What is the HP/TQ limit of 2 bolt main LT1 shortblock?
09-06-2009, 04:04 PM
#41
I fail to see where splaying them improves any of this.
09-06-2009, 07:10 PM
#43
I think consensus is that you'll run into limitations of the ECM and stock CID before you over-power the stock bottom-end NA.
09-07-2009, 11:46 AM
#44
TECH Apprentice
Lol ok.. Splaying them would require less clamping force to have the same or more holding power. Man thats the whole point. Just think about it you spread the load acrossed a greater span of material when you throw shear in the recipe. If you think about it you are putting compressive loads on the material on either side of the bolt, as opposed to trying to pull it apart with a bolt thats strait. But hey, you believe what you want to believe. And im sorry to the OP about the thread getting astray from the topic. Im done with this thread.
09-07-2009, 08:10 PM
#45
Lol ok.. Splaying them would require less clamping force to have the same or more holding power. Man thats the whole point. Just think about it you spread the load acrossed a greater span of material when you throw shear in the recipe. If you think about it you are putting compressive loads on the material on either side of the bolt, as opposed to trying to pull it apart with a bolt thats strait. But hey, you believe what you want to believe. And im sorry to the OP about the thread getting astray from the topic. Im done with this thread.
09-07-2009, 09:57 PM
#46
TECH Apprentice
well i mean the block is what contains all of it. Its the block you are clamping everything to. None of this will really cause an instant failure given a sound engine to work with, but can cause premature failures of other pieces. It just boils down to how long a engine can run at a given power level without killing bearings. If you are seeing fretting then that means your making enough power to stretch the main bolts and cause the caps to walk. It wont cause a instant failure so to speak but campared to if they were perfectly stable (which is unlikely at your power level in a small block) then it might cause the bearings to experience some more pain. Im not saying splaying the mains will totally eliminate fretting at extreme power levels but it can prevent some of it. The only way to somewhat solve that is pinning the mains, and even then ive seen some fretting on some big inch big blocks and anything making extreme torque. I see you got saving the block and saving the crank in parenthases. Well the block is the foundation of the engine. Without a sturdy block then it could inflict demage to the crank and if the crank is the weaker link then it will be the first to break, and not be the root cause of the failure. When you bolt an engine together it has to all work together as a whole.
09-07-2009, 10:50 PM
#48
09-08-2009, 06:16 AM
#49
... boils down to how long a engine can run at a given power level without killing bearings. If you are seeing fretting then that means your making enough power to stretch the main bolts and cause the caps to walk. It wont cause a instant failure so to speak but campared to if they were perfectly stable (which is unlikely at your power level in a small block) then it might cause the bearings to experience some more pain. Im not saying splaying the mains will totally eliminate fretting at extreme power levels but it can prevent some of it. The only way to somewhat solve that is pinning the mains, and even then ive seen some fretting on some big inch big blocks and anything making extreme torque. I see you got saving the block and saving the crank in parenthases. Well the block is the foundation of the engine. Without a sturdy block then it could inflict demage to the crank and if the crank is the weaker link then it will be the first to break, and not be the root cause of the failure. ..
If keeping the main caps firmly in place on the block is the challenge, then I still can't see any mechanism on a splayed main that accomplishes this. Side-to-side stability is already taken care of by the register fit and stretching the main bolts is directionally worse with splayed.
I could make a case for increased block strength with splayed, but most will see main cap stability issues before they ever crack a well-prepared block.
Mike
09-08-2009, 09:06 AM
#52
Both splayed and straight 4-bolt will support more power than 99% of the people who use them, so you need not concern yourself unless you're in the 900+ hp range.
Last edited by engineermike; 09-08-2009 at 09:20 AM.
09-08-2009, 09:23 AM
#53
Originally Posted by engineermike
I think consensus is that you'll run into limitations of the ECM and stock CID before you over-power the stock bottom-end NA.
09-08-2009, 11:49 AM
#54
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I think a lot of folks are applying what they heard about gen 1 blocks to LT1 blocks which are a different casting.
Lots of blind bench racing going on without any regard to what ACTUALLY WORKS. Which is absolutely perfect because that is all the OP cares about, bench racing.
Lots of blind bench racing going on without any regard to what ACTUALLY WORKS. Which is absolutely perfect because that is all the OP cares about, bench racing.
09-08-2009, 12:27 PM
#57
TECH Apprentice
I agree that keeping the mains stable is the primary concern here, but your previous statements about putting the block in compressive stress will do nothing for that. It may do something to prevent block cracks, but nothing for main stability.
If keeping the main caps firmly in place on the block is the challenge, then I still can't see any mechanism on a splayed main that accomplishes this. Side-to-side stability is already taken care of by the register fit and stretching the main bolts is directionally worse with splayed.
I could make a case for increased block strength with splayed, but most will see main cap stability issues before they ever crack a well-prepared block.
Mike
If keeping the main caps firmly in place on the block is the challenge, then I still can't see any mechanism on a splayed main that accomplishes this. Side-to-side stability is already taken care of by the register fit and stretching the main bolts is directionally worse with splayed.
I could make a case for increased block strength with splayed, but most will see main cap stability issues before they ever crack a well-prepared block.
Mike
09-08-2009, 12:40 PM
#58
Well its like i explain before with the nails and wood except you are basically using the tensil strength for clamping force and the shear for stability (preventing stretching the center bolts). If the theory doesnt work then why does it make seperating 2 pieces of wood with simple nails (minimal clamping force and none when force is applied against them) much harder? Its all about the shear.
Last edited by engineermike; 09-08-2009 at 01:49 PM.
09-08-2009, 05:18 PM
#59
TECH Apprentice
Dude shear is shear whether its in a nail or a bolt. If the theory is evident with a nail which has no threads or means of clamping load its dang sure going to be evident with a bolt that has clamping capabilities. The head of the bolt stabilizes the bolt against the surface of the cap. Its not like the bolt is going to just snap when shear is evident. It has been working for many many years now. If it was going to cause a failure it wouldnt have been so popular in the performance industries. And to answer the question about what direction it supports, well the load is pounding downward on the cap. Read between the lines man i said it prevents stretching the center two bolts. Shouldve been a big clue there. Im sorry you cant look at this picture as a whole. Its real evident why it works. Shouldnt be to hard to grasp the concept. But like i said before you believe what you want to believe, meanwhile millions of engines will be assm. with splayed mains. Ive said enough, if you cant understand it by now then im not going to be any means of helping you understand the concept.
09-08-2009, 05:41 PM
#60
Dude shear is shear whether its in a nail or a bolt. If the theory is evident with a nail which has no threads or means of clamping load its dang sure going to be evident with a bolt that has clamping capabilities. The head of the bolt stabilizes the bolt against the surface of the cap. Its not like the bolt is going to just snap when shear is evident. It has been working for many many years now. If it was going to cause a failure it wouldnt have been so popular in the performance industries. ... Read between the lines man i said it prevents stretching the center two bolts. Shouldve been a big clue there. Im sorry you cant look at this picture as a whole. Its real evident why it works. Shouldnt be to hard to grasp the concept. But like i said before you believe what you want to believe, meanwhile millions of engines will be assm. with splayed mains. Ive said enough, if you cant understand it by now then im not going to be any means of helping you understand the concept.
But, hey, don't believe me with my measly 900 hp and straight 4-bolt mains. You could always asked George Baxter, who make over 1100 hp on straight 4-bolt mains.
Since I got no satisfactory response from you, I did some digging on my own. It seems they splay the outer bolts simply to tie them into a stiffer part of the casting, which prevents cracking in the block. It has nothing to do with main cap stability, putting the bolt in shear, or nailing wood, after all.
Mike
Last edited by engineermike; 09-09-2009 at 07:24 AM.