HP Loss
Race Director
Joined: Jan 2000
Posts: 13,014
Likes: 2,257
From: Corsicana, Tx
2020 C2 of the Year - Modified Winner
2020 Corvette of the Year (performance mods)
C2 of Year Winner (performance mods) 2019
2017 C2 of Year Finalist
All depends on which chassis dyno..Mustang and Dynojet are different for example though they have software to simulate each other.
Also depends on transmission, how loose converter is if there is one, accessories, exhaust and drivetrain type. How it was tested on the engine dyno will make a difference. 300 RPM per second or 600 RPM per second. Was it corrected to Std or SAE or some other version?Even aluminum flywheels, driveshafts etc can show up as an improvement along with lighter wheels, various fluids etc etc. Newer Vette's are a lot more efficient than older ones for example.
I also found that it's not linear throughout the curve. It seems to vary somewhat with percentage of loss. I've seen from 12% up to 30%+.
The only reason I'm saying all of this is that a chassis dyno is best used to tune and compare parts back to back. Not so much wrapped in the number to compare with other cars.
JIM
Also depends on transmission, how loose converter is if there is one, accessories, exhaust and drivetrain type. How it was tested on the engine dyno will make a difference. 300 RPM per second or 600 RPM per second. Was it corrected to Std or SAE or some other version?Even aluminum flywheels, driveshafts etc can show up as an improvement along with lighter wheels, various fluids etc etc. Newer Vette's are a lot more efficient than older ones for example.
I also found that it's not linear throughout the curve. It seems to vary somewhat with percentage of loss. I've seen from 12% up to 30%+.
The only reason I'm saying all of this is that a chassis dyno is best used to tune and compare parts back to back. Not so much wrapped in the number to compare with other cars.
JIM
Pro
Joined: Sep 2008
Posts: 508
Likes: 1
From: Olive Branch MS
Jim is on the money. There are indusrty estimate standards like 20 - 25% for automatics and 10-15% for manuals, but there are alot of variables from the back of the engine to the wheel contact patch. You can change from steel wheels to light weight alumium racing ones and pick up rear wheel horsepower. You can just run yours and then calculate what the loss on your vehicle is. Then you can make changes throughout the drive line to look for improvements.
