Dyno Horsepower
Race Director
Joined: Jan 2000
Posts: 13,018
Likes: 2,262
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
Many years ago with the first version of my 540...I put it on a Dynojet soon after running it on a well known, established and proven engine dyno.
It made 732 flywheel HP with open headers and water pump being driven by a belt.
In the car it made 615 RWHP with water pump operating by belt and driving the alternator and open headers. It also had a steel flex fan spinning and contrary to popular belief...when it was removed it only picked up 3-4 RWHP which was nearly within run to run variation. I also began the tests with the 3" exhaust and Flowmasters in place. It only made 565 RWHP capped up and immediately jumped to 615 when uncapped!! 50 RWHP is HUGE! Needless to say that exhaust system was quickly replaced!
When comparing the chassis runs against the engine dyno throughout the RPM range...there was a definite difference in percentage losses at each point. It wasn't an equal loss and it wasn't linear.
A later version of it as a 555 made 871 HP on the same engine dyno with an electric water pump drive and open headers and 742 RWHP on a Dynojet with the water pump/alt operating with a belt and the exhaust was capped up with 3.5" exhaust and mufflers out the rear. (This exhaust has proven to not hurt HP one bit...even with my current 1240 RWHP turbocharged version). It also had the DANA 60 IRS set up in it vs the original Vette diff that was in place during earlier testing. Transmission was also changed to a G-Force GF5R 5 speed with straight cut gears vs the Doug Nash 5 speed it had previously. So not all apples to apples...but gives some insight.
JIM
It made 732 flywheel HP with open headers and water pump being driven by a belt.
In the car it made 615 RWHP with water pump operating by belt and driving the alternator and open headers. It also had a steel flex fan spinning and contrary to popular belief...when it was removed it only picked up 3-4 RWHP which was nearly within run to run variation. I also began the tests with the 3" exhaust and Flowmasters in place. It only made 565 RWHP capped up and immediately jumped to 615 when uncapped!! 50 RWHP is HUGE! Needless to say that exhaust system was quickly replaced!
When comparing the chassis runs against the engine dyno throughout the RPM range...there was a definite difference in percentage losses at each point. It wasn't an equal loss and it wasn't linear.
A later version of it as a 555 made 871 HP on the same engine dyno with an electric water pump drive and open headers and 742 RWHP on a Dynojet with the water pump/alt operating with a belt and the exhaust was capped up with 3.5" exhaust and mufflers out the rear. (This exhaust has proven to not hurt HP one bit...even with my current 1240 RWHP turbocharged version). It also had the DANA 60 IRS set up in it vs the original Vette diff that was in place during earlier testing. Transmission was also changed to a G-Force GF5R 5 speed with straight cut gears vs the Doug Nash 5 speed it had previously. So not all apples to apples...but gives some insight.
JIM
