Crankcase stiffening options.

[grubscrew]

 What is considered as  cranckcase stiffenening in relation to a larger engine capacity. Im aware of the steel plate that can be used if say the pistons are taller than standard and then there is the ally sump against the mating surface using a mastic as opposed to a  paper gasket.
I know Rusty is making or has done a larger cc engine . There is of course the welding of various areas of the block.........of course the sky is the limit (with perfect balancing etc,which goes without saying) , but ones aim is not to have an out and out racer but something usefull. Ideas any one?

[Darrell]

I've heard of the steel plate under the barrels, they do shorter barrels to compensate for this.
I've got an alloy sump but went for the larger capacity so not sure of the effectiveness of the stiffening from it.
The trouble with all these mods is there is no black and white information on what we can expect from what.
eg. alloy sump would mean a safe rpm of ?
I also wonder if the increased compression ratios etc put more strain on the crankcase.
I am tempted to try for bigger barrels shortened for the plate, and get the plate next time I start my madness. Have a few other ideas.
They all talk about dynamic balencing like it is the nectar of the gods, but who has done it and does it really make it any better than standard?

[grubscrew]

 I was hoping you would respond. Thankyou. I agree with what you say.  There is no definate "yes this is whats needed":......... Any way today I took the crankcase to this like minded chap for some ally stiffening with the TIG, he did say that there may be a small amount of distortion of the end housing but could be line bored out if needs be to allow the bearing carrier to be re inserted. Lets see what happens.
As for the the plate stiffener Im going to require a 5mm or 2x 2.5mm, but woul prefer the former , is there such a thickness? Mike.

[Rusty's Uncle]

If you are talking about boring out the standard 499ccs crankcase to fit 594 or 652 ccs then you will need a 10mms spacer. As for strengthening the crankcase , I got the tip about lapping/mating the alloy sump from Smallcox and if he is putting 100hp through a standard crankcase with no extra welding etc then that is good enough for me. As Darrell says if we win the lottery we can get everything balenced but mine is a more "suck it & see" approach. Put a lot of interesting bits together with a lot of TLC and see what happens 
So I have the 652/499ccs engine with syncro box pretty much ready to drop in the 500 then I have the rebored , now 662ccs engine almost ready for the 126. Both with some spicey goodies 
They may run like cr*p or blow up pretty quick but I am looking forward to giving them a go 

[grubscrew]

If you are talking about boring out the standard 499ccs crankcase to fit 594 or 652 ccs then you will need a 10mms spacer. As for strengthening the crankcase , I got the tip about lapping/mating the alloy sump from Smallcox and if he is putting 100hp through a standard crankcase with no extra welding etc then that is good enough for me. As Darrell says if we win the lottery we can get everything balenced but mine is a more "suck it & see" approach. Put a lot of interesting bits together with a lot of TLC and see what happens 
So I have the 652/499ccs engine with syncro box pretty much ready to drop in the 500 then I have the rebored , now 662ccs engine almost ready for the 126. Both with some spicey goodies 
They may run like cr*p or blow up pretty quick but I am looking forward to giving them a go 

Being fairly agricultural engines I recon they might put up with a lot more abuse than one gives these engines credit for, lets us know of your outcome, I would certainly be interested. Thanks Mike.