2 bolt mains
06-11-2012, 04:12 AM
#4
Its really not the hp its the RPM along with big hp that does it. 2 Bolt main actually have more meater webbing to them. That is why alot of ppl like 2 bolt mains and have it converted to 4 bolt. I would say 850 to 900 hp I would really look to 4 bolt at that point. And 6500 rpm and under I wouldnt worry.
06-11-2012, 07:41 AM
#6
Its really not the hp its the RPM along with big hp that does it. 2 Bolt main actually have more meater webbing to them. That is why alot of ppl like 2 bolt mains and have it converted to 4 bolt. I would say 850 to 900 hp I would really look to 4 bolt at that point. And 6500 rpm and under I wouldnt worry.
The webbing argument is based on Gen 1 stuff not LT1.
The LT1 4-bolt main factory blocks are the same as the 2-bolt block just extra holes drilled.
Also it is NOT breaking a main you worry about it is the cap wiggling under load. I wont venture a guess as to the exact numbers but a genuine 700rwhp has to be a gamble
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06-11-2012, 08:12 AM
#8
When Gm did my motor from broken piston lands they told me that the 2 bolts were thicker than the 4 bolt...... I'll have to look up a buddy that works at a junk yard cause I want to know forsure myself by seeing it....
06-11-2012, 09:30 AM
#9
The dealership that sold my car NEW argued with me over the existence of the L99 4.3L V8 when I brought it in for a TSB back when it was stock.
Don't trust an idiot just because they work at a dealership.
Like I said the often referenced main web "differences" 2-bolt to 4-bolt are a gen 1 thing
Don't trust an idiot just because they work at a dealership.
Like I said the often referenced main web "differences" 2-bolt to 4-bolt are a gen 1 thing
06-11-2012, 10:30 AM
#10
134 mph (137 spinning) in the 1/4 mile at 3850lbs with 2 bolt studded mains and an early Scat cast crank. I keep the revs below 6200. I ran many years with this combo.
06-11-2012, 12:05 PM
#13
Of course.
Not sure what you mean there....lateral force from the bigger counterweight?
Regardless, the extra stroke (longer crank throw / lever arm) puts more prying force on the cap during the power stroke, so ANY vibration or additional loading will get you closer to cap separation/walk than in a shorter stroke engine.
Because the "balance" in a a recip engine has counterweights heavier than the opposing crankpin/rod bigend mass, there is always lateral loading on the mains. That difference may or may not be worse in a stroker, depending on rod and piston choices, and how much overbalance the builder decides to go with.
Regardless, the extra stroke (longer crank throw / lever arm) puts more prying force on the cap during the power stroke, so ANY vibration or additional loading will get you closer to cap separation/walk than in a shorter stroke engine.
Because the "balance" in a a recip engine has counterweights heavier than the opposing crankpin/rod bigend mass, there is always lateral loading on the mains. That difference may or may not be worse in a stroker, depending on rod and piston choices, and how much overbalance the builder decides to go with.
06-12-2012, 11:23 PM
#14
Ive got a set of billet splayed caps I will sell ya for what I bought em for Dont really need em since I bought an LT4 shortblock & on an LT1 or 4 theyre the same Got my LT1 & an LT4 at the shop My billet caps , factory 2 bolt & 4 bolt caps are the same thickness The mating surface is wider on the factory LT4 but the webbing is all the same thickness PM me if ya want the billet caps A sbc is thicker on a 2 bolt Thats why I never go nuts tryin to find a 4 bolt 400sbc LoL
Last edited by warriorcustoms; 06-12-2012 at 11:29 PM.
06-13-2012, 05:23 PM
#16
ya were the cap mates with the webbing But thickness of caps & webbing is the same The mating surface on the 4 bolt is wider to compensate for 4 bolts instad of 2 Only difference Had my cheap calipers on it to see if it was like the 2 bolt sbc Its not lol So if anyone wants to buy my billet splayed 4 bolt main caps PM me Id rather spend the extra 250 for some custom je nitrous pistons lol
06-28-2012, 04:53 PM
#17
Hope fully my engine last till I get another block to build. Got everything all done and just found out that I should of got a splayed motor. Dam engine builders didn't even offer me that option knowing that I was going with a blower set up and shooting for 600 to the wheels one day. Currently at 550 to the wheels at 9 psi spinning it to 6400 rpm just want the extra insurance.
