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Key trick is the LsX 454 uses 6.0 rods to move the piston pin down and the piston not being pulled down as much(rings are nearer the pin) with a 6.125 rod. Oil burn Relief* done simple as the LsX block doesn't have a cylinder that is quite as long as the Ls7 more like a 6.2 cylinder length to be exact. One thing to consider if you purchase pistons. 6.0 rod Piston vs 6.125 rod piston*
The reason is that I have ran the LSX for a while now with a custom set of Mahle pistons. A rod finally gave up and I want to source a better rod for it. lots to choose from but if I can get one the same weight I will not have to rebalance.
Key trick is the LsX 454 uses 6.0 rods to move the piston pin down and the piston not being pulled down as much(rings are nearer the pin) with a 6.125 rod. Oil burn Relief* done simple as the LsX block doesn't have a cylinder that is quite as long as the Ls7 more like a 6.2 cylinder length to be exact. One thing to consider if you purchase pistons. 6.0 rod Piston vs 6.125 rod piston*
Using the 6” rods actually doesn't have anything to do with the cylinder length. It’s just to get the pin boss out of the oil ring groove. The rings still end up at the same point at BDC because the stroke isnt’t changing.
The downside to a shorter rod like that is that the crank has less room to fit a counterweight, so balancing will be tougher (ie $$$).
The reason is that I have ran the LSX for a while now with a custom set of Mahle pistons. A rod finally gave up and I want to source a better rod for it. lots to choose from but if I can get one the same weight I will not have to rebalance.
It’s going to be tough to find a stronger rod at the same weight. They usually get heavier as the strength increases.
The reason is that I have ran the LSX for a while now with a custom set of Mahle pistons. A rod finally gave up and I want to source a better rod for it. lots to choose from but if I can get one the same weight I will not have to rebalance.
I'd want to be absolutely certain what caused the rod to fail before I just put a "better" rod in it.
Rods typically have enough margin of safety in their design to prevent a mechanical failure of the rod itself.
Can you share any pics of the failed rod, the rod and main bearings from the engine, crankshaft, and any specific details of what was happening at the exact moment the rod failed?
Having said all that, here are the specs you are looking for:
GM Part Number - 19244040
Big End - 414g
Small End - 161g
Total Weight - 575g
The small end of the rod came apart. The application stresses the rod pretty good also. Marathon endurance jet boat racing. It runs for periods of up to 40-50 mins at WOT under full load at 6000 rpm +- 200 with rev limiter set at 6500.roughly 750-800hp. These rods have roughly 40 hrs on that way and finally one gave up. The particular operator when it blew was new to the sport and was coming out of the water alot, hitting the rev limiter hard alot of times. G2X data showed he had achieved 7600 rpm even with the rev limiter. The big end and bearing look pretty much new as does the wrist pin. Thanks for the info. I can't seem to get a pic loaded.
Last edited by allblowdup; 06-25-2018 at 03:29 PM.
The small end of the rod came apart. The application stresses the rod pretty good also. Marathon endurance jet boat racing. It runs for periods of up to 40-50 mins at WOT under full load at 6000 rpm +- 200 with rev limiter set at 6500. These rods have roughly 40 hrs on that way and finally one gave up. The particular operator when it blew was new to the sport and was coming out of the water alot, hitting the rev limiter hard alot of times. G2X data showed he had achieved 7600 rpm even with the rev limiter. The big end and bearing look pretty much new as does the wrist pin. Thanks for the info. I can't seem to get a pic loaded.
That’s actually very helpful. Those rods use a .866” pin which might be overstressed. A rod with a .927” pin might fix that. Weight on the small end has less effect on the bobweight as well, so a rebalance might not be that bad
Pins are upgraded to .200 thick and dlc coated.. No scuff marks on the bushing or pin and no heat makings on the rod. It really looks like a fatigue break over time. .927 pin may be better but would require a redesign of the piston. I can get a better rod but the price is up there also. The guy that owns it will have to decide I guess.
Thanks for pics and info. That definitely helps tell the story.
I would agree that it looks like a fatigue failure of the small end. Jet boat racing does put A LOT of load on the rotating assembly. A 4.125" crank at 7600 rpm moves the rods and pistons up and down pretty quickly. Do you think it could have knocked the bushing out of the small end before it let go?
There are a number of options for you to choose from. I'd look at something like a Callies Ultra, Oliver or Crower I-Beam with a .927" pin and whatever length you choose to go with your piston of choice. I really didn't like the LSX454 rod when I saw it the first time. The thickness around the big end looks like it could use some more material, the .866" pin is quite small and the small end could use some help (obviously).
The bushing looks like it remained in place until the rod let go. I agree about the .866 pin for sure. I have talked to Dyer rods and a few others. It will be up to the owner if he wants to spend the $ for better rods or just know that a couple of seasons is about all one can expect from the factory.stuff spinning it at 6000. I ran it down at 5800 and it didn't make alot of difference in speed so that is another option that may help some but ya the rods are a little weak for this application. Thanks for the help.
06-25-2018, 11:19 AM
