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Block strength

Paul Secoy

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Hello all.. I am very near wrapping up my latest build, a turbo 400 low deck engine, and I am already wondering how far I can honestly push my luck.
I have read and learned from friends that turbo builds pretty regularly produce higher numbers at a safe and repeatable level than most power adders, but its all speculation at this point.
Anyways, I'd love to hear from, or be pointed towards anyone with some real world experience that I can draw from regarding turbo charged Mopar low deck big blocks.
Thanks in advance guys, much appreciated!
 
Really depends on the integrity of the block your'e using meaning variables such as core shift, over bore size. Should be fairly safe until 700ish hp. I know of some guys running well pass that number so they will argue it's higher. A girdle may help keep things stabile but may also cause clearance issues depending upon your set up. Your'e gonna hear numbers all over the place.
 
Really depends on the integrity of the block your'e using meaning variables such as core shift, over bore size. Should be fairly safe until 700ish hp. I know of some guys running well pass that number so they will argue it's higher. A girdle may help keep things stabile but may also cause clearance issues depending upon your set up. Your'e gonna hear numbers all over the place.
I think this is an honest and accurate answer as you're going to get.
OP please make a build post if you are able, I'd love to do a turbo build myself.
 
Accord to Wallace Calculators my sons stock block 360 with the stock cast crank makes around 850Hp uncorrected. Been together for years.
Doug
 
As with any higher HP big block Mopar the girdle is great advice. I also went with aluminum billet main caps, forged Pistons and rods. Opening up the oil holes to the main bearings is a good idea too. The bottom end is the weak spot so beef it up.
 
RB I was told 650/700 tops otherwise time for aftermarket block.
 
The 400 block has a lot more meat in the lower end than a 383 or 440 block, so that is a good start. And i think that rpm is harder on parts than boost is.
A safe 900hp turbo power wouldnt surprise me. I would NOT try to build 900hp with nitrous and a stock block.
As always, tune matters.
 
The 400 block has a lot more meat in the lower end than a 383 or 440 block, so that is a good start. And i think that rpm is harder on parts than boost is.
A safe 900hp turbo power wouldnt surprise me. I would NOT try to build 900hp with nitrous and a stock block.
As always, tune matters.
Any kind of boost isn't exactly easy on engines. Just depends on how much boost one adds to it.....but I'm with most that anything over 650 on a stock block is pushing the limits. So long as the tune is good 650 should last a good while.

Accord to Wallace Calculators my sons stock block 360 with the stock cast crank makes around 850Hp uncorrected. Been together for years.
Doug
What's the skinny on this one? If you've posted it, I missed it. Sure seems a lot for a stock block little block especially with a cast crank. I know that y'all know y'all's stuff but....man, that's wild sounding!
 
Any kind of boost isn't exactly easy on engines. Just depends on how much boost one adds to it.....but I'm with most that anything over 650 on a stock block is pushing the limits. So long as the tune is good 650 should last a good while.

What's the skinny on this one? If you've posted it, I missed it. Sure seems a lot for a stock block little block especially with a cast crank. I know that y'all know y'all's stuff but....man, that's wild sounding!
That's Dizuster's more-door 62. Hasnt been around much lately, busy personal life.
3600lb (or thereabouts) 3.55 gear, i think, ran a best of mid nine quarter, single turbo 360.
A rocketship.
Edit: also agree on boost, but with both a centrifugal and a roots driven off the crank, and the usual shock to the drivetrain of a big nitrous setup, i think a turbo would be the easiest of the bunch on the lower end/crankshaft.
 
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.550 hyd roller, 9.5-1 diamond pistons, eagle rods, Eddy heads, truck manifolds turned around backward, 750 E85 carb, no intercooler. 3.54 Dana push button 727 w/brake, 275 M/T radials. Ran it a couple of weeks ago right off the street without touching anything 9.82@138. Only has a roll bar, no cage. It'll be at Norwalk for Monster Mopar next weekend. Along with my street car since the 64 is still waiting on parts. Had this thing since 77. Been setting 10 years. Working all the little bugs out from prolonged storage. No it's not as fast as my sons. And the paint is 35 year old lacquer, a little ruff up close.
Doug
 
Ok, thank you all, I've had a really hard time finding many turbo B engine guys willing to talk much about specifics, so as I progress, I will keep you all up to date.

The engine specifics are;

Early 1973 block, I believe its the second most sought after casting, the block is square decked, align honed, and bored .040". It has ARP studs, a steel stud girdle, and has been hard blocked to the water pump holes, 1/2" oil pick up, 7 qt Milodon pan.

Steel crank, standard journal sizes, stock 3.38" stroke, balanced.

Eagle level 2 rods, rated to 1,200HP at 8,500 Rpms, checked for roundness and clearanced, .990" pins.

JE boost pistons with a small dish, 10.0/1 compression, rings gapped for boost.

Edelbrock heads, valve job corrected, guides clearanced and mild bowl porting, they flow 282 Cfms at .550" lift, ARP head studs, Cometic gaskets.

Bullet solid flat tappet cam with EDM lifters. 114 LSA, 247 degrees at .050", .547" lift, degreed.

Harland Sharp rockers, Smith Bros push rods, valve train geometry kit from B3 racing.

MSD programable ignition, MSD distributor, NGK spark plugs, #7 heat range, gapped for boost.

M1 single plane intake, dual needle and seat blow through carb, -10 fuel lines, Aeromotive A1000 fuel pump, E85 for fuel.

Starting with a Borg Warner S475 75mm turbo, but will go bigger if I need to.
 
DVW...Posted the wrong picture.
picture not matching description. Looks like a small roots 471 on a modified factory intake. Stock heads, Dual AFB's
 
That is the substitute for my racecar. I've run this with a 6V-71 since the mid 80's. Ran it on the stock block and crank for years. Now has an R block a friend donated. This is the 62 motor.
Doug

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Other than what you have listed I would have put aluminum main caps. With that short stroke and the fact the block is filled I think you are good to 1000 hp. I think the turbo will be maxed out before you reach that point. Aluminum rods would be easier on everything and give you a wider tuning window. I work with a friend who has a turbo motor. Started out as an 400 block 470 with a 98mm and is now a Indy Maxx 528 with a 106. The one thing that stands out is how NICE everything has looked when I freshened them. The pistons and bearings look like NEW every time. It has something to do with the rotating assembly being under constant pressure. There was a very good article in National Dragster from Reher-Morrison a while back and through the years they determined that Turbos are the easiest on parts, Superchargers are in the middle and Nitrous is the worst. (Besides Nitro) Hope this helps. Watch the plugs and you're tune and you will be fine.
 
Thanks! Finding anyone with turbo B or RB experience is rare! Do you have any idea how much your friends 470 made? Did he run it a lot before going to the bigger engine?

Turbos really do seem much easier on parts, and I agree with the constant pressure cushioning parts. I kept the short stroke as I figured it would be the easiest on parts, and I was going to do the aluminum main caps, but the engine shop said they weren't equipped to do them.

The turbo is rated to 1,050 HP, but I expect I will see more back pressure than I would like, and I will likely upgrade within a year, assuming it survives the little turbo, lol.
 
I know back when stroker 400s was the "In thing?" The 400 "230" date stamp prior to Oct 1971 were said to have strongest web cast for the 400 block? While 630s had the thickest cylinder walls? (So reported)

The question? 230 vs 630 on a turbo build? Sonic tests usually ends any comparison between two or more given blocks? And of course build and component quality on any sound bare block has by far the greatest chance of success. Good luck and good hunting on your turbo build.
 
The 452 B1 engine, 400 stroker with cut down 3.75” crank that was in our Cuda made just under 800 hp at 7600 RPM. Broke 1 crank, but caught it before it hurt anything, after the Cuda it then went in a Daytona drag car for several seasons until our friend sold the Daytona and we lost track of the car (in other words….engine had a lot of runs on it). Aluminum rods, no girdle, stock main caps and studs. Don’t recall the year of the block now. Only thing I would have done different on your engine is would run aluminum rods for past 1000 hp, but would think you could easily push that 1000 hp mark with the turbo, especially with filled and has steel girdle. Sounds pretty wild.
 
I don't see many turbo big blocks, it should be a neat project.
 
I don't see many turbo big blocks, it should be a neat project.
Turbo efficiency falls off as cubes increase. Thus the logic is they are better for small engine world? But the counter logic describes. "Efficiency? Who cares? There is nothing efficient about 1000+ HP in a passager vehicle?" Its about testing limits?"
 
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