So how accurate is VDR v5.71?

**Greg E** · 12-17-2011, 12:34 AM

Been using this program for about a year to flash tune cars. Recently there was some concern about the accuracy of this dyno calc program.

Planing a trip to GZP before it snows to get all this verified on a real dyno, but in terms of AirFlow calulation...

Here's the airflow Map on my completely stock 98 with the boost turned up to about 15psi. The orange column represents Grams of Air per Cylinder during the intake stroke.

VDR puts me at about 266hp Uncorrected.

So how accurate is this?

I'm flowing a peak of .912 grams of air per cylinder @ 6500rpms.

That means = 2.736 grams of air per intake stroke. (3 cylinders during the intake stroke)

SO that's about 17784 grams/min @ 6500rpms.

Which means that divided by 1.18 = 15071.186 lbs/min or 532.6 cfm

That's 266.28cfm per turbo.

Since we know 1.6 CFM = 1hp, that means my car was putting down 332.8 hp at the crank. Figure 80% drive loss means 266hp at the wheels.

How about THAT!?

...We'll see how it does on a real dyno soon!