What seems to be the limit on a 2bolt prod-block mains?
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this ought to be interesting......
My personal findings are as follows......
I dont think studs add any more Hp handling capacity. If you have good clean used stock bolts they will be fine. The threads in the block are the weak link IMO.
On a perfect tune I have seen them hold 800 HP no problem.
On a bad tune I have seen MAJOR cap walk at 700 HP.
Me and Lem had a talk about this about 1-2 years ago maybe he will chime in.
My personal findings are as follows......
I dont think studs add any more Hp handling capacity. If you have good clean used stock bolts they will be fine. The threads in the block are the weak link IMO.
On a perfect tune I have seen them hold 800 HP no problem.
On a bad tune I have seen MAJOR cap walk at 700 HP.
Me and Lem had a talk about this about 1-2 years ago maybe he will chime in.
how about thread inserts?
Have you actually seen the threads pull from the block? What about using thread inserts? Theoretically, a good insert could make that junction a whole lot stronger and it wouldn't be expensive to have that done.
When I did my block research, the magic number was 800ish hp before the 2-bolt mains were very problematic.
For the cost of a girdle, I think I'd run one on anything that came anywhere near 800ish...
Byron
Have you actually seen the threads pull from the block? What about using thread inserts? Theoretically, a good insert could make that junction a whole lot stronger and it wouldn't be expensive to have that done.
When I did my block research, the magic number was 800ish hp before the 2-bolt mains were very problematic.
For the cost of a girdle, I think I'd run one on anything that came anywhere near 800ish...
Byron
Stock bolts? You've got to be kidding!
I have seen stretched main cap bolts, and it was ugly.
For the cheap price of ARP main bolts, or even studs for that matter, it is welcome insurance.
I would NEVER use those extra small wimpy factory bolts in any performance application.
Just my 2 cents from what I have seen...
Greg
I have seen stretched main cap bolts, and it was ugly.
For the cheap price of ARP main bolts, or even studs for that matter, it is welcome insurance.
I would NEVER use those extra small wimpy factory bolts in any performance application.
Just my 2 cents from what I have seen...
Greg
Jon said:
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(steel main caps): One thing I have never understood is why they offer steel main caps!? To me sticking with two simular metal would be the way to go. Rather than haveing two disimular metals expanding at different rates.
Has anyone ever seen a main cap pull apart?
I like the new Gm cobalt 4 cylinder engine. The way they made the mains into the block rather than bolting the mains too the block. It's like you pull the block apart to ge the crank out. (I know it is simular to a airplane, vw and subaru engine, yet its is an inline!)
Has anyone ever seen a main cap pull apart?
I like the new Gm cobalt 4 cylinder engine. The way they made the mains into the block rather than bolting the mains too the block. It's like you pull the block apart to ge the crank out. (I know it is simular to a airplane, vw and subaru engine, yet its is an inline!)
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In the BB Mopar world, aluminum main caps seem to be the trend. Apparently they are better at absorbing some of the shock rather than transferring it into cap walk or bounce.
I'm kind of surprised no one is running them here. :?:
I'm kind of surprised no one is running them here. :?:
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2 bolt
I built a 557 a few years ago for Flow Technologies to demonstrate the horsepower capabilities of their cylinder head on a very basic short block. It was a 2 bolt D1VE block with studs and a halo, Scat 9000 series 4.500 stroke crank, Eagle 6.700 rods, JE pistons, very basic stuff. That engine made 902 horsepower at 7000rpm on my dyno running on racing gasoline with one Dominator carburetor.
Later the engine was run in a dragster and sometimes they would run a 100 horsepower shot of nitrous for part of the run. It ran a best of 7.38 1/4 mile with a 1.06 60ft time and it was very very consistent. Anyway, the crankshaft was the weak link in the engine and it broke in the back rod throw after about 75 passes in the dragster, 15 dyno pulls and about 5 test passes in Wes' car.
When the engine was taken apart it was a mess of course but the main bearings and caps looked fine, as did the rod bearings, cylinder walls etc. The block wasn't any worse for wear and if the crank had not failed it would have lived just fine.
I do feel that this was pushing it, by a long shot however I do feel that if you're making around 800 horsepower the two bolt block can live just fine without problems, same goes for the Scat cast cranks, I think they would live a very long time at that power level, given the proper tuneup of course...
I built a 557 a few years ago for Flow Technologies to demonstrate the horsepower capabilities of their cylinder head on a very basic short block. It was a 2 bolt D1VE block with studs and a halo, Scat 9000 series 4.500 stroke crank, Eagle 6.700 rods, JE pistons, very basic stuff. That engine made 902 horsepower at 7000rpm on my dyno running on racing gasoline with one Dominator carburetor.
Later the engine was run in a dragster and sometimes they would run a 100 horsepower shot of nitrous for part of the run. It ran a best of 7.38 1/4 mile with a 1.06 60ft time and it was very very consistent. Anyway, the crankshaft was the weak link in the engine and it broke in the back rod throw after about 75 passes in the dragster, 15 dyno pulls and about 5 test passes in Wes' car.
When the engine was taken apart it was a mess of course but the main bearings and caps looked fine, as did the rod bearings, cylinder walls etc. The block wasn't any worse for wear and if the crank had not failed it would have lived just fine.
I do feel that this was pushing it, by a long shot however I do feel that if you're making around 800 horsepower the two bolt block can live just fine without problems, same goes for the Scat cast cranks, I think they would live a very long time at that power level, given the proper tuneup of course...
I have not seen the threads pull from the block . I have seen the 2 bolt deals crack from a bolt hole to the cam tunnel . The 2 bolt stuff is better than they have a right to be ...but ...they are not a 4 bolt deal ...and yes a poor tune up can make all the diff in the world .
Re: Stock bolts? You've got to be kidding!
Was the bolt stretch from excessive HP or Detonation??? Thats the question. Yes they are cheap insurance or peace of mind but they put more stress on the threads and it is more likely to split the webbing on each side of the bolt hole. I Personally had this happen on one of my old motors.
Greg_Pettit said:
Was the bolt stretch from excessive HP or Detonation??? Thats the question. Yes they are cheap insurance or peace of mind but they put more stress on the threads and it is more likely to split the webbing on each side of the bolt hole. I Personally had this happen on one of my old motors.
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I've heard that too about how the weak link in the two bolt setup is that it will crack the main webbing from the bolt holes down to the camshaft tunnel and then break out a pie shaped piece, not cool. I would say that having only two bolts into the main web just concentrates too much stress way out in the middle of the webbing. A wider 4 bolt cap fixes that problem before it can start.
It is true however that the 2 bolt setup on one of these engines can be better than it's supposed to be....
It is true however that the 2 bolt setup on one of these engines can be better than it's supposed to be....
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2,857 Posts
pie shaped piece.
I saw what Dave was talking about a couple of weeks ago. My neighbor's distributor was acting up and allowed the timing to fluctuate wildly. This is on a 466 that runs 9's in a Fox Stang. He noticed a problem with his oil pressure and tore it apart. When I got there, he was holding a slice of cast iron pie. LOL. Luckily, he was able to transfer the entire rotating assembly into one of his other blocks.
I saw what Dave was talking about a couple of weeks ago. My neighbor's distributor was acting up and allowed the timing to fluctuate wildly. This is on a 466 that runs 9's in a Fox Stang. He noticed a problem with his oil pressure and tore it apart. When I got there, he was holding a slice of cast iron pie. LOL. Luckily, he was able to transfer the entire rotating assembly into one of his other blocks.
The failed bolts I had were stretched due to overtorquing
I made the mistake of using moly lube on the threads of the factory bolts during assembly.
Every single bolt stretched, but only the very last one one stretched noticeably during final torquing. After pulling the bolt out, I saw it was REALLY stretched out.
Pulled the rest of them and they were all stretched as well.
So, it was my mistake that caused them to stretch, but the block was just fine after all that. I used ARP bolts in it and had no problems afterwards.
The ARP bolts use moly and a higher torque rating than the factory bolts, and they do not stretch. They must be stronger!
Point is, the threads in the block are probably NOT the weakest link in the fastener system, at least with stock bolts.
Greg
I made the mistake of using moly lube on the threads of the factory bolts during assembly.
Every single bolt stretched, but only the very last one one stretched noticeably during final torquing. After pulling the bolt out, I saw it was REALLY stretched out.
Pulled the rest of them and they were all stretched as well.
So, it was my mistake that caused them to stretch, but the block was just fine after all that. I used ARP bolts in it and had no problems afterwards.
The ARP bolts use moly and a higher torque rating than the factory bolts, and they do not stretch. They must be stronger!
Point is, the threads in the block are probably NOT the weakest link in the fastener system, at least with stock bolts.
Greg
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Out of tune: as little as 600HP could concevably kill a block, perhaps less.
Proper tune, prep & setup: I know a guy that running a production block, .080" overbore, running bone dry/unfilled cooling jackets, running on nitromethane and going over 200 mph, no problems. (You'd better select the block carefully and really know what you're doing.)
Paul
Proper tune, prep & setup: I know a guy that running a production block, .080" overbore, running bone dry/unfilled cooling jackets, running on nitromethane and going over 200 mph, no problems. (You'd better select the block carefully and really know what you're doing.)
Paul
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Hey paul, what would be the problem running a 20% mix of nitro in a race engine? I play with nitro in my Rc cars engines. What would be the down fall of running a 545 with a flying toilet with a 20-30% mix?
So to ask an off topic question.
So to ask an off topic question.
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903 Posts
Caps
It's best to install aftermarket 4 bolt steel caps. Some of the chattering that is defined as cap walk is actually the cap distorting. I have recycled some A-460 nodular caps and they are quite strong. The Boss 9 caps are very hard and difficult to align bore. The hardness of the cap causes the cutter to deflect. SAE 1010, 1020, or 1075 hot rolled are good choices. Some sound reasons to install 4 bolt caps are:
The cap material is stronger.
They will not distort, even if your tune-up is off slightly.
The outer bolts will spread the load more evenly.
They offer peace of mind not having to worry if the stock cap will fail. :wink:
It's best to install aftermarket 4 bolt steel caps. Some of the chattering that is defined as cap walk is actually the cap distorting. I have recycled some A-460 nodular caps and they are quite strong. The Boss 9 caps are very hard and difficult to align bore. The hardness of the cap causes the cutter to deflect. SAE 1010, 1020, or 1075 hot rolled are good choices. Some sound reasons to install 4 bolt caps are:
The cap material is stronger.
They will not distort, even if your tune-up is off slightly.
The outer bolts will spread the load more evenly.
They offer peace of mind not having to worry if the stock cap will fail. :wink:
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