Burtz engine dyno results

Dave in MN

Dave in MN

Well-known member
Late yesterday, I had the opportunity to test a Burtz engine on the dynamometer. The engine build included a Burtz camshaft and 6.5:1 head. The peak output was at 2500 rpm where it produced 105 foot-pounds of torque. Without any corrections, this equals 50 hp.
The engine was fitted with a standard Zenith carb, original intake manifold and original distributor. The advance was about 27 degrees during the test.

Today, we will run it again and check the torque at 2200 rpm and then compute the hp. After the tests, we will change to a Weber carb and intake, complete a tuning of the carb and then run a full load test of the engine with those components.

Follow up comment:
I suspect the peak output at 2500 rpm (and not higher rpm) is the result of the limits the standard Zenith carb and Model A intake manifold placed on the engines ability to breath. The timing at 27 degrees may also have a minor limit on the max rpm the engine could deliver.

Second dyno session:
The engine produced exactly 40 hp at 2200 rpm fitted with the stock Zenith carb and original manifold.
The Weber equipped Burtz engine produced 64.4 hp at 3250 rpm with 27 degrees of advance. The carb is currently setup lean. Because of the lean condition, the dyno session was brief. We will order jets and make changes to correct the air to fuel ratio.

The engine pulled through all of the test rpm ranges without a shutter. Pretty impressive results after almost no dyno time.
Good Day Everyone!
 

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Nice work Dave. I believe you are right that the Zenith limits the peak output rpm. By output are you referring to torque or horsepower? I think with the Weber you will find the peak horsepower somewhere between 3,000 and 4,000 rpm.
 
It would be helpful, Dave, if you could also try a Model B carb and intake (or bored-out Model A intake) to settle the non-ending speculation on this website about whether installing this combo on a Model A engine will really increase power and if so, by how much.
Thanks for your work to bring us these results, even if the vast majority of us don't own a Burtz engine.
Marshall
 
Does anyone have the URL for the site that published hp and also carb cfm figures for a series of dyno runs? I was looking for it this week and couldn't find it.
 
Thanks, Benson. Yes, I am familiar with Dennis' and Ron Kelley's dyno tests from years ago. Good information and probably more directly related to most Model A owners' engines than the Burtz engine. I was curious if the upgrades in the Burtz engine paralleled dyno results 1:1 with the earlier tests using the same components. In other words, would a Model B carb and intake manifold replicate the same increases proportionately to those parts when installed on Piranio and Kelley test engines? I should think the main difference in horsepower upgrades between the two would be the camshafts, meaning how much of an improvement is imparted by the Burtz grind than the earlier camshafts tested. I believe stock Model A and B cams were tested back then, as well as one of Bill Stipe's.
Marshall
 
"I would think the ports in the Burtz block would be improved somewhat."

Agreed. Teamed up with a more aggressive camshaft than was used in the Piranio and Kelley engines, larger ports and intake valves in the Burtz engine would definitely increase horsepower. In the final analysis, our engines are nothing more than big air pumps: the more air you can get in at a faster rate and the more air you can get out at a faster rate, the more power is built. Camshafts and healthy breathing larger intake valves are major players in that game.
Marshall
 
The jets have their size stamped on them. 40 indicates .40 mm. The larger throat is the more important one for power. I would try a 45 or 50 size jet there or maybe even a 55. The smaller throat can go up one size too.

If you want to short circuit the post office, you can drill out the jets.

You will not have to change the idle jets unless you plan to use it in a car.

That muffler looks pretty restrictive. You may want to use an Ares performance muffler.

Cleaning up the intake ports a little will help too. Just enough to eliminate the step where they are bored. Also check the exhaust manifold fit to the exhaust ports. Some grease will provide a print when the manifold is fitted to the engine.
 
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It’s a slippery slope, hotrodding model A engines..when the the thing that drew you in at first..low end torque is the proper name for it.. is improved out far beyond what it came with, it’s like that old gum jingle “double the flavor? Double the fun”
 

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Steve Ross in the early to mid-1990s besides publishing online the "Rebuilding the Model A Engine the KRW Way" published Dyno tests of various engine manifold/carburetor setups.

The former (Model A Engine) is here at this site, https://www.fordbarn.com/forum/showpost.php?p=1823977&postcount=6 but the latter may have disappeared into Internet History.

It might be nice if someone downloaded this at the time to now bring it up "for the record?"

I may have the print-out somewhere in my notes.

Joe K
 
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