MitsuStyle - 7 bolt girdle

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- - 7 bolt girdle (http://www.mitsustyle.com/forums/showthread.php?t=9883)

I've done some searching in the last few days and couldnt find any answer to my question.

What is the main purpose of having all the main caps attached to a girdle like that? I've been trying to figure this out but no one I talk to seems to know. Hopfully one of you has an idea.

Thanks

Jake

Re: 7 bolt girdle

it keeps them aligned with one another.

Re: 7 bolt girdle

Well I figured that... But when looking at a 6 bolt they dont have a girdle and yet dont have any main bearing problems.

I was shown a post on NABR about a guy making a girdle for the 6 bolts because of them "swinging/dancing" under high cylinder pressure.

[RANT]If your going to flame me for posting it up here, then dont even respond. NABR has such shit rules about "stealing info" its retarded. Why would someone get so pissed if all they use the info for was to help someone! Its like their own little cult. I know some of you are on NABR and will probably go back and post this just like how I got banned... Seriously, grow up, we are all trying to do the same thing and gain knowledge, why keep everything a "secret"?!?[/RANT]

Sorry... Ok here is the post:

Quote:

After seeing some nasty fretting where the main caps bolt to the block, I decided to make a main girdle. The caps on a 6-bolt dance around at high cylinder pressures, where the 7-bolt has a nice integral girdle. I wanted the larger rod journals the 6-bolt has, but with better structural integrity.

I'm considering making some of these and I wanted to gauge interest. The price I'm shooting for, if I can get enough people interested, is $125 on the initial run. There are a couple bosses for the rear cover bolts that need to be ground away and the oil pan lightly interferes with the ARP studs at the rear of the motor (nothing a ball peen can't easily fix). Both these things are pretty minor to work around.

The part is designed to clear crower rods on a stroker motor. It will easily clear everything on a 2.0L. I don't know about other rods because this combo is all I have.

Another poster:

Quote:

Honestly, though, the first thing I thought when I saw the topic was "crankwalk." The girdle is the major difference between 7-bolts and 6-bolts that hasn't been investigated with regards to crankwalk.

Also, how would this keep the caps from dancing around? Just the friction of the girdle to the caps? Is the problem that you are trying to solve cap movement or the mains moving around with respect to one another?

Original poster :

Quote:

The problem I was having with the main caps was fretting due to them flexing at the axis the 2 bolts per cap makes. This was the worst on the center main as it isn't tied into any others in OEM form. Basically, the front and rear edges of the main cap and mating block surface become fretted and pitted. The goal of this part was to stabilize the top of the cap so they can't do this swinging dance anymore.

From what I've seen, I don't think the caps are moving around due to bolt strength or preload. I didn't really improve the main cap fretting when I upped the torque from OEM spec to 50ft-lbs with moly lube. Unfortunately, I don't think this will work well with OEM bolts. They have larger heads than the ARP's and will get into the oil pan worse. It would probably take a decent bit more beating on the pan to get them to clear.

I installed the pan on my race engine tonight. The last 2 studs only interfere by about 1mm. I set the pan on the block and smacked it with a deadblow hammer until the nuts formed large enough dents in the pan that the pan bolt holes all lined up.

I don't see any reason this would require a line hone. Its not changing the clamp load on the caps or their alignment in any way. I wouldn't be scared to drop the pan and just slap it on an otherwise existing engine.

Actually, I've never line honed a mitsu engine. They always seem to rotate nice and freely with new bearings and I've never seen a wear pattern in the mains that indicated any axial misalignment. Maybe I've just been lucky though, I don't know.

I was just shown this and I dont know what to think... Anyone else feel the need to comment?

Re: 7 bolt girdle

Some honda B series guys go with aftermarket crank girdles, not a bad idea if you are getting "dancing" main caps, thus, bad bearing wear.

Doesnt that article explain why you would need them? The girdle basically binds all the caps together, reducing the chance of any 1 cap swinging independently.

Re: 7 bolt girdle

Yes it explains it, but thats 1 guys knowledge. I wanted opinions from more than 1-2 people. Just because 1 person and it works doesnt mean its right. Like I said, I dont know what to think.

With the amount of holding force the ARP main studs have, how the hell do the main caps "Swing/Dance" is what I want to know?!?

Re: 7 bolt girdle

It's usually the guys like Shep and Brent who have problems with the main caps "dancing". The 2.4l 6-bolts have worried me a little bit, since they use all individual 2-bolt main caps, instead of the paired sets and 1 individual main cap found in the 6-bolt 2.0l motors.

Re: 7 bolt girdle

So is there any advantages to the individual 2 bolt caps? Like say the main thrust bearing cap on a 1g. Its the only one by itself, yet thats what seems to last the most as far as thrust bearing issues go.

Re: 7 bolt girdle

Most of the higher hp applications we "pin". This helps provide a positive center for the caps when assemblying the motor, and also helps prevent the cap from pivoting or "dancing" on main studs.
Most of the 7 bolt motors I have experience with have warped girdles. They are a pita to line hone, but I perfer the "interconnected" design.
Thats why we bush/pin the most 4g63/4g64 motors we do (or atleast recommend it).

Re: 7 bolt girdle

Medium to high HP V8 guys often goto 4 bolt main caps. That and the lack of the support girdle is what worried me about the 2.4l 6-bolts.

Re: 7 bolt girdle

Ok, I understand now... Thats all I was asking for! Thanks guys!!

Re: 7 bolt girdle

Quote:

Originally Posted by niterydr

can you explain "pinning" a bit better? This is something new to me. Is this something along the lines of adding a pin that goes from the cap to the block to keep the cap aligned properly?

Re: 7 bolt girdle

It's adding a dowel pin machined into the cap and the block that the main studs go through. It provides tighter clearances to supposedly keep the caps from moving at all.

I've been a little leary of the unsupported caps on the 2.4 as well. But I have no intentions of spinning mine past 8200 rpm, whereas Kiggly on NABR is spinning well past 10K on a 2.0. The 2G's also have a windage tray that bolts up along with the girdle. I had one to put on my 2.4, but it would have been easier to just make my own, and just got scrapped when time got short.

In short, yes, girdles are good. But most will probably never really need them.

Re: 7 bolt girdle

Quote:

Originally Posted by Goat Blower

Nail with hammer, good post :). The caps DO NOT move with the pins in there.
I can't remember, but I think you can use 2.0 main caps on a 2.4 motor. Again, its an "I think" obviously you'd need to have the block line honed/possibly bored. I remember Mike saying something about it one time...

Re: 7 bolt girdle

Here's a good pic of the pin around the ARP's on my motor.

Re: 7 bolt girdle

Nice, Carl can we steal that pic for our motor building page?

Re: 7 bolt girdle

Quote:

Originally Posted by niterydr

Nice, Carl can we steal that pic for our motor building page?

Thats funny I stold it from the qpr page. Ive got a few more if you want them

Re: 7 bolt girdle

I took that pic, what a pussy motor though ;)

Re: 7 bolt girdle

Now since this is a 7 bolt motor, would it be worth having it pinned or will the girdle be fine? I've heard may people say, always pin it. But isnt that what the girdle is for... To keep the main caps from pivoting?

Re: 7 bolt girdle

Quote:

Originally Posted by EclipseGST

Pinning it can't hurt