**600hp sbm block limit? Or is it bs!!**

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pink340swinger said:
I had a 1970 340 block that I raced and it eventually made 602 HP on the dyno. I ran it for several years until the main webbing literally split the block in half! It had 4 bolt mains installed and all the other tricks done to it but it just could not handle that power run after run. It did run 9.50s @ 138 MPH shifting at 7900 rpm. 3.58 stroke crank in it. Naturally aspirated. I had a lot of passes on it over the years and refreshed it every year at the end of the season. It started out with W-2 heads and then W-5 heads which made way more power and it only lasted for 40 runs when I went that route making 602 HP. I have since went to an R3 block W-9 heads and have never looked back.
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Maybe the rpm of 7900 was the real killer, bob weight, timing, etc.
 
Supershafts said:
I never used a stud girdle and put in 400hp on 2 stgs, i have broke cranks, pushed out gaskets, but not the block using n2o, but i leave off idle on the system and that seems to play mayhem on the bearings which will make them need changing more often.
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If i understand your post, you leave off idle with nitrous flowing? If so, the cylinder pressure would be through the roof. A 100 hp shot at 2600 rpm adds over 200 ft lbs torque at that rpm, and the horendous cylinder pressure to create it. No wonder there has been mayhem!
 
I would love to bend the ear of an engineer that understands crankshaft balance and the value of a fully counter weighted(ccw) crank and how much stress it takes away from the block due to rhe outboard counter weights no longer having to balance out the center cylinders. I noticed in my 2432 bob weight 4.15 stroke megablock that the difference was enough to eliminate cap walk and fretting at 850 hp and 7200 rpm
So how much could it extend the life of a stock smallblock casting? My WAG ( WILD ARSE GUESS) is maybe another 150 to 200 hp, given the rpm didn't go a lot higher? Then block life might be limited by cylinder wall strength, and head gasket sealing?
 
gregsdart said:
Maybe the rpm of 7900 was the real killer, bob weight, timing, etc.
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The engine was originally designed in the 1990s for that rpm range based on what was standard practices at that time. 372 cubic inches, splayed 4-bolt mains added after cap walk was found during freshening, tubed lifter galley, W2 heads, Holley Pro dominator tunnel ram, two 750 Holleys, long ford 6 cylinder steel rods, welded truck crank 3.58 stroke, balanced, o-ringed, etc, etc. Doug Nash 5-speed and a lot of fun buzzing it. Eventually aluminum rods, better heads and more power split the mains out of the stock block. Made a lot of passes before it let go but knowing what I know now I would just buy a race block regardless of what rpm I want to run. On a side note, every time I build a smaller engine my car goes quicker and faster. Running a 312 cubic inch motor shifting at 9800rpm now and would never consider racing anything that needed shifted below 8,000rpm.
 
pink340swinger said:
Running a 312 cubic inch motor shifting at 9800rpm now and would never consider racing anything that needed shifted below 8,000rpm.
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What's that making ? 700+ hp ?
Is that like a 4.10" bore and 2.96" stroke ?
 
So 750hp is the new 600…..
to be honest you rarely hear about block issues with the LA. Our old 340 block served us well until the Eagle rod exited. Mains looked like new when it expired just short of 200 passes.… but it led an easy life. My dad short shifted it for most of its life as the car wasn’t 9.99 legal. Think he was shifting at 5800. We ramped it up to 7200 one time and it clicked of a 9.7. Prob was 9.5s in it if the damn W5s wouldn‘t have broken our hearts. Our block was 1/2 filled and we did run aftermarket main caps.

IMG_0610.jpeg
 
I can speak to one high-HP late model magnum block and crank. These both have seen solid 850HP via single blow-thru turbo. (9.5x @ 3700lbs) Alas only a few times at that power level but a know a good number of runs at 7-750. It's melted a few pistons in it's time but the block and crank are still good.
 
What head gaskets are you guys using with the turbos? Any problems with blowing them out? Not much clamping force at that level without the extra head bolts that the aftermarket blocks have.
 
There was someone on moparts who claimed magnum blocks had more material in pan rail and main web and even had comparison pics. Also believed they had a better nickel content. I’m building a 650ish hp motor with a 98 magnum block and billet aluminum main caps. Block passed sonic check.
 
1bad360duster said:
There was someone on moparts who claimed magnum blocks had more material in pan rail and main web and even had comparison pics. Also believed they had a better nickel content. I’m building a 650ish hp motor with a 98 magnum block and billet aluminum main caps. Block passed sonic check.
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Neither is true. The iron content is the same as any other block and the only production block that had filled pan rails is the TA block.
 
1bad360duster said:
I found the thread showing photos of pan rails and weights of a bunch of la vs magnum blocks. Take a look, decent amount of samples
Stock SB block info
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Is the first picture that comes up indicative of all of them, because that’s not a filled pan rail from what I could see in that picture. Plus it needs to have the main bearing bulkheads filled in and I couldnt see from that picture.
 
There’s one attachment showing a typical la pan rail and another attachment a couple post down showing a magnum rail. While not a race block I definitely see a difference between the two
 
Magnum looks slightly beefier, but not night and day stronger.
 
bigfoot said:
Magnum looks slightly beefier, but not night and day stronger.
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Yea, I think so too, slightly more material from bottom of bore to pan rail. Guy who posted pics had quite a few samples so I’m assuming this is how most of them are
 
1bad360duster said:
Yea, I think so too, slightly more material from bottom of bore to pan rail. Guy who posted pics had quite a few samples so I’m assuming this is how most of them are
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I know my 2002 360 block looks like the one posted above.
 
I know this engine from engine masters comp has been posted as well. They believed magnum blocks are better as well. Who really knows but interesting theories. Crazy thing is they bored this one .100 over. But dyno engine only

IMG_3101.jpeg
 
9secRR said:
What head gaskets are you guys using with the turbos? Any problems with blowing them out? Not much clamping force at that level without the extra head bolts that the aftermarket blocks have.
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6428E714-1AB3-4EC4-9676-88C7FCD36B5B.jpeg

I run SCE Pro Copper head gaskets.
My heads are O-Ringed with receiver grooves cut in the block.
 
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