Any Guesses to HP Loss With Emission Control?

[K5lwq]

I thought this might be interesting to see what others think.

Tractor is a Branson 4815C with a claimed 48HP engine and 40HP at the PTO.

I had it put on a PTO dyno and it was producing 35HP at PTO.

I replaced DPF with a turbopack style performance muffler. Today I am having it tested again.

Any Guesses on the HP change?

 

[CobyRupert]

What do we win if we guess right?

36.8hp

 

[Stan B]

I replaced DPF with a turbopack style performance muffler.

Hold up. How'd you do that without the computer throwing a code?

 

[K5lwq]

Coby, lunch on me next time I see you!

Stan, Branson does not have a computer. It uses a data logger that you simply unplug.

 

[Thunder chicken]

if it sounds louder, it ought to have at least 5 more hp and go 10mph faster!..... at least that's what the local kids think on their snow mobiles.

on a side note, i removes all the emissions (dpf and egr) from my VW tdi, with a computer retune have +40hp, +80ft/lbs torque, 10-15% better fuel mileage and am doing 20,000km oil changes vs 15,000 as the oil stays cleaner without that pesky EGR.
i think you're lucky to have that passive DPF on the branson rather than an afterburner like a lot of other vehicles. you can take yours apart and clean it too if you ever need to.

 

[CobyRupert]

if it sounds louder, it ought to have at least 5 more hp and go 10mph faster!..... at least that's what the local kids think on their snow mobiles.

...but did he put a Flowmaster or Magnaflow (or whoever made muffler) sticker on the tractor? It's a well known fact in car & truck modifications that "Each sticker adds 5 hp, so you do the math"

 

[K5lwq]

The answer is 1HP gain. But there is more to the story as torque increased by 70 ft lbs. That makes zero sense to me. But that is the results from the dyno tests.

 

[RickB]

Well if the observed hp increased that was caused by either an increase in torque or shaft speed, or both.

 

[jaydee325]

Unless the tractor was dyno'd before and after mod, the results are meaningless. Original torque values were not provided in the original post, only HP values. We have no way of knowing how much torque changed.

A 1 HP change is within the margin of error. You could dyno it again on a different day with different atmospheric conditions and have less HP.

 

[RickB]

Unless the tractor was dyno'd before and after mod, the results are meaningless. Original torque values were not provided in the original post, only HP values. We have no way of knowing how much torque changed.

A 1 HP change is within the margin of error. You could dyno it again on a different day with different atmospheric conditions and have less HP.

And if the shaft speed isn’t monitored and exactly the same when the hp value is recorded, all bets are off. We know nothing about the dynamometer’s capabilities. There are a lot of dynos at dealerships with a 4” analog gauge for output and a smaller gauge for shaft speed.

 

[K5lwq]

It was tested before and after.

Weather conditions very similar both days.

First dyno was showed 35 HP and 345 ft lbs of torque. This is stock with filter and 9 hrs on the tractor.

Today it was 36 HP and 415 ft lbs. It actually hit 438 ft lbs before falling completely off at 500 PTO rpm. Tractor has 15 hrs after test was complete.

The dealer does not have the printer for the dyno so no print out to share. They only use it for loading tractors while diagnosing issues. They never use it to rate HP so it has never been calibrated.

If you use the formula HP=torque x RPM / 5252 you get a 7HP gain. That would put the tractor at 42 PTO HP and more in line with advertised rating of 40 PTO HP.

There is another thread in the Branson forum where I documented the process. This thread was intended to be fun to see who could guess the change. However, the results to me are questionable as the dyno contradicts itself.

I monitored the readings and RPM as both test were done by same tech. It held power down to 500 PTO RPM then fell off quick. This was a computer monitoring dyno.

 

[finn1]

Dealership pto dynamometers are notoriously inaccurate. They are not equipped with laboratory grade instrumentation, and you really can’t really can’t rely on a simple back to back pull for good information.

I spent thirty five years in an Oem engine lab environment, with upwards of forty engine test cells and a half dozen chassis rolls. The instrumentation had a calibration program with traceability to the National Bureau of Standards.

At the very least you would have to do a number of back to back to back to back (A-B-A-B) tests to establish test to test reproduce ability with such a crude setup, and even then, the absolute numbers would be garbage.

Our test cells cost upwards of several million dollars each, and had a dozen or more support staff, something no dealership service department could afford.

The torque reading disparity between the two runs is particularly questionable if you understand how back pressure affects airflow. I assume the engine you are dealing with is naturally aspirated. Airflow is pretty much a function of engine speed, so back pressure is nil at low to mid engine speed. Eliminating a restriction in the exhaust would have little effect at peak torque compared to rated, so there would be little effect at peak torque compared to your reported results.

Garbage information.

Also, remember that a dyno measures torque only. Horsepower is a calculation of torque and engine speed, or in this case, pto speed. (HP= TorquexRPM/5252)

 

[K5lwq]

Dealership pto dynamometers are notoriously inaccurate. They are not equipped with laboratory grade instrumentation, and you really can稚 really can稚 rely on a simple back to back pull for good information.

I spent thirty five years in an Oem engine lab environment, with upwards of forty engine test cells and a half dozen chassis rolls. The instrumentation had a calibration program with traceability to the National Bureau of Standards.

At the very least you would have to do a number of back to back to back to back (A-B-A-B) tests to establish test to test reproduce ability with such a crude setup, and even then, the absolute numbers would be garbage.

Our test cells cost upwards of several million dollars each, and had a dozen or more support staff, something no dealership service department could afford.

The torque reading disparity between the two runs is particularly questionable if you understand how back pressure affects airflow. I assume the engine you are dealing with is naturally aspirated. Airflow is pretty much a function of engine speed, so back pressure is nil at low to mid engine speed. Eliminating a restriction in the exhaust would have little effect at peak torque compared to rated, so there would be little effect at peak torque compared to your reported results.

Garbage information.

Also, remember that a dyno measures torque only. Horsepower is a calculation of torque and engine speed, or in this case, pto speed. (HP= TorquexRPM/5252)

Thank you for the information. At least I tried. Lol

What does surprise me is understanding that the dyno measures torque and calculated HP, how can the computer hooked to the dyno show 415 ft lbs of torque and only 36 HP at 540 rpm? Makes no sense.

None the less garbage information is correct.

 

[LouNY]

It was an interesting test and now your tractor is feeling better to you and pulling a bit better,
with no filter to plug up and cause issues.
enjoy her