Loved the recent articles in the International magazine about the carb comparison and the dyno testing. I still am shocked at the variation in H.P.
As I looked over the data, I soon realized most of the engines had very similar modifications, such as aluminum pistons, 280 cam, etc. I would love to hear from the dyno savy what is the main reason for the differences in H.P. Many possibilities no doubt, but, how much of it is the carb, the state of wear, the adjustment of settings like carb needle and timing advance, etc????
I was surprised at how low they all are. The first engine that is conceivably Montana 500 legal on the MTFCI dyno list is Jim Allmeter's 1914 touring with 17.9 h.p. Steve Coniff's Montana 500 car with a stock high head was dyno'ed at 31 h.p. as shown on the Tulsa site.
Does the article say how the air/fuel mixture and timing was set on each test? Did they readjust the air/fuel mixture and timing at each RPM during the test?
Did they use the same coils and timers on each test?
I would think that if they really wanted to compare carburetors, then the same engine should be used and just the carburetor switched out. There are just too many variables to do anything else.
What looks like low readings are because the values are rear wheel HP not at the flywheel. Ford measured the HP at the flywheel and will look higher. There is a formula to figure flywheel HP from rear wheel values but, I don't know it.
The evening before I drove to the North Rim I dyno'ed my touring and pulled 16.4 HP. While at the park the next day I noticed the carb bolts loose on my car. I don't even know how it was running but I didn't even notice a difference. I tightened the carb and when we came in that evening, I dyno'ed it again and got 17.1HP. Just from tightening the carb, go figure.
How did they correct for weather conditions, without corrected data the end results would be questionable.
I would also point out that James difference is 4.2% which is well within the margin of error of a really good dyno test. So was it really an improvement ?
Mike, I don't know how they made their calculations. They did all that with a computer and, I didn't ask. I do know, everyone was figured the same. The second figure on my car was definitely an improvement because I could feel it. For me, it was just something to do and, without knowing it, was an experiment in how loose parts affect the power of the car.
I think that this dyno test is for bench racing purposes. It was a run em on run em off testing. If it was a tuning session I am sure that most results could have been improved. Numbers can vary between dynos and operators so this just compares the vehicles on this tour. Like they say, your mileage may vary. They did correct for altitude.
Good, correction was made for altitude, but what about humidity, temperature and barometric pressure. Temperature should be read at the inlet of the carb, it makes a big difference. 70 degrees ambient will more than double in the engine compartment easily. All of the above effect the reliability of the data from the dyno. I think it like comparing apples and oranges
You are discussing TWO separate tests and trying to compare. The March-April 2014 issue of Model T Times has two articles.
One: p. 22 Bench testing Model T carbs. by Dr. Jim Cowart, Navel Academy. Used a fixed engine, test unit, at 1200 and 1600 rpm. This gave test info on torque performance and flow rate.
Two: p. 35 Dyno Testing at 2103 Kanab UT tour. Tom Graham and Charlie Volkening. Dyno on rear wheel devices, computer calculated. Owners described in what detail they wanted to describe mods to engines or ignition or other...vauge on what each owner's engine condition or mod. But useful info anyway.
I agree. Different test. Interesting but shouldn't be the base to say what one did over another from car to car.
Yep, your right. I did the Tom Graham rear wheel dyno on the MN tour, fun. Obtained 18+ hp at rear wheel. Tires a'spinnin' and with the heat on that tour, glad there was a fun pointed at the radiator!
But who would figure, a vaporizer carb car beat my T with NH!
Know the limits of your equipment when you test on a dyno, here is a video of 30 "dyno disasters"...
Oh, and be sure not to step on the spinning dyno rollers!
I was concerned that my HP ratings were significantly lower on the Kanab tour compared to the Minnesota tour, with the same car and accessories. Then I realized that altitude likely made the difference. 4898 ft vs 1302 above sea level.
I had the 3rd highest non O/H test with my '12. I think I could have won the bet with Bill Bohlen's if I had tweaked the carb a bit. I unloaded it from the trailer and ran the test. Its a pretty good jump from sea level to Kanab. I was really pleased with the first dyno of my car. Thanks to the guys for running the tests!
Gene, from a seat of the pants perspective, how would you compare the power of your T to Garrett's roadster?
Tom, That's a hard question cause the Roadster is like driving a Cadillac compared to my light little Torpedo with the O/D. I thinking my T might be quite a bit quicker as it should.
I sure liked Garrett's Roadster and offered to keep it but of course he wouldn't let me... Darn