Turbo VS. Supercharger
There’s an old adage that says that numbers don’t liebut they can be misguiding when taken out of context. Based on the peak power numbers alone, one could assume that the Heffner R8 TT upgrade is the clear winner. But oftentimes, the devil’s in the details. I played detective and delved deeper into the differences between the numbers and here’s what I uncovered.
When comparing numbers, you have to make sure you aren’t comparing apples to oranges. From years of doing the Proven section for ec, immediately when I looked at both dyno charts, a few thoughts popped into my head.
First, these runs were done on two completely different dynos. The Heffner was run on a DynoJet versus the VF on a Mustang. It’s common knowledge that DynoJet hp numbers are on average about 10-15% higher than Mustang hp numbers. Plus, there are inherent differences between any dynos even if they are from the same manufacturer.
Second, the rwhp on the Heffner graph indicates that they only measured power generated at the rear wheels where VF’s graph indicated all four wheels were used. An all-wheel-drive dyno will have lower numbers which reflect the parasitic drag from the front wheels and since rear-wheel drivetrain loss is less, more power reaches the wheels, inflating the numbers.
Third, the Heffner run used 93 octane which will add 10-20 whp on a forced induction vehicle and the VF engineering graph used 91 octane.
Finally, the Heffner turbocharger installation comes as a package with an exhaust and intake system where the VF is running a supercharger on a stock intake and exhaust. Adding an exhaust system to a stock R8 can add 16-21 whp and an intake system can add 8-10 whp.
On both graphs it’s unclear what run is being represented- is it the 1st, 2nd, 3rd or 6th? Modern vehicles typically show big gains in the first run before the ECU has adapted or the car has completely warmed up.
The same R8 looks completely different whether it’s turbocharged from Heffner or supercharged by VF. Before you compare numbers and shell out money for the obvious choice’ look further. A better comparison would be to equip the VF R8 with an intake and exhaust and run both vehicles on the same dyno, with the same fuel octane, and testing conditions.
| ||Heffner R8 Twin Turbo ||VF R8 Supercharged |
|Dyno Type ||DynoJet ||Mustang |
|Horsepower Acquired ||Rear Wheels Only ||All Four Wheels |
|Peak Power ||536.48 hp @ 122 mph ||439 hp @ 7650 rpm |
|Test Octane ||93 ||91 |
|Exhaust ||Full turbo back ||Stock |
|Intake ||High flow ||Stock |
|Boost ||6 PSI ||6-7 PSI |