Instead of sidetracking the other thread I wan't to have a separate discussion about this.
Since methanol burns cooler and slower than gas and is resistant to detonation why the theory of less timing than gas? It would seem that you could run more timing with methanol and light it off sooner without the detonation.

Your thinking is correct. It boils down to, what are your goals for your engine program.

I want my car to start every time. I ran 34 on alky and also run that on gas. We’re bracket racing.

I have spent a lot of time and money on the dyno and it liked 28* timing best on my motor 454 SBC with AFR 235 heads and Enderle injection on alcohol. My bearings always look good.

I know from personal experience with 23-degree style SBC engines, less timing is faster with Methanol. I have not experimented with the lowest/fastest setting but for sure 32 degrees is faster than 36, 38, 40 degrees.

So there ya go EMAN. Your thinking is correct, but I always say listen to your motor and give it want it wants. People tune there motors for different reason. And if your paying the bills it's exactly what you should do. Also lots of old wives tales out there that have a life of there own. The best thing is to learn how to read plugs, so you can tune the motor and read what it's telling you. The Dyno will get you in the ball park, but from there the motor typically on the track will want more timing and less fuel....Have fun racing.

Here’s what I did this year changing from Enderle to Rons injectors with mfi in my new engine. I installed an EGT sensor in one of the exhaust tubes to make sure the starting point wasn’t too lean. After I had this temp reading that was acceptable, I removed the EGT and have been moving timing and pill size to try and achieve the most consistent tune up.

your statement of "methanol burns cooler and slower" is correct when you are using the same A/F ratio. Methanol has fewer BTU's per lb. But when you are using stoichiometric air-fuel ratios, Methanol will have more BTU's per lb of air and burn faster.

I ran about a dozen engines on my dyno both gas and methanol. All of them made more power on methanol and required less timing to do it.
(the largest was a 605)



Joe

This message has been edited. Last edited by: sr4440,

EMan, I don't know the scientific answer to your question, (other than to say what Joe & Ron said seems to make sense).
FWIW, my results match what Verne (Cashflow)said. I ran 36* when I was on Gas, based on timeslip MPH performance and plug readings.
I switched to alky in 2014, found that new plugs were difficult for me to read. But MPH seemed to favor 34*. A year later, on an open test day, I performed an 'A-B-C-D-A' test on my setup. (13:1 BBC 468, 1050 Dominator slightly fat). Began at 34*, tried 36*, 38*, 32*, and back to 34* with less than a third of a MPH difference, (0.31 MPH spread), and less than .02 ET differential. DA was really steady that day, my log shows spread of 151 feet.
So I figured why push the timing for no net gain? It seemed to start easiest at 34*, that setting also had the best 60' by a hair, and best MPH, so that is where I have kept it.
Oh, one note that may be important - Steel heads. I know on gas you can run a couple more degrees of timing with aluminum heads, don't know if that applies on alky.

Just moving timing is only part of the combination. Fuel AFR has to be part of it. Reading the plugs is a big part of getting what the engine wants. For most bracket racers they are more interested in consistency and that is understandable. For me, I can't stand leaving power laying on the table. My own curse.

quote:

Originally posted by Ron C.:
Just moving timing is only part of the combination. Fuel AFR has to be part of it. Reading the plugs is a big part of getting what the engine wants. For most bracket racers they are more interested in consistency and that is understandable. For me, I can't stand leaving power laying on the table. My own curse.

Then you wouldn't approve of me using a restrictor plate to slow my car down from 9.4's to 10.0's....

I tried gas at 33* then at 36* with the thinking gas likes more timing, and it slowed up almost a whole 02. On alky I went from 33* to 35* and it picked up almost 01 and I gained a solid 50 conv stall and about .5 mph, so it must of made more power. Those were this year with the 632.

When I had these heads on the 582 it liked 36* over 34*, about 01 faster. So I think there's some truth to this.

However when we ran gas way back, didn't have a lot of compression 454 and a 555. the 454 liked 44* and the 555 was 38 or 40*. So cubic inch and compression may have something to do with it as well, like some have said, its the whole combination.

This is one of those deals I have tried for years to put my head around. My 23 degree small block combo has had several cams, pistons and induction systems on it, and has always run the best at 36* on alky. Never been tainted with gas so I can't speak to that.
Why some like so little timing with similar combustion chambers always baffles me.

36 for me on alky on a na 598

Another factor that may play into the timing requirement, is the size and shape of the combustion chambers and piston domes. Don't know if they affect flame front travel differently for different fuels...

quote:

Originally posted by FootbrakeJim:
Another factor that may play into the timing requirement, is the size and shape of the combustion chambers and piston domes. Don't know if they affect flame front travel differently for different fuels...

This is what I ran into on my engine. 14:1 with domes it wants more timing. Run it at 36 but is best at 38 but I have hard start issues right now. Flat tops with good combustion chambers want less.

quote:

Originally posted by moparacer:

This is what I ran into on my engine. 14:1 with domes it wants more timing. Run it at 36 but is best at 38 but I have hard start issues right now.

Consider using Grid programmable ignition to fix this problem.

quote:

Originally posted by Mike Beck:

Then you wouldn't approve of me using a restrictor plate to slow my car down from 9.4's to 10.0's....

........LOL...."Your killing me Small".......just pull a spark plug wire off and save the work installing anything .

38 on gas 38 on alky

quote:

Another factor that may play into the timing requirement, is the size and shape of the combustion chambers and piston domes

I think this is why the last several 408 SBC I built perform well at 32 degrees. They have a 56 CC chamber and small rounded dome giving around 13:1 compression.

One combination won a 7 round race without changing the dial. [3000 pound with driver 1990 Firebird with 6.13 ET]