I have a new GM lt1/lt4 4-bolt shortblock, this was the marine short block provided by GM. I'm currently using the same type of block in my hot-cammed SS.

I'm building an engine for American Iron.
From what i understand this has all the LT4 bottom end components, would it be safe to say that this block could rev to 7k reliably? With the proper combination of peripheral parts of course.

I'd also would change the rod and main cap bolts to ARP if that would help

 

I have revved 2-bolt Gen-I blocks past that point.

If you want to rev high, your bottom end must be optimized. That means balanced, reasonably lightweight, chamfered and cross-drilled crank, scraper, line boring, zero-decking, etc.
Quality components are also important.

Provided the bottom end was properly prepped, i would not think twice about revving an LT1 well past 7000 rpm.

However, if you want to go that high, you're going to run into other problems, the computer system being the first. I'll let others who are more knowledgable of the specific issues take it from here.

 

thks for the input. I just want to make sure my bottom end stays together and be very reliable (at least a couple of years of racing), with a 7000-7200 peak redline. Engine will be in the 3500-6800 rpm range. I have good idea of cam / head stuff and inectors. I might be using an aftermarked ECU such as FAST or Electromotive. MOTEC would be nice tho $$$. I'm really after some decent reliablity more so than total all out extreme hp and Revs.

 

If you are talking stock rods, rod bolts and pistons as well as crank, two seasons of racing with 7000 redline sounds iffy to me. That stock stuff isn't very light, and 7000 is a lot.

What heads are you using for power in the high 6's?

Here's a thread about an Auto-X 3500-6500 engine with stock innerds. It might be of some interest:

Stock internal Auto-X engine with camshaft change

 

Thanks! I read that thread a few days ago. I've been in communication with LLoyd Eliot for the heads and cam package, I'm just weighing my options on the bottom end. I would not be shifting at 7k just a little fat beyond 6800 with the 3500-6800/6500 range road racing

 

I have a stock GM Lt1 shortblock I bought off of Ebay that came with 4bolt mains and I dragrace but I have turned it 6800-7000 a couple times w/o issues (knocks on wood). I raced it this weekend on saturday and Sunday never shifted under 6500rpms. I even sprayed it for 5 passes to 6300rpms and ran 5 10sec. passes so it's pretty tough.

 

Thanks looks like i'm going to use it. It's going into a dedicated race car so if something breaks, It wont have to be running by monday like the SS.

top car


inside

 

Just curious, you do know you're limited in 9.5lbs per hp in AI right? Unless the car is pig heavy it sounds like you're going to end up making more power than you can use (legally).

If you want to run AIX then disregard what I just said

 

I'll be running AIX , just speakin of american iron genericly .... I might as well cost for engine build comes out to about the same Plus i'll be running other classes such as PS-0 for Profesional Autosports and SCCA ITE, etc...whenever ... whatever... time and budget