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598 bbc 13.1 compression on the street

25K views 19 replies 16 participants last post by  69 Ratt Vette 
#1 ·
Hey guys I just stumbled across a smoking good deal on a 598 big block chevy has dart big m block forged bottom end brodix 2plus cnc ported heads solid roller cam 800-748 lift Jessel rockers 1050 dominator brand new thinking about dropping in my mini tubbed 68 camaro but not sure how the compression will be on the street motor makes 1043 hp at crank only gonna run 32 degrees timing and run it rich will pump gas mix with race gas work?
 
#3 ·
Brian personally I wouldn't try to run a blend like that with 13 to 1.... the cheapest race gas is usually a 110, probably $8-$9/gal in most places around here. If you have E85 where you are that would be the cheapest pump fuel to run with that much compression. You just need a E85 prep'd carb to do that...;)
 
#6 ·
I agree, I used to run a 13.5-1 BBC on the street and what a PITA. I now have a pump gas motor thats alot easier to deal with. Getting race gas is a real hassle, where I live you have to pump it into a can and not a car.
 
#8 ·
That's what puzzles me I was right at 13.1 comp in my 496 38cc pistons and heads milled to 112 and I would mix 112 octane with 93 and drove it everywhere never heard any pinging or clatter just didn't know if this big of a motor would do it I already bought the engine have all the paperwork for it everything is brand new it's a shaffiroff short block dude just added heads and intake
 
#9 ·
So here's a question for the pro's that I'm sure everyone has pondered at one time. What is the Max safe cranking compression and compression ratio that can be run on 93 octane. I've heard of big BBC engines run high compression on pump gas due to cylinder pressure being bled off by big cams. Is there any truth to this or racers tales.
 
#10 ·
I agree, those heads by Brodix's own numbers only low about 320 cfm. With those heads, that many inches will be done at about 5800@ rpm.

If you were happy with your 496 at that compression, you will probably be happy with the big inch engine as well. But that being said, 95 percentent of the world thinks that much compression on the street is unjust asking for problems.
 
#11 ·
Too much compression and what is the cam duration? A piston change for sure and cam change maybe? Is it worth it??
 
#13 ·
if it's available, i'd run E85 in it and see what happens... you can get cheap testers that tell you how much alcohol is in any given batch of fuel- it's just a test tube with marks on it that you fill to a line, add water to another line, and shake. then you look at how it all separates out using another set of lines.. then you can pull the timing back a few degrees or whatever if you get less than the ideal amount of ethanol..
 
#14 ·
These heads are hogged out pretty good the were on a 588 before and the intake is port matched to them I look at the brodix 2plus cnc heads on my 496 and these look totally different in the runners
 
#17 ·
I say if it's a good enough deal then buy it and do it right. Change the pistons and the cam and be done with it.
Why cheap out on an engine of that high of quality and risk wasting it over a grand or $15oo bucks?

How much is it anyway? Does it come with dyno sheets showing that it's making the #'s with THOSE heads?
 
#19 ·
Who has e85 carb dominator?
 
#20 ·
I also seriously doubt that engine makes almost 1050 HP, that being said it should be good for 900 or so.

That engine would love E85. If you can get it in your area, I would run it.
 
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