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Discussion Starter #1
What's the limit of the various windsor blocks? I've only heard about breaking 302 blocks, but I know that 351's aren't industructable either.... Thanks.
 

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I'd say upper 400 range for the early blocks and lower 400 range for the later blocks


but it all comes down to whats spinning inside
 

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MAT88GT said:
I'd say upper 400 range for the early blocks and lower 400 range for the later blocks


but it all comes down to whats spinning inside
Has to be more than that 302's can take 450/500 on there blocks.
With good internals.
 

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limits?

as far as the blocks go, i've talked to people getting more than 700 out of production blocks,it does of course help to have good forged cranks, steel rods, etc..but the block is pretty strong...the strongest production blocks are the early 69-70's, but the late model blocks are pretty strong also i hear..hope this helps
 

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Discussion Starter #5
That does help. Although I've heard of a few people dipping into the 9's with a 302 block, I've heard of alot more cars doing it with the 351 block and keeping it in one piece. Pretty much everyone says the 302 limit is about 550hp, but I guess I really don't know how much more hp is required to go mid nines. That sounds about right at 700. How much stronger are the sportsman blocks? I know that there's some circletrack 351 sportsman blocks and then the higher doller stuff. Is it really necessary to go with the more expensive stuff(past the sportsman)?
 

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what about the sportsman 302 block? About 600rwhp was the limit on my stock production 302 roller block.

Split block Jim
 

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450hp and up on a 302 block is in the red, your on barrowed time.
It's a waste of money and time to put a forged crank in a stock 302 block. forged cranks weight too much for the sh** 2 bolt mains they walk and the block will fail sooner.

The 302 sportsman block ford says is good to 600 hp but and 2 bolt mains

stock 351 block is good for at least 600 hp I know more than 1 person in this range with on problems.
 

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I've personally made over 700 on a 351W block, however I cant seem to keep it together. Broke a crank once, damaged a piston once. The block shows no signs weakening.
 

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FMS cat says 700hp @ 7000 on the sportsman, I have heard the stock blocks will do that with a girdle. Thats my plan for the 408 I have in the shop right now. 94 block plus DSS MSS.
 

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Discussion Starter #11
Slart said:
I've personally made over 700 on a 351W block, however I cant seem to keep it together. Broke a crank once, damaged a piston once. The block shows no signs weakening.
Were those rear wheel figures (700) that you are talking about? Did you have a girdle on it?
 

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Just for information's sake, at least one version of the current "sportsman" blocks are just overbored factory blocks.
 

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> Were those rear wheel figures (700) that you are talking about?

No. Actually I dont have any dyno for the first engine, but the 1/4 mile trap speed indicated 730 flywheel hp, as did the air consumption datalogs.


> Did you have a girdle on it?

I've had two supercharged 351's so far. The first (the one who's power I'm estimating based on trap speed) did not have a girdle.

It was essentially a stock bottom block/crank/rods with TRW pistons. The crank was champhered, the rods were polished with ARP bolts, and it had a good balancer (ATI) and good flywheel (ram aluminum), but none of those things have much to do with block strength. Really, nothing special about it. I put about 4000 miles on it before breaking a piston due to tuning problems. Block was fine.


When I rebuilt it I put on a 1/2" steel girdle, main studs, ane better rods/pistons (which have nothing to do with block strength as far as I can see). That engine moved 5150 lb/hr of air, which is about 740 worth, however I had some more tuning problems that caused me to fire it at 46-52 BTDC when I thought it was 20-26 BTDC.

The actual power output was 496.6rwhp. It didn't detonate because I put a lot of work into avoiding excessive cylinder pressure. It eventually broke the crank.

Here's the interesting part: If it made airflow for 740hp (approx 680-690 rwhp) but it actually only made 497rwhp, then what was going on is firing it that early was building cylinder pressure before top dead center. My best guess is it was making 95hp BTDC then 645hp ATDC, resulting in the 497 net rwhp. You can conclude that the first 190hp was pushing the crank straight down onto the mains.

This had to be much, much worse on the block than if it had fired at the right time and made 740hp. Anyhow, the impression I took away from this is that 351W blocks are a heck of a lot stronger than we're giving them credit for. I wouldn't be surprised if one with a girdle could take 900hp.

- Steve
 

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Oh.. a few more thoughts. This was a '74 block.

Also, when you assemble an engine one of the clearance you're supposed to test is the thrust bearing clearance. The thrust bearing takes a beating on power adder cars (actually I've never pulled a power adder automatic trans engine apart so I can't say if they see the same abuse as a manual trans, but I'd guess not).

Anyhow the way I do this is take a screwdriver and pry the crank one way then measure the gap on the other side of the bearing. I'll tell ya one thing, when you do this you can see noticable flex in the main cap even with them torqued on. Put a girdle on there and the flex goes away.

I dont know if this is an issue because I dont know if the main caps get loaded in that direction, but it's food for thought.

- Steve
 
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