Reply With Quotewhat comp r u building it for on idle, what comp piston
Men,
Moving along on my rebuild and wanted to get everyone's thoughts on compression (well, at least people who know what they're talking about...) Running a Gen V 454 with a roots-style B&M 174 and only 5-6 lbs of boost. 91 or 92 octane pump gas. Nothing radical, pleasure boating and looking for reliability. What should I be shooting for with respect to compression? Thanks!
SM
what comp r u building it for on idle, what comp piston
Forged, flat-top Speed Pro's, right around 8.7 to 1 compression. Does this sound reasonable?
really all depends on what u want the comp to be, i runa bbc on alky with 8-71 stg 3 and comp around 8.5 on idle but higher the comp the least u can spind the blower the loser the comp the more u can spin it and make more power if not worried on changing pulleys for boost then i would stay as highas 8.5 or as low as 7.5 for reliable perf my .02
later
promod
I always stay under 8:1 on pump gas.
Even with only 5-6 lbs of boost, you'd recommend staying under 8:1? What's the downside of where I'm at now?
And will I take a big hit in HP? Just curious...
I would say 8 to 8.7 on 91-92 with 6 lbs max is OK, 8 to 8.5 would be better but as long as you don't go above 6 lbs you should be OK with what you have said and timing should be aroud 30-32 total around 3000. 8.7 is on the high side of what I would feel comforatable with on pump gas.
Go look here http://www.kuhlsuperchargers.com/tech%20p05.htm
Originally posted by Shallow Minded
Even with only 5-6 lbs of boost, you'd recommend staying under 8:1? What's the downside of where I'm at now?
And will I take a big hit in HP? Just curious...
My reply was a bit brief.
There is nothing wrong with what you have. The downside would be when you want to boost it some more later on.
It will be just fine for now if that is what you were asking. If you are buying new pistons I would still stay under 8:1 That is just my personal opinion.
Since it is a small blower and not intercooled, I would keep compression low. The day when you get some poor gas will be the day when you are happy that you went with less compression.
Why doesnt anyone ask where this guy lives? I could have two different answers depending on his where abouts.
So shallow where are you running this motor elavation wise?
Sunny Omaha, Nebraska. Elevation approx. 1000 feet.
So, it sounds like I've got a little more "margin for error" if I back off the compression a little...
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