Re: 1960 283 chevy
I built a '91 Camaro for a customer, it is a low 10 second small block footbrake car. We broke our turbo 350 on Saturday, changed to a powerglide on Sunday and went back to the same track to test. Car was over a tenth slower with the 'glide. I built both trannys myself, the turbo was a stock 2.52 low and the glide was a 1.76, using the same torque converter. Car suffered out of the hole and lost most of the et. by the 330, I was driving the car myself. I think the biggest problem was the loss of gear ratio with that 1.76 low, probably would not have been near as much a difference if we had a 2.08 first gear. But that was what I saw in the comparison with a 3200 lb. car on 9 inch tires.
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Re: 1960 283 chevy
The heavier the car the more et will be gained using a 3 speed trans. Since Jack's car weighs 4,000 plus pounds it should really pick his car up. Going from a 2.18 low gear to a 2.75 or lower first gear should really help get the car moving and not having a big drop when you shift should help it down the track. I would bet it would be worth at least .15 on his car.
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Re: 1960 283 chevy
Watch that tach Jack. You will be shifftin in to second gear right after the 60 foot cone,not and the end of the grandstands!!!!!!!!!
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Re: 1960 283 chevy
Is Jack going to use a 200 or a turbo 350?
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Re: 1960 283 chevy
Jack,
You better look into getting some wheelie bars. |
Re: 1960 283 chevy
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How about in a 3300 lb 327 GT car, 2.08 low, very good PG versus a 2.52 low, very good Rossler 350? The PG is in the car and I have access to the Rossler. Any data or thoughts? |
Re: 1960 283 chevy
A powerglide versus turbo 3-spd difference is not that easy to figure out. A pure back-to-back swap won't give you correct answer. You need to optimize each setup i.e., cam, gear, tires etc.
That said, I would guess an optimized turbo 3-spd would be better due to less converter slippage and ability of trans to keep engine in a more narrow power range. There are some on this board who have good knowledge of converter efficiency, would like to hear their input... |
Re: 1960 283 chevy
Bruce Fulper did a story a few years ago with regards to engine rpm and how quick an engine rev's etc.
It was with pontiac's (of course) but the gist of it was, a bigblock or long stroke/heavy rotating assembly engine rev's up slower than a lighter small block/short stroke/etc. A bigblock that prefers to spin up at 600rpm per second would be quicker with a glide due to less parasitic losses (spinning up the assembly) than a 3spd which would require 900 rpm per sec. A small block however that loves 900 rpm per sec would be slower (or at least not faster) with a glide because it doesn't have the reserve torque. Veh weight the same, gearing the same, all else the same, a slow reving (reving up) big block is quicker using torque where a quick reving smallblock needs more gears/closer ratio. More coming back to me...two 455's on a dyno, the newer one with an extra 20hp was actually slower because it was tested at 600rpm per sec and the gearing of the car and the old 455 was set up for 900rpm per sec. The new motor couldn't spin up as fast and was therefore slower on the track. Speaking of Bruce..anybody heard from him lately? Reading some old BracketRacingUSA mags the other day and came across a couple other of his stories. |
Re: 1960 283 chevy
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Exactly! Get that pig of a car moving as quickly as possible! If I hadn't just invested a ton of money in a 2.03 powerglide, I would have taken advantage of a th400. Big wheelies, and should be quicker. |
Re: 1960 283 chevy
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Get on the Pontiac Forums much? Some "questionable" business practices have hurt his reputation. Too bad, as he was one of the "go to" guys when I started getting into Pontiacs about 20 years ago. |
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