My Dyno Experience

[Roscoe]

Well last week I decided to put my Cobra on a dyno and just see all those four-hundred and yadda yadda horses I've been bragging about. Just like talking to a new date, we tend to embellish things.

Now my engine certainly has the potential for power: 351W bored +40, TRW forged pistons, Edlebrock performer plus cam and timing setup, 58cc AFR alum heads with Harland Sharpe Roller Rockers, Edelbrock Performer intake, 650 Speed Demon, etc. and running 93-94 octane.

I was really disappointed when I saw my hp at 267 and torque at 330. I really thought that I would be more powerful than that. Hey, with a 2600 lb car that will still propel it down the highway at tremendous velocity but, still, I should be getting more…right? Even allowing for 18% power loss through the drivetrain that is still only 315 hp at the crank.

Well I faxed the dyno sheet down to the Demon tech guys. They were very helpful and I made the following changes:

1) Replace the progressive linkage to one-to-one
2) Raise the throttle cable on the carb to the big 1/2" hole to allow for full stroke of the linkage and better leverage.
3) Rejet down 2#'s from 70/78 to 68/76
4) Replace my 1/2" open spacer with a 1" 4 hole spacer.

Well I did all this, at very little cost, and took another run on the dyno yesterday.

I made three runs and all were about the same: 291 hp at the wheels and 365 lbs of torque!! What an improvement!! This is almost 350 hp at the crank and there is still room for improvement.

I just faxed the results down to Demon for more suggestions.

Anyway, I guess the point is that we all tend to talk up our cars but you never really know what you have, or where you need to tweek it, until you get it on a dyno. I certainly had the potential but was not tuned properly.

By the time I get done I should be in the 320-325 hp at the wheels and in the very high 300's at the crank. Certainly a big difference over last week.

Roscoe