15psi into a forged 383, looking to get into the high 600's to the ground. some places i have talked to say splying it is easy, not too cheep but easy. others say there is a risk of cracking the mains or some thing and staying 2 bolt mains with studs will work just fine for my goals...whats the honest anser?

 

Yeah. $900 is what they quoted me ($500 labor and $400 parts) for a good 4-bolt splayed setup.
The OEM 4-bolt are the ones that tend to have cracking issues, not so much the splayed.

At 600rwhp F/I, it's certainly something to consider.

I recently said to someone "It seems silly to build the block to handle 1100HP when the rotating assembly is only rated to 750?"
To which he replied "It seems silly to build a rotating assembly to 750 when the block will go first!"

Not that I plan to go half-fill my block or anything, but I'm starting to rethink my initial
decision to go with studded 2-bolt mains.

Oddly enough, I did end up using the L19 rod bolts, now I kinda feel foolish for not spending the $900.

EDIT: I called the shop today, they had broken into the water jacket while clearancing for those big L19 bolt heads.
We're gonna 4-bolt and 1/2 fill it after all. Better safe than sorry.
Now I just need some upgrades so I can juice the hell out of it

 

I always like to do things big and go way overboard on things. I have a 400 RWHP car now that is running on a DAna 60.

Overkill, Yes.

Ever having to worry about it breaking, NO.

Go with the splayed mains. Do it right the first time so you can upgrade in the future if you want and don't have to worry about it then.

 

Just out of curiousity, what are you going to running at 15 psi blower (if so what brand and model), or turbo?

I ran a 383 with around 15psi through a D1 on a studded 2 bolt. held it just fine, the F/I setups are ALOT easier on the bottom end then a Nitrous setup.

But IF you do reach your goal of high 600's whp, You're kinda playin with fire. that's pretty borderline. It's up to you if you wanna play that game or not.

 

I've worked with all three configurations in drag race motors. A two-bolt main set-up tends to show ample evidence of "cap walk" in 7000 to 7500 RPM configurations. It's better with studs but there's still too much elasticity in the bottom end for my taste. I view them in the same light as a hand grenade with the pin out under extreme use.

Another motor that sees RPM in excess of 8200 with a filled block and factory four-bolt mains seems to be a lot more stable. There's are no visible signs of cap walk in this block. This one has over 200 hard runs on the block and shows no signs of distress.

The set-up that I prefer for RPM over 7000 is a splayed cap conversion. The last one I had done cost a little under $800. In this business there are no guarantees, obviously, but you pay your money and take your choice. Done correctly, I don't think you can do much better if you're keeping an LTx block.

Bottom line? Four-bolt all the way, especially if there's the possibility of boost or juice.

 

+1 for your way of thinking....
I built a 383 stroker, fully forged and splayed bottom end for my Formula and it was going to be a NA setup. BUT if I ever wanted to use nitrous it would have been ready for it... I was also gonna go with a Dana 60 rearend and I would've only been pushing 400+ RWHP.... But at least thats 1 less thing to worry about later like you said... So I agree completely...

BTW to the OP, I only paid an extra $500.00 to get my block drilled, tapped, align bored and billet splayed mains with ARP bolts...
Just depends who does the work. But I'd suggest doing it!

James

 

GTS76 that came with the OFI kit, according to jose(i do belive thats his name, if im worng please correct me) site, it should feed it just fine, most of the DD would be a lot lower, i just want ti to be able to hack 15psi and lay down some big numbers

Cnorton, if i am understanding part of what you said correctly, a factory 4 bolt will hold up better then a splyed converstion? soo if i can find a corvette 4 bolt block that would be a better investment then splying or studing my mains?

 

m6Z28,

I apologize if I left you with that understanding. In re-reading, I see that I may not have stated my opinion clearly. I have run a Corvette 4-bolt block successfully over 8000 RPM for several seasons but that block is also filled to the bottom of the water pump. It has survived but I don't think it's as good as a splayed 4-bolt. Ultimately, as long as I'm going to throw a lot of drag racing abuse at an LTx block, I'd think that a correctly filled, splayed cap combination would be the strongest. Be sure to have the caps installed before doing any filling of the water jackets.

Sorry for any misunderstanding.

c

 

got it. its gunna be a street car thats DD. talked to another local shop and they said splyed 4 bolt is the only option on the 3 main caps and adding studs on the end to make 100% sure ntohing is going any where..