I need to build a new bottom end, and instead of a 346 I've been looking at some alternatives, and wondering why there are not any more iron block 370s? It'd be no more expensive than a forged 346, but should be capable of producing signifigantly more power/torque due to the much larger bore (4.030 -vs- 3.905), kinda like the old MTI "All-Bore" motors that were popular a couple years ago. 500/480 would be pretty easily doable with a good set heads (S3 TEA/AFRs, a big cam (244/248 or similar), 11:1 compression and good exhaust, right? What am I missing here? Why NOT do this, what is the drawback involved? Anyone running a similar motor? Just thinking out loud.

Pros:
Larger bore
Stronger block for NOS
Cheaper/easier to machine

Cons:
110lbs of added weight

 

Got one right here. Its a customer car we built, C5 Vette. Haven't done the final tune on it, have to finish breaking it in. Should have numbers for you this time next week. Its 11.1:1 cr, 244/248 610/615 114 lsa, Stg III heads. Built with nitrous in mind. I'll let you know.

 

Besides the weight there is no other draw backs. In theory it should make more power, they are more stable compared to the aluminums.

 

Been there, done that! You're right Spanky that its a good combo if you don't want the cubes and have a good crank or just want to save some money. The 408 is nicer but we also do a 3.900 steel crank deal for some people too when they want even more piston top and a better crank too. If you have a good crank though there are some good combos with pistons and rods for NA or power adders and that bore. I don't even think the iron block weighs 110 more? I am almost sure its less than 80 but I will measure them again later this week.

 

It is 80lbs more than the LS1. How do i know this i have a 370 in my car. It has 400miles on it right now. It was built for boost. So i have 9.1 CR. The damn thing makes *** load of TQ.

 

if this is who I think it is, the motor is one we built.

 

iron block is 92 lbs

 

I've been running a 370 for almost two years now. I've put over 18,000 miles on it. Even through an automatic transmission and a loose converter it makes great power. If there are any drawbacks I haven't found them.

 

Ummm Gold Z arent you running that G5 cam. How in the hell are making 638rwhp with that cam. I could have swarn you had an ls1 in your car. You just put in that G5 a couple of mouths ago. Am i missing something

 

I'm running a G5-X2 cam...........a lot stouter....

 

Woops i was thinking of GoldLS1

 

It is. Tell Brad we got everything worked out, I will be driving the car this week to break it in, and take it to Durham for the finish tune late this week. Motor runs like a top. Even keeping it under 4k rpm, you can tell its got power. I'll give you guys a call and let you know what kind of power it makes.

Tom