Dyno Results?

[Terry Keeley]

Much easier to look at your gallery now Jim, thanks a lot!

Just another Q about you dyno results if you don't mind?

I had a buddy make a simple dyno years ago using airplane props and a hanging weight to measure torque, crude but it worked somewhat. What he found was that his engine mods could make higher peak HP figures on the dyno but when the motor was run in a boat it didn't have enough bottom/mid torque to launch any decent sized prop.

When measuring power output do you look closer at the torque values/curve more than peak HP? Do you want a fairly flat torque curve?

I'd imagine for oval racing torque is good for getting through/off the corners, but what about SAW? Do you want the highest peak HP there? Can you go faster running past the peak HP rpm?

Well, guess it was more than one Q.

 

[JKramer]

If you want to see a good looking torque/HP curve check out the VZ-b Spec OS 21. Peek HP and torque are almost at the same RPM range.

http://rcnitro.com/RN/articles/dyno_vzbvspec4.asp

 

[Jim Allen]

If you want to see a good looking torque/HP curve check out the VZ-b Spec OS 21. Peek HP and torque are almost at the same RPM range.

http://rcnitro.com/RN/articles/dyno_vzbvspec4.asp

Very good example to look at. The O.S. 21 VZ-B's peak BHP is 2.93 @ 28,050 rpm & its peak torque is 104.6 oz. in. @ 26,500 rpm. The Collari .21 GT's peak BHP is 3.02 @ 34,500 rpm & its peak torque is 94.8 oz. in. @ 27,700 rpm. The Collari's torque curve is very flat over a wide rpm range allowing the motor to develop high HP at high rpms. Also notice the large differences in the construction of the liners of these two motors.

 

[AndyBrown]

3 HP on 30% nitro?!?! <_< Sure!!!!!!

I just wonder why we boaters are messin' with 60+% in our .21's. When we could buy an O.S. Max and get 3 HP with 30%.

Marty Davis' best dyno pulls were around 3 HP on 70%, so what gives?????

I think the company with the biggest advertising budget gets biggest dyno

power.........

I put the MAC car engine in a mono on 30% nitro....it was real slow. With 60% it came alive.

The very MAC car engine on 30% will run with that O.S. in the car, so I guess on 60% in the boat it's making 4+ HP!!!



I doubt it!! :lol:

I saw two different dyno guys do a Rossi car engine and published the result in two different car mags. One guy got peak HP @ 22,000 rpm. The other guy got about the same peak HP, but at 34,000 RPM. They were both the same stock engines.

 

[izitbrokeyet?]

3 HP on 30% nitro?!?! <_< Sure!!!!!!

I just wonder why we boaters are messin' with 60+% in our .21's. When we could but an and get # HP with 30%.

Marty Davis' best dyno pulls were around 3 HP on 70% so what gives?????

I think the company with the biggest advertising budget gets biggest dyno

power.........

I put the MAC car engine in a mono on 30% nitro....it was real slow. With 60% it came alive.

The very MAC car engine on 30% will run with that O.S. in the car, so I guess on 60% in the boat it's making 4+ HP!!!



I doubt it!! :lol:

Quit Pumping the Hype Andy we’re tired of it……..

If I want hype I’ll turn on the TV

Firstly your Mac Car engine is actually a Mac Buggy engine…only people who buy them are the cronies who are spending money to buy your stuff and be your friend. Your Mac daddy motor gets spanked at almost every Off-road race and I can pick one up on Flea-bay for a song.

Please show us the results of the killer nitro motors you built for offroad : LOL

(pay attention since this is just another question...lets see if andy Brown plays the drama card again)

I’d be particularly interested in seeing the race results from all your super-mac motors that nobody will buy

KB

 

[AndyBrown]

Kevin,

Go to the Car side of CMDRACING.COM and check out the REAL race results.

The stock MAC runs good and the MOD MAC will run with any Mod anything.

MAC engine sales slowed because CMB built junk crankshafts that wore out in one gallon of fuel

and yes, after the first gallon they got spanked because the crank pin diameter is reduced by .003".

That is the precise reason CMB no longer builds MAC engines.

Wow......do you have issues or what???

 

[Tim_Duggan]

Torque curves and peak rpm have as much, if not more to do with the engine/pipe combo and length than anything else IMO. Not disclosing the pipe and length is not giving the whole story.

Terry - power beyond peak and a torque curve with no nastly low end dip in torque are useful heat racing marine engine traits. Ian Inverarity (Nitrocrazed) has some awesome data on this subject.

 

[AndyBrown]

Kevin,

Here is the results you were asking for. I could supply more if you wish.

http://www.cmdracing.com/updated/road/track_report.html

 

[izitbrokeyet?]

C-mon Handy....could you dig a little deeper? :lol:

the current year is 2005....you're BS has been gettn spanked for over a year now :lol:

Congrats on all those 3rd and 4th place wins with your 60% nitro Mac killer engines that "really came alive"

I mean really….not even a 4th place finish in all of 2005….you’re killin me andy :lol:

please just stop the Hype B)

 

[Jim Allen]

Terry,

I'm still not finished with the gallery yet; thanks again for the much needed help.

Your buddy's simple dyno is exactly what my torque cradle dyno is. One good feature of the torque cradle type is that the load is present at all times. Usually, if you can pipe the engine up "rapidly", from half throttle to full throttle, you will be able to pipe the engine up at the lake. I look at the torque developed from 18,000 to 35,000 rpm when testing an engine, usually in 2,000 rpm steps. I do not repeat this on future dyno pulls unless something strange shows up. I do look carefully at what is happening around that peak HP as changes are made.

With the hydraulic dyno, it is necessary to apply the throttle & the load together, because single cylinder motors can be easily over loaded. This feature of single cylinder motors, when using the hydraulic dyno, can cause a problem which results in a motor that turns very high rpm but has low torque.

A flat wide torque curve is what is best with high engine rpms, because HP is a function of both torque & rpm. I would want an engine like this for SAW. You should not go faster when running past the peak HP rpm because both torque & rpm are decreasing.

 

[Don Ferrette]

Quit Pumping the Hype Andy we’re tired of it……..

If I want hype I’ll turn on the TV

"We're tired of it" ??? Ya got a mouse in yur pocket ' cause the only one bitchin' is YOU.

Enough of this crap already. I don't know what's gotten into you but this one man mud slinging campaign you're bringing is doing nothing but draggin' this board down. <_<

 

[Jim Allen]

3 HP on 30% nitro?!?! <_< Sure!!!!!!

I just wonder why we boaters are messin' with 60+% in our .21's. When we could buy an O.S. Max and get 3 HP with 30%.

Marty Davis' best dyno pulls were around 3 HP on 70%, so what gives?????

I think the company with the biggest advertising budget gets biggest dyno

power.........

I put the MAC car engine in a mono on 30% nitro....it was real slow. With 60% it came alive.

The very MAC car engine on 30% will run with that O.S. in the car, so I guess on 60% in the boat it's making 4+ HP!!!



I doubt it!! :lol:

Andy,

Do you think these dyno test by people like David Gierke & Mike Billington are bogus? I have more than 30 of these in my posession that were printed in different magazines. I wonder ???????????

I saw two different dyno guys do a Rossi car engine and published the result in two different car mags. One guy got peak HP @ 22,000 rpm. The other guy got about the same peak HP, but at 34,000 RPM. They were both the same stock engines.

 

[Tim_Duggan]

You should not go faster when running past the peak HP rpm because both torque & rpm are decreasing.

Jim - if you "go past" peak - doesn't that mean your rpm has increased from peak? Torque and power decreasing - yes.

If the motor has sufficient torque beyond peak to allow the prop to get to a higher rpm beyond peak then it should equate to a higher mph due to pushing more water. Correct?

Tim.

 

[Jim Allen]

You should not go faster when running past the peak HP rpm because both torque & rpm are decreasing.

Jim - if you "go past" peak - doesn't that mean your rpm has increased from peak? Torque and power decreasing - yes.

If the motor has sufficient torque beyond peak to allow the prop to get to a higher rpm beyond peak then it should equate to a higher mph due to pushing more water. Correct?

Tim.

Tim,

In any motor that I have dyno tested, before you reach peak HP, the torque is already decreasing. After peak HP the torque decreases rapidly. I think you want to run the motor where the peak HP point is.

Jim

 

[Brian Blazer]

Jim, (or anyone)

Have you tested the "S" bend vs the slight "S" bend with the stuffing box on the dyno? I have been meaning to set something up to test the differences, but haven't gotten around to it.

thanks, Brian

 

[AndyBrown]

You should not go faster when running past the peak HP rpm because both torque & rpm are decreasing.

Jim - if you "go past" peak - doesn't that mean your rpm has increased from peak? Torque and power decreasing - yes.

If the motor has sufficient torque beyond peak to allow the prop to get to a higher rpm beyond peak then it should equate to a higher mph due to pushing more water. Correct?

Tim.

Only if the air prop is too small, will the engine rev past peak HP, but these higher revs will be at a HP level that is less than the engine's real peak HP. If the prop is the correct size the revs will stop at peak HP. If the prop is too big the engine will never reach peak HP. This pertains to an air prop used on a dyno.

When using an air prop for a load, finding the correct prop to match the engines real HP will requier many test runs until the correct prop is found.

The MAC 21 (and many other buggy engines) will push a buggy to 45 mph or better. At this speed the rpm is about 43,000, but the HP at this point is well below peak. The buggy just doesn't need much power to keep it rolling against the air drag at 45 mph. Buggies weight 8 pounds and the big HP is needed for acceleration down in the 10 to 20 mph range.

The biggest load on the buggy engine is at about 20 mph when the engine is only turning about 20, 000 (depending on clutch slippage).

This is also close to the peak HP range of most buggy engines. A buggy engine dyno graph that shows peak HP at 30,000 rpm is very suspect, because buggies do not have gearing avalilible to make use of the HP being made at that rpm.

SAW boats need the torque and the HP to peak at the same RPM, which is also the rpm that will give the boat it's top speed. There is no such thing as going through the HP peak with higher revs for a SAW boat, unless the pond is very short and accelleration is part of the equation.

 

[Don Ferrette]

Jim, (or anyone)

Have you tested the "S" bend vs the slight "S" bend with the stuffing box on the dyno? I have been meaning to set something up to test the differences, but haven't gotten around to it.

thanks, Brian

Brian, Rod Geraghty did tests on S bends vs. straight & gently curved tubes & found the S bend offered less drag as it controlled cable whip better. B)

 

[Jim Allen]

Jim, (or anyone)

Have you tested the "S" bend vs the slight "S" bend with the stuffing box on the dyno? I have been meaning to set something up to test the differences, but haven't gotten around to it.

thanks, Brian

I don't know Brian, because I only run solid shafts.

Jim

 

[Jim Allen]

3 HP on 30% nitro?!?! <_< Sure!!!!!!

I just wonder why we boaters are messin' with 60+% in our .21's. When we could buy an O.S. Max and get 3 HP with 30%.

Marty Davis' best dyno pulls were around 3 HP on 70%, so what gives?????

I think the company with the biggest advertising budget gets biggest dyno

power.........

I put the MAC car engine in a mono on 30% nitro....it was real slow. With 60% it came alive.

The very MAC car engine on 30% will run with that O.S. in the car, so I guess on 60% in the boat it's making 4+ HP!!!



I doubt it!! :lol:

Andy,

One explanation for these very high HP readings on small motors could be the method used to measure the small amounts of torque being developed. I do not know what type of device is being used, load cell, spring scale, or torque wrench, but measurement is difficult at best. Big motors with big torques are easy to measure.

Jim

I saw two different dyno guys do a Rossi car engine and published the result in two different car mags. One guy got peak HP @ 22,000 rpm. The other guy got about the same peak HP, but at 34,000 RPM. They were both the same stock engines.

 

[Tim_Duggan]

Andy,

One explanation for these very high HP readings on small motors could be the method used to measure the small amounts of torque being developed. I do not know what type of device is being used, load cell, spring scale, or torque wrench, but measurement is difficult at best. Big motors with big torques are easy to measure.

Jim

I'm betting it's the dartboard method! Or better yet, the spanner on the prop nut method -"whoa -it flew X feet, must have X torque"

SAW boats need the torque and the HP to peak at the same RPM, which is also the rpm that will give the boat it's top speed. There is no such thing as going through the HP peak with higher revs for a SAW boat, unless the pond is very short and accelleration is part of the equation.

By that I assume you mean - under-propping for accelleration rather than peak speed - Obtaining the fastest possible speed for the pond available....kind of like reducing pinion gear diameter to suit a car track?