Engine vs Chassis dyno
Thread Starter
Melting Slicks
Joined: May 2001
Posts: 3,270
Likes: 26
From: Winchester VA
Cruise-In V Veteran
Engine vs Chassis dyno
We have seen first hand the occasional discrepencies between performance and chassis dyno #'s. So we know they can be inaccurate.
What about engine dyno's, more reliable/accurate?
The reason I ask... I am currently building a new motor and the shop that is testing the heads has an engine dyno. I would like to have it run on the dyno before installing it. It would be nice to know if I had a dud before installing it, a cam change is much easier on the stand than in the car.
It would be run with my electronics, likely a gen7 mostly for the fun of being to play with it myself once installed w/out having to purchase burner/eraser/romulator(I don't even know what that is) and so on.
What about engine dyno's, more reliable/accurate?
The reason I ask... I am currently building a new motor and the shop that is testing the heads has an engine dyno. I would like to have it run on the dyno before installing it. It would be nice to know if I had a dud before installing it, a cam change is much easier on the stand than in the car.
It would be run with my electronics, likely a gen7 mostly for the fun of being to play with it myself once installed w/out having to purchase burner/eraser/romulator(I don't even know what that is) and so on.
Le Mans Master
Joined: Jan 2003
Posts: 8,596
Likes: 19
From: Portland Oregon
Originally Posted by RainDelay
We have seen first hand the occasional discrepencies between performance and chassis dyno #'s. So we know they can be inaccurate.
What about engine dyno's, more reliable/accurate?
The reason I ask... I am currently building a new motor and the shop that is testing the heads has an engine dyno. I would like to have it run on the dyno before installing it. It would be nice to know if I had a dud before installing it, a cam change is much easier on the stand than in the car.
It would be run with my electronics, likely a gen7 mostly for the fun of being to play with it myself once installed w/out having to purchase burner/eraser/romulator(I don't even know what that is) and so on.
What about engine dyno's, more reliable/accurate?
The reason I ask... I am currently building a new motor and the shop that is testing the heads has an engine dyno. I would like to have it run on the dyno before installing it. It would be nice to know if I had a dud before installing it, a cam change is much easier on the stand than in the car.
It would be run with my electronics, likely a gen7 mostly for the fun of being to play with it myself once installed w/out having to purchase burner/eraser/romulator(I don't even know what that is) and so on.
An engine dyno works on the exact same principles as a chassis dyno. It too uses a loading device, a load cell for torque measurement and some sort of PC controller that does the calculations that gives you torque and Hp numbers. The only difference between engine dynos is the methods of their loading device. Some uses a water brake and others uses a eddy current brake. A eddy current is much faster in response times to different loading adjustments by the operator.
If its run correctly it should show results from different combinations either for the good or the worse. Just as a chassis dyno should.
Instructor
Joined: Dec 2004
Posts: 176
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From: Oakland CA
I would run it on the engine dyno. You can break it in and chase any leaks while it is accessible. Also, no risk of overheating. Your tuning will be close but there will be differences between running it on an engine dyno and real world conditions on the street or track. If possible you should try to use the same exhaust system on the dyno as you are running on the car. Sounds cool.
Melting Slicks
Joined: Jun 2002
Posts: 2,152
Likes: 239
From: Northern VA
Hey Steve, who is doing your work? Mine is sitting on jackstands as I contemplate what direction to go. I definitely want mine bench dyno'd so I don't run into the same problems I had before!
Thread Starter
Melting Slicks
Joined: May 2001
Posts: 3,270
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From: Winchester VA
Cruise-In V Veteran
Originally Posted by jerkyboy
Hey Steve, who is doing your work? Mine is sitting on jackstands as I contemplate what direction to go. I definitely want mine bench dyno'd so I don't run into the same problems I had before!
Coy Miller Racing Engines in Harrisonburg. It's a back alley type of shop but he has the equipment and a record for the fastest full weight (4100lb) Thunderbird SC. You can goooooogle him.
I know you want to dyno w/SC on if you go that route, he can certainly handle it.
I don't have references for him, I will see how he handles the little job on the heads and go from there. Choices are just limited in these parts of God's country.
Race Director
Joined: Sep 2004
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From: St. Peters MO Sometimes you have to prove yourself by doing alot of killing or alot of dying...
Originally Posted by STL94LT1
I would be very interested to see how your car dynoed on the engine dyno and then a chassis dyno. The comparison would be very interesting.
Thread Starter
Melting Slicks
Joined: May 2001
Posts: 3,270
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From: Winchester VA
Cruise-In V Veteran
Originally Posted by tjwong
An engine dyno works on the exact same principles as a chassis dyno. It too uses a loading device, a load cell for torque measurement and some sort of PC controller that does the calculations that gives you torque and Hp numbers. The only difference between engine dynos is the methods of their loading device. Some uses a water brake and others uses a eddy current brake. A eddy current is much faster in response times to different loading adjustments by the operator.
If its run correctly it should show results from different combinations either for the good or the worse. Just as a chassis dyno should.
If its run correctly it should show results from different combinations either for the good or the worse. Just as a chassis dyno should.
As a follow up...
Would you say that an engine dyno removes enough chassis dyno variables to be a more accurate tool? I guess what I'm trying to avoid is *apparently* missing my goal by 25-40HP only to find out after I made a change that wasn't necessary. One that trades off more driveability.
Rat C4,
I have read that before about tuning changes, I guess that does play into the above scenario. I could lose 25-40HP for the in car tune, so whether the dyno is right on the money or not means a little less than I thought it would. You raise some other good points as well, never know what you'll have to chase down and it too is easier on a stand.
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Le Mans Master
Joined: Jan 2003
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From: Portland Oregon
Originally Posted by RainDelay
Thanks TJ.
As a follow up...
Would you say that an engine dyno removes enough chassis dyno variables to be a more accurate tool? I guess what I'm trying to avoid is *apparently* missing my goal by 25-40HP only to find out after I made a change that wasn't necessary. One that trades off more driveability.
Rat C4,
I have read that before about tuning changes, I guess that does play into the above scenario. I could lose 25-40HP for the in car tune, so whether the dyno is right on the money or not means a little less than I thought it would. You raise some other good points as well, never know what you'll have to chase down and it too is easier on a stand.
As a follow up...
Would you say that an engine dyno removes enough chassis dyno variables to be a more accurate tool? I guess what I'm trying to avoid is *apparently* missing my goal by 25-40HP only to find out after I made a change that wasn't necessary. One that trades off more driveability.
Rat C4,
I have read that before about tuning changes, I guess that does play into the above scenario. I could lose 25-40HP for the in car tune, so whether the dyno is right on the money or not means a little less than I thought it would. You raise some other good points as well, never know what you'll have to chase down and it too is easier on a stand.
Safety Car
Joined: Dec 2002
Posts: 3,655
Likes: 24
From: Charleston SC
This may sound like a stupid question but how do you run a FI motor on an engine dyno? Does the owner have a wiring harness, sensors and ECM for your motor? I have never seen an EFI motor ran on an engine dyno so I am curious as to how they do it.
Thread Starter
Melting Slicks
Joined: May 2001
Posts: 3,270
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From: Winchester VA
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Cool TJ, thanks. I wanted to make sure the results were going to be worth the cost at least in terms of accuracy and meaningfulness.
FD2BLK,
He said it would be no problem with my own electronics. He has what he needs to run Fords, mostly for his own car, a Thunderbird SC. So basically he is prepared to power up, run, and monitor an FI system on the dyno.
FD2BLK,
He said it would be no problem with my own electronics. He has what he needs to run Fords, mostly for his own car, a Thunderbird SC. So basically he is prepared to power up, run, and monitor an FI system on the dyno.
