Dusty Bradford
Well-Known Member
- Joined
- May 24, 2001
- Messages
- 5,802
I wanted to know who has done it and how many times.. There is only three that I know of personally that have done this with a stock block. "There is one guy touting his 8 sec 109 but haven't seen proof yet."
Been reading alot of stuff about this said individual...Is he really that disliked???
Being an engineer, I wanna ask a question about the 109's. I see most of the guys posting in this thread are well educated in the engines and pretty darn fast. What is the weak point, of the block, at the 8 sec power level? Bottom end or the 8 head bolts? Just wondering how much stronger the girdle makes it and if adding 2 splayed bolts thru the girdle and into the billet caps would gain us anything? Of course, you would need custom made caps, but thats what I do. I make anything I need. Just need a steel type and hardness to start. Any thoughts would be great. If this is of no discussion, my bad.
Coach:biggrin:
For us with Chris Hogelands motor it's the block webbing. 3 broken blocks without hurting any of the rotating assembly. He tried 1/2 head studs without success. Stock caps or billet caps didn't matter, actually the stock caps looked better after some abuse. Tried dowel pinning the caps without success. So far the girdle and stock caps seem to work the best. The latest engine has a girdle that was cut from a harder material and the issue was found that has caused the prior engine failures from being shaken apart. We were looking for issues with the block, turns out it was with the crank. New engine is going back together.
We're in a situation where it's cheaper to play with this than it is to play with the Stage 2. Engine blocks are cheap and easy to find. Chris has taken up the engine machining himself so if we want to try something, he goes to the shop and handles it himself. There is a stage 2 engine already assembled and ready to go when we give up on the 109 stuff.
. Pretty much all steel has the same stiffness (Young's Modulus of Elasticity) so going to higher carbon steel than 1018 or going to 4340 chrome moly or case hardening isn't really going to help. The main thing that determines stiffness is the dimension perpendicular to the flex direction, or in this case the thickness of the girdle. The stiffness is proportional to the cube of the thickness, so doubling the thickness gives you eight time the stiffness. Making it wider (making the windows between the caps and the pan rail smaller) doesn't help nearly as much since stiffness is just proportional to this dimension so making it completely solid would only roughly double how stiff the girdle would be. I can't comment on how much adding extra bolts to tie the girdle to the block and caps would help, but I'd definitely try making one twice as thick (or 2.7 times as thick if you want a factor of 20 gain in stiffness). You could try keeping the pan rail area the same thickness and adding ribs down the cap bolts but please email me to discuss this if you want to try it; I can calculate the relative stiffness of various designs for you before you make chips.
