The 400 block is considerably stronger vs a 440 block in the main web. I am a 400 block fan. IF, and that is a big IF, you can find a good one. Check for core shift and sonic check is a must. I had 4 blocks and only one I used for this build.

At 2860 lbs I have ran 5.44 in the 1/8. I have not scaled my car in years but I might be close to 2900 now. What is that, 8.60's in the 1/4? That is up in the 800's pretty good. Block filled. Steel caps and no girdle. I did have to sleeve #8 due to a crack 3 years ago but this block has been run every summer hundreds of passes since 2019....

In general, cylinder pressure drops with rpm so the same boost at 6500 is harder on the bottom end than at 8500 rpm. From what I’ve seen of the LS guys the boost targets are pretty flat, so if it drops a couple thousand rpm on a shift you get increased cylinder pressure and the stress of the rod being slowed down too. For oem stuff we have to be very aware of timing and boost at the various engine speeds to keep the engine safe, and it isn’t realistic to map a drag engine like that- they can’t be held at full load that long.

I thought force/stress on the block itself is primarily a function of weight and rpm though.

I went aftermarket block with mine just because I don’t like to gamble and I hate worrying, lol

Well bearings are here, boosted cam is ordered, and its like 15* in my garage, so gonna hide in the house for a day or two, but it looks like we are going to find out if a 400 will be ok making really good HP with a little boost.

Anyone know the weights of the various blocks? I had heard the after market Callies Hemi blocks I have are over 300lbs...What is a 400 block weight?

A Callies block is around 295 lbs and a 400 is bit over 215 lbs

Isn’t your duster for sale?

some of the later 440 and 400 blocks are a tiny bit lighter, I've seen from 210 to 225 lbs. on both blocks depending on how much crud is in the cooling passages, I think

It's ALWAYS going to be a roll of the dice. OLD production blocks, questionable casting quality, water jacket corrosion levels, can all play into the scenario. After all that there is the chance of accidental detonation if you experience a "Hiccup". Having said all this I'd still try it, you never know it might just work! No guts, no glory!!

Yes



So I am knocking about 100lbs off with the 400...Cool, the car weighs 3203 with the big Hemi...

my World iron block weighed right about 300lb with caps . Added 90lbs to Plymouth over a stock 440 block , everything from stock block was swapped to World block .

Tex

do those ls motors come with fully counter weighted cranks?

See what I mean!

We are at 1350 ft. BTW and that was with a DA of over 3,000.

We have run the stock blocks up to +700hp and if RPM is limited to 6400 or so, they live long enough for me like that.

Have you ever thought about the stress a blower puts on the bottom end through drive pressure?
Dragging 100+ hp off the crank snout can lead to a bending moment in the crank. It will use the front main as a fulcrum. That increases the stress on the second main with it trying to keep the crank from flailing about like a jump rope.

Roots blowers put massive loads on cranks. Centrifugals are a bit easier on them but still have significant loads.

Think about the belt tension alone. Guys keep wrapping those belts tighter and tighter without thinking about where that load is going.


If you're going to push a stock block you're much better off going turbo.

f you're going to push a stock block you're much better off going turbo.
I've heard this before, my current 230 block has held together at 792 HP @the crank.

I am a little worried....So going to keep it mild if I can...The direct gear drive ones are nice, but I can't fit one.

And at this point with what the chassis updates are going to cost me, it might not get a blower, or I might leave the Hemi in it.

Just think what you could get out of it with a turbo.

It's not as much the stock block, but a good tune is what will help make the stock block live.

agreed, but after seeing cap walk in my megablock 528 and seeing it go away when i bought a fully centerweighted crank for it, i am sold that is a big help, along with light rotating assemblies, and moderate rpm.

That's the plan