Like I said above, I hope you find minimal wear on the bottom end and are able to keep with what you have short block wise.

Be sure to show us some pics of those piston skirts.

 

Tell this to the BMW M3 guys with their 1.48 rod ratio. It makes the nearly 1.5 of the 6.125/4.100 combination look good. The reduction in rod ratio from a 4.100" crank to the typical 4.00" crank is minimal enough to be negligible. In the absolute worst case scenario I'm talking about, even a 6.000" rod on a 4.100" crank is still over 1.46. Again, negligible.

With no adjustments in the bore size, yeah a short piston will rock more, but honing technology and ring packages today should allow plenty miles from a combo such that we are discussing here. There are plenty of high performance factory cars/motorcycles out there with extremely short pistons lasting a good while. Some of which spin 50% (or more) rpm on a regular basis.

I'm not disagreeing with what you're saying. As a matter of fact, all that you say is true....I'm disagreeing with the severity of the situation. It's not that big of a deal.

I'd likely change my mind if I was trying to build a turbo motor. You can size a turbo such that power production is never a problem. In any N/A build, I'm gonna shoot for as big as I can get.

In the case of my 408, it was supposed to get a 4.100" crank, there just wasn't one readily available at the time we ordered all that **** years ago. I'm still disappointed that it doesn't have a 4.100" crank in it.....then again my tune ups only allow around 7 miles of drive time before a freshen up is needed. ****** turbo trucks.

 

Ehhhh I dont know. I just had apart a 416 that had 15k miles on it and the cylinder wear was BAD. I'll never run a 4" stroke LS... put it that way. Not on a street vehicle anyway.

 

I have a 4" stroke motor for a street vehicle. Lets see how long it lasts for me haha.

 

Mine lasted 49k hard miles...being rebuilt right now with no bottom end damage. Ate a lifter and a lobe. Swapped out the pistons for offset pin Diamonds to reduce wear and rocking. Hope to get more out of it this time around.

 

Don't forget the 400 SBC engine. 5.565/3.75

Heck, I still have 2 of them kicking around.

 

It's not so much the ratio that is a bitch, it's how far the piston drops out of the liner at bottom dead center on a GEN 3 iron block.

 

Are Gen4 blocks better?

 

Gen 4 aluminium blocks have longer liners to the best of my knowledge.

 

They are supposed to.

I still wouldnt do it. The worst wear I saw was not at the bottom of the stroke. I'm sure they are kind of egg shaped down there... but the cyl wall mid stroke looked horrible.