Just like the title says, im just wondering i read somewhere that with all APR 600+hp with a 2 bolt main block... true? i know that 500hp pertty much max for a 2 bolt or so i heard....

 

I dont know if i would even want to go up to 500HP on a 2bolt, not saying that they wont handle it but i wouldnt do it.

You can pick up a used 4bolt for very cheap or a already machined block for a fairly descent price so why chance it?

 

j/w nothing important, and what if one used 4 bolt main caps....
iv heard many things saying that it weakens the block or makes
its stronger....

 

I'll tell you, if you tell me how long is a piece of string?

I/e you can build a motor to make 500 HP for a day, or forever. You can build a motor to sustain the 500 HP output consistently, or intermittently.



Now how long is that piece if string?

 

are you responding to my 4 bolt main cap question....

 

I'm responding in general as to what your end goal may be.

i/e you can build a 500HP motor to putt around on the street for months at a time and dsust a fe wcars here and there without doing a whole lot nore than inserting parts...or you can build a 500 hp motor that will see 8-10 bracket races aweekend, that will need more than stock fasteners, etc. You may want a 500 hp motor to run ovals on a weekly basis....

FWIW as far as mains, it's pretty widely known that a two bolt block with splayed caps, is stronger than a factory 4-bolt block.

But do you need it? Some want the "best of the best", some want to get by and have fun, then there's the old timers that think factory Mopars could top out over 200MPH

 

well i dont have a goal right now but like i said i was just woundering thanks for your replys tho

 

i'd spend more time, and money, making sure the parts are flat, straight, round, square, etc. than the number of bolts in the mains and then the block and everything else will be able to hold and live with more HP.

 

there is no max number that a 2 bolt can take. there is no max number a 4 bolt can take. when they come apart, they are just broken. people have ran well more than 500hp in a 2 bolt block and had it survive just as people have had 450hp 4 bolt blocks that had a failure. the main caps are rarely a cause for the failure. i'm not sure why the question though since you already stated you know that 500hp is pretty much max for a 2 bolt. you must be an expert on the issue already.

 

Its like every engineering class you take. The teacher hands out a box of paper clips and follows by telling everyone to bend that paper clip till it breaks. Each person is required to write down exactly how many times it takes to break. While there is an average of how many times a paper clip takes to break you will have some paper clips break sooner or longer than others. If you apply this reasoning to engines it will give you an idea of how much a block will take. While some will withstand 500 HP and beyond while some will not even get close. So by taking this into consideration by applying a safety margin you would be better off keeping the power below this threshold if you want the engine to last.

 

Alot of it depends on how high you are going to spin the engine to make the power too. A 500 hp 350 that is spinning to 7,000 rpm is going to be alot harder on the bottem end than a 500 hp 400 that is only spinning 5,500.

 

im not, like i said so i heard....

 

Twice the distance from the center to the end.

 

The strongest is a splayed 2 bolt main. so splay it for 4 bolts...

 

Yes.

Since the question was answered, a particular 2-bolt main SBC can handle 696.46HP.

Another one cannot.

 

how many rps you looking to turn?

 

From what I've read, a 2-bolt should not be used if power levels are over 450 hp, even with ARP hardware. I seriously doubt any 2-bolt could handle 696.46 hp for any substantial amount of time in any event. I've also heard that there are kits available to convert 2-bolt mains to 4-bolt. I personally would never bother with a 2-bolt block, since 4-bolts are so cheap and readily available.

 

A two bolt converted to a 4 bolt is called a SPLAYED 4 bolt. The two outer bolts are drilled and tapped at an angle by the machine shop. These two bolt blocks, when SPLAYED, are stronger than 4 bolt blocks. Do not count two bolts out though, I have seen them run 10's. Generally you will have a block failure (Crack) before anything else goes.

 

You can also put 4 bolt caps on without splaying.

 

I use a 2 bolt with ARP main studs and put out about 350hp and 500TQ at the fly since mine is still a LTR setup. I spin to about 5500. I had EVERYTHING included when I had it balance and I chose to have it internally balance for better perfeormance.

 

I have 30k miles on a small journal 2 bolt 327 with the stock tiny rods and FORGED pistons on them, that I routinely spin to 6500 on the street (it has a lot of cam for a 327, cam card says the cam is good 2500-6800). I had the motor apart last week and there are no signs of cap walk, all bearings looked new. This is the weakest bottom end you could get in an sbc and it is throwing heavy pistons around at a lot of r's, no problems yet.

 

Thats pretty impressive, seems like most people on this site are having alot of success with the stocks cranks. Did you touch the crank when you put in the new pistons (have it cut, micro-polished, or at least new bearings)? I haven't really done to many mods to my car yet because I wasn't sure if the stock bottom end with 84k miles could handle high levels of power.

 

When the motor was built 30k miles ago everything was done -- crank ground, obviously new bearings, etc.