Hey guys I happened on a killer deal on a gently used ($1200) LSX block from a ARCA race team, I’m would like to build this up on a budget. I was wondering if the L8T rotating assembly could be used in the LSX block? Don’t really have $2500-3500 to spend on a new rotating assembly so I’m looking at good used parts from my pick and pay. Any help is appreciated

 

The LSX block is dimensionally the same as an OEM LS block, as far as bearing journals go, bore spacing, etc. Now you’ll need to do your homework here on your LSX block and find out if it’s a std deck height, what the cylinder bore is currently, and especially the cam bearing diameters. Circle track (endurance engine builds in general) engine builders like to bore the cam bearing journals oversize so that a bigger base circle cam…with larger journals obviously..be utilized, which makes for a more robust valvetrain foundation. Often times roller cam bearings are used there.
In a nutshell, the L8T crank will absolutely fit as long as your block hasn’t been modded for different main bearing diameters. That’s another circle track engine mod that reduces bearing temps and adds life to the narrow bearings that often get used in endurance engine builds. If you don’t have the means to properly measure all of these areas, take it to a shop and have them do it for you. I wouldn’t purchase anything before verifying exactly what will work in that block.

 

You will have to clearance the center bulkhead for the 8cw crank. Not a big deal, but it needs to be done.

 

Good to know Dave!

 

Those one of them 4.180 bore blocks I've seen on marketplace?

LSX is just like the Gen3 blocks and as Dave said needs the clearance, I think the only ones that don't require that are the Gen4 aluminum and the Dart SHP Pro for CCW.

I'm not sure if MAST is still advertising their rotating assemblies for the L8T as they had custom pistons for that setup. You'll need to know your deck height as that can then lead you to your piston/rod selection as you can go with a 6.125 or 6.200 as well as a 4" stroke piston that are plentiful (based on CH height). Based on a 9.230 deck you'd be looking for a 1.176 CH with a 6.125 rod and 1.101 with a 6.200 rod. Both Wiseco and Diamond have shelf pistons really close to the 1.101 CH so knowing the deck height will tell you if they are going to be in the hole or out.

 

L8T cranks tend to need Mallory for balancing with aftermarket rods/pistons. Add the cost of that into your math to see if its worth it.

 

I think Mast stopped with the L8T rotating assemblies. Which is sad, because that was a deal for what it was. They did not really advertise them much so it never took off. That and there is a few added costs like 8 bolt flexplate, iron block clearancing, etc that all add into the equation.

 

yea the 8 bolt is the deal breaker id say.....sucks if you already have a clutch thats broken in and you like to have to get a new flywheel or clutch kit.

 

A buddy is building one for boost, he got the crank and pistons from Scoggin Dickey. I'll post some updates in here once he's farther along in the build.

 

I talked to Mast recently regarding a L8T rotating assembly and they still have them. I ended up going 3.9 stroke so I wouldn't have to spend another $7-800 on a 8 bolt flywheel.

 

Aside from the added 8 bolt crank flange out back added expense the L8T is a very nice crankshaft.
Molnar makes a good 6.2" rod that will work just fine with that crank. Depending upon what your build will be you have a ton of options for pistons as long as it isn't some unusual bore size.
RaceTech will make custom pistons for a pretty reasonable price.

 

The L8T rotating assembly, being a part designed for a truck application with a more specific stroke and rod length, might not be the best fit for the LSX block without some modifications. The LSX block is capable of handling higher horsepower and built for more aggressive builds, so it typically requires a rotating assembly designed for performance (stronger forged parts, etc.). The L8T's stock parts are not likely to offer the strength or performance characteristics needed for serious power builds, and there might also be some fitment issues, especially with the pistons and crankshaft dimensions.

If you're trying to stick to a budget, looking for used performance parts is a good option, but keep in mind that using a rotating assembly that isn't designed for the LSX block might compromise the engine's performance and reliability. A better route might be to find a used LS3 or LS7 rotating assembly, or something from a similar high-performance platform that fits the LSX block’s specs. Alternatively, you could look for a deal on a forged rotating assembly that’s designed for higher power levels while still being budget-friendly.

Overall, it’s possible to use the L8T parts with the LSX block, but it may not be the most optimal or durable choice for a high-performance build.

 

It sounds like CURRENCY is a bot so disregard any info posted by "him". Multiple people have made 2000hp with a stock L8T crank so that isn't a weak link.

 

Hes not a bot. I looked through his posts right as he posted this response here to see if he was a bot. I do disagree with his info here, as do you and others, but everyone is entitled to their opinion I suppose. Fwiw, the L8T assembly is incredibly strong for an OEM setup.

 

A buddy is doing a L8T crank, LSX block, with probably ported CID heads, turbo combo.

 

I am seriously considering doing the same with my LSX block in my AMX. I want to go 8-71/10-71 screw blower, though. The L8T crank is the only reasonable way to go strength per dollar. The connecting rods are going to be pricey, though.

 

I wonder if the PWR ADR 6.200" rod would be heavy enough to avoid needing Mallory in the crank to balance it out.

Pairing a 6.2 rod with a 1.115 piston would be just about perfect.

 

You could always get the PWR ADR Plus rods which are even heavier.

 

I think my buddy bought Speedway Oliver rods, I'll ask him and how much. He's looking to make 1600hp.

 

That's not how that works, the heavier the parts the more Mallory you will need. It' been said these cranks are around 1700g (most aftermarket LS cranks are around 1800) bobweight which will be really hard to get any high power rods/pistons without adding Mallory. You could probably do a NA deal with Mahle pistons and a light I or H beam rod and not add weight.