Running a high compression engine on pump gas

[elonblock]

Educate me on the subject of running a high compression engine on today's pump gas.

The engine I am considering is a bone stock 11:1, L-72.

Here's the background. I live in a rural area and finding high test gas can be difficult at times. Many gas stations only have two choices, either regular or premium. And there are many occasions when the premium grade is sold out.

The car will be driven occasionally for cruises and similar events. Maximum distance may be 150-200 miles round trip. There will be no drag racing, or stop light antics. Maybe an occasional running it through the gears,but no high rpm operation.

I have a number of questions....

1) What is the reality of running an 11:1 compression engine on pump gas with the given scenario and not have it detonating and pinging?

2) Is this something which I could run on premium and add an octane booster?

3) Aside from race fuel, or av gas, are there any other products which work well in a 11:1 engine?

4) If you currently, or have had a similar engine/set up, what has been your experience driving with pump gas?

School is in session...let the education begin!

Elon

[Salvatore]

You can keep your timing retarded a little and run 93 octane or you can run a fuel/led additive. I would run 93 octane and try to buy some Sunoco racing gas or even aviation fuel. Don't run your motor real lean either. VP is very good racing gas also. I have around a true 10.75 to 1 in my 69 Z/28 and I used 93 octane and some of Jack Podell's additive "Max lead 2000." It may or may not have helped but never had any pinging or detonation. I now run 5 gals. of Sunoco 112(all that I can get around here with lead) with about 6-7 gallons of 93 with about 36 degrees timing. Have your distributor recurved also for power and better timing adjustments.

[TimG]

I've owned my share of L71 Corvettes, some very original low mile versions. I've found nothing works like a splash of race gas. Jack's stuff works for 10 to 1 big blocks or high compression small blocks, but L72 and L71 need race gas to keep them happy. I use one gallon to three or four gallons of pump fuel.

[PxTx]

Tim, do you think the gains from the race gas is due to thr stock distributor configs from back when good gas was common? Or more to do with the nature of big blocks simply not responding to timing mods? Were the distributors modified on the low mile original cars?

[MosportGreen66]

With the cost $ of leaded race fuel in positive inverse proportion to the quality of pump gas, unless you're willing to spend copious amounts of money on race fuel, compression must decrease. There is no substitute.

[Salvatore]

I like that answer young man!

[Tracker1]

My LS6 Chevelle is dead-nuts on 11:1 compression - I use VP Racing Fuel - 5 gallons for very tank of 92 octane unleaded. Happy car. Without it, she's a dieseling b#*tch.

[Big Block Bill]

I agree. Anything from back in "The Day" with points, a carb, and over 10:00 to 1 compression will eventually get the rings rattled out of it if you don't give it a shot of real, honest to goodness, 100 octane leaded racing fuel in it once in awhile. In the real scope of things, with what we all have invested in our cars, what does it really cost for a 5 gallon can of Cam2 leaded racing fuel any way? Long live the Big Block!

Bill

[Salvatore]

occasional driving the racing gas won't kill ya in price. Don't really need alot just a decent mixture.

[MosportGreen66]

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: [email protected]</div><div class="ubbcode-body">I like that answer young man! </div></div>

I crafted that with you in mind Sammy... lol...

Dave and I are frustrated with this very notion. We're building the motor to our '70 LT1 Corvette now and are hovering around 8.5:1 compression with a more radical than stock cam. We also had the heads ported for even flow throughout the rpm band. We'll be identical power without the headache or financial drain of always running race fuel.