Designing main girdles

I'll tell you don't loose Grumpy's Book.
Are you and ADAM connected some how? @oxracing?

If your buying a 3.8 you want the version 2. I think it was called the W-2 3.8 buick. It had a counter balance shaft to cut down on fourth order vibration. They shook pretty good until you started buzzing them and then they came apart. We have a 2005 Monte Carlo with the 3.8 Supercharged and I played with the PCM ECM controllers I had it up to 150 MPH. It still wanted to go. Thats the engine they were putting in the Cop Crusiers 3.8. Are you going to school?

I'll tell you when I was 26 I had spent 22 Months in VietNam worked 12 hours a day and got an Engineering degree. We had all 3 of our kids,We bought our first house 2 years later I was transferred to New Jersey from Conn. Where we are all natives of. I apologize I was 28. Believe me I worked my ass off for all of it like anyone else. You probably know that by now. I live in Mass. now I was transferred here in 1985.I guess the best way is PM me if you need some info.
Thanks
Bob  

Yeah, I will be keeping it. His S/A design book is expensive. Some day maybe.

I have not met him in person before Bob, just on here. I grew up in a southern Minneapolis suburb and raced at the track he is at, thats all. I wish I was in school again. I have 4 years in automotive and heavy truck tech diplomas. I would like to do another major, but, that won't happen for a while. I have a library and my imagination right now for studying in my spare time.

Yeah, will probably take you up on that Bob. I have a question as far as the steel grade when I choose to start. I know there is 'mild' steel etc out there, did you have to record what the material was when you did your girdle?  

Spent some time puttsin' around with some drawing on the computer. I just used the basic layout of the V8 engine. Here is what I am thinking in a very vague way unfortunately. I will get more detailed in the near future since I will have a scanner at hand and will just scan-in my hand sketches.


Since sharp edges/corners become stress points once twisting, stretching or compressing comes into play I utilized radii in as many areas possible. As for the radius in red in the above sketch, that will most likely be employed by welding in a reinforcement piece.  

the idea of the main girdle.. is to keep the main caps from floating around..

stop any sideways movement that will shear the main cap fasteners..



the idea is to let the crank throws with rods attached.. and the counterweights swing through the openings if you need to ..  so you can keep the girdle as close to the top of the main caps as possible..

if you open the image in a new window.. you will see that i included some ideas for using the tapered cones ... i just don't know.. if i would put the tapered cones on the studs so the cones stick into the plate  from the crank side..

or have the cones stick in after the plate is set over the studs...

i would think it would be significantly stronger with the cones sitting on the top of the main cap Nuts  and the girdle hold down nuts against the flat surface..

it is the other way on axles..   but that would allow for variations in counter boring the holes on a flat axle flange...

i would want the cones to NOT be totally below the surface of the girdle..

the plate will flex just slightly as you tighten the top nuts down...

you still have to get an engine oil pan on it...

perhaps you were thinking about an engine bed plate???

this is on a 4.7 mopar motor





 

Really Good Information Wayne:

Thats why the W2 version of the 3.8 was designed with the counter balance shaft. It stop that vibration that was pulling them apart. I heard and I don't know how true it is, the 3.8s would run all day at 7,800 but you couldn't push them to 8,000 they didn't like it. Thats when the W2 Version was made.

If you remember the older 4.3 Chevy's had that problem also. Then they installed the counter balance shaft and the vibration went away.

We have the 3.8 My wife's car has the 3.8 Supercharged in her 2005 Monte Carlo SS I had a  friend redo the electronics and I don't think it has a shut off RPM or Speed. I had it at 135 MPH and it was as smooth as it could be.  
Bob  

Let me know what your up to and if I can help you I will. I met Don Garlets and his wife around 1994 up at Epping New Hampshire. I'll tell you this man is NO PHONEY either. His wife was as much into his racing as he was. Of course like a lot of us we are slowing down. My boys never wanted anything but their Motorcycles. My Dad was into motorcycles and the jalopys they ran at the local State Fairs. Then when they were really into the higher end of racing he unexpectedly died on us.

If you ever get to Ocala Fl. you have to get to Garlets Museum. He has Swamp Rat 1 on up. I know he sends cars to the Smithsonieum in Washington. Another place you have to go! Enough of that...  
Bob  

Well, I guess you could consider it a combination of the two, but also have the basic main-girdle in mind as well Wayne. Maybe incorporate some anti windage attributes too. Thanks for the reply. There are numerous things I having running around my head as far as strengthening a main girdle similar to methods that strengthen body panels along with heat treating. But, there are numerous ideas floating around the brain at the moment.  

What would you guys say on a double bend opposed to single bend per side?  

You lost me on the single or double bend?  

single or double bend.. does not really matter..

it does not take a lot of bend to strengthen the plate form

the chance of it deflecting any is mostly NIL..  

most of the plates are flat..  with just holes cut by mill or water jet..

the bed plates as i posted pictures of..  take care of some of the noise vibration and harshness issues from motors.. where sounds can be transmitted through the oil pans..

i personally think that you won't have room for a double bend main girdle..  once you try to fit it inside the engine oil pan..

if you really want to improve high RPM stability.. you might want to search out a crank that is evenly counterweighted for the entire length..   with that .. you should be able to get by with smaller counter weights on the ends.. as each section is evenly weighted..  should remove any out of balance issues in the middle of the crank..  this is corrected by having larger counter weights in other locations..     i was discussing this issue with a crank designer about 14 or 15 years ago..    think about this.. if you have a rotational mass that is closer to the centerline.. you should be able to spin it faster, easier.

the only advantage i could think of to having less counter balance weight in the middle.. and heavy on the ends might be to change the harmonic frequency of the crank...  kinda like a beehive valve spring because of the variable size of the winding.. it does not have a set harmonic frequency..

OEM engine design engines do not really reach the crank rotational speeds where the middle of the crank can whip and wipe out the center 3 main bearings..  but high RPM race engines can reach engine rotational speeds and input pulses that can cause the center of the crank to deflect and whip around..


now that you are totally confused..  as engineering is confusing.. i would probably in a HIGH RPM race engine rather have a crank that is evenly weighted along the entire length.. and handle the harmonics with something like a fluid damper harmonic damper..

just typing this out has given me an idea..  transverse OEM installations use the inertia ring of the harmonic damper to drive the accessory belts in some applications.. a pulley like a that bolts to the front of the damper as conventional crank pulleys fit. but it folds backwards over the damper with grooves for belt alignment..  this would allow the harmonic damper inertia ring to actually dampen the torsional vibration.. with the belt driven accessories driven via a pulley solidly mounted to the damper hub..  i don't know if the newer engines already do this.. as i keep my head under the hoods of long out of warrantee..  

All I was looking at Pepsi, once you move away from the main studs and you bend the girdle slightly, would making a second bend in the opposite direction benefit you any further. Opposed to just having the single bend facing the cylinders.  

No confusion here Wayne. I understand and comprehend what you have said, just gave me some more to chew on for a few days more. Thank you.  

You may want to mill the mating surfaces under the head of the bolts a little wider so you can get more material on the main caps. One thing if you are planning to change over to main studs,you will have to line bore the block.  

When you install studs it moves the cap location slight enough to get a runout on the bearings. You will see it as side loading or bearing meaterial pick-up.