Originally Posted by showdown496
I am looking at building a new chevrolet engine for my pulling tractor. Before I get into it and get told "oh no for pulling you need lots of torque" let me explain. With the clutch and driveline setup we have we can leave the line at 6000+ rpm with no problem and probably will never drop below 5000 rpm in a run. Now my idea is to start with a dart big M block and bore it out to 4.6" then run a 3.76" stroke crank. (499 cubes when limited to 502) The only issue would be the heads. We are limited to OEM heads which would mean rectangular port GM cast iron heads. Would I be able to get enough airflow through them to make power at 9-9500rpm? What do you guys think? Would this engine combo run better than an exact match 496 (4.310X4.250) or would i be wasting a lot of money to do it?
I am a truck puller and have to deal with the OEM headed motors for a while. There is a friend of mine who is running a motor like your trying to build except his bore is 4.5 X 3.76 stroke and making 850 + hp on Q16 fuel. The intake runners are pretty good on the 990 or 188 casting heads, but the exhaust really suck because the exhaust almost does a 90 degree turn. I know he paid quite a bit of $$ because the guy ported a Brodix intake to go with the heads.
Does your rules allow you to raise the exhaust ports? Recently I ran into a builder and he told me that they take a 990 head, heat the head, and then weld to the top side of the exaust port. This way they are relocating the exaust port and the air does not have to make such a sharp turn. There is more to it than that, but that is the short version.
