street motor compression

Old 06-06-2007, 12:38 PM
  #21  
woodsman
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Brian I went and tried it again an came up with the same thing. I just took the 900 hp that Scott's 632" has at 10.75.1 and the 945hp that Zane has at 11.3.1 and still come up with 11.22 hp gain. So I am going to stick with what I know the starter botton on the dash.lol. Wesley
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Old 06-06-2007, 12:47 PM
  #22  
sp2816
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It is just like Ed said, the numbers don't match up and it shows that Bowers is using different math than the rest of us. You can't have 11:1 compression with the flat tops (-3cc to -6cc for valve reliefs), 124cc chamber, 11.5cc for head gaskets, not even to count the 1 to 2 cc's for the top ring to top of the block. You are closer to 10:1 compression because the total combustion chamber volume is from 140cc's to 145cc's.

The sweep volume ( V ) is the volume of one cylinder in cc’s, which is 1293.8cc’s. The total combustion chamber volume ( C ) is calculated as the head combustion chamber plus the head gasket volume minus the dome volume of the piston (yours will be add the valve relief volume), plus the volume due to deck height and ring land. So, that is roughly a total combustion chamber volume of 140cc’s or 145cc's. The compression is calculated as ( V + C ) / C

(1294+140) / 140 = 10.25 : 1
or
(1294+145)/ 145 = 9.92: 1

I had another shop tell me that they could get the big compression with the flat tops. You can but the head chamber needs to be smaller.

Good luck on the rest of the combination of the engine and the Willys sounds cool.

Bill M
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Old 06-06-2007, 01:28 PM
  #23  
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i got to tell you . you guys are smart i just called ross tech line asked if i had there flat top piston gave him bore stroke and cc's of head with out knowing piston # he ask me for that first. what would be compression he said 10.25 i ask if you can get 11.3 out of it with that cc he said absolutely not.what should i do know
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Old 06-06-2007, 02:05 PM
  #24  
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just called bowers told him ross pistons said you can't make that compression with a flat top piston. bowers said he will send me the math over and out zano
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Old 06-06-2007, 02:15 PM
  #25  
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You do Nothing but run the motor...whats happened is you got in the end what you wanted..a lower compression streetable BIG block...i am not as techinal as Ed and Bill but i know what Time it is.....the only thing i see that is in question is how the camshaft is going to perform on the street.

IF I WERE IN YOUR SHOES...i would mix 93 octane with some 104 or 110 gas...so your covered on this compression thing no matter if its 10 to1 or 11.3 to 1,..it will run pretty much all the same on this mixture...what your trying to eliminate or avoid by using a little higher octane gas is detonation..the higher the compression the more octane you will need..

DON'T WORRY !!..put the motor in the car and mix your fuel and see how it runs....if it runs good...then GREAT !!!..you have no worries....if the motor doesn't idle good or doesn't perform as to how you think it should..then come back and start picking these guys Brains...or even use one of them to go back thru it ..worse case...

i have fell victim in the past when i was learning the same as you..i got so caught up in listening to so many diffferent opinions and ideas that i ended up changing stuff..long before i ran the motor...so take my advise and benefit from my loss/mistakes in the past....do the obvious which is protect your motor from the NO #1 unkown and concern..COMPRESSION..using mixed fuel or straight 104 or 110 will safe gard you against detonation and destruction..that is compression vs fuel related....the rest of it is all guess work at this point...put the motor in the car and try it out...You might just have you one hell of a combination in that motor.....and it runs great !!....possible right ?????

if you DO NOT do what i said above...then the only option left is send the motor off to another builder and get about 2,000 or 3,000 in hand and hope they are honest....

just an example; If you sent your motor down here to say PAR or Gene Fulton...and they tore it down and put it right back together..your gonna bust up a few thousand after its put back together with new gaskets and re-checking all the tolerances etc... ...

its almost impossible for anyone to say how your motor will or will not run..there is opinions and good ones but not enouigh for you to go back in at this point.....just protect the motor with good fuel..until you know for sure..

and you also have to keep in mind that Bowers probably knows you are on this forum.people cannot stand him for his piss poor business ethics.....he is probably checking these post himself...so i would not be surprised that when you call him up asking these questions He is screwing with you..knowing its coming right back to this post.....YES BOWERS does know his way around this forum..and i would bet BIG $$$ he is reading this and laughing right now..he has caught Hell ON THIS SITE FOR SOMETIME and he isn't about to give away any secrets.....THINK ABOUT IT.....the one thing you have going for you is that you at least have your motor before he learned you came on this forum....if not i would say you might have some issues...but i would have to say you probably got a motor that he done his best work possible.....now just run it and see....if its a 900 hp motor...TRUST ME YOU WILL KNOW AS SOON AS YOU PRESS THE PETAL...THERE IS NO MISTAKING OR GUESSING WHAT A 900HP STREET MOTOR FEELS LIKE....trust me here...

Brian
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Old 06-06-2007, 02:29 PM
  #26  
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your right thanks zano
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Old 06-06-2007, 02:34 PM
  #27  
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Zane I am like Brian #1 be thankful you got your engine #2 be thankful that it is a BBC (but unable to tell what size). If it where me and I was made of money than I would get it checked out so I could have a clear mind but if not. Than I would do just what Brian said and put it in my hotrod and go have some fun. Wesley
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Old 06-06-2007, 03:12 PM
  #28  
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That was well said Brian, because you won't know how it will run until you try it.

Bill M
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Old 06-07-2007, 10:01 AM
  #29  
edvancedengines
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I agree. Try it and see. If it needs something different it will let you know.

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Ed
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Old 06-10-2007, 02:58 PM
  #30  
zano
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i finally got paper work went to edelbrock heads are 118cc clean up was .002 felpro head gasket .041 thickness can you figure compression with flat top pistons now thanks zano
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