Block & Crank power handling

[ALLTRBO]

In short, does anyone know if a 3400 block and or a 2.8 crank would handle 600bhp @ roughly 30psi?
For the record, yes, I know what would be involved to get to that power level. It's a serious question.

The Gen III block is supposed to be stronger in critical areas than previous Gen's, and the 76mm stroke crank should be stronger than the 84mm stroke crank if there are no differences in material or manufacturing (verification needed on that end).

I haven't been able to find anyone who broke either one from too much power, so my assumption is that it's still an open-ended question (read: guessing).

Thanks for any insights.

[bszopi]

30psi should yeild way more than 600bhp, first off...

I personally wouldn't worry about either of those 2 components when it comes to power handling. The the cross bolted mains of the 3x00 block, that adds strength to the bottom end, and I have seen a couple Gen 1 blocks (1 with a stock bottom end) in excess of 400hp. As long as you use the correct hardware (ARP studs in particular), I don't think you have anything to worry about. You could look into getting the crank cyro-treated for added strength.

[blownarrow]

wow 600hp ......... sweet

[blownarrow]

30psi should yeild way more than 600bhp, first off...

I personally wouldn't worry about either of those 2 components when it comes to power handling. The the cross bolted mains of the 3x00 block, that adds strength to the bottom end, and I have seen a couple Gen 1 blocks (1 with a stock bottom end) in excess of 400hp. As long as you use the correct hardware (ARP studs in particular), I don't think you have anything to worry about. You could look into getting the crank cyro-treated for added strength.

Was this Gen1 block a hybrid build? 3X00 top end?

[bszopi]

Nope, neither of them were. Both that I can think of off the top of my head were turbocharged iron head engines.

If I had more moeny right now, I'd tell you a definite yes or no. We are looking at 800hp+ for the Mustang build, but I have neither the money nor the time right now to even start working on it.

[blownarrow]

Did Arizona Succeed from the union? You guys are using Moeny now?.... Damn...
whats this world coming too?

Damn Ralph Nader!.......lol

[bszopi]

Arizona is AZ... Try again.

[blownarrow]

Arizona is AZ... Try again.

lol oh Arkansas that explains alot.... never mind..

[ALLTRBO]

Actually, I'm thinking ~27-28psi to get there (30 is a good round number), but it will probably take that much with the setup I have in mind. If I actually am over-estimating the boost figure, great. I try to plan conservatively so I have decent margin for error.

If I had more moeny right now, I'd tell you a definite yes or no. We are looking at 800hp+ for the Mustang build, but I have neither the money nor the time right now to even start working on it.

Awesome. Hopefully you can start before too long, it would be nice to follow.
I'm heavily considering parting and/or selling my twin-turbo IROC-Z to fund what I have in mind, but should be able to do it anyway by next winter.

[Joseph Upson]

I would certainly look into the bottom end support further. I recently asked Sappy if he thought making the the oil pan cross bolts fit more rigid by adding a sleeve for a snug fit in the oil pan passage would be helpful in moving a little closer to a four bolt main fit. I posed the question because while snooping around on the Grand National forum for cam specs I happened across a GN with the crankshaft literally blown through the bottom of the engine. The rear half of the crankshaft with the torque converter still attached was on the ground.

Since the 60 degree motor has an even greater Southern push on the main caps due to the narrower angle perhaps that may be an issue at power levels that high. ARP mainstuds would certainly be in order.

[dskopek]

I ran a early 2.8 with a blower at about 11 psi and I took out the #3 rod and crank journals 2 times, the 2nd time did break the crank. This was with the early small main crank. I redid the motor with a newer large journal crank and made about 325 HP and 7000 RPM. I am now building a twin turbo 3.4 and it has a lot more meat in the block and in the crank. I'm looking to make about 450 HP and I don't think I will have any problems other then maybe head gaskets.

[geoffinbc]

If you want some added security start with a 3X00 block and then get some extra long ARP studs and strap the center caps or build a girdle to fit. But until a block breaks with proof there was no detonation then no one here really knows the breaking point.

As for the crank, yes a shorter stroke will be stronger with all other factors being equal. However a forged 3500 crank keeps the long stroke and introduces larger rod bearings for even more strength.

[ALLTRBO]

Thanks for the info guys.

With me, the strongest hardware everywhere is a given.

I guess I should have clarified, I'm only talking about the later large journal crank, but it's good to know what happened to an earlier one.

A 3x00 (3400 specifically) block is what's in question. I haven't heard of strapping the center caps, I'll have to look that up. I was thinking about a main girdle but that's a load of custom design and fabrication. Still something to consider heavily, though, yes. Maybe I can make a few friends at the machine shop at work, hmm.

I'm not interested in the 84mm stroke, I have other reasons for the 76mm stroke in mind, the improved strength is an added bonus.
The 3500 VVT has a 76mm stroke and from what I've been able to gather, it's forged, or at least steel, like the 3500 non-VVT crank and the 3900 crank, but it also has 2.25" rod journals like they do. This doesn't work out for the planned OTS rods so I'd have to get the journals turned down to 2" (or 2.1") and re-hardened. On top of that, I'd need an external crank trigger. All of that work adds up in extra cost so if the large journal FWD 76mm crank would hold the power, all the better because there's no machining required.

I might put it all together as is (the block and crank as is, anyway) and see where these all-elusive limits are, providing they are under 650hp max. A few pistons, rods, valves and heads and the turbo might survive, lessening the cost of the rebuild.

[ALLTRBO]

BTW betterthanyou, I've been meaning to PM you but I'll just ask here in case it benefits others as well.

Are you still making header flanges, and if so, is it possible to get (3400) flanges in SS and 1/2"?

[Superdave]

I forget where but i seem to remember there being a forged aftermarket crank for the 2.8.. i know JBP sells a 84mm stroke version. Not sure where they are sourcing it from though.

I wouldn't buy it from them, it probably has a 200% markup.