Hemi 572 run on 91 octane.

[K-chai]

i'm about to buy creat hemi 572 engine for my car. The problem is i want to run it on the 91 octane,and the company that gonna build engine for me told me that 10:1 cr would be fine.
I'm gonna use aluminum block and head. Would it be ok with 10:1CR or i should reduce to 9.5:1
thank inadvance

 

[mmissile]

You're gonna have a TON of torque. Not knowing anything about your fuel, I'd err on the side of caution. No details of the build are listed, and how reputable is your builder?

 

[K-chai]

i'm chossing between indy and prestige motorsport any idea on both?. They are use mostly the same setting.

 

[Bigal75]

My 11:1 572 runs on 94. No problems

 

[K-chai]

the engine spec. anyway the best fuel i can find around my place is 91 octane

 

[reeltime]

I have a 572 wedge. 11.5 car with aluminum heads. Will run on 91. A great one to talk to and build your engine is Hughes engines. Dave did a 493 for me years back that had 13.4 car and I raced it and street drove it for 6 years running on pump 93. It all goes by your camshaft and cranking compression. Call Dave at Hughes and talk with him. I am sure you will be supprized !

 

[IQ52]

Mild 11:1 572 on 91 octane. 723 LB-FT and 781 HP.

 

[Cranky]

I can make an 8-1 engine ping itself to death just as good as I can make a 11-1 engine run on pump gas. There's a lot of things that come into play in making any engine run right but it's not hard to make a 10-1 engine run good on pump gas.

 

[Kern Dog]

My understanding is that the more efficient HEMI chambers are less likely to detonate and can tolerate higher compression ratios than a wedge before knocking.

 

[spinach]

If I might ask, what are you looking to spend on that crate 572? Thanks.

 

[HEMI-ITIS]

History says not to deal direct with indy. Depending on your wallet,there are many engine builders that can give you what you want. But,as said it has a lot to do with the cam profile.
My 545 is 8:1:icon_mrgreen:

 

[nuteguy]

I can make an 8-1 engine ping itself to death just as good as I can make a 11-1 engine run on pump gas. There's a lot of things that come into play in making any engine run right but it's not hard to make a 10-1 engine run good on pump gas.

I've read this in a few places. How would the 8:1 ping itself to death? I have a base understanding of why higher octane is necessary for higher compression but I would like to learn more.

 

[HEMI-ITIS]

It's in the cam profile,cam can build cylinder pressure or bleed it off. my8:1 creates it's own creates it's own.

 

[shag766]

I can make an 8-1 engine ping itself to death just as good as I can make a 11-1 engine run on pump gas. There's a lot of things that come into play in making any engine run right but it's not hard to make a 10-1 engine run good on pump gas.

X2 on the 10-1, 823hp here.