Main cap girdles re-discussed

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There seems to be a popular opinion that none of the comercially available main cap girdles for a SBM are proven to be effective in preventing catastrophic engine failure.

My first question is, at what point are these engine blocks/caps *actually* failing?

I'm interested in anyone's first hand observations and confirmed anecdotal experiences.

(Ie Not that your cousin's friend's roommate's boyfriend says they fail at *** hp.

The internet is notorious for false or misleading info to be repeated endlessly despite not being factual)

Secondly are these engines failing because of lack of crankshaft centreline control, or is something else in the block moving/flexing/breaking/vibrating/harmonics *before* the crank/caps are spat out, and the damaged caps/saddles are caused by something else being insufficient?

I truly can't see how a main cap girdle wouldn't immediately add both structural integrity and vibrational dampening to the main caps and crank saddles.

If you were to get a junk block and set up a dial indicator on a tightened main cap, and smack it with a hammer in either a left-right axis or front-back axis, it would certainly absorb a certain amount of kinetic energy and move the dial indicator.

I'd almost guarantee that doing the same with a main cap girdle installed, that measurable movement on the dial indicator would be reduced significantly, since the energy is now absorbed by both the area of the girdle and the other 4 main caps.

But let's say for curiosity's sake that the commercially available girdles currently offer no advantage at all.

In this case, what improvements would need to be made to create a highly functional main cap/girdle package that would allow a SBM to live happily at 1000hp or beyond?
 
frosty_the_punk said:
There seems to be a popular opinion that none of the comercially available main cap girdles for a SBM are proven to be effective in preventing catastrophic engine failure.

My first question is, at what point are these engine blocks/caps *actually* failing?

I'm interested in anyone's first hand observations and confirmed anecdotal experiences.

(Ie Not that your cousin's friend's roommate's boyfriend says they fail at *** hp.

The internet is notorious for false or misleading info to be repeated endlessly despite not being factual)

Secondly are these engines failing because of lack of crankshaft centreline control, or is something else in the block moving/flexing/breaking/vibrating/harmonics *before* the crank/caps are spat out, and the damaged caps/saddles are caused by something else being insufficient?

I truly can't see how a main cap girdle wouldn't immediately add both structural integrity and vibrational dampening to the main caps and crank saddles.

If you were to get a junk block and set up a dial indicator on a tightened main cap, and smack it with a hammer in either a left-right axis or front-back axis, it would certainly absorb a certain amount of kinetic energy and move the dial indicator.

I'd almost guarantee that doing the same with a main cap girdle installed, that measurable movement on the dial indicator would be reduced significantly, since the energy is now absorbed by both the area of the girdle and the other 4 main caps.

But let's say for curiosity's sake that the commercially available girdles currently offer no advantage at all.

In this case, what improvements would need to be made to create a highly functional main cap/girdle package that would allow a SBM to live happily at 1000hp or beyond?
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I'm of the mind to agree with you generally, about the main girdles. From what I've read so far, most of the complaints seem to come from the fact the girdle isn't really tied to the caps at all, just sandwiched on top of them by the studs. I'd be inclined to believe that if the girdle was keyed to each of the caps, or the caps and girdle were one piece like a 4g63 or other import motors that I've seen, that would improve rigidity greatly.
 
DNasty777 said:
I'm of the mind to agree with you generally, about the main girdles. From what I've read so far, most of the complaints seem to come from the fact the girdle isn't really tied to the caps at all, just sandwiched on top of them by the studs. I'd be inclined to believe that if the girdle was keyed to each of the caps, or the caps and girdle were one piece like a 4g63 or other import motors that I've seen, that would improve rigidity greatly.
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Was thinking about this today.

I'm sure that the most ideal situation would be a single piece of material which incorporates all 5 main caps with all the webbing to connect them, and is positively located and fastened to the bearing saddles as well as the oil pan rail. All mounted with studs.

The engineering principles in the attached picture seem like an ideal (aside from the fact that it's an antiquated 3 main cap engine).

however, a block of billet large enough for this is going to be ****-off expensive, and a cast piece is probably going to have insufficient strength. Plus the machining tolerances are also extremely fine and would require pretty complicated fixtures.

The next best thing, and much more practical would to try to replicate this in multiple pieces fastened together.

So 5 separate main caps with level flat machined surfaces on top, a fabricated skirt for the block and then just add the required intermediate pieces needed to fasten the main caps to the skirt.

With enough r&d something like that could be developed. But there's always potential for unintended consequences and you can pretty much forget about them being comercially viable. It would be pure mad-scientist stuff for the joy of hot-rodding.

As far as making a girdle which utilises the factory main caps, I'd say there is a limitation which only really allows the "steel ring" type like those sold by Hughes etc.

Whether they actually work. I don't think anybody seems to know for certain. Not even the people who sell them.

girdle003.jpg
 
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gagembassett said:
I was just rereading a thread I commented on a long while ago about main cap girdles and the ending consensus was a no..... HOWEVER I did read it and it seemed to me that everyone was only implying it to 2 bolt main girdles on an LA factory block. Now I do understand that some people still run 4 bolt caps and leave the outer bolts unused just to help transfer the stress across a more broad surface area. So my question is what does everyone think about running 4 bolt caps for that and adding a girdle on top? Yay? Nay? Why?
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Rover found fretting on the Aluminium blocks under the main caps. This was the reason that Rover went to cross bolted mains. Originally designed by the General with two bolt mains. I do not know how the Buick/Olds blocks stood up in that regard. I have one on an engine stand but not ready to tear into it yet. Would seen to be a prime candidate for a main cap girdle.
Back to the Mopar question, IMHO it would depend on the build. If building a somewhat mild engine, then a girdle is not needed. However if building a boosted engine or intending to wind it to the moon, a girdle would be advised. In that case, hardened washers under the inner bolts of a four bolt to allow a girdle to clear the outer bolts will not do any harm. There is David Vizard's 100pHP Ford block Youtube to watch that discusses the issues. Another is I think Unity Motorsports Garage Youtube that compares the SBC, SBF and SBM blocks and compares strengths, weaknesses and a quickmention at weight. Combine the information to get an idea of how to proceed. I noticed an UTG header for one of Tony's episodes that hints at a design flaw. Let'a face it, all the manufacturers have their strengths and weaknesses. For the most part the American engines have been pretty good designs, but they all have put some crappy ones out.
 
DNasty777 said:
I'm of the mind to agree with you generally, about the main girdles. From what I've read so far, most of the complaints seem to come from the fact the girdle isn't really tied to the caps at all, just sandwiched on top of them by the studs. I'd be inclined to believe that if the girdle was keyed to each of the caps, or the caps and girdle were one piece like a 4g63 or other import motors that I've seen, that would improve rigidity greatly.
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If you watch the David Vizard video you will get the information you need. Now his explanation was concerning the SBF engines breaking the main web out of the block. With his extensive list of industry contacts, he talked to a Ford engineer who informed him that the caps under high power and RPM would resonate front to rear. When you get to a resonante frequency that matches the natural frequency of the block or multiples of it they will break the block. The solution is to change the natural frequency. You do this by changing the mass of the part or the length or clamping it. What a main girdle does is clamp caps together, effectively changing their mass.
I was exposed to this while working in a facility building oilfield compressor packages. On some units a company was contracted to come in and measure the natural frequency ot the piping and vessels. That frequency was compared to multiples of the engines designed full load RPM. If the engine operating RPM is 1300, then a natural frequency of 650, 2600, 3900 etc were to be avoided. Sometimes just building a pipe out of the next gauge heavier or larger diameter would change it enough. Sometimes a sleeve could be welded on the outside in the center of a length of pipe did the trick. This was not the best.
You have probably seen vehicles with a weight bolted to the transmission tail housing. That is what it is for, to change the natural frequency away from the driveshaft RPM frequencies. Same principles and physics involved.
 
pittsburghracer said:
I don’t know what we would do without these YouTube trained guys telling us fords are weak. Thank you.
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Just repeating what DV has stated. He has extensive experience in the high performance industry. Others have broken SBF blocks also. Now if you watched the DV video, he states he has not broken many blocks, but all were over 500HP. I like the Fords myself for their compact design. DV also states the older blocks, production line, are stronger. The FRPP blocks are stronger and heavier than production line blocks.
Now if you are going to build a 550 to 600HP small block, that is going to require an expenditure of hard earned cash. By the time you pay for machining, forged rods, pistons, possibly crank, cam and valvetrain and heads whether porting factory or aftermarket, your wallet is going to be lighter. To me a little insurance to help prevent a failure that ruins a good chunk of those expensive parts is probably well advised.
 
Dale Davies said:
Just repeating what DV has stated. He has extensive experience in the high performance industry. Others have broken SBF blocks also. Now if you watched the DV video, he states he has not broken many blocks, but all were over 500HP. I like the Fords myself for their compact design. DV also states the older blocks, production line, are stronger. The FRPP blocks are stronger and heavier than production line blocks.
Now if you are going to build a 550 to 600HP small block, that is going to require an expenditure of hard earned cash. By the time you pay for machining, forged rods, pistons, possibly crank, cam and valvetrain and heads whether porting factory or aftermarket, your wallet is going to be lighter. To me a little insurance to help prevent a failure that ruins a good chunk of those expensive parts is probably well advised.
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But why bring so much ford trash on a MOPAR website. We come here because we love MOPARS not damn rust bucket oil guzzling furds.
 
NOTHING could help these "guys", they wouldn't flush the alcohol out after race night. The cylinders would pit up, AND worse yet, the carb would drain down, fill a hole, bend and burst ****. Was the brace needed, imo no.
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Everything has a design flaw when you push it beyond the original expected limits. BB mopars love to crack between the main and cam bearing on #4 IIRC Stuff like that. Mopar should have done the OEM blocks like the X and R series to start with BUT, that would have meant more raw materials. DOH! Instead of making 50 blocks from a certain level of iron, they could only make 47-48 which cost $$$$$$ from the bottom line.That isn't consistent with cost accounting/making the most of what you have and providing a profit to company and shareholders.

Want to waste money on a SB girdle, go for it. No amount of dv talking will change the fact they are a waste of $. Pick your parts, pay your money.

It's not going to save an OEM production block from eating itself, same as fords at extreme HP/RPM levels.
 
crackedback said:
Everything has a design flaw when you push it beyond the original expected limits. BB mopars love to crack between the main and cam bearing on #4 IIRC Stuff like that. Mopar should have done the OEM blocks like the X and R series to start with BUT, that would have meant more raw materials. DOH! Instead of making 50 blocks from a certain level of iron, they could only make 47-48 which cost $$$$$$ from the bottom line.That isn't consistent with cost accounting/making the most of what you have and providing a profit to company and shareholders.

Want to waste money on a SB girdle, go for it. No amount of dv talking will change the fact they are a waste of $. Pick your parts, pay your money.

It's not going to save an OEM production block from eating itself, same as fords at extreme HP/RPM levels.
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Don't the race blocks have a higher nickel content than factory blocks? My R1 block fresh from the hot tank was a different color than my 340 or 360 blocks.
 
It's my opinion that simply saying "they don't work" isn't helpful to a conversation about main cap girdles.

In other applications, you betcha they do.

So if they don't/can't work in a SBM... I'd be interested to know why.

Is there something about a SBM that makes them incompatible with an effective main cap girdle?

Or is it simply that an effective bespoke main cap girdle *could* be made.. but never has been?
 
IF you had a PROPERLY designed and executed girdle, with a MATCHING set of PROPERLY designed caps, DESIGNED to interface with said girdle, then you could actually see structural improvement.

The problem with all of that, is no such off the shelf solution exists (to my knowledge anyway), and you will damn sure spend more having that stuff made, than just finding and spending the dough on a 4 bolt race block to begin with.

So, all the theory is moot. I could tell you how to design this properly but it ain't gonna be cheap to have made and therefore it's a fool's errand.
 
I do tend to agree that the limits of a well set up factory block seems to be overstated. The guys that say the block has a power limit of "X" don't reference any specific evidence. The only broken blocks I've seen so far are due to other things failing. Ex. Broken pistons (detonation/rings butting), snapped or bent connecting rods, broken engine mounts etc.

I'm not saying it's never happened, and I do trust the guys here that have been running hard for decades, they know what they're talking about. But I would like to see what the documented limits of a well set up stock block are. A block that didn't have the carnage of other broken parts cause the block failure.
 
frosty_the_punk said:
It's my opinion that simply saying "they don't work" isn't helpful to a conversation about main cap girdles.

In other applications, you betcha they do.

So if they don't/can't work in a SBM... I'd be interested to know why.

Is there something about a SBM that makes them incompatible with an effective main cap girdle?

Or is it simply that an effective bespoke main cap girdle *could* be made.. but never has been?
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In what applications have YOU seen them work?

What engine did you build that **** it’s guts out and you installed a girdle and it went out and rotated the earth?

Ive installed many of those and not one did a damned thing. They can’t. They move the load to a place it shouldn’t be when it shouldn’t be there. Just like stud girdles for stud mounted rockers.

Ever seen what happens when you excite a tuning fork and then get it close to another fork? It will excite the other fork without touching it.

Everything has a resonance frequency. This stuff all moves around.

Stud girdles, like filling a block with concrete is at best a bandaid. They don’t fix anything. Main bearings don’t like.

Rather than waste money a time on a girdle if you want to help the block and crank use aluminum rods and a damper that doesn’t use rubber bands.

That investment will actually do something. A girdle just makes your wallet lighter.
 
frosty_the_punk said:
I'm sure that the most ideal situation would be a single piece of material which incorporates all 5 main caps with all the webbing to connect them, and is positively located and fastened to the bearing saddles as well as the oil pan rail. All mounted with studs.
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Supposedly someone in Brazil was making a one piece setup. Was posted to mopar engines group on fbook. No idea if it works, I stopped paying attention.

8A8674DF-5A07-4CC9-A971-C062DD15BC69.png


2738210F-5E6B-44C9-B270-AE36D4AEBB0A.png
 
Yeah. That's what I imagined. But something like that... that's crazy expensive to make. So it's a non starter.
 
Dale Davies said:
Just repeating what DV has stated. He has extensive experience in the high performance industry. Others have broken SBF blocks also. Now if you watched the DV video, he states he has not broken many blocks, but all were over 500HP. I like the Fords myself for their compact design. DV also states the older blocks, production line, are stronger. The FRPP blocks are stronger and heavier than production line blocks.
Now if you are going to build a 550 to 600HP small block, that is going to require an expenditure of hard earned cash. By the time you pay for machining, forged rods, pistons, possibly crank, cam and valvetrain and heads whether porting factory or aftermarket, your wallet is going to be lighter. To me a little insurance to help prevent a failure that ruins a good chunk of those expensive parts is probably well advised.
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DV DOES have extensive experience....in writing books and now YouTube panhandling. What he DOESN'T have are "60 years of race winning engines" because he never built ****.
 
replicaracer43 said:
DV DOES have extensive experience....in writing books and now YouTube panhandling. What he DOESN'T have are "60 years of race winning engines" because he never built ****.
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I'm not sure I agree with that now. I don't think the guy is a straight up liar.
 
Rat Bastid said:
In what applications have YOU seen them work?
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Barra, 1jz, 2jz, 4g63, rb30 etc have all had development in bottom end rigidity and been shown that their failure point can be raised to a higher power figure.
And have all managed to make well over 1000hp.
Sometimes double that.

If you look at how modern engines fasten their main caps six ways to sunday, and how often these motors can be boosted to the moon and make serious numbers reliably...it becomes clear that the rigidity matters.

I do understand that vibration and harmonics is part of the equation, but a well designed girdle should be able to dampen harmonics rather than amplify them. That requires a size/shape and density that resonates at a different frequency to the thing it's bolted to.

The idea that "they don't/can't work. not here, not ever. they're just a waste of money" isn't something I can get behind.

I'm quite happy for us to just agree to disagree on this one.
 
frosty_the_punk said:
Barra, 1jz, 2jz, 4g63, rb30 etc have all had development in bottom end rigidity and been shown that their failure point can be raised to a higher power figure.
And have all managed to make well over 1000hp.
Sometimes double that.

If you look at how modern engines fasten their main caps six ways to sunday, and how often these motors can be boosted to the moon and make serious numbers reliably...it becomes clear that the rigidity matters.

I do understand that vibration and harmonics is part of the equation, but a well designed girdle should be able to dampen harmonics rather than amplify them. That requires a size/shape and density that resonates at a different frequency to the thing it's bolted to.

The idea that "they don't/can't work. not here, not ever. they're just a waste of money" isn't something I can get behind.

I'm quite happy for us to just agree to disagree on this one.
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Yep, disagree all you want but I have experience on my side.

And every example you posted is nothing like a girdle like we are discussing.

So there is that. And I’ll say it again just to irritate the general public. If you are having issues to the point you think you need a girdle, or a block fill or both you need to save your money and buy a block.

Unless of course you think the factory is stupid and the aftermarket is stupid and the people who buy good blocks are stupid. Then you are on your own.

One more time for clarity.

A main girdle doesn’t work no matter how bad you want it to.
 
replicaracer43 said:
DV DOES have extensive experience....in writing books and now YouTube panhandling. What he DOESN'T have are "60 years of race winning engines" because he never built ****.
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I think DV is best at self promoting.
 
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