Engine to Chassis Dyno HP lose
Discussion
Not wanting take an old thread to far off, so I started this thread.
While must of this does not apply to this subject, there are a couple of examples where people say that they have seen much greater power lose between engine and chassis dynos than talked about here.
http://www.yellowbullet.com/forum/showthread.php?s...
Stan
While must of this does not apply to this subject, there are a couple of examples where people say that they have seen much greater power lose between engine and chassis dynos than talked about here.
http://www.yellowbullet.com/forum/showthread.php?s...
Stan
Stevie,
Yes, that is what the thread is mostly about.
Extracted from some of the posts. Most post were about how the Mustang Dyno's numbers are lower than other chassis dynos.
That Mustang Dyno is a Heart Breaker our 620 RWHP 975 HP went 9.18 in a 3500 lbs car
620/975=.635 or 63.5% Something seems strange there.
Ive witnessed similar percentage of loss on a mustang many times. Reinforces the fact that the dyno is a tuning tool as opposed to a comparative marker.
Mustang Dyno, issue they don't give up the number like the others do. You want a bigger HP number take it to a different dyno. I dont care what the number is I just try to move it up.
We've seen from a real honest dyno
18/22% manual trans
29/32% auto trans
Loss to power at wheels
Stan
Yes, that is what the thread is mostly about.
Extracted from some of the posts. Most post were about how the Mustang Dyno's numbers are lower than other chassis dynos.
That Mustang Dyno is a Heart Breaker our 620 RWHP 975 HP went 9.18 in a 3500 lbs car
620/975=.635 or 63.5% Something seems strange there.
Ive witnessed similar percentage of loss on a mustang many times. Reinforces the fact that the dyno is a tuning tool as opposed to a comparative marker.
Mustang Dyno, issue they don't give up the number like the others do. You want a bigger HP number take it to a different dyno. I dont care what the number is I just try to move it up.
=================================
We've seen from a real honest dyno
18/22% manual trans
29/32% auto trans
Loss to power at wheels
Stan
Edited by Stan Weiss on Thursday 9th July 18:26
Pumaracing said:
Stan, when you type "lose" I presume you mean "loss" as lose makes no sense. Not that you make sense much of the time. This is a strange aberration though, to so frequently misspell a simple four letter word. Do you think dementia is setting in already or is it just an American thing?
Dave,Not yet. I am not sure when I will be following you on that journey.
Stan
I have been off doing some other things, and just got back to this and found this article. For me it was a very interesting read.
http://www.superstreetonline.com/how-to/engine/mod...
Stan
http://www.superstreetonline.com/how-to/engine/mod...
Stan
Peter,
If all I was doing was looking to run a simulation then the chassis dyno numbers would be great, and I would have no problem using them. But lets say that a car you had on your chassis does a standing mile run and goes 201 MPH and a few cars later someone goes 207 MPH. The two owners talk to each other and the engine that went 207 MPH was on an engine dyno. It would be nice to see know if the car that went 207 MPH did it because of more HP or because of some other reason.
Stan
If all I was doing was looking to run a simulation then the chassis dyno numbers would be great, and I would have no problem using them. But lets say that a car you had on your chassis does a standing mile run and goes 201 MPH and a few cars later someone goes 207 MPH. The two owners talk to each other and the engine that went 207 MPH was on an engine dyno. It would be nice to see know if the car that went 207 MPH did it because of more HP or because of some other reason.
Stan
PeterBurgess said:
That's interesting Stan. Do you think that is because there are more engine dynos than chassis dynos Stateside or folk divulge more info from engine dynos?
Peter
Peter,Peter
I believe that different groups will have a different average usage between the 2 types of dynos. When I had my 4.6l Mustang that group used the chassis dyno much more than the drag racing groups I deal with do.
When you get your 901 up and running I do not know what output you are going to give people. But some here in the states give them the SFD files. I have had people send me SFD files and that is the reason I have the SF program to read and display those files on my computer.
Stan
Pumaracing said:
That's not much help when what you've got to work from is flywheel bhp or OE manufacturer road car power curves. It's essential to be able to at least approximate transmission and tyre losses.
In fact much of the early work I did circa 20 years ago on establishing what true transmission and tyre losses really were was by computer simulating many cars tested by Autocar and Motor magazine and seeing what level of losses were required from the quoted flywheel bhp to match the tested performance. Now of course there's no guarantee that every car tested had exactly the claimed flywheel bhp but averaged over many simulations I was able to find very consistent patterns of loss which eventually gave rise to the loss equations for manual transmission cars on my website.
https://web.archive.org/web/20110909141356/http://...
In the 15 or so years since writing that I've found nothing to alter my view that these give a very close approximation of real losses for most cars.
Dave,In fact much of the early work I did circa 20 years ago on establishing what true transmission and tyre losses really were was by computer simulating many cars tested by Autocar and Motor magazine and seeing what level of losses were required from the quoted flywheel bhp to match the tested performance. Now of course there's no guarantee that every car tested had exactly the claimed flywheel bhp but averaged over many simulations I was able to find very consistent patterns of loss which eventually gave rise to the loss equations for manual transmission cars on my website.
https://web.archive.org/web/20110909141356/http://...
In the 15 or so years since writing that I've found nothing to alter my view that these give a very close approximation of real losses for most cars.
There has been changes in automatic gearboxes over the last twenty year. Have you done any calculations with vehicles using the ZF 8H or 9H gearboxes?
Stan
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