I know TPI was built to run on 87 octane, but I thought 91 would make it run stronger. Why am I wrong? I mean I switched a few weeks back when I lost my job to save $2-3 on fillup and temps have gotten 10-15* hotter, so this whole situation doesn't make sense. Hotter, 87 octane = faster car. I mean even the top end feels stronger.

Maybe it's because the car knows I will be swapping to LT1 in the next couple weeks and it wanted to show me that it still has what it takes.

 

its your ignition timing, the higher grade of fuel/engine compression you have the more you advance the distributor. If you are running a 93 octane gas bump it up two degrees on the advance it will be a more controlled burn. Problem is if you advance it and run cheap fuel your engine will ping.

 

It's because your car is set to run on a certain octane. My LT1 is set to run 91, but here in Texas they only have 87-89-93. It runs ok on 89 and crappy on 93, so usually I stick about half 93 and half 89 to get a good mixture that my car likes! Like Mcdamit said, adjust your timing with the richer mixture and you'll be doing ok.

 

It's because higher octane doesn't mean power unless you need it. With a stock 305 engine the only time you would need it is with a custom PROM/advanced timing.

 

Higher octane is more stable, so it contains a marginally lower amount of energy, and is a waste of $ if not required for detonation prevention in engine.

More ignition advance can be used with higher octane. but all that is doing is compensating for the slower burn in the cylinder so peak pressure occurs at the same time as with the faster burn of the lower octane. -Nothing is gained.

 

High octane --> more carbon, less hydrogen, more
soot formation, just plain nastier
Use only as directed.

 

i just can't believe how much more powerful it feels. I want to take it to the dyno .

 

I didn't think higher octane gas burns any dirtier.

The higher the octane, the more resistance there is to combustion. Lower octane gas starts combustion easier. Unless a car is high-compression or high-timing or boosted/sprayed, lower octane will usually yield better results, with nothing gained going to a higher octane.

 

i dont think it does burn that bad does it. if so i'll retard my timing and use the cheap stuff, may i ask has anyone ever done this..
TPI305 with a 5 speed, 45 degree advance uncomputer controlled, my computer isn't advancing/retarding so...,

but either way i know she picks up much better than with the stock settings except when i let off it crackles a little