A couple weeks ago, RPNW did a dyno day with Groundzero motorsports (Thanks again Ralph!). There was only 1 other 8 there besides myself. What I noticed was that octane rating realy affects how much power the car puts down. Bill White, was running regular unleaded in his car, and it put down around 7rwhp less than my car. I was running about a 1/2 of tank of super unleaed with about 4 gallons of 110 octance race gas. Bolth are 6spds.

I also noticed that my car made peak power right at the rev limiter. I thought this was extremely strange. The dyno sheet is'nt %100 accurate, but its close. According to my tack in the car, the rev limiter would step in right about 9,400-9,500rpms. Right at about the time the dyno run would be complete. (If you've ever ran your car on a mustang dyno, you'll see the little green bar that has to be filled up in order to make a full run.) The down side is that the dyno sheet/end of the run, stops at 8,500. Right at the point where my rev limiter came in. So basicly, the dyno was off around a 1k rpms towards the end of the dyno run.

So, what I'm wondering is where your car made its peak power? CJ

 

not to jump to a conclusion, but if the dyno is off by 1000 rpm, that will signifigantly affect your power output, since HP is a function of TQ.

 

The factory rev limiter is at 10,000 rpm's according to the tach of the car that I hit it in.

 

Of course your car will make more power on higher octane. It may burn slower but there is so much more energy released when it does burn.

According to Mazda peak power is "supposed" to be at 8500 rpm.

 

Ocatane has nothing to do with energy content, high octane is the same, or usually lower energy content then regular,...

 

The reason the lower ocatane fuel shows lower power numbers was likely due to the excessive burn rate. The fuel ignited at normal timing, but maximum explosive force was achived before the rotor finished the compression phase. As a result, the rotor had to fight through the explosion before being accelerated by it. It is always wise to run the lowest octane the car is rated for. Timing is calculated with a particular burn rate assumed.