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Thread: 502 block max horsepower?

  1. #1
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    502 block max horsepower?

    I have a 540 built by shafiroff that came in a car I bought. Just freshened it with JE pistons, bearings etc. Has eagle 4340 crank, h beam rods w/ L19 bolts. I am running a fogger on it and was wondering if anyone had any suggestions on max horsepower this block will handle. It's about 15:1 compression and I have already sprayed 150 shot with no problems. Do I dare try a little more squeeze? If so any tips on nos/ fuel jetting and fuel press.

  2. #2
    Senior Member MASTER BUILDER
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    Re: 502 block max horsepower?

    Quote Originally Posted by 71
    I have a 540 built by shafiroff that came in a car I bought. Just freshened it with JE pistons, bearings etc. Has eagle 4340 crank, h beam rods w/ L19 bolts. I am running a fogger on it and was wondering if anyone had any suggestions on max horsepower this block will handle. It's about 15:1 compression and I have already sprayed 150 shot with no problems. Do I dare try a little more squeeze? If so any tips on nos/ fuel jetting and fuel press.
    shaffiroff builds some pretty stout engines....yours is prob well in the 600-700 hp range without the nos....I have a plate system with 300 hp pills in....WOOO HOOO....your fogger is it 1 stage or how many stages?

  3. #3
    Senior Member RACING JUNKIE TheRabbit's Avatar
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    Don't push a factory 502 block much past 850hp. I ran a 548 with 868hp no problems, but was always a little nervous to go anymore.

  4. #4
    Senior Member RACING JUNKIE
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    I don't know about the cylinder wall thickness of the 502 blocks, but I ran a 427 tall deck truck block at .100 over bore, to 1200 dyno'd crank HP.

    It gave up the ghost when I banged the blower from too much timing and not enough fuel. Put an "H" crack in the side of #5 cylinder.
    -WJ Birmingham

    OneBadGMC.com

  5. #5
    Senior Member MASTER BUILDER
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    Is it bowtie block?

  6. #6
    Senior Member EXPERT BUILDER
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    15:1 COMPRESSION AND ONLY GIVING HIM 600-700 HP?!?!?!???

  7. #7
    Senior Member RACING JUNKIE TheRabbit's Avatar
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    Quote Originally Posted by russ67chevelle
    15:1 COMPRESSION AND ONLY GIVING HIM 600-700 HP?!?!?!???
    It all depends on the heads, but 15.1 usually has really good heads. My guess if he's flowing around 390 - 400cfm is 775-800hp maybe even a little more. Sounds like his build up is close to my old motor. 502 blocks are known for being weak. Not that their bad just not as strong as other GM blocks. Like I was, sounds like he's a little worried about pushing it to far and loosing more than a block.

  8. #8
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    Yeah, it should be around 850 hp or so. It ran 8.50 in my 2000lb altered at 5800 ft in denver. 8.11@163 with a 150 shot. At lower altitude you can figure .6 sec faster. Wish I would have went back to Kansas and raced it before I got rid of the car. It went 8.000 one time at great bend before I had the heads ported. Ported the heads before I ever ran at denver but it seems to have picked up .5 sec. or so. My buddy from there runs 7.70's in kansas and 8.30's when he comes to denver. May never get in the 7's now with a heavy old chevelle! Anyways, it seems I may not want to hit it with a 300 shot. I'd rather not blow it up and crash the car. Heads flowed right under 400 cfm after the port job, 310 cfm before! Just some junk old 305cc brodix -2's. Block is not a bowtie. Wonder why Shafiroff ever put these together without a dart block? Has anyone seen any actual problems with these or is everyone just worried like I am? Sounds like the cylinder walls are a bit thin is the problem.

  9. #9
    Senior Member RACING JUNKIE TheRabbit's Avatar
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    Mine block was fine, but it did run warmer than I liked.

  10. #10
    Junior Member SHOW GUEST
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    My motor is a 509ci. The motor made 800hp and i run a 300 shot on it. Ive had no problems with it at all.
    RUNNING TOUGH ON CHEAP STUFF.


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