110 Leaded Octane fuel

[Lawrence S.]

I have been burning the above fuel (about a tank and one half) through my 67 L-36. Car runs very well, but should I mix this fuel with 93 at the pump just to extend the range of the good fuel? This stuff is $8 a gallon.
Does this fuel adversely effect my freshly rebuilt engine?

Thanks

Lawrence

[Duke W.]

Re: 110 Leaded Octane fuel

Why?

If the engine is freshly rebuilt, what do you think the CR is? What's the head gasket thickness? (You can measure at the corners of the head block interface with feeler gages.)

If it was rebuilt with OE equivalent pistons and a thick composition gasket (OE is .028" shim type) then the CR is likely no more than 10:1, and it should run detonation-free on 93 PON, but you need to test.

Let the tank get to near empty and add about three gallons of 93 PON. Then test for detonation. Load it up at low revs by climbing grades at 1000-2000 revs in third or fourth gear. If you don't detect any detonation let the tank go to near empty and run the sequence at least two more times, and if no detonation all you need is 93 PON, and you can then get some light springs for the centrifugal advance to bring it in earlier, which will improve low end torque and fuel economy.

The other issue you could get with E10 is percolation and/or vapor lock so be on your toes. These problems have been extensively discussed on the TDB.

Duke

[Michael W.]

Re: 110 Leaded Octane fuel

The engine didn't need such high octane when new, it shouldn't now. It might run fine on straight 93 as Duke says. It certainly doesn't need leaded fuel of any rating.

[Tom P.]

Re: 110 Leaded Octane fuel

I USED to buy 100LL Avgas as well a 110 leaded race gas for my 2 FI engines (SB400 and 327), 383 in the 51 Chevy, SB400 in the Chevelle, W30 spec 468 Olds in my Cutlass, as well as the VERY HEALTHY 420SB in the boat. But for the past 2-3yrs, I've been running 91 octane NON-ethanol in all of them. I have NOT NOTICED any adverse issues with any of those engines. So from now on I'm using the 91 non-ethanol.

https://www.youtube.com/watch?v=ToxC147ExmI

https://www.youtube.com/watch?v=V1I9q3QAMac

[Lawrence S.]

Re: 110 Leaded Octane fuel

Why?

If the engine is freshly rebuilt, what do you think the CR is? What's the head gasket thickness? (You can measure at the corners of the head block interface with feeler gages.)

If it was rebuilt with OE equivalent pistons and a thick composition gasket (OE is .028" shim type) then the CR is likely no more than 10:1, and it should run detonation-free on 93 PON, but you need to test.

Let the tank get to near empty and add about three gallons of 93 PON. Then test for detonation. Load it up at low revs by climbing grades at 1000-2000 revs in third or fourth gear. If you don't detect any detonation let the tank go to near empty and run the sequence at least two more times, and if no detonation all you need is 93 PON, and you can then get some light springs for the centrifugal advance to bring it in earlier, which will improve low end torque and fuel economy.

The other issue you could get with E10 is percolation and/or vapor lock so be on your toes. These problems have been extensively discussed on the TDB.



Duke

I am just trying to make sure the engine is running at peak performance.
We used OE specs to build the engine and endeavored to achieve 10:1 CR.
I will run the detonation test, but have not experienced any to date. I have about 1000 miles on the rebuild.
I read in another post you wrote Duke, that BB's liked 8* timing. I have not checked my timing because the engine has been running fine. I would expect the builder set it up to stock 4*. But will check.
I installed the ligher springs in my 69 Z and it can't believe how much better it runs. Will do that to the L-36.
Thanks guys

Lawrence

[Domenic T.]

Re: 110 Leaded Octane fuel

Lawrence,
You said you want peak performance, and there are many good suggestions about what you should put in your tank. The one thing that is missing about what fuel does what is a dyno test which seems to be avoided. I can tell the difference by my back tires. I can lay a 300' strip with a good octane and about 100' or so with what can be bought at the pump. I use the timing that the GM engineers that designed the engines use with a good fuel, but have to de-tune to use other available fuels. I would like to see a dyno report using factory tune specs with both fuels. Years ago at the drag strip I had better times using the best I could get at the time. All my car engines have very high factory compression and I have already took the chance running a lesser fuel with damage to one engine. If you watch your driving habits you can use those fuels, but if you get the bug to blast the road, it can be a bit disappointing. I do agree that they can be operated just fine with what is at the pump, but I like the extra edge using better fuel. I do about a 50/50 mix.
Now I have put auto fuel 87 in one tank and 100 low lead in the other tank of a airplane and switched tanks finding no difference in RPM or power. BUT the compression ratio was 7:1. With compression above about 8:1 you are forbidden to use lesser than 100 low lead or, As the manual says you will cause damage. I have seen as high as 10:1 in some airplanes and helicopters that are required to use 100 low lead.
It's really your choice as to what burns best, I can feel the difference and have had a few tickets doing so.

Dom

[Michael W.]

Re: 110 Leaded Octane fuel

Now I have put auto fuel 87 in one tank and 100 low lead in the other tank of a airplane and switched tanks finding no difference in RPM or power. BUT the compression ratio was 7:1. With compression above about 8:1 you are forbidden to use lesser than 100 low lead or, As the manual says you will cause damage. I have seen as high as 10:1 in some airplanes and helicopters that are required to use 100 low lead.
It's really your choice as to what burns best, I can feel the difference and have had a few tickets doing so.

Dom

Please don't bring aircraft engine requirements into the discussion. It's apple and oranges.

[Domenic T.]

Re: 110 Leaded Octane fuel

Michael,
Sorry but that was actually in favor of the prior posts, and I will use a go-cart if needed. There is a lot of good advice here but not to much in the way of practical tests, only paper results. The AIRCRAFT ENGINE is a internal combustion engine that suffers the same problems as FORDS, Chevrolet, and other 4 cycle engines. and can have the fuel switched from tank to tank try that! The one thing that I can say is that I tried both fuels and a lot of experts have only used pump gas. Can't always bebieve all that is in print about fuel, or can you?
If you don't like what I post then don't read it. The point I was trying to make to Mr Shaw was that he can choose to eat hot dogs or steak, both have the same results the next day, but one seems to be beter than the bare esentials. My opinion is based on using both fuels from 1971 to today, and there is a difference. This has been beat to death and there are people that swear by racing fuels,100 LL, pump and other gas and additives. I listen and have tried .

Dom

[Joe L.]

Re: 110 Leaded Octane fuel

All------


This has been stated many times before and, likely, will be stated for many years to come. It's always been true, is true now, and will be true in the future: with one exception, if one's engine runs without detonation on a certain octane fuel, all things being equal, it will not "run better" on a higher octane fuel. Period. The ONLY purpose for octane rating is to control detonation. There's no other purpose or function.

The exception: if you have a later model car with computer control AND knock sensors, you MAY achieve some increased performance by using a higher octane fuel.

[Lawrence S.]

Re: 110 Leaded Octane fuel

Thanks for the posts guys.
I can say from my personal experience that my car runs better overall with the 110 leaded fuel. Starts better, fast idle seems to work better, hot starts better etc. My original questions were if I should blend it, and will running it straight hurt the engine. Ya'll answered those and I appreciate it as always. I think I will blend a 50/50 mix and see how it runs and also do Duke's recommended detonation test. I also need to confirm the timing.

Lawrence

[Michael W.]

Re: 110 Leaded Octane fuel

Michael,
Sorry but that was actually in favor of the prior posts, and I will use a go-cart if needed.

You're hijacking the topic of octane ratings by discussing the need for lead in the fuel. TEL is required in some aircraft engines for very legitimate and easy to understand reasons. Those reasons do not apply to Corvette engines.

[Joe L.]

Re: 110 Leaded Octane fuel

TEL is required in some aircraft engines for very legitimate and easy to understand reasons.

Mike------


Not for much longer. Leaded aviation fuel is on the way out.

I have been told that there is only one plant in the world that currently manufactures tetraethyl lead and that plant will cease to produce it after it goes away for aviation fuel.

[Domenic T.]

Re: 110 Leaded Octane fuel

MICHAEL,
You profess to ONLY be a fuel engineer, Try the real World!!! Octane ratings are dependent on the time it takes to create the burn....
Talk to the WW2 veterans that put the (NOT KNOWN TO YOU) 145 octane in the military jeeps and burned the exhaust valves out, BECAUSE The fuel was still burning as it went out the exhaust. HIGH OCTANE burns slower (lights slower) than lesser octane... Don't contaminate people that want there HP engines to run GREAT. Do your own thing and don't advise them to ruin there engines. I already lost one engine taking advise on RON/PON. No more, DOES NOT WORK on HP engines. Sorry DUKE and JOE , Come and see what it did!!!
This needs to be put to rest... Don't race me with that CRAP in your tank...

[Joe L.]

Re: 110 Leaded Octane fuel

HIGH OCTANE burns slower (lights slower) than lesser octane...

Dom------


Yes, it does. That's how it controls detonation.

[Duke W.]

Re: 110 Leaded Octane fuel

High octane fuel doesn't "burn slower". I just has a higher autoignition temperature and longer ignition lag time. That's why in some cases it can tolerate more spark advance and maybe make a bit more power compared to pump gas, which may have marginal octane rating for the as-built CR.

Duke