cgarb wrote: ↑Wed Sep 19, 2018 12:41 am
I bought this part for my SBC, its cast out of aluminum and it ties both heads together so that the block wont flex...its called an intake manifold.
Then why doesn't the intake manifold keep SBC engines from cracking along the camshaft tunnel down through the mains under severe horsepower applications? The block cracks in two like an egg!! I want to say that I would be on barrowed time if I made more than about 750 hp before a 1st Gen. SBC block cracked into two pieces.
I'm thinking along the lines of 12 to 1500 hp here by blowing it!! I'm reading about all these LS- engines making this kind of hp so I would like to do the same thing with a 1st Gen. SBC engine. Using either one big or two smaller, matched, turbochargers here..
pdq67
Then buy an aftermarket block instead of messing around with 40 year old oem crap!
cgarb wrote: ↑Wed Sep 19, 2018 12:41 am
I bought this part for my SBC, its cast out of aluminum and it ties both heads together so that the block wont flex...its called an intake manifold.
Then why doesn't the intake manifold keep SBC engines from cracking along the camshaft tunnel down through the mains under severe horsepower applications? The block cracks in two like an egg!! I want to say that I would be on barrowed time if I made more than about 750 hp before a 1st Gen. SBC block cracked into two pieces.
I'm thinking along the lines of 12 to 1500 hp here by blowing it!! I'm reading about all these LS- engines making this kind of hp so I would like to do the same thing with a 1st Gen. SBC engine. Using either one big or two smaller, matched, turbochargers here..
pdq67
The LS engines have a MUCH, MUCH stronger block. There is a LOT more metal in the webs as well as in the valley. Hell the valley is a full perimeter type and the heads close in the valley with a third row of bolts. Structurally speaking, the SBC looks like a cardboard box with a side missing, and the LS looks like a box that has had a hole cut in one side. Large difference in valley strength alone, and this isn't even where the main "foundation" of strength lies.
It's been a while but IIRC an "iron LS" bare block weighs more than a Mopar RB.
I have ran my share of OEM blocks and I know the risks. No bolt on part will fix those shortcomings of an inadaquate casting. It's like putting a band aid on a compund leg fracture. If my plan was to make big power from the beginning an aftermarket block would be the start of the build period.
cgarb wrote: ↑Wed Sep 19, 2018 3:09 pm
I have ran my share of OEM blocks and I know the risks. No bolt on part will fix those shortcomings of an inadaquate casting. It's like putting a band aid on a compund leg fracture. If my plan was to make big power from the beginning an aftermarket block would be the start of the build period.
I think you are correct but for more modest power increases a girdle is a good idea in many cases. When people tell me they are building a KA24DE I generally ask them if they are turbocharging the engine or have plans to. In that case they should leave the arms in place. If not I tell them about the experiences of racers that have cut out the girdle arms.
About 45 years ago when Porsche was developing their all alloy V8 with a bedplate their durability testing caused the initial bedplate design to fail. The redesign for strength passed the durability testing (thousands of hours) but created some unfortunate oil control issues. Engineering is full of compromises.
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It all boils down to clamp load of the fastener. The caps will walk if the clamp load isn't up to task. A good quality stud will do more than a girdle bolted on there...it just adds to the problems for the most part. The problem with the block splitting in the cam tunnel area...nothing you can bolt on the mains or on the valley area is going to be a "fix" for that. It may make the end user feel better, but that's about it.
Yes that all makes good sense. When you look at all the old small block engines the original criteria was likely for 550 hp max. Now a days 1000 + is not far out there with heavy nos hits and turbos. The strength of new blocks Are very impressive in terms of what they can handle.
