Alcohol or gas

RCJ

Member
I’m building a motor for the local economy modified class. 212 ,12.8 c/r .superman 275 from Dover cam, ported Hemi head.I’m going to order a carb from Dover and alcohol is legal. How much more hp will alcohol make ,will the pulse pump flow enough,how will the motor temp change?
 

95 shaw

Premium User
10% more hp is the general rule of thumb.
Methanol burns slower, so more ignition timing and more compression can be run. Less power loss is experienced if ran too rich, so lower cyl head temps are experienced.
If too lean, things can go south quickly.
 

Pete_Muller

Moderator
Methanol without question. Just a way better fuel all around.

Be aware that you will need to "flush" the engine (with gasoline) after a race day, as methanol will attack aluminum after a period of time. As long as you do that though (and never let the engine "sit" for a long period of time with it being flushed with gas), you will never have an issue.

PM
 

RCJ

Member
While not a true a to b test.we had a gas motor with a carb we reamed to .640 ,that made 11.4hp. Put a .640 Dover outlaw carb for alcohol.14.4hp.. Our carb building skills need to improve so it is hard to say how much was better cab and how much was fuel
 

alvin l nunley

Premium User
While not a true a to b test.we had a gas motor with a carb we reamed to .640 ,that made 11.4hp. Put a .640 Dover outlaw carb for alcohol.14.4hp.. Our carb building skills need to improve so it is hard to say how much was better cab and how much was fuel
Maybe a little misleading, but the honesty about the set- it's up was commendable. "Set-up", properly, and monitored with an EGT (exhaust gas temperature gauge), those numbers might have become a little closer to each other. Just speculation on my part, and it might be true, but I'm wondering.
A 26% increase in horsepower may be a little overly optimistic. Again, just speculating. All the other estimates that I have seen anticipated only, roughly, a 10% increase.

I've never conducted this test on my dyno.
 

RCJ

Member
I'm going to hook the egt up on the next motor. I always been under the impression that the sensor had to be in a plate between the head and the pipe to get accurate and consistent data.
 

Chipg56

Member
No, If I remember correctly Mychron recommends 6" from the port. I install mine about 2 inches from the port to minimize the chance of damage. Like anything in data acquisition consistency is the key.
 

alvin l nunley

Premium User
I'm going to hook the egt up on the next motor. I always been under the impression that the sensor had to be in a plate between the head and the pipe to get accurate and consistent data.
I
I always placed my probe 3 1/2 inches from the piston face, plus or minus is okay. I used a digitron with the tip of the probe in the middle of the flow (center of the pipe).

I don't think it's all that important, within reason, but it does ensure consistency of the readings from one installation to another.
 
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