4 Bolt Straight vs 4 Bolt Splayed Theory

[JoeliusZ28]

I think splayed is stronger in theory (forces are angular as well as straight down) but the reality of what is stronger is going to depend on if the block is designed to be load bearing in that area or not. I will choose the straight four bolt for a small block but anything else i would need to research.

[1bad83ta]

guys, shear really doesn't come into effect. Most bolts like that rely on the friction force created by bolting the two pieces together, the shear strength of the bolt is just an extra bonus. In theory splayed bolts will require more force to break the bolts for the exact reason you said, the forces are on different axes.

EDIT: As long as you have four bolts you will be fine. I think in the "normal" relm of HP engines you do not need splayed mains. I would go so far as saying that this is more of a preference than anything else.

[c0ncEpT]

In theory splayed bolts will require more force to break the bolts for the exact reason you said, the forces are on different axes.

Is the issue really about the bolts breaking? Are LT1 guys breaking aftermarket bolts/studs?

[Fox Slaughter]

I have never heard of someone breaking a bolt. Unless it was like 2 bolt with like 1200bhp. A guy told me his caps on a 2 bolt started to walk at like 700whp. So drop 4 bolts in and there would be no chance of the bolts breaking or walking within the limits of a the blocks horsepower.

[JoeliusZ28]

Is the issue really about the bolts breaking? Are LT1 guys breaking aftermarket bolts/studs?

I don't have a source to cite on the topic, but the problem "I have heard" with splayed mains in LT1s is an increased chance of the block cracking. Normally on an LT1 the block is not a point of failure, and niether are the bolts/studs other than stretching.

[ThreeHonks]

I have never seen the bolts in a 2 bolt main in anything break. For 99.99999% of people this is a moot topic. I wwould assume the oems went with straight because of a cheaper tooling cost. The oems did not
engineer anything to be 3000hp capable. This is a big argument, but the question cannot e answered unless we are talking about a very specific block. It's all about the strength that the strength and thread count in the area where the fastener is anchored. You could use a 300,000psi stud is low nickel steel and get nowhere.

[JoeliusZ28]

Definitely is a moot point. but we haven't had a good arguement lately

[masterfab]

I think splayed is stronger in theory (forces are angular as well as straight down) but the reality of what is stronger is going to depend on if the block is designed to be load bearing in that area or not. I will choose the straight four bolt for a small block but anything else i would need to research.

I don't have a source to cite on the topic, but the problem "I have heard" with splayed mains in LT1s is an increased chance of the block cracking. Normally on an LT1 the block is not a point of failure, and niether are the bolts/studs other than stretching.

i feel you are correct. before you can look at bolt angle strangth. you have to look into what holding the bolts. main webs. lt1's be it 2 bolt or 4 bolt. have weaker webs. now take a 400 sbc. the 4 bolt block has a weaker web. while the 2 bolt main is much stronger. i have had luck doing both with supporting mods. if im planning on running above 600hp (I) generally start with a 2 bolt main block and the have it spayed, then run a main girdle on it. for durability reasons you have to make the supporting mods. or your throwing your money away. not doing so would be like taking a stock 350 sbc and throwing a pro fogger kit on it with nothing to support the power. this is why Dart/GM Performance/RHS/ect... companies have produced after market blocks to handle these loads. Your not just buying a new block with more options for cylinder bore diameter. they have thick decks for better clamping force. wider webs. thicker cylinder wall. and yes alot of these block are splay cap mains. and i still run main studs and a main girdle on these block. its better to over do it alittle than to blow a $7000+ engine over not wanting to spend the extra $300-$1500 mods to make it stay together.

the Question is a good one here. but its not wood useing a nail that is smooth with no biting threads in place. And understand the reason for the differances in peoples opinions here, there are always going to be differant results for every person. becouse of so many differant variances. blocks/build styles/ mods to support power/ ect...

alot of people with main problem either broke the main web out or spun bearing. or just tryed to run to much power and gave no attention to that area of the build. this topic has been a long debate for years. all becouse of differances. of couse splay isn't need if your running 450-500h or below. its a good idea for anything above. and if you go above 700-800hp weather your running splayed or straight (and i run either or) you should be do alot of extras to hold the bottom together. just my opinion.

(Ryan) ThreeHonks i have never seen the bolts in a 2 bolt main in anything break. For 99.99999% of people this is a moot topic. I wwould assume the oems went with straight because of a cheaper tooling cost. The oems did not
engineer anything to be 3000hp capable. This is a big argument, but the question cannot e answered unless we are talking about a very specific block. It's all about the strength that the strength and thread count in the area where the fastener is anchored. You could use a 300,000psi stud is low nickel steel and get nowhere.

Ryan you are very right.