Which option will stand up best for the hi-perf 6.5?

I just want to be prepared for when this thing finally goes *poof*

The block will actually be weakened by going to a splayed bolt pattern. Unless you can find a 2-bolt 6.5 which does not exist, you have to pilot drill and tap 6 new angled bolt holes and have new caps made and then have the block align bored and align honed. So you will have the stock bolt holes going vertical through the main webs and then the angled holes. This would all cost about $ 600-800 to have done start to finish, also.

Girdling- Hard steel supports connecting the lower caps together in a “bridge” or ladder with each cap holding the other from flexing. No real block machining required. I am in the process of making these little beauties and will have pics in a week or so. Most Hi-perf race engines are girdled due to its high efficiency of helping keep everything bottom-end wise much stronger. I am thinking about maybe making a few sets, at least one extra for Bagalac and you could even just drop your oil pan and put em on in a day. Studs will have to be put in the main caps but that is no problem. I will have more to come though as far as a drawing at least or even a pic or two. Any other questions, ask me anything block related. I have experience with alloy-race blocks, machining work, studs, girdles and forged components.

Can open. Worms everywhere!

:D

This is going to be a big debate, kinda like the water mist vs. intercooler and timing chain vs. gears ones.

I personally think that splayed is stronger. But I can see the point behind removing material from the block will only make it weaker.

I went girdled primarily for logistics reasons. But I would have splayed 'em if I could have gotten all my ducks in a row.

Tim


P.S. ChicagoTDP - Your "current mods" in your sig is killing me :lol2:
I feel your pain, Brother! Maybe we should start a Cracked Piston Club?

Ah, yes! What are we going to make the caps out of? Nodular iron, steel, etc? What material are the studs made of? What's the best tensil strength? Too hard, they are brittle, too soft and they stretch? What about cylinder concentricity after bolting them on and line boring?....and on, and on. CowRacer, you're right! (but, it's fun!)

Maybe International will cast some blocks without the outer main boss holes and we can add our own caps. Splaying would be a snap!

:whip: I like worms!

Yes, with splayed bolts drilled and tapped, that would without a doubt cause a lot of cylinder distortion.

PS, COW, i will try and post a piston-pic, i have two good ones, they are beauties :o:

The steel that i am making my girdles out of is a high strength tool steel with a low coefficient of expansion and high fatige rate. Its expensive at like 30 bucks a pound but its what I feel is needed. The studs will be a set of ARP main studs with a standard tensil strength that ARP uses for mains. Girdles are a great alternative to block modification.

Hey cow, u got a pic of the girdles you used and maybe an idea of the material, thickness and such, so I can have an comparison to my design?

Cool, will the girdle cover all the mains or just the three in the center? I guess the rear main would cause interference with the pan, huh? Don't know, just asking. Looking at the front, it's kinda tight too. Could you tie into the outer bolts on the front and rear caps?

I know DSG builds one for the three center mains. Don't know much about it and haven't seen one installed. A local machine shop called and asked for their number a few weeks ago. He had machined a 6.5 only to find a crack in one main web after he assembled the short block. Wanted to try to save it by using thier support. I gave him their number and told him, "I wouldn't try it, look for another block."

The one i am building will be clearneced for the rod swing, comming close to the crank and will connect ALL the caps. The pan clearence is tight, with the ends of the pan being very close but the girdle needs to connect them all for maximum strength. The fact that I am keeping the girdle so close to the rods and crank is to also have it act as a crank scraper to get off all the excess oil to reduce windage and excessive friction involved as well as lowering the roatating mass. Lots to consider here but time and effort are what is needed to suceed as well as looking at maximizing the effectiveness of the part being engineered. Basically, I am OVER-engineering this part.

This came up before, but don't you need to machine the block to use a girdle too? I thought that you have to do that with the girdle installed to ensure that you have no distortion in cyls and in main journals. What's up?:confused:

I had the Avant's put a DSG girdle in it. Attached is the pic from the DSG website. It only covers the middle three caps.

Tim

Block machining after bolting it on will true up all the surfaces. Measuring the roundness of the bores before and after installation will tell you if additional machine work is necessary. You may get lucky on the bore concentricity depending on the thickness/hardness of the block. These things are pretty beefy and the webs are thick.

At any rate, torque plate honing is a must when resizing cylinders, regardless of the line bore. The caps, girdle, etc., must be installed and the line honing done before the cylinders are finished.

i have taken off all the main caps and indexed them for height and taken about .003-0.008" off the flats where the girdle will sit under the nut where the stud is. This is all the machining that has to be done and it is not major, took like 30 minutes but i also have access to a CNC mill, most people do not.

Chicago,

just from your signature, did you really have a cracked cam? I haven't seen much of this, just curious..

You can't be serious thinking that the Girdle is Stronger than Splayed Mains.

It's a good Second Choice though...

My cam did not crack in half but the lobes for the #5 cylinder on the cam got creamed when the connecting rod decided to leaves its home in the number 5 cylinder after it divorced the piston by detatching at the wrist pin hole of the piston.

Billman - In our application, having the limitation of a sturdy foundation to build a stout short block, we have no choice but to either recast an engine block or use girdles. My race motor in my pro-street 71 nova is a splayed 4 bolt Merlin small block and there is no way that motor would be together every time it gets beat by the 300 hp of extra juice that it gets without those angles bolts.

But anyway, girdles will do. It will be stronger in our application but if there was a 6.5 block that was 2 bolt, i would have found one and splayed it a long time ago. Splayed caps would be easy to make, again I have the resources of a CNC mill to build just about anything within reason.

I just want to be prepared for when this thing finally goes *poof*

I love it! Altogether the NASA countdown 10-9-8 . . .
We have it, CR is on his way, beautiful, pieces laying all of the ground. . . such carnage. . .

:funnypost I almost fell out of my chair reading that! ):h

When it happens you will fall off your chair laughing at me as i'll have pics of proof of the engine going *POOF*...... damn thats almost a rhyme....

PS: Nice to see Billman's still hanging around... I miss his input every now and again.

GMCTD, I had a question for you..... then i had 3 whiskeys.... things got a little cloudy and then i forgot what it was.... hopefully tomorrow will be clearer...

Gotta love those canadians:funnypost

"PS: Nice to see Billman's still hanging around... I miss his input every now and again."

...There's a first.

Do your own research, weed out the moronic advice, and come up with your own decision.

Well.....here's a second - I, too, enjoy your input Billman, as well as your approach.
Hang in there, my friend.

And , since someone rattled my chain -

The 6.5 mains webbing cracks and crumbles out of the pan rails, usually starting around the outer main bolt holes.

Seems highly unlikely that a girdle will prevent that, where plugging those holes and relocating the outer bolts - splayed - into the stronger sidewalls of the crankcase would likely result in a stronger engine assembly.

There are, however, full perimeter girdles which attach to the entire pan railing, and allow main cap attachment, or attach to the machined main caps, as well as full perimeter girdles with integral main caps.

Which is best?

How much money do you have?

Which is best?

How much money do you have?

:exactly: :agreed:

Tim

To trump the splayed cap design, one would need a pan rail/cap support all in one like the Buicks use...

www.taperformance.com (http://www.taperformance.com) makes a girdle on p 21 of their catalog. I was unable to find any other images.

that is not a stud girdle, that is a block extension:eek: . That is like having a skirt on the block. That would be challening to machine all of that. The block would have to be extensivly machined for trueness though, making sure the mating surfaces were all flat.

That's what it'll take to trump the splayed caps...

Maybe so, but anything to add strength to the bottom will be a plus. It seems the "splayed block" idea is out until it becomes cost affective. If you can't modify the block to "take the bolts", the whole idea is pointless. Let's get International to cast one without the outer bolt bosses drilled and tapped. Chev did it for years.

The idea of having a skirt on the block is for increased strength, rigidity in the mains area.

Check out the Ford big block with the main caps bolted thru the side skirts - now, that's strong.

Expensive to cast and machine, but rigid - solid, immoveable.

But we're still talking indirect injection, here, where the heads will always give over-heating problems with increased thermal output.

The question becomes - 'is it worth it?', not 'can we do it?'

duramax

It's a whole lot more cost effective than doing it twice. I speak from experience on that one. The mod process isn't exactly rocket science and will be discussed in great detail in an article being written for another site.

The vacated outer holes do very little to weaken the block, as they are now held under compression of sorts...


Maybe so, but anything to add strength to the bottom will be a plus. It seems the "splayed block" idea is out until it becomes cost affective. If you can't modify the block to "take the bolts", the whole idea is pointless. Let's get International to cast one without the outer bolt bosses drilled and tapped. Chev did it for years.