ideal hillclimb gear ratio?

Anyone have a guess as to the best gear ratio for a heavy sedan (4000 lbs) with about 350 hp and automatic trans. I'm trying to set up my 55 chrysler.

 

What kind of MPH are you aiming for....and how badly do you want to abuse the car?

 

find one that keeps you close to your peak torque rpm.

 

This car will run in vintage historic (no prize) so I'm thinkin 80/90 in the straights, maybe. The early Hemis (mine) don't like to rev over 5 grand for very long.

 

well what's your trans final drive ratio and tire diameter? auto or manual, if auto what's stall speed?

 

Tire size is 275/60r/15 the torque converter is a stock TH400 and the trans is stock with a B&M shift kit.

 

I used to hill climb a 283 power pack '61 Impala back in the early '60's. It was a 3 speed overdrive with 3.70 gears. Most of the courses were fairly short straights - rarely got into 3rd but spun the revs up around 5000 in 2nd. With that torquey hemi and the fairly short tires a set of 3.50's might get it done.

Charlie

 

you running a Chev or a Hemi? And why would run a auto in a competition like a hill climb? .
You are behind the 8 ball from the start.
I would have used a 5 or 6 speed to get a decent range of ratios plus an overdrive to enable a bit of street use.
That way you can a 4.11 diff to get the peak torque ( forget about horsepower it aint gonna get you up a hill) in the working range of the engine.
Nobody can advise you of what ratio to run if they don't have any idea of the engines Mods.
A stock early hemi aint gonna do much in that car either.

 

Depends on how long,and how steep,the hill is.

 

I understand your point of view. My cars were original autos and to comply with F.I.A. rules had to stay that way for vintage racing. Because my cars were built for long distance road racing (2000 mile plus) engine mods had to be whatever would run best on low octane fuel and was easy to repair from the local economy. The idea was to use the basic car set up without changing everything, just the rear axle ratio. the engine is a 354 hemi.

 

Pikes Peak, 12 miles, 14,000 ft. how hard could that be?

 

In that case i would be looking at a later type of auto with overdrive and still using a 4.+ -1 diff. In fact if I myself were really serious ( I have run 354's too) I would chase up a DB 4 speed auto from a Mercedes Benz 300SEL 6.3. The ratios would be perfect for a 354.The trans are bullet proof but use a fluid coupler instead of a convertor. ( hence 4 speeds when TQ trannys then were 2&3 speeds) The shift is both manual and automatic so you are able to drive as though you are using a manual and seriously fast changes without slipping between the shifts.
They would be almost period perfect and have been used in competition back in the late 60's and early 70's.
Another Option I would Pursue would be a pont a mouson truck trans as was used behind Hemis in lemans etc etc .

 

I think the torque peak for that engine with a stock cam is about 2800 rpm if that helps.

Don't use a torque converter with too high of a stall, or the transmission will run super hot and probably burn up.

 

You would use deeper gears for a shorter hill,
because the top speed is not as high.

 

Where are you in Co.? Do you know Lenoard Vasholtzs? Maybe give him a call at Vasholtz Automotive in Woodland Park. He's probably forgot more about running the peak than most others know.

 

Have you thought about a Gearvendors under/overdrive set up? that would help with the cruising and yet still give you the off the line. I think that they are good to like 1000hp.