Alcohol and low compression...

# Thread: Alcohol and low compression...

1. ## Alcohol and low compression...

...I know in a NA application alcohol likes high compression, but how does it work with lower CR's like 10-11:1. A buddy was asking and I don't have a clue.

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3. [QUOTE=David 519;981771]...I know in a NA application alcohol likes high compression, but how does it work with lower CR's like 10-11:1. A buddy was asking and I don't have a clue.

Yes It like's higher comp, but will run on 10-1 just fine,, after you 362 run's 9.60 at 107 with a 10-1 408cid,,not bad !!!! .....Eric

4. So with our panel of resident experts, this is all we can come up with? I guess a few guys must be out of town right now. I am the friend Poffy was refering to about the question, so not being certain, I can only guess. I have seen charts, and have them somewhere, the question is where. I want to say that in the 10:1 to 12:1 range every full point of compression was worth approximately a 5% gain in power. As the compression goes up, the gains start to go down. Anyone???

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6. O.K. I found one of my charts, I was off a bit. One example from the chart would be going from 10:1 to 14:1 you could expect around a 5% gain. To qoute something from the source..." As the compression ratio goes up, there is less power gain from each point increase. For example, raising compression ratio from 8.0:1 to 9.0:1 nets greater power increase than a similar power increase from 11.0:1 to 12.0:1 ( 2% versus 1.3% increase in power)." I imagine these figures are based on gasoline though, and not sure how to adjust for alcohol.

7. Originally Posted by Factory1
O.K. I found one of my charts, I was off a bit. One example from the chart would be going from 10:1 to 14:1 you could expect around a 5% gain. To qoute something from the source..." As the compression ratio goes up, there is less power gain from each point increase. For example, raising compression ratio from 8.0:1 to 9.0:1 nets greater power increase than a similar power increase from 11.0:1 to 12.0:1 ( 2% versus 1.3% increase in power)." I imagine these figures are based on gasoline though, and not sure how to adjust for alcohol.
YEAH , this is true , So If you have a choice in the piston ( new build ) and want max power, this is one case that more is better ,,, If you have a 10-1 motor and want to just change fuel , the alcohol will give you a lil hp and MORE torque , Are you trying to figure at what point of compression you will not gain enough to make it worth the \$ to get custom made part's ?? so enough of the mind reading -What is your real question ??..........E

8. Maybe this will help.
Local guy....cole flat 468 N/A deal on race gas....12 to 1 compression.....runs 108 mph at local lake (4500 ft. static). Wants to go to alky cause tired of hassle buying race gas and has alky hydro anyway.
So we do the carbs and larger fuel pump for alky. After tuning with pyrometer...the thing needs 40 degrees to run it's best of 109 mph....but the guy swears it leaves harder than with gas.
Now the only reason I went along with the swap is that he had alky for the hydro already.....I have one hell of a carb guy here in town I feel is the best of the best.....and I knew we would eventually go in there and change cam on the flat and as much compression as we could get in it for alcohol....and was curious how it would run against gas.

9. Originally Posted by alkyexpress
so enough of the mind reading -What is your real question ??..........E
The real question is if you have a blown injected alcohol motor with compression somewhere between 10.0:1 and 11.0:1 and you pull the blower off, put a tunnel ram on it, and the injector hat back on, is it going to run like a turd because of the realatively mild compression, or will it still make some beans?

10. Originally Posted by Fiat48
Maybe this will help.
Local guy....cole flat 468 N/A deal on race gas....12 to 1 compression.....runs 108 mph at local lake (4500 ft. static). Wants to go to alky cause tired of hassle buying race gas and has alky hydro anyway.
So we do the carbs and larger fuel pump for alky. After tuning with pyrometer...the thing needs 40 degrees to run it's best of 109 mph....but the guy swears it leaves harder than with gas.
Now the only reason I went along with the swap is that he had alky for the hydro already.....I have one hell of a carb guy here in town I feel is the best of the best.....and I knew we would eventually go in there and change cam on the flat and as much compression as we could get in it for alcohol....and was curious how it would run against gas.
OK , not trying to say your carb guy is not good, but I dont think( my opinion ) that carb's work well with alky, alky work's better with injection,( something about the amount of fuel trying to be drawn in verses being sprayed in under pressure ) , now the way gas burn's and alky burn's is the reason for more torque, ( gas go's boom ,and the resulted pressure created pushes the piston down, ALky light's off and continue's to expand the whole travel of the piston (and then some )like all the way out the pipe ))( that is why a alky motor is louder ) , which create's a lot more torque , ( that is why the driver is saying it leaves harder ) , Again just my opinion I think you might of gained a little mph if you would have used injection , does that help any ,, ..................Eric

11. Originally Posted by Factory1
The real question is if you have a blown injected alcohol motor with compression somewhere between 10.0:1 and 11.0:1 and you pull the blower off, put a tunnel ram on it, and the injector hat back on, is it going to run like a turd because of the realatively mild compression, or will it still make some beans?
It will still make some bean's (but if you were used to the blower motor) you cant compare the 2,, ...............E

the hat on a tunnel ram I have heard run's well......

12. I have heard though that the tune up on the injection isn't as forgiving as a carb, when elevations and temps change?

13. Originally Posted by Factory1
I have heard though that the tune up on the injection isn't as forgiving as a carb, when elevations and temps change?
Well not sure about gas and carb's (dont run either ) , But I can say that alky is very forgiving,,( you can run on the rich side and still make power ) but on gas if it get's rich it run's like a turd and foul's plug's ...........Eric

14. I think the combination of alky and injection is very forgiving.............E

15. Hey Todd

there is a guy ( his first name is mike , cant remember his last name right now ) running a tunnel ram injection on alky , say's he love's it , just talked to him at cfw on new yr day, He would be a good guy to talk to ,, ........E

16. Sorry Poffy, wasn't trying to highjack your thread, just stoke the fire on it!!

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