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Horsepower limits of a Service Block?

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jpnjim View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote jpnjim Quote  Post ReplyReply Direct Link To This Post Posted: Feb/09/2018 at 2:42pm
Originally posted by shootist shootist wrote:

Well since the service block is ultimately a small bore 390/401 block (to my knowledge, correct me if that is wrong) I know 800-900 is easily doable in the stock setup without even going 4 bolt mains because I have done it and a few AMC friends of mine have done it. Now if you go 4-bolt then I would say 1,000 would be easily reachable without hurting the block. What I have seen on the otherhand in 401 bore blocks and I find to be the most likely weakness is the thin cylinder walls. Out of all the block damage to the heavy webbed blocks (for which I have seen) I find blown out cylinder walls the most common. I believe this has a lot do do with mold shift causing some thinner areas but that is just an educated guess. The other types of damage I have seen have been such a mangled mess it is hard to determine what exactly happened because cranks and rods flopping loose in the crankcase at high RPM tends to destroy stuff pretty well.

Anyway, I wouldn't be at all concerned with block failure at or under 1,000 HP with reasonable levels of prep which you mentioned doing. I am putting 14lbs of boost on my 401 now with a ProCharger and there are a few others out there doing the same.

great reply,
thanks!

Makes me wonder how many of the 401's with failed walls were bored +.045, +.060, or more (?).
I also wonder how much strength a std, or .010-.020 over 401 gives up compared to a Service block with 4.125 or less of a bore(?)

It's a shame that some of the others sawed themselves in half before they could tell what went wrong,
but if it was like a 302 Ford splitting in half,
or a Buick 455 spitting out the mains I think it would be obvious.

Thanks for the info,
The strength of running a Service Block seems to be worth the cubes given up, and the slightly less flow/more valve shrouding of the smaller bore.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Lyle Quote  Post ReplyReply Direct Link To This Post Posted: Feb/09/2018 at 3:48pm
I believe I read Pentske sleeved some race engines right from the start.  
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Post Options Post Options   Thanks (0) Thanks(0)   Quote one bad rambler Quote  Post ReplyReply Direct Link To This Post Posted: Feb/09/2018 at 5:06pm
I find it hard to believe that 800HP is the limit...Harmonic`s can be an issue...i never realized how much a crank flexes untill it was showed to me on a dyno with a strobe light...Several years back we were sent 3 engines to be dyno`d ...At the customers request we were asked to push all 3 to failure (Through Boost) then they could be gone trough for future improvements ...This was done on a chassis dyno...his goal was a reliable 1,200hp to the wheels out of a 3.5l Mitsubishi V6...The money spent was mind blowing 
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Post Options Post Options   Thanks (1) Thanks(1)   Quote Hurst390 Quote  Post ReplyReply Direct Link To This Post Posted: Feb/09/2018 at 5:41pm
Originally posted by shootist shootist wrote:

I know 800-900 is easily doable in the stock setup without even going 4 bolt mains because I have done it and a few AMC friends of mine have done it.

I don't agree with that. I would bet the farm your walking the cap with 2 bolt mains at 8-900 hp.
Pull it down and you will see how shiny the mating surface is on the caps and block.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Lyle Quote  Post ReplyReply Direct Link To This Post Posted: Feb/09/2018 at 9:41pm
An article on crankshafts:
http://www.hotrod.com/articles/crankshafts-how-to/
Notice picture #3 in the article and the material of the "stronger" crankshaft that has been removed.
Big "IF" someone spent the money or could order a billet crankshaft with much less mass then the current crankshafts available then I believe 1000 + HP could reliably be made. All the other pieces are there - just the missing link, my opinion. 
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Post Options Post Options   Thanks (0) Thanks(0)   Quote jpnjim Quote  Post ReplyReply Direct Link To This Post Posted: Feb/10/2018 at 4:48am
Originally posted by Lyle Lyle wrote:

An article on crankshafts:
http://www.hotrod.com/articles/crankshafts-how-to/
Notice picture #3 in the article and the material of the "stronger" crankshaft that has been removed.
Big "IF" someone spent the money or could order a billet crankshaft with much less mass then the current crankshafts available then I believe 1000 + HP could reliably be made. All the other pieces are there - just the missing link, my opinion. 

thanks Lyle,
do you mean this picture?

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Post Options Post Options   Thanks (0) Thanks(0)   Quote jpnjim Quote  Post ReplyReply Direct Link To This Post Posted: Feb/10/2018 at 4:49am
Originally posted by Hurst390 Hurst390 wrote:

Originally posted by shootist shootist wrote:

I know 800-900 is easily doable in the stock setup without even going 4 bolt mains because I have done it and a few AMC friends of mine have done it.

I don't agree with that. I would bet the farm your walking the cap with 2 bolt mains at 8-900 hp.
Pull it down and you will see how shiny the mating surface is on the caps and block.

Interesting,
did you go to 4 bolt caps at that point and did the caps stop walking?
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Post Options Post Options   Thanks (1) Thanks(1)   Quote Hurst390 Quote  Post ReplyReply Direct Link To This Post Posted: Feb/10/2018 at 4:55am
If you want to be safe? I wouldn't recommend 2 bolt mains at anything over high 600's
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Post Options Post Options   Thanks (1) Thanks(1)   Quote Hurst390 Quote  Post ReplyReply Direct Link To This Post Posted: Feb/10/2018 at 5:17am
My experience has shown me that 2 bolt caps showed signs of cap walk @ 700hp..
That was an iron headed 420 that ran 145.11 mph 1/4 mile @ 2950#

My advice would be to make the investment in 4 bolt caps...

The guys running 900 hp 2 bolt mains..what do they run and how long have they been together?

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Post Options Post Options   Thanks (0) Thanks(0)   Quote purple72Gremlin Quote  Post ReplyReply Direct Link To This Post Posted: Feb/10/2018 at 6:14am
Originally posted by Hurst390 Hurst390 wrote:

My experience has shown me that 2 bolt caps showed signs of cap walk @ 700hp..
That was an iron headed 420 that ran 145.11 mph 1/4 mile @ 2950#

My advice would be to make the investment in 4 bolt caps...

The guys running 900 hp 2 bolt mains..what do they run and how long have they been together?

I would agree. I myself would be leery too
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