Milwaukee Midget

[Captthundarr]

" Graham, you're spot on with that assessment - yes, that's rear wheel horsepower."


I understand the need to know engine hp. but isn't rear wheel hp kind of where the rubber meets the salt. Other than tune up improvements there is little that Chris can do for the parasitic losses so wouldn't they be considered constant?

[Interested Observer]

Chris,
Having now perused the Dynojet web site, it is clear that the machine is capable of much better results than what you got.  It appears that the model you were on is a 4 wheel inertia dyno with the optional eddy current brakes. 
If you are paying good money for dyno time, you should get good results, not a bunch of chicken scratching.  The A/F function was not operating at all, and the torque/power results are barely discernable and certainly nothing you could hang your hat on.  If the operators choose not to recognize these deficiencies and cannot fix it, your efforts and dollars are pretty much going to be wasted.  If you get no plausible explanation from the operators, you might send the data to Dynojet and ask them if this is representative of their capabilities.  They might even diagnose the problem(s) and chide the operators for bringing disrepute onto their product.

Digital data recording is by its nature “pixilated”, but that doesn’t mean the value of the variable should jump all around.  Those great big heavy rollers should virtually eliminate any rapid fluctuations in the results.  I would hazard to say they have a data acquisition problem.

Drive train losses --  Power losses (for a given drivetrain) are generally thought to be in proportion to the power transferred because more power generally arises as a result of more torque, and more torque implies more loading on the bearings and gears, and more loading produces more friction which is then more loss.  It can be more complicated than this, but at least this rationale pretty much explains why power loss is not a constant.

[Stan Back]

Thanx for that.  I was thinking that it took X HP to turn a transmission at Y RPM, X HP to turn a rear end at Y RPM.  There I go thinking again.  A hobby this late in life I'm sure not to master.

Stan

[Milwaukee Midget]

Interested Observer -

Thanks for that - I'm still very new to this. 

I googled images for dynojet, and none of the images of printouts looked this erratic.  I've got a message in to Dynojet, along with links to the pic, and the videos of the pulls.  LMT is closed up for T-day - I'll chase this down a bit harder after the holiday weekend.

Speaking of which - Happy Thanksgiving, everyone.

[Captthundarr]

Just recorded Chris' Dyno pull for my ring tone

[Milwaukee Midget]

Remind me to hide your cell phone . . .

[Milwaukee Midget]

Just got a reply from the folks at Dynojet - he's asked for the dyno run files, which I don't have, but I intend to get hold of.  Questions asked were full throttle? what gear? automatic or manual?

With the exception of the exhaust reading, and I just wiped out the tailpipe with a white paper towel and found no evidence of a rich mixture, I remain fairly confident in Jeff's assertion regarding the shape of the power curve.  Admittedly, it's a sense of feel on my part, from sitting behind the wheel and flogging it pretty hard.  My senses tell me the whole car was working like a unit - smooth, consistant application of power to the rollers.  While I can't discount the idea that I might be fooling myself, I've also got to be cautious of second guessing myself into a stall on the project.   

Investigation continues.  Weekend is shot, but I'll try to slip over to the shop and talk with Jeff next week.

IO, I appreciate your observation, and your research.  Thank you.

Anyone else have a printout from a Dynojet they'd like to share?  Post 'em here.

[Dr Goggles]

Thanx for that.  I was thinking that it took X HP to turn a transmission at Y RPM, X HP to turn a rear end at Y RPM.  There I go thinking again.  A hobby this late in life I'm sure not to master.

Stan

In an email where we discussed the flywheel versus tires as a place to measure hp with Chris I stated " proportionally your losses would be quite high". I assumed that a given drivetrain would soak up a given amount of power discounting the escalating losses as the power applied increased, as IO pointed out above.However I was thinking about proportional to the power of the motor, as a proportion of 60hp.Thinking thedrive train probably takes 10-20hp..........that might only increase by a few hp if you were putting another 50hp through it, now I need to have a lie down.

[saltwheels262]

mm,
will email printout to you now and you can post on the forum.
not savvy enough to post pics.

bill franey

2 pics of the same graph have been sent.

[Milwaukee Midget]

Thanks, Bill - here we go -





Koncretekid sent one to me, too, but I haven't quite been able to set it up.

What I've noticed in the three that I've received, and the ones I've seen on Google, is that the "SAE smoothing" were all set at 5.  My print out was set at 3.

 

Anybody know for sure if that might be the difference?

Thanks again.

[saltwheels262]

no problem. hope that it helps.

bf

[Tman]

Chris, the Eagle has left the building. Look for Sat? Wisco is close, Priority mail box.

[Milwaukee Midget]

Chris, the Eagle has left the building. Look for Sat? Wisco is close, Priority mail box.

And the Wort is Wapped and Weddy.  I'll PM you a twacking # on Fwiday.

It's all a secret code, folks - nothing to see here . . . 

[Elmo Rodge]

That's weawwy wonderful. Don't forget Wayno.   

[Captthundarr]

code busted = suds for latches I recognize