Ideal compression ratio for Animal

K

Killswitch

New member
I have searched the forums and wasn't able to find any info on ratios for alcohol animal. what is the ideal CR for a stock Gen5 block and head Animal? Stock I mean without O-ringing the block. Also assuming a WF or ARC rod and outlaw track rules. is 12:1 to 13:1 reasonable?
 
Killswitch said:
I have searched the forums and wasn't able to find any info on ratios for alcohol animal. what is the ideal CR for a stock Gen5 block and head Animal? Stock I mean without O-ringing the block. Also assuming a WF or ARC rod and outlaw track rules. is 12:1 to 13:1 reasonable?
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with alky, and there's some disagreement on this, there's no detonation, or as some say 125 octane, which means there could be some detonation, so in either case, you can run more compression than you can with gasoline, and as I'm fond of saying, "compression is the Holy Grail".

I think the limiting factor is getting the head sealed. Lots a compression could mean blown head gaskets. And with lots of compression, you might want to run a very cold plug.

Comments compliments criticisms and questions always welcome.
If the data does not support the theory, get a new theory.(Al Nunley)
 
alvin l nunley said:
with alky, and there's some disagreement on this, there's no detonation, or as some say 125 octane, which means there could be some detonation, so in either case, you can run more compression than you can with gasoline, and as I'm fond of saying, "compression is the Holy Grail".

I think the limiting factor is getting the head sealed. Lots a compression could mean blown head gaskets. And with lots of compression, you might want to run a very cold plug.

Comments compliments criticisms and questions always welcome.
If the data does not support the theory, get a new theory.(Al Nunley)
Click to expand...

That's really my question. What can these these blocks, heads and currently available head gaskets handle safely with out O-ringing block? I believe more compression = more possible hp with any given cam and carb combo.

I have never seen any CR listings and this may be due to WKA rules limiting piston popup and head milling for stock classes. But this is outlaw rules so.....

Back in the day we used to build 14.5:1 CR small block chevy alky motors running Hilborn FI and some guys went even higher.

Thanks guys for your reply.

Paul
 
alvin l nunley said:
with alky, and there's some disagreement on this, there's no detonation, or as some say 125 octane, which means there could be some detonation, so in either case, you can run more compression than you can with gasoline, and as I'm fond of saying, "compression is the Holy Grail".


Alcohol motors are less forgiving running lean and will detonate, but are more forgiving in the fatter range. Cooked a few pistons not getting the initial setup right.
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I have never seen a flat head or an Animal damage a piston because of a mixture issue. (lean)
If it's that lean it comes off the track because it doesn't have any power and the problem gets fixed. (usually)
 
Jimbo said:
I have never seen a flat head or an Animal damage a piston because of a mixture issue. (lean)
If it's that lean it comes off the track because it doesn't have any power and the problem gets fixed. (usually)
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Thanks Jimbo, yes i agree. Back then the driver didn't know enough to pull off the track in time not cause damage.

Getting back to CR, what is a common CR for a modified alcohol Animal?
 
I run open Animals at 12 to 1. Maybe a little higher. They run great but the head gasket is iffy above that. I have worked hard to solve this but the head is a bit unstable when heated up and does not remain flat. I run a copper gasket with silicon. Good luck!
 
Wes Snow said:
I run open Animals at 12 to 1. Maybe a little higher. They run great but the head gasket is iffy above that. I have worked hard to solve this but the head is a bit unstable when heated up and does not remain flat. I run a copper gasket with silicon. Good luck!
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Hey thanks Wes, That is what I was looking for. So 12:1 is basically good and still reliable?

Is it feasible to O-ring the block and and use studs to go above the 12:1? Or is there not enough HP gain to go the trouble?
 
I think there is more hp with more compression. The head will not remain flat and if you could solve that studs would be a plus. At 12 to 1 you will be happy and finish the race. A billet head would solve this and Jimbo at Faster Motors will have some soon. Remember that you will want a large cam to match the increased compression ratio or head gaskets will be a real issue.
 
I see so many people on here recommend the 275 and I have no idea why. I don't know what RPM you are looking for or what kind of track. The 308 would be minimum. If you increase lift with rockers it will be fine. The quality of the porting and size of valves also factor into it. Lift is your friend! It will increase power at all usable RPM.
 
Killswitch said:
Alcohol motors are less forgiving running lean and will detonate, but are more forgiving in the fatter range. Cooked a few pistons not getting the initial setup right.
Click to expand...
I raced McCullough's for many years and never found that to be true. If you get them lean yes they will detonate, but it was never a problem for me. You could hear detonation long before it sticks the motor. Did I stick a few, oh yes, maybe more than my share, but not after I learned about detonation, what it sounds like and what causes it and what it feels like. All this before I learned the advantages of the EGT. I've taught newbies how to use the EGT and had them winning races in their first year.

From the desk of Al Nunley
Comments compliments criticisms and questions always welcome.
If the data does not support the theory, get a new theory.(Al Nunley)
 
Wes Snow said:
You were mixing oil with your alky. Big difference.
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"big difference"

can you explain what you're trying to tell me?

From the desk of Al Nunley
Comments compliments criticisms and questions always welcome.
If the data does not support the theory, get a new theory.(Al Nunley)
 
alvin l nunley said:
"big difference"

can you explain what you're trying to tell me?

From the desk of Al Nunley
Comments compliments criticisms and questions always welcome.
If the data does not support the theory, get a new theory.(Al Nunley)
Click to expand...

Oil will cause detonation. If you ever run an extremely high compression 4 stroke you learn to keep the oil out of the combustion chamber at all cost!
 
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