Girdle/oil pan combo for a stage 2 block

[BlownV6]

I have been comtemplating building a combination of a girdle / oil pan for my engines. With these new heads , 1471 blower , 65 -70# of boost Im sure Im going to test the limits of the main cap system next year!! Anyone ever seen or thought about some kind of design to help the mains out? I know about Jasons girdle , but Im thinking something even stouter may be a good thing. Series 2 engines I believe use some sort of pan that does something similar although I have never seen one. Just brain storming here any and all ideas appreciated.
Thanks Mike

 

[Mike E]

There is an ongoing thread on yellowbullet.com about nascar motors. Apparently they do something similar with their pans. Post 43 shows a little bit of an ilmore built ford with the pan tied into the main caps.
NASCAR Engines... - Page 3 - Yellow Bullet Forums

Poston used to sell a big block buick pan that tied the main caps into the pan. Poston Girdled Pan 455-430-400 - V8Buick.com
I don't think the main cap bolts passed through the pan, rather there were adjusters that preloaded the caps.

Has anyone ever split the mains on a stage block from too much power? Are you running the block with all 4 caps cross-bolted or just the front and rear?

 

[BlownV6]

All 4 bolt mains. The front and back are cross bolted thru the sides of the block and the center 2 are splayed. I havent really seen a problem with the mains BUT!!! I dont want to find out I should have done something about it , after is to late. Mike

 

[Mike E]

I think the ulitimate setup would be a one piece cap and girdle assembly with dowels around the straight main studs to locate everything for and aft.
That's really the only thing I think that would be stronger than having all 4 caps crossbolted. If you made the "girdle" section of it thick enough, it could double as the oil pan sides and add some rigidity to the block. Add some struts from the girdle/pan section up to the heads and you might be able to contain a small nuclear explosion in the cylinder.

It would only be a couple months worth of machining on a bridgeport. :biggrin:

 

[BlownV6]

Thats basically what Im thinking about. A one piece machined out billet oil pan that would basically be a 3 to 4" thick girdle like RJC girdle , but with the pan bottom included or possibly removable. Any machinist out there that may try to tackle something like this?
Mike

 

[turbofabricator]

Mike,
I think to get the most out of what you are trying to accomplish, you would need to machine the block pan rail completely flat along with the main caps. You might as well just use the RJC girdle and be done with it. Not sure you would gain much with a 3-4" billet aluminum vs. a RJC girdle. With the steel caps on a StageII I think you could benefit from adding a couple of dowels between the cap and the girdle to help prevent cap walk. Just drill 'em about .750" inboard of the vertical main studs. Two .250" pins should help. I think the biggest hurdle will be proper torquing of the splayed cap bolts in the center. I don't feel that they will torque correctly by installing and torquing them prior to girdle install. You can always use a crows foot to torque them after girdle stud torque. (requires some math to get the right torque) Installing an o-ring in the girdle to seal it against the pan rail would help seal it up. If you use a one piece main cap and girdle assy., that would be a HUGE undertaking. It would of course be the strongest way, especially out of steel. Doable by a competent machinist, for sure. He could also add a couple of center bridges (front to back) just inboard of the main studs. I see another CNC project in your future.

 

[Mike E]

Here is a couple views of a fuel car bottom end. It's from the link in this thread. http://www.turbobuick.com/forums/turbo-lounge/351207-short-block-assembly-pics.html

No girdle, no splayed bolts, only cross bolted. I would guess the studs are 9/16" and made from arp's top shelf material. Good enough for 8000+hp with only 526".

I don't see any doweling either.

 

[BlownV6]

Mike,
I think to get the most out of what you are trying to accomplish, you would need to machine the block pan rail completely flat along with the main caps. You might as well just use the RJC girdle and be done with it. Not sure you would gain much with a 3-4" billet aluminum vs. a RJC girdle. With the steel caps on a StageII I think you could benefit from adding a couple of dowels between the cap and the girdle to help prevent cap walk. Just drill 'em about .750" inboard of the vertical main studs. Two .250" pins should help. I think the biggest hurdle will be proper torquing of the splayed cap bolts in the center. I don't feel that they will torque correctly by installing and torquing them prior to girdle install. You can always use a crows foot to torque them after girdle stud torque. (requires some math to get the right torque) Installing an o-ring in the girdle to seal it against the pan rail would help seal it up. If you use a one piece main cap and girdle assy., that would be a HUGE undertaking. It would of course be the strongest way, especially out of steel. Doable by a competent machinist, for sure. He could also add a couple of center bridges (front to back) just inboard of the main studs. I see another CNC project in your future.

I just cant see removing all the material need off the main caps on a stage 2 block as being a good idea in any way. I see the billet pan with thru bolts threaded thru the webbs in the pan with tapered points on them and drilled center points inside both 1/2" main studs similar to what your talking about with the pins. You could set up the block on a mill and drill the center points in an exact pattern. Then machine the pan/girdle with the thru bolts exactly where they need to be. Install the pan and center up all the thru bolts into the cap and then torque down the pan rail bolts and torque a preload into the thru bolts. Actually would be fairly simple but Im thinking very effective. Mike

 

[gnxtc2]

No girdle, no splayed bolts, only cross bolted. I would guess the studs are 9/16" and made from arp's top shelf material. Good enough for 8000+hp with only 526".

I don't see any doweling either.

It's hard to tell from the pics but it appears that the main stud is larger where it goes into the block. I don't know if this is a locator/dowel for the main cap.

Didn't the Pontiac big blocks have a ring around the main studs?

Billy T.
gnxtc2@aol.com

 

[Mike E]

I think what you are seeing is the counterbore for the hole. I doubt they would locate the caps off a step in a stud. A threaded stud doesn't really have a good center to locate off of. Too much clearance in the threads.

Big block Pontiacs have dowel pins just outside the main cap bolt holes on the stock 2 bolt blocks.

Chris Hogeland is apparently putting dowel's around the main studs like your thinking about. He put a pic in this thread. http://www.turbobuick.com/forums/engine-tech/351305-steel-caps-girdle-stronger-2.html#post2819017

 

[BlownV6]

Im pretty sure that Im going to attempt to make a billet girdle/pan combo this winter. Anyone have the main stud & 14 bolt oil pan exact demensions?? Those would quite handy. Thanks for all the input guys!! Mike

 

[Mike E]

The power source book has the 14 bolt pan bolt pattern dimensions, but no main studs. You probably already have it, but if not...

Without tearing a page out of the book, this is the best scan I can get. The cut-off dimensions are 1.76, 1.76 and 0.64.
link to fullsize

 

[BlownV6]

Mike, Thanks , I forgot about my power source book. My little mind has the gears turning on this. Mike