Had the Z dyno tested

[AmericanZ28]

i like to run 93 in my bird. Then i throw in a 10 point octane booster. that wakes it up.

When I first got my car, I always ran 87 Octane on it because of a tight budget. I've ran both 91 octane and 87 octane at the track and have not seen/felt any difference. Now that I make more money, and dont use it as a daily driver, I always use the 91 octane fuel(highest available). However, I've yet to feel a difference. I've had the car scanned a few times with the TECH 2 tool used at dealers, and there has never been any recorded incident of knock. I take it the HPP 160 degree thermo and re-programmed fans are to thank for this. My car never heats up past the quarter mark, and usually always rides below it. Isn't engine temperature a contributing factor to knock?

[Injuneer]

Reducing coolant temperature reduces knock. It also reduces the thermal efficiency of the engine, and hence reduces HP output. Its a complex balance of coolant temperature and its impact on detonation and air charge preheat; A/F ratio; and ignition timing that needs to be optimized to produce the best power. Cooler is not necessarily better.

There's what appears to be a very good article on the various engine dynos in the May 2004 issue of Hot Rod magazine. They compare the Dynojet inertia, Mustang eddy-currrent, Superflow eddy-current and Dynapack hydraulic dyons, using a Mustang 4.6L SOHC. The found that the Mustang produced results approx. 4.7% lower in HP and 11.1% lower in torque ("Standard" correction) than the Dynojet. The article also explains the differences in the way the torque or HP is measured (and the other calculated) on each dyno system, and the +'s and -'s of each system. I think it should be recommended reading, BEFORE you put your car on the dyno.

It also emphasizes the huge affects in results that can be caused by tire air pressure, the way the car is aligned on the unit, the tension used to strap the car down, location of external cooling fan, location of dyno ambient air temperature sensor, subtle changes the operator can make to "skew" the results, etc. It makes it very clear that it is next to useless to compare the results on different cars in different locations on different machines, run by different operators. It becomes a numbers game. The dyno is a useful tool for measuring the changes you have made in your car, particularly when always done in the same shop, on the same machine, by the same operator. But don't let your feelings toward your car rise and fall on your absolute HP number vs. one quoted by someone 2,000 miles away. It can be as meaningless as head flow numbers.