So I stopped by this Indy mechanic's shop to pick up a quart of oil-we start talking about engine mods I am doing this winter and he starts telling me I can't do them because of the poor quality of gas on the market today?
He claims that he gets constant "pinging" on his 10:1 motor (Running 91 octane). I asked if he is running a ignition on it to which he replies "Yes." He said the only way it doesn't happen is if he adds an additive like Rocket fuel or similar.
Anyone ever heard of this? I am skeptical (to say the least) on what this guy had to say.

 

I run 10.5:1 in my '03 Electraglide. I try to buy 93 octane but settle for 91 sometimes. I never run any additives and yes when I get bad gas it pings. I take it easy until the tank gets low as the ping is under rapid acceleration. As long as I donbt make any rapid twist on the throttle or try to run the RPM's too low, I won't get the ping.

 

the gas nowadays is ****........i could take his comment into consideration.....

 

I haven't gotten (or at least noticed) any pinging on my 10.5:1 compression. On my recent trip, there were a few times where I only had access to 91 octane, ran fine.

 

I only run marine grade ethanol free 94 in everything. that way if I have to buy crap gas at least there is some good gas to mix in with the garbage fuel.

You get more power from head flow then compression anyway, so go lower compression and have the heads CNC ported or buy aftermarket heads that flow better. Either way high compression isnt paying off on the dyno with the garbage fuel we have now.

Stock compression is around 8.9 so even bumping to 9.5 -9.7 comp is better than stock. I usually push the envelope on compression numbers for pump fuel on my dirt bikes, but am not goin to on my Harley cuz I need it to last and dont want to blow the top off a piston cuz i got a bad tank of fuel far away from home.

 

I believe it the local HD dealer by me sells a lot of gas additives (octane boosters) for this exact reason.

 

There is mostly 91 in my area (I try to run non-oxygenated gas in my bikes) Perhaps I will stick with the original plan of 9:8:1. Sucks that our fuel has gotten so crappy.

 

If your bike is stock compression the dealer is robbing you....

 

One of my bikes is a 10:1 motor and runs fine on 91 gas. If it knocks, try a cooler plug before going with expensive additives.

 

My motor is 10.2:1 CR.....I have singh grooves milled into my heads...NEVER does my motor ping or knock even on cheap 7 11 gas...also a good tune will do wonders for that