The only main bearing girdle that I have ever seen that had any value was one for the 289 - you could probably get it for any engine. It was a forged or billet piece that replaced your main caps and attached through the pan bolts and main bolts - spacing the pan down by 1/2 inch in the process. It had to be line bored to fit it to your engine. It made all the caps (1-5) a one piece unit. You torqued it from the center out and finished with the "pan" studs. They had a head on them and sealant was used to seal it to the block pan surface and the pan gasket was used when the pan was installed with nuts. The heads of the studs were counter-bored in the girdle. You could add a windage tray and / or scraper just as you would with stock bearing caps. The girdle effectively tied the entire bottom end of the engine together with 1/2 inch steel which incorporated stronger than stock caps in the single piece. (thicker and taller) I am not impressed with the plates that bolt over the top of the stock caps and even less with the ones that require shaving the tops of the caps flat to install a steel strap that goes over the modified cap. I don't think they add much, if any, strength. The one piece "all in one girdle" adds signifigantly to the strength of the bottom end. I would not hesitate to spend the money for one if I was going to put a blower or big nitrous system on my small block Ford.
Streetrod, I will have to go through my old notes and information - I will get back to this thread with the info.
I spoke with an Engineer on this very Device. Ford engineers are working on putting them into production in the near future on the 4.6s 5.4s. They help tie the lock together to make it stable. Reducing Harmonic vibrations that lead to block failures. The block does not twist as much. Does it work? I don't know. I do know that Ford engineers feel it does.
Ford engineers also felt that three or four threads would be just fine to hold the spark plugs in the early 5.4 blocks and still believe that spindly 8mm studs threaded directly into aluminum are just fine for holding a cast iron exhaust manifold on.
Actually, they have been in use already. The newest 5.4 iron blocks have them for NVH and the aluminum 5.4 GT block has them for strength. If you look at any of the aftermarket Hemi blocks or the Boss 429 aftermarket blocks you'll see them cast in as well.
Ive been intrested in thes valley girdles for a couple years now waiting on responses from comsumers. I thought it may help, I was thinking instaling main and valley girdle then do the machining and then a half pour of block filler, with that id say you could make 700 hp on a stock block. Just my thoughts
Save your money, please. Get a Sportsman block, if you can't afford a (fill in your favorite aftermarket block). You have a ticking time bomb w/ the stock block and any bolt on strengthening piece. Then you put a rod through, then oil down the back tires, and now your car is in the wall...
If there was ever a block that could benefit from this, it'd be the ones you mentioned. You can put a 4 cylinder engine in the valley of those beasts. With the block being aluminum also, the "valley rods" would stand a better chance at providing more strength (IMHO). Just to compare the valley depths, Versus
I'll agree with Rick. I don't see much gain from this. Especially if it's the mains cracking and propogating to the lifter bores. (which I suspect it is). I will agree that they will change the natural frequencies of the block. However! Unless you run the engine RPM at a mode that increase the stress significantly for a sustained period of time, then I don't see much gain other than it will feel better and be quieter. I've done lots of vibration analysis, and you try to stay out of the 1st and 2nd order harmonics. Third and fourth order aren't really worrisome as the deflections and thus stresses tend to be very small. For instance. If you have a stick and you wave it back and forth, the 1st order harmonic is the just the tip wagging back and forth. Lots of deflection and high stress. 2nd order harmonic is when the stick gets a bend in the middle when you wave it and gets a kind of S shape to it. 3rd order adds another wave and so on and so forth. As you can imagine, to put these extra waves in your stick you need to wiggle it pretty quick and movements become very small and stresses go down. The stiffer your stick is, the quicker you have to wiggle it to get it to bend. Cast iron is incredibly stiff and as such generally need a high input frequency to get it vibrating. The aluminum engines aren't as stiff and will vibrate at a lower frequency and may end up in the cruising RPM range. Especially the modular blocks as was posted above. Once you add the big heavy DOHC heads to those things the distance from the bottom of the valley to the top of the head get's to be kind of ridiculous. The bottom end girdle that Paul was talking about is the only way to go IMO. It's similar to how the caddy northstar was designed. The only difference being that the caddy mains run all the way across the bottom end. Anyway, by tieing all the mains together and then tieing them into the outer walls, you provide much more support for the engine. To add residual compressive stress to the main webs it would be a good idea to mill the edge where the plate bolts to the outer wall a couple though short so you're actually squeezing the mains up into the block when you nut that part down. /lecture off/
