I'm confused confused...time to beat a dead horse....lol

Here's my dilemma, I dropped of my block and parts today to engine builder. I'm building a 383 blower/stroker motor with Callies crank, Compstar rods, -31 dish Diamond pistons, Vortech supercharger, Advanced Induction ported stock heads, etc.. When i gave him my 4 bolt splayed main caps he said I didn't need to splay to a 4 bolt and the stock 2 bolt mains would be fine. I also am using arp stud kit for mains.

I then went to another builder in the area and he pretty much stated the same thing and walked me in the back area to show me a block area cracked due to splaying to a 4 bolt, saying to save my money.

I've searched google, this site, and others...alot of different answers, mostly older posts/topic date...

any new insights or suggestions, to splay to a 4 bolt or go with 2 bolt on a 383 blower motor?

thanks guys..

 

i'm a newb, but i've read a lot about building up motors (always wanted to do mine but never had the cash since college and rent are my first priorities ATM)

from what i've read, spinning your engine at high RPMs is where 4 bolts are necessary, with 2 bolts your caps are prone to "walk". And i'm sure it's also necessary at high power too.

 

First you should not have dove this far in without an engine builder already. They are all going to be difficult to deal with at this point because you are bringing them a pile of parts they had no input on.

Far as the cracked block, I am rather sure it was not an LT1 block, which is a BIG problem guys have with trying to built LT1s, shops want to blindly apply older knowledge where it no longer applies.

Far as the 4-bolt conversion, 2 bolt holds a LOT, 4-bolt is done much more often than necessary but if doing a blower build with good heads I would be doing 4-bolt.

 

Agreed with the above. For 85% of the "builds" on the forums nowadays, 2-bolt mains are fine. But for what you're looking to do, I would go for the 4-bolt.

 

Please don't kick me for jacking but what's everyones opinion on safe RPM's for a two bolt? I was told to keep it under 7000.

 

IMO it depends on power and rpm.
I know of well machined 500+rwhp studded 2-bolt being just fine banging the pcm's rev limiter every pass down the strip.

You have something making 700rwhp but only turning 6500, I would want to see 4-bolts and aftermarket caps.

Another thing I think worth saying is if you have the money I don't ever think it bad to go 4-bolt most of us are aiming ever higher so who knows what next year might bring. But if someone is doing a normal NA build and ruins their topend budget to get 4-bolts on the bottomend then that is a mistake. We see things like that all the time, the guys that want 4-bolts and a stroker crank but then want to cheap out on the heads and valvetrain. That is foolish.

 

My budget fell short on machine work so I opted to just do ARP studs with the two bolt. I don't think I will be hitting 500 to the wheels...this year.

 

Realistically there are stock shortblocks with upgraded hardware putting down well over 500rwhp on nitrous without a problem.

 

I really appreciate the opinions/comments. I found it weird a builder would stop me from spending the extra money...not only one but two different ones. Been waiting two years for this build...last time I think the wife will let me...lol.

 

The LT1 block is by pretty much all accounts stronger in the main webbing than gen 1 motors, but basic "street" LT1 builds also tend to make more power than the average street gen 1 build.
Shops familiar with the gen 1 motors just have a hard time adapting to the compression the LT1 can use and the power they can make. Now the gen 1 can make just as much BUT they rarely are done well enough to get there.

 

You're right about the compression thing. When most people ask me what compression I'm running (11.3) they tell me that's too much for the street. Then I have to inform them of the stock ratio.

 

Which vortec supercharger and how much boost is the pulley suppose to give? Or what planned boost you going to run?

Good combination of parts so far. I run the same internals minus the pistons, I have JE's, on my twin turbo build...was 800-850 hp, now gonna be over 1000.

With ported heads and decent cam, you'll probably push 600whp without much effort. My car made 640 on just 12 psi on a very stingy mustang dyno. Likely near 700 on typical dynojets. Even tho I'm at 400 cubes, a 383 would not be far behind that mark.

you have the powerplant to get big numbers if the blower is one of the larger ones.... 4 bolt main is nice piece of mind to have

 

going to run a lowely s trim for now...gotta save up for a t trim eventually. dont really know how much boost i'll get, going to have a 7 inch crank pulley with i believe a 3 inch blower pulley. i'll spin the crap out of the s trim for now and see what happens. i know my set up will handle more boost, i kinda want to dial things in first and then go higher boost since this is my first boost build.