before it is practical to shift into high gear.autogear wrote:The correct stall would cover up some of the sins. If the owner of the car, in his youth, mis-identified his (presumably) Muncie as a close ratio M21; and it was actually an M20...it would be much more lively feeling in 1st, 2nd and 3rd.MikeB wrote:Thanks for all the comments.
Looking at the bicycle, it might be geared OK for an easy getaway by a big kid, but a little kid would need more teeth on the rear sprocket to get it moving!
Also, that's an interesting comment by cpmotors about gearing for just past peak hp RPM at end of 1/4 mile. The guy I'm arguing with says back in the day he raced two 57 Chevys, each with a 6500-7000 RPM 327 and 3.36 axle. Yes, 3.36. One had auto trans, the other a manual. Presumably they had 1:1 top gears. Is there any way the 3.36 axle ratio could have been optimal? Might it have worked OK with high T/C stall?
M21 (2.20/1.64/1.27/1.00), 3.36:1 rear, 7000rpm shift point and a 27" tall tire according to Wallace Racing:
After 1st Shift: 5,218 RPM. 25.45 % RPM Drop
After 2nd Shift: 5,421 RPM. 22.56 % RPM Drop
After 3rd Shift: 5,512 RPM. 21.26 % RPM Drop
1st Gear is 76.10 MPH at 7000 RPM
2nd Gear is 102.08 MPH at 7000 RPM
3rd Gear is 131.82 MPH at 7000 RPM
4th Gear is 167.41 MPH at 7000 RPM
M20 (approx 2.56/1.88/1.48/1.00), 3.36:1, 27" tire and 7000rpm:
After 1st Shift: 5,141 RPM. 26.56 % RPM Drop
After 2nd Shift: 5,511 RPM. 21.28 % RPM Drop
After 3rd Shift: 4,730 RPM. 32.43 % RPM Drop
1st Gear is 65.40 MPH at 7000 RPM
2nd Gear is 89.05 MPH at 7000 RPM
3rd Gear is 113.12 MPH at 7000 RPM
4th Gear is 167.41 MPH at 7000 RPM
Realistically, as BigJoe alluded to, sometimes the car responds better to holding it in a specific gear longer. In the above case, I'd probably hold it in 3rd gear a little longer to keep the RPMs above 5,000 when shifting into 4th. Reminiscing our youth also might make things appear faster than they were, or unbeknownst to the driver, his 3.36s had been swapped out for 3.55s
yep.. that's par for almost every new car being built with 6 or more forward gears these days. I think my wife's 6 speed V6 Camry is 4.4x 1st gear. Small/mid-sized multi valve engines love more gear.panic wrote:Toyota turned much of this upside-down in 1993 with the Supra 6-speed: .793:1 overdrive with a 3.13 axle ratio = overall high gear ratio 2.484:1. This is a small, low-torque engine (225 hp?) and a 3,500 lb. car.
What's the missing element? 3.83:1 1st gear, yielding 11.99:1 crawl ratio.
My wifes 1970 Chevelle is a typical street car in my definition. All steel, 3780lbs, full exhaust with tailpipes, 3.36 gears and 275/60-15 tires that are effectively 27" tall, TH400, 781 iron heads on a 496, PS/manual discs car, etc. She drives the wheels off of it when its out, as in 1000 miles a month. Grocerys, Mary Kay appointments, errands, etc. Runs on typical BP 91-93 octane without issue like any street car. Non typical is that it has a 1050 I built on it and a good size solid roller, averages 10-13 mpg,has a 8" 4500 converter and she shifts it @ 7000 rpm. Cruises really nice @ 23-2600 rpm in that 60mph range. She's run 125mph in the quarter, but only turning 5400 rpm, which is a long way from the 67-6800 rpm it should be running for optimum track times.MikeB wrote:Thanks for all the comments.
Looking at the bicycle, it might be geared OK for an easy getaway by a big kid, but a little kid would need more teeth on the rear sprocket to get it moving!
Also, that's an interesting comment by cpmotors about gearing for just past peak hp RPM at end of 1/4 mile. The guy I'm arguing with says back in the day he raced two 57 Chevys, each with a 6500-7000 RPM 327 and 3.36 axle. Yes, 3.36. One had auto trans, the other a manual. Presumably they had 1:1 top gears. Is there any way the 3.36 axle ratio could have been optimal? Might it have worked OK with high T/C stall?
