260whp with bolt ons, cams and headwork?!?
08-24-2016, 07:43 PM
#11
I calibrate test instruments for a living. What I think is weird is that there are no published accuracy specifications for these different dynos. I might be able to source them if I found the right engineer but they are not readily available on their respective sites. (I looked up mustang and dynapack) All I could find for specs were max loads they could handle (torque, hp, weight, rpm) So if there's no accuracy specifications available then how are they calibrated? Why is a dyno 9.1% different than another is beyond me when it comes to giving the client accurate numbers. It's like saying pumping 93 Octane at Shell vs Wawa at the same price will yield you a significant difference in the amount of fuel you get. They shouldn't as both are inspected by the Dept of Agriculture so you don't get ripped off. I do not know if dynamometers require a calibration like airport scales, gas pumps or precision clocks but now I'm curious as I'm about to get my car tuned in a week and will ask these questions. Just seems like they all should be standardized to what their manufacturer specs them at so you get reliable numbers.
08-25-2016, 09:39 AM
#12
I calibrate test instruments for a living. What I think is weird is that there are no published accuracy specifications for these different dynos. I might be able to source them if I found the right engineer but they are not readily available on their respective sites. (I looked up mustang and dynapack) All I could find for specs were max loads they could handle (torque, hp, weight, rpm) So if there's no accuracy specifications available then how are they calibrated? Why is a dyno 9.1% different than another is beyond me when it comes to giving the client accurate numbers. It's like saying pumping 93 Octane at Shell vs Wawa at the same price will yield you a significant difference in the amount of fuel you get. They shouldn't as both are inspected by the Dept of Agriculture so you don't get ripped off. I do not know if dynamometers require a calibration like airport scales, gas pumps or precision clocks but now I'm curious as I'm about to get my car tuned in a week and will ask these questions. Just seems like they all should be standardized to what their manufacturer specs them at so you get reliable numbers.
Church's uses a HUB dyno. So no rollers. You take the wheels off and bolt it directly to the dyno. It's safer and easier to use. But you loose the whole rolling resistance bit so Dynapaks tend to read higher
08-25-2016, 11:09 AM
#13
Originally Posted by truancy143' timestamp='1472096631' post='24047179
I calibrate test instruments for a living. What I think is weird is that there are no published accuracy specifications for these different dynos. I might be able to source them if I found the right engineer but they are not readily available on their respective sites. (I looked up mustang and dynapack) All I could find for specs were max loads they could handle (torque, hp, weight, rpm) So if there's no accuracy specifications available then how are they calibrated? Why is a dyno 9.1% different than another is beyond me when it comes to giving the client accurate numbers. It's like saying pumping 93 Octane at Shell vs Wawa at the same price will yield you a significant difference in the amount of fuel you get. They shouldn't as both are inspected by the Dept of Agriculture so you don't get ripped off. I do not know if dynamometers require a calibration like airport scales, gas pumps or precision clocks but now I'm curious as I'm about to get my car tuned in a week and will ask these questions. Just seems like they all should be standardized to what their manufacturer specs them at so you get reliable numbers.
Church's uses a HUB dyno. So no rollers. You take the wheels off and bolt it directly to the dyno. It's safer and easier to use. But you loose the whole rolling resistance bit so Dynapaks tend to read higher
08-25-2016, 12:18 PM
#14
You are not getting crank numbers, that is impossible on any dyno but an engine dyno, you still have everything but the wheels sapping power (transmission, driveshaft, diff, etc). This isn't an engine dyno, it's a hub dyno. Figure 17% loss for RWD, and Church's dyno reading 9.1% high, that equates to 7.9% loss on his dyno, which means if you want to find crank numbers, take your number at Church and multiply by 1.079.
08-25-2016, 01:11 PM
#15
You are not getting crank numbers, that is impossible on any dyno but an engine dyno, you still have everything but the wheels sapping power (transmission, driveshaft, diff, etc). This isn't an engine dyno, it's a hub dyno. Figure 17% loss for RWD, and Church's dyno reading 9.1% high, that equates to 7.9% loss on his dyno, which means if you want to find crank numbers, take your number at Church and multiply by 1.079.
08-25-2016, 03:09 PM
#16
Dynos will show changes. These depend on alterations and climate conditions. Same car on two different days will give different numbers. Take it across the street to a different dyno and use the higher number. I'm sure it's good business practice to market a dyno that gives the largest number and suspect some folks seek out these dynos for warm fluffy feelings about having the most power.
If the Mustang dyno that recorded 221bhp for my car reads 10% lower than some other dyno can I claim 243bhp at the rear wheels? Yep, that's my new number -- 243!
-- Chuck
I'm sure it's good business practice to market a dyno that gives the largest number and suspect some folks seek out these dynos for warm fluffy feelings about having the most power. If the Mustang dyno that recorded 221bhp for my car reads 10% lower than some other dyno can I claim 243bhp at the rear wheels? Yep, that's my new number -- 243!
-- Chuck
08-25-2016, 03:43 PM
#17
Originally Posted by truancy143' timestamp='1472096631' post='24047179
I calibrate test instruments for a living. What I think is weird is that there are no published accuracy specifications for these different dynos. I might be able to source them if I found the right engineer but they are not readily available on their respective sites. (I looked up mustang and dynapack) All I could find for specs were max loads they could handle (torque, hp, weight, rpm) So if there's no accuracy specifications available then how are they calibrated? Why is a dyno 9.1% different than another is beyond me when it comes to giving the client accurate numbers. It's like saying pumping 93 Octane at Shell vs Wawa at the same price will yield you a significant difference in the amount of fuel you get. They shouldn't as both are inspected by the Dept of Agriculture so you don't get ripped off. I do not know if dynamometers require a calibration like airport scales, gas pumps or precision clocks but now I'm curious as I'm about to get my car tuned in a week and will ask these questions. Just seems like they all should be standardized to what their manufacturer specs them at so you get reliable numbers.
Church's uses a HUB dyno. So no rollers. You take the wheels off and bolt it directly to the dyno. It's safer and easier to use. But you loose the whole rolling resistance bit so Dynapaks tend to read higher
08-25-2016, 03:44 PM
#18
08-25-2016, 05:53 PM
#19
No one here with an N/A s2000 or even moderately boosted s2000 is spinning tires to skew the results form a hub to roller dyno. % of hub dyno reading higher is up for debate, but logic says its going to read higher regardless, based on less less duty the engine has to move to get a reading. A 1000whp Supra will be skewed due to traction, sure. And 9% of 1000whp is a hell of a lot more then 9% on 260whp as well. Just sayin.
08-25-2016, 06:21 PM
#20