Main Cap Studs with Girdle. CANT FIND EM!

[BADASYJ]

Again, the flimsy little metal girdle attached with a nominal fastener size does little to support the main cap integrity. One can only guess as to what the engineering team at Chrysler was trying to achieve. Their reasoning is above the knowledge of most that post on the forum.

The girdle was a great idea from the engineers but was ruined by the bean counters that cheaped out. Research main girdles on the google n learn something man. Instead of one single cap absorbing all the shock from the crank the girdle distributes that shock load over all of the caps, think teamwork. It is overkill on 98% of the jeep motors out there but high revving race motors do have a tendency to crack the main caps. Girdles are almost mandatory on any 2-bolt high HP motors.

Granted I have not been in all the late model 4.0,s the ones I have all had girdles. Do I have no idea what you mean about the bean counters killing it.

If it was such an important issue with the 4.0 why did they revert to hollow main caps from the 4.2 ?

Granted SOME high performance engines Benoit from the girdle. Not so much our little 4.0 families.

BTW, it's not shock load. It's structural stiffness.

Again, I don't know where you get your info but it tends to be tainted.

The bean counters are the money men who tell the engineers to make it as light and with as little material as possible to save millions over time. It could have been built stronger.
As with the difference in 4.0 and 4.2 caps, again this is where the bean counters come into play and tell the engineers to make it as light and with as little material as possible. Money and efficiency are higher on the list then performance and longevity.
Every engine benifits from a girdle, that is non arguable as it does in fact strengthen the bottom end without detriment to anything else. The higher in cylinder pressure and rpms you go the more beneficial it becomes. As I said before the girdle is overkill on 98% of the motors out there.

Let me break it down Barney style for you.
The shock load caused by the explosion on the other end of the piston is transferred to the crankshaft which then transfers the load to the other rods and the main cap. Which by it self must absorb the 75 impacts per second at only 4500 rpms. If you run a girdle the load does not stop at the single cap. The girdle transfers the load and harmonics to the other main caps which will share the load in turn strengthening the bottom end. No idea how you tied shock load and structural stiffness together with anything I said. I could see a gain in structural stiffness from using the girdle though.

BTW I never said he needed to run the girdle. I'm just stating that a girdle is benificial and serves a good purpose to those who say otherwise.

You had to end it with that doushe bag condensending comment again?

[jsawduste]

Sorry but again your wrong. Study the dynamics of a crankshaft and the loads and forces thrust upon it.

Your illogic on a number of topics has earned you a spot on my ignore list.

Do us all a favor and keep your opinions to yourself.

[BADASYJ]

Bwhahahahahahhaha oh boy the dreaded dustybrains ignore list. Dude grow up.

[BADASYJ]

How is it main caps crack with no shock load?
How is it that HP motors pound out the main bearings with no shock load?
What causes cap walk?
Better yet what in the world holds the crank from getting blown out of the bottom of the block?
Why does almost every HP motor out there run a main girdle? Dust those brains off, wake up. I know its hard to swallow your pride but come on already.

[jsawduste]

BA, I've worked on Top Fuel engines and one of the aspects we look for are the some of the factors you mention. I can show you rods and caps with the bearing imprints in them. Would you like to see broken main caps to go along with them ?

My point which you cannot seem to grasp is this a simple inline 6 engine used for a mundane purpose. While your shot of NO2 would work for a drag racer it's hardly applicable to the usage most of us are asking this engine to perform in.

A little common sense towards the application would go a long way towards adding credibility to your responses.

Your close but you need to think things through a little bit more.

[Cheromaniac]

I'm just stating that a girdle is beneficial and serves a good purpose to those who say otherwise.

Unfortunately the girdle fitted to the Jeep 4.0 doesn't exactly fall into that category. Sure it's better than nothing but it's only held to the mains studs by a few nuts and doesn't really add much structural rigidity to the bottom end.
High HP engines have a bedplate where all the main caps are tied together as one solid unit that really does add bottom end rigidity. Unfortunately Chrysler chose the cheaper route with limited effectiveness, and the fact that the 4.0L engine was stuck with near enough 190hp for 15 years (a pathetic 48hp/liter by today's standards) tells you how much Chrysler cared about engine development.

[BADASYJ]

Again, the flimsy little metal girdle attached with a nominal fastener size does little to support the main cap integrity. One can only guess as to what the engineering team at Chrysler was trying to achieve. Their reasoning is above the knowledge of most that post on the forum.

The girdle was a great idea from the engineers but was ruined by the bean counters that cheaped out. Research main girdles on the google n learn something man. Instead of one single cap absorbing all the shock from the crank the girdle distributes that shock load over all of the caps, think teamwork. It is overkill on 98% of the jeep motors out there but high revving race motors do have a tendency to crack the main caps. Girdles are almost mandatory on any 2-bolt high HP motors.

Granted SOME high performance engines Benoit from the girdle. Not so much our little 4.0 families.

BTW, it's not shock load. It's structural stiffness.

Again, I don't know where you get your info but it tends to be tainted.

So what you are saying is structural stiffness pounded out the bearings and cracked the main caps on the top fuel motor? Please clarify that. Also, I'd say that the longer crank (4.0 family) will benifit more from the use of a girdle then a short crank would as there is more harmonics involved with the longer crank. But, as I said before ALL motors will benifit from a girdle even if it's only purpose is for smoothing the motor out by cutting back on some of the harmonics produced. Is it necessary for proper operation of 98% of the motors out there? No, it is not......
Why would you offer to show me damaged parts? What will that prove?
Sawdust, quite a few of your comments and questions lead me (and others) on here to beleive you had very little to do with a top fuel motor. Stacking parts on a cart, rolling tires out, or driving the push bike dosent count in my book.

[BADASYJ]

I'm just stating that a girdle is beneficial and serves a good purpose to those who say otherwise.

Unfortunately the girdle fitted to the Jeep 4.0 doesn't exactly fall into that category. Sure it's better than nothing but it's only held to the mains studs by a few nuts and doesn't really add much structural rigidity to the bottom end.
High HP engines have a bedplate where all the main caps are tied together as one solid unit that really does add bottom end rigidity. Unfortunately Chrysler chose the cheaper route with limited effectiveness, and the fact that the 4.0L engine was stuck with near enough 190hp for 15 years (a pathetic 48hp/liter by today's standards) tells you how much Chrysler cared about engine development.

I do agree that Chrysler cheaped out on the part as it could have been stronger with better studs and serve more of a purpose, no doubt about it. At the same time though they seen fit to produce millions of them. Definitly not a cheap undertaking. I'd think it adds a good deal of rigidity just by connecting the seven mains together. The strength will come more from the block then the actual peice itself.
Not sure of the bedplate thing. Are the main caps actually machined into the peice itself or does it just tie the main studs in with the oil pan bolts?
Yes dino, 48hp per liter for 15yrs isn't much and its discouraging, but as you know horse power comes with engine speed. Lowend torque is what an inline 6 motor was designed for. Thats where we have the advantage on almost any other motor design out there.

[BADASYJ]

My point which you cannot seem to grasp is this a simple inline 6 engine used for a mundane purpose. While your shot of NO2 would work for a drag racer it's hardly applicable to the usage most of us are asking this engine to perform in.

A little common sense towards the application would go a long way towards adding credibility to your responses.

Your close but you need to think things through a little bit more.

BTW, I think you posted this in the wrong place. Remember, you are stalking me on more then one thread.

[Cheromaniac]

Not sure of the bedplate thing. Are the main caps actually machined into the piece itself or does it just tie the main studs in with the oil pan bolts?

A proper main cap girdle looks like this:



and an engine bed plate looks like this:

Yes dino, 48hp per liter for 15yrs isn't much and its discouraging, but as you know horse power comes with engine speed. Low end torque is what an inline 6 motor was designed for. That's where we have the advantage on almost any other motor design out there.

HP = Torque in lbft x RPM/5252

Unfortunately the torque figure was also stuck at near enough 225lbft for almost 20 years (a pathetic 57lbft/liter by today's standards). Chrysler could have developed the engine to produce more HP/TQ without adding any displacement, but they pretty much sat on their laurels from '91 onwards and that's why we're posting here today,

[jsawduste]

BA, you seem to have a bit of knowledge but your responses are sometimes not well though out. Slow down and think about what your writing. Look at it from more then just one angle. Make the response pertinent to the subject matter.

Unless a cap is faulty or the design limitations are exceeded.......Which includes the fastener and the cap itself.......It isn't going to fail from shock loading nor will it walk. There are other factors involved from structural stiffness, clamping tension to harmonics. Think about that for a moment before you reply.

I mentioned TF. Here is a picture of a Brooks TF rod that you can see the markings of the bearing transferred to the rod itself. This is from only one run. It didn`t fail but it did tell us how that cylinder was running. From that same engine at the same time the mains looked fine. Again, think about what is written before jumping to a conclusion.