I have a question about horse power

[2manycars]

The model A engine is 200.5 cubic inches in displacement. It made 40 horse power at 2200 rpm. The model B engine was the same displacement, but with a different cam profile and slightly higher compression, and larger carburetor, and made 50 horse power. The V8 was only 221 cubic inches displacement, but made a claimed 85 horse power. How was that possible? Was the compression of the V8 that much higher? The early ones still had babbit bearings. Was the cam profile that much different? The way they idle so smoothly, one would think it was a pretty tame profile. The valves were still pretty small, and Ford had not yet figured out that intake valves need to be larger than exhaust valves. So why is the horse power so small on a model A engine, and so much higher on the slightly larger V8? Other engines of that period made a lot more power on similar displacement. Any ideas as to why this all is?

[Tom Wesenberg]

Here's a chart for the 1930's V8.

http://www.vanpeltsales.com/FH_web/f...cs-85early.htm

[Dave in MN]

I don't have any info on the V-8 engines but here is a bit more detail on the A & B engines.

I think you are correct, the A engine was rated 40 hp at 2200 rpm.
Having placed over 50 Model A engines on a dyno for break-in, I know that the A engine never produced 40 hp in its stock condition; it was closer to 37 hp.

From my reading, I believe the B engine was rated 50 hp at 2800 rpm. The modified cam profile, larger carb and intake passages and an improved intake port in the block allowed the B engine to maintain good torque at the higher rpm resulting in more horse power.

I have not placed any stock B engines on the dyno for break-in so I do not have a comparison as to what hp they produce. All the B engines going through my shop are modified in some manner to deliver more power.
Good Day!

[100IH]

Put in your mind a term; Dynamic HP. That is the HP created by the breathing ability of the engines intake system that is going to be compressed. Greater cylinder fill with the same displacement, when compressed, will result in a bigger bang. Add to that, a higher compression ratio, gets an even bigger bang. Camshaft lift and duration and port dia. and shape result in the potential for a bigger fill of the cylinder with the same bore and stroke.

[2manycars]

Thanks for all the interesting answers. So it seems that a cam with some more lift and duration, better porting, larger intake valves, and higher compression would result in a noticeable increase in power in the model A engine.
I noticed in Tom's chart that the compression remained fairly low by today's standards on the V8 engines, even after insert bearings were introduced. I wonder what is a safe compression ratio for a model A engine with stock oiling.

[denis4x4]

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The 40HP is at the flywheel. With modifications as outlined by DaveinMN, I'm getting 60HP at the rear wheels using a 1931 block.

[C26Pinelake]

What are you trying to create ? Wayne

[1Tudoor]

In conjunction w/ all of the above input , equally important is a balanced & well supported bottom end which many of the early engines did not have .
Many types of (stock) engines over the yrs have been improved at the top only to come apart from vibration & brg failure @ the bottom end .
I should add , bottom end failure would most likely happen w/ sustained high RPM's & not the daily driver wanting a bit more performance .

[Bruce Lancaster]

Also...pure arithmetic! Torque from an engine is measured (sometimes in extremely simple and clear ways), horsepower is computed from RPM and torque by a simple formula, with 5252 as a divisor. This means low HP numbers on engines running well below 5250 RPM, rapidly improving numbers as revs go up.
Aside from better breathing, the V8 revved a lot higher than A or B and produced good torque in its upper ranges (still well below 5200 R's), with highest power calculated at 3800.
No revs, no power.

[katy]

So it seems that a cam with some more lift and duration, better porting, larger intake valves, and higher compression would result in a noticeable increase in power in the model A engine.

So what does that do to low end pulling power?

[100IH]

Response to #9.. Smaller dia. ports force the air charge to speed up and create a "freight train" of sorts, with its inertia to better fill the cylinder. Then valve timing comes into play and must work hand in hand with the desirable higher velocity. All of the 90 degree bends in the air path very much put the brakes on the velocity and larger diameters also kill the air speed. Now visualize side draft air flow with only the valve pocket to deal with. Its actually possible to over fill the cylinder at wide open throttle if everything is built with today's technology but our flat head engines with up and downdrafts are at a physical disadvantage from the start.

[George Miller]

I never checked but I would think the model A engine has more torque at 2000 rpm than the 221 V8 does at 2000 rpms. HP is about a lot of things, it is all about the combinations. Long stroke like the A has good torque, shorter stroke with all the other things equal has less at lower rpm.

[Kahuna]

Bruce has the answer: RPM

[Charlie Stephens]

Originally Posted by 2manycars

The model A engine is 200.5 cubic inches in displacement. It made 40 horse power at 2200 rpm. The model B engine was the same displacement, but with a different cam profile and slightly higher compression, and larger carburetor, and made 50 horse power. The V8 was only 221 cubic inches displacement, but made a claimed 85 horse power. How was that possible? Was the compression of the V8 that much higher? The early ones still had babbit bearings. Was the cam profile that much different? The way they idle so smoothly, one would think it was a pretty tame profile. The valves were still pretty small, and Ford had not yet figured out that intake valves need to be larger than exhaust valves. So why is the horse power so small on a model A engine, and so much higher on the slightly larger V8? Other engines of that period made a lot more power on similar displacement. Any ideas as to why this all is?

Just a minor correction, the 1932 V8 was rated at 65 horsepower. Although a lot of factors affect the horsepower you can see the horsepower and compression ratios at: http://www.vanpeltsales.com/FH_web/f...cs-85early.htm

Charlie Stephens

[pgerhardt]

Speaking strictly from an ex science teacher point of view. Since an engine gains the energy it supplies to the rear wheels from the fuel burned would not 8 cylinders result in more "bangs" per minute than 4 cylinders thus giving more power even with similar displacement?

[BILL WILLIAMSON]

Horsepower is relative to "VOLUMETRIC EFFICIENCY"--DON'T ask me to explain it----------(DUH!)
Bill Dense

[Bruce Lancaster]

Peak torque I believe occurs at the speed at which cylinder filling on an intake stroke is most complete, producing the biggest bang when it is lit. From here, on the graph, power goes upward because even though each bang may be weaker (torque is dropping from the peak), there are more of them per minute. Eventually, the engine reaches serious limitations on the breathing front, and power drops off.
Basic formula for HP is torque X RPM divided by 5252. This means that below 5250 RPM, horse power will always look feeble in comparison to a high revving engine.
I have somewhere in an old Rod&Custom magazine a comparison road test of a Model B and a Model 18 1932, both of them high quality restorations by Harrah. Low end torque of the banger allowed the B to leap ahead right off the line, and to lunge forward strongly at each shift...but the V8 in each instance pulled tight on ahead as its engine speed went up.
Horsepower is a CALCULATED value and the 5250 bit controls it very strongly. This corresponds to the effects of higher HP in a race, and pretty well ignores the effects of the mighty A-B low end torque in street driving.
Neither in stock form gets anywhere near the above-5252 RPM level where power starts to compute higher and higher, but the V8 in any form is going to be at least a thousand RPM above what any A or B (not looking at OHV conversions) can do at any comparable level of hopping up.

[2manycars]

This is all very interesting. So because the model A engine runs at a lower rpm, the HP is less than the torque. I once heard that torque gets you moving, HP keeps it there, what ever that means.
What compression ratio is safe for a model A engine with factory stock oiling system?

[prpmmp]

See!! I learn something every day!!I always though that HP was how fast you hit the wall!! And torque was how far you push it Pete

[FrankWest]

model A's and Model B's have up draft intakes. Convert to Downdraft intakes and you can add 10 HP.
If you go from a single intake carb to a dual intake carb like the stromberg 48 which for added 10 the 1934 v8 cars, you can add another 3 HP.
Someone said that adding Marvel Mystery Oil to your oil and gas you can again increase HP?