Limit of stock crank & 2-bolt mains?...

Hey guys,

Here are the details of my set-up:

-350 ci. LT1 block - 24,000 miles when taken out - inspected and re-honed
-STOCK crank - 24,000 miles when taken out - inspected, polished, magnafluxed - and re-used.
-Stock 2 bolt mains
-SRP -24CC forged/dished blower pistons. Compression at around 9.1
-Eagle 6" forged H-beam connecting rods
-All bearrings, rod bolts, etc. are of very good quality and the shop that assembled my shortblock really knows what they are doing with clearances, etc.

I am currently running around 9 lbs. of non-intercooled boost making a tad over 500 RWHP (Reving to 6500 RPM) on a Vortech S-trim for about 2 years now.

**QUESTION: Is this about the limits of my bottom-end. Or can I increase the boost a little along with methanol injection or add a small nitrous shot? Some have told me to enjoy it as it is - but some have said that I can easily get more out of it. I want to get the most I can out of it, while hopefully not blowing it up right away. I have been enjoying it "as is" for about 2 years now.

thanx in advance for your responces....

Call me crazy but I would say max 650 with studded mains at least on the stock crank. But if I were you I would get splayed 4. Never heard of a crank breaking due to too much power but not saying it won't happen either.

I wouldn't dump nitrous on it though only more boost and then get a great tune.

p.s. a lot of other parts will start breaking before the crank will i.e. rear tranny etc.

Kiel, did you use ARP main studs on the rebuild? The vast majority of blown LT1 guys over the years have had no problems with 550-600rwhp and 2-bolt mains/ARP studs. There are a handful that have made significantly more without problems. If you are on stock main bolts, I would be a little more cautious on pushing too much more than where you are at now.

Jason

I don't think I've ever heard of anyone breaking a stock LT1 Crank before or breaking a Main bolt or cap. I've heard of people breaking the snout off but you shouldn't have to worry about that unless your using a cog setup.:)

Yes - I did use ARP main studs on the rebuild.

Plus - I figure with the 6" rods, this makes the rotating assembly much lighter due to the decreased piston mass. Which means there should be less stress on the crank and mains. Especially when only spinning to 6500 RPM's.

So I guess I will try to throw a little more boost at it......:)

Throw a water injection setup on it with more boost since you dont have an intercooer.....then it will get real fun :) But before you do ANYTHING, you definitely need to put a 255lph intank pump in the car...not just the "inline" one. You will go lean. I would also think about doing a dual 255lph intank or a single 255lph intank+a Boost-a-pump.

Jason

Cars like yours make me happy. Its good to see someone with a pretty nice setup without going all out. Keep us updated on what you do.

I am shooting for a similar power range if the turbos are not too small. If they are screw it and Ill do 500hp and 800tq

My motors gone 30k with the stock crank/2 bolt mains making 450-500rwhp so keep on truckin!

Cool :D

Thanks for all the replies guys....

I know its an old post but I would like to see if they lasted. How did eveyone make out with the 2 bolt mains. Anyone have bottom end failures or problems.

Im thinking of staying with my 2 bolt. My car will not see track use. 500-600whp with a D1SC 383 .

Mine was still holding up. Sold the car a couple of months ago.:)

My motor is apart now. 600ish rwhp 700tq for something around 4k miles. The main bearings look great, the caps/registers show some spidering and have moved some.

For what it's worth I'm going 4 bolt this time to be sure. Adding another 200hp too though. Lost 3 pistons - ringlands on srps just like I was told would happen around 600hp if you want to know the cause of failure.

My motor is apart now. 600ish rwhp 700tq for something around 4k miles. The main bearings look great, the caps/registers show some spidering and have moved some.

For what it's worth I'm going 4 bolt this time to be sure. Adding another 200hp too though. Lost 3 pistons - ringlands on srps just like I was told would happen around 600hp if you want to know the cause of failure.

Same deal here. Ring lands warped with the SRPs at ~600rw. No dyno proof but went 135mph most times (best 137) at 3850 lbs. Too much heat.

FWIW I had ARP studded 2 bolt mains and a cast crank. Crank is fine and the main bearings looked fine. No walking of the crank. I am going to a 4 bolt this time around for peace of mind. I've had that motor together since 2002. 8 years in not too bad. Could have lasted longer if I didn't have 2 meth failures.

Meth? Whats that? :)
Air to air and pump gas here.

Meth? Whats that? :)


An addictive drug made of common household substances, but being from the midwest region, you should be familiar with it (i.e. hearing about it a ton). :o

An addictive drug made of common household substances, but being from the midwest region, you should be familiar with it (i.e. hearing about it a ton). :o

:lol:

ARP main studs would be a safe bet with 500rwhp for most street engines. At some point based on rotating mass, rpm, detonation, the two-bolt caps are going to walk around and cause problems. Two studs and stock cap surface area just can't provide enough clamp load for the 'next step' decision most of us are faced with :D

-Scott.

Kinda just started my venture so I cant say for longevity, but it definitely puts out some power. Just got her back together after blowing both head gaskets. I used arp main studs (2 bolt). Ive got a small meth kit, need to upgrade to a larger pump and maybe 2 nozzles. I would think you're closing in on the failure point, especially without a way to cool the charge, but i dont think it will be the crank. I would not up the boost anymore until you decide on a cooling method first. Ive read a small shot of nitrous actually works pretty good. Ive got a 75 shot setup on mine now but haven't tried it with this setup.