Rear wheel horse power
 

Has anyone had there stock A on a rear wheel dino. How much horse power would you expect at the rear wheels?

Re: Rear wheel horse power
 

My A made 39.6 at the rear wheels on the chassis dyno,97 carb and later cam.
would have made a bit more ,but the operator held it flat in top gear,and it was way too rich as it was on the power valve that was too big,still not bad,my boys falcon ute was next on the dyno,it made 716 hp at the wheels,not bad for an aussie 6 cyl engine.
Lawrie

Re: Rear wheel horse power
 

If i remember bone stock is 20 hp

Re: Rear wheel horse power
 

I think at the flywheel on a blueprint restored engine factory bore is like 38hp. Once it goes thru 2 gearboxes filled with oil about 3 weights away from grease I dont doubt it would be 20hp.

Re: Rear wheel horse power
 

Re: Rear wheel horse power
 

It is torque that counts. Torque accelerates and horsepower sustains speed. What does the dynamometer torque curve look like?

Re: Rear wheel horse power
 

I got 60 HP at the rear wheels and as best I can remember, 180 ftlbs of torque

Re: Rear wheel horse power
 

I haven't had one on a dyno, but commonly quoted is a 15-20% loss flywheel to rear wheels (even more for an auto trans car). Here's a few sources...

https://www.google.com/search?q=hp+l...hrome&ie=UTF-8

Assuming that, you could expect to net 32-34 HP at the rear wheels in "new" Model A. If you aren't making 40 HP at the flywheel (wear, tune, etc) and/or if you have greater powertrain losses (thicker trans/rear end oil, worn parts, etc) you can expect less.

As far as torque goes, it looks like the 128 ft pounds of torque are all in at 1,000 RPM...

http://model-a-ford.org/technical-re...pecifications/

This is likely why why our cars perform so well even with only 40 HP, and why the handbook tells us to shift at relatively low speeds (at or near the torque peak).

Re: Rear wheel horse power
 

Yes which is why on new cars/trucks that HP rating is absolutely useless. Take the f150 for example - the 5.0 standard V8 does make something like 385 HP but at 5750 rpm! who the heck drives thier vehicle flat out all the time? Its peak torque is 387 ftlbs at 3875 rpm while the v6 ecoboost has 470 ft/lbs at 3500 while it has 10 less HP at 5K+. That extra 90# of torque really shows on acceleration. (apparently for 2017 they have a H.O ecov6 - 510 ft lbs at only 3500rpm!)

There is a reason a 4 banger honda can smoke a 5.0 mustang - power to weight and torque it can produce.

Re: Rear wheel horse power
 

Not quite. An engine produces only torque. Horsepower is calculated from a formula which factors in RPM, or how fast torque is produced. A dyno only measures torque output and RPM. The formula is torque times RPM divided by a constant which is 5252.
Peak torque for a stock A is 128 ft. lbs. at 1,000 RPM which calculates to 24.4 HP. At 2200 RPM, torque is down to 95.5 ft. lbs. but horsepower is up to 40, which is peak for a stock A (factory rating). An engine's maximum efficiency is at peak torque RPM. Torque drops off above that point, but since it is produced faster (higher RPM) horsepower goes up, to a point.
Picture a 128 lb. person standing at the end of a one foot long bar attached to a dyno. He/she is producing 128 ft. lb. torque, but zero horsepower. Now imagine the bar is a crank and the person has enough strength to turn it at one RPM. The result is .0244 horsepower. If he/she could turn the crank at the rate of 1,000 RPM while still exerting 128 ft. lbs. of torque, they would be putting out 24.4 HP.
So an engine designed for maximum efficiency (air flow) at low RPM will have peak torque at low RPM and horsepower will be a low number. Build that engine for max air flow at high RPM and peak torque will be at a higher RPM, and horsepower numbers will follow. So if a Model A had the same peak torque of 128 at 5,000 RPM, peak horsepower would be 121.9.
So, it's a little more involved than saying torque does this and horsepower does that.

Re: Rear wheel horse power
 

Check with Bill Stipe. I do not recall all the details but about 8 years ago I discussed this subject with Bill as I had purchased a Brumfield 5.9 head and was considering including a Stipe IB-30 cam. I was planning to use the stock Zenith carb, had an Aries muffler, and modern valves. As I recall Bill told me they had recently rebuilt an engine for use for one of the Model As at Greenfield Village in which they basically did the same as I was planning and the engine tested at 56 HP. All I can say about it is I thought I had a good strong engine prior to those changes but after the changes there was a world of difference in the performance and the gas mileage went from about 17 to about 21 MPG.

Re: Rear wheel horse power
 

Nice, the barras are a good engine.