Thread: ZZ4 Dyno Numbers

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Hello:

I have a stock ZZ4 with about 3600 miles on it since it was installed into an 83 TransAm. A recent Dyno test produced 256 RWHP and 300 TQ at 5,250 rpm. The numbers seem low and I’m not sure if that should all be attributed to parasitic loss and possibly less than optimum tuning.

(1) Given the following, how much might I expect to lose at the FW:

- Power Steering Pump, and Alternator (V-Belt)
- Flexalite Fan - no clutch
- Stock Water Pump.
- 1&5/8 Hedman Shorties with cutout open after the y-pipe for dyno run.
- Speed Demon 650 DP, no choke, Jets are 72/80, no air cleaner on it for dyno run.
- Timing is 15* initial with 34 total and all in by 2800 with VA disconnected.
- Fuel, Sunoco 94


(2) Given the following how much drive train loss might I expect to see:

- TH350C
- 2400 Stall
- 3:23 Rear
- 275/40/17s on Ronal Hawk Rims

The motor seems to be running pretty good in general although it had a stuck valve from the factory which was repaired under warranty. My concern is whether or not something related to the valve problem might be causing lower HP numbers. I will be going back to try and optimise tuning on the dyno but first I will have a leak down test done.

I realize that any estimates based on the above will not be exact and that percentage is not the best way to account for drive train loss but I’m wondering if the numbers suggest a problem with the motor or if they are more or less normal for what I’ve got.

I tried searching this forum and it sent me to clubcobra which is sort of strange..lol

Thanks

Those numbers sound pretty good for stock. A few simple mods would get more.

Tuning the carburetor can make a big difference. Make sure you are at an optimum fuel/air mixture because if you are running too rich, you are losing hp. Make sure your air filter is not too small and restricting your air. An appropriately sized K&N unit will help if you are not running one already. A less restrictive exhaust/muffler system will also help you gain some hp. You should figure a minimum of a 20 per cent parasitic loss with accessories and your transmission. So if your ZZ4 is rated at 385 hp at the flywheel, then you should expect no more than 308 hp at the wheels. And that would be best case scenario.