It’s not going to be perfectly round at the mating line of the bearings (after bearing installation) anyhow IMHO. Seems like they normally wear a little different at that area.

 

IIRC there's eccentricity designed in to the bearings; they are thinner at the parting line. I guess the idea is to help create an oil film wedge on the sides and to provide crush relief. If there's too much width in the bore diameter that will change how the bearing crushes... if, when measured, the crushed bearing ID exceeds the out of round spec that could lead to issues... maybe. One of those things where experience counts.

Honestly, after seeing how much the the block flexed after having the ARP studs torqued down, and after having torn town maybe four or five blocks and seen horribly fretted main caps with uneven main bearing wear... given the Powerstrokes that followed had bed plates or cross bolted mains, or the DTs/Cummins/cats where they have deep skirts, huge main webs, and in the Cummins reinforcement girdles, and given the VGT that will end up on this engine will bump up the low RPM torque/cylinder pressures A LOT, I'm thinking a bed plate is probably a far better idea than a plate girdle. Plate girdle might *reduce* cap walk but does nothing to stiffen the block and reduce the chances of cracking a web (which might be more of a concern since I'll be using more rigid billet rods that will impart a sharper impulse to the caps). Bed plate eliminates the cap walk issue and takes some load off the main webs and stiffens the block.

IIRC Swamps used to talk about how they had to test and cherry pick blocks to find the rigid ones for their above stock power builds (no build dates or serials would correlate; is completely random), and that the issue with main web cracks coming from the cam area were much more common with increased low end power. Kind of makes me appreciate that the reason the 7.3 has a great rep is because it's not cranking out enough power to break anything, even if the caps are wobbling a little along the way.

For future readers of this thread, wouldn't recommend doing a performance 7.3 build that needs to be a reliable daily driver on your own. A *lot* of money gets tied up, you need to know reliable people who do good work, and there's no way to know if your block is one of the lucky rigid ones or one of ones that will flex. There's a lot of knowledge that only experience can reveal, and when spending this kind of money you either need a warranty from those with that experience OR you need to over build it such that there's no need to pray that it will hold long term. All it takes is one fatigued rod, one cap register that is a little looser, or one web casting that isn't as dense to cost you everything.

 

I mean, why not, bed plate with fasteners is only like $3,700.

Just go ahead and p pump it at this point since you”ll have the engine for it.

 

Hypermax's bedplate is 2,300 with fasteners, but the oil pan brings the cost up to what you're saying. I'll get a little money back from selling the girdle but yea, it's spendy any which way. I probably wouldn't be doing it if I didn't have the money from all these parts from the various cores.

Don't think I've ever seen a p-pumped engine in a street truck. Competition trucks have good justification since they need to rev high and pump out 1500 HP.

I'm not looking to do that, but I am looking to get the low end torque comparable to the VGTed engines (6.4 in red, 6.7 in green). All those engines either have bed plates or deep skirts with stiffening plates, or deep skirts with cross bolted mains. The stock 7.3 (orange in the graph) simply wasn't designed to reliably pump out that much low RPM torque, which is why the rods and the main webs are the weak points that break when you try and do so (as DP Tuner never seemed to learn IIRC).

 

I certainly love this build, it just seems to be getting a bit wild for a "400hp" setup.
It sure is a shame we can't get 32 valves instead of 16 on these old beasts... that would be handy for what you want to do with the power/torque curve

 

How is the Hypermax bedplate going to solve the issue of the main bores being a bit wide? Still going to have to line bore the mains and the hone...correct?

 

I bought a long block that was assembled by above average mechanics at home. They dyno’ed nearly 600hp with hybrids, dual HPOP’s and T4 turbo with it and had about 2500mi driving it like that after build. I put AC codes and S366 in it (dyno’ed 375hp) and put 125k miles towing heavy often as well as dyno runs, drag races and a few sled pulls. Ran GREAT, until it didn’t....






I’ve always wondered if more attention to details like this contributed to what I consider less than stellar service life - especially after the amount of time and money that went into building that block. This has also kept me from rebuilding these engines in spite of the fact I had more than a dozen put away at one point...

on edit: my block was at the machine shop for months when I found the ‘built’ engine for sale. I was able to ride in the truck with scan tool, etc and confirm I wanted to buy it before they pulled it. The cost of that long block was a little less than I was going to spend and this one was broken in, so I could hook the camper to it and go! I figured if it was built to take 600hp it should last ‘forever’ at <400hp....

 

I think if I wasn't doing the VGT, using hybrids instead of A codes, and had a few blocks to choose from, I'd be just stick with the plate halo girdle. My focus on bringing that HP down sooner in the RPMs has landed me in this predicament since that's hardest on stock bottom end. More valves would be nice but the VGT tuning will do a lot to make up for the poor CFM of the stock heads.

IIRC the bores come a little under sized which gives machinist and I some additional room to work with when we do the line bore. Plus, given the radically different way it attaches to the block/different torque sequence, the block portion of the bearing bores might distort less on the horizontal plane.

I think there's a lot of popular recipes for x amount of power that get thrown around due to people's experience bolting stuff on their trucks or doing a cheap rebuild and the engine not blowing up. Problem is selection bias is going to be a problem; the bulk of the people throwing around those recipes are the ones who got lucky and didn't blow their engine. In addition, not every horsepower is the same... is it made on the track? In front of a trailer? Unloaded on the street? On the dyno? For how long? At 1800 RPM? At 3000 or 4000 RPM? With how wide of a powerband? With what sized tires? What kind of transmission? What gearing? Whose tunes? High EGTs or low EGTs?
Just a ton of factors at play that are often left out of the equation.

When I was deciding on whether to go with billet rods I poured over the posts Swamps made on various message boards and condensed them down in to a few paragraphs that gives a taste of the mental calculations of what must be considered when building an engine from the ground up:

 

Was/is all of this to have a tow pig or a hot rod?

 

Yes and yes. Also add "reliable" and "learning experience".

 

Have you considered measuring the crank bores with the bearings installed to see how out of round it is at actual assembly condition?

Wondering how much the bearing may add to the equation. Bearings are soft though. 😏

 

Goneril kept asking her dad, who retired from the throne and pretty much handed her the keys to the kingdom, why he still wanted to keep a hundred knights for himself... much like today's ex-Presidents still have Secret Service protection.

Neither Goneril nor her sister Regan could understand why their dad wanted 100 armed agents, rather than say, just a couple.

The King snarled back "Reason not the need!"

Of course, these daughters were worried that 100 knights loyal to the King would bring to justice each sister's outsized lust for power and control over the kingdom, so they wanted to emasculate their dad by removing any means he might have to fight back against elder abuse.

In another abuse of power, anyone who stands in the way of Prius Lover getting a Hypermax bedplate is getting sent to the committee that answers this question:

I've been dying to see someone run one of these bedplates on the street. Let PL have his 100 Knights NOW!

 

I vote go with a bedplate made from 4140 tool steel

 

Dont screw around, get a CGI block!

 

FIFY.
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