Rebuilding the engine and would like opinions or pros and cons on using 6.125 I-beams and pistons to match with the stock crank. If it's a bad idea please lemme know. Was just wondering if the lil extra stroke would be beneficial

 

Rod length does not change the stroke. The crank throw length determines that. Longer rods simply put the piston farther from the crank.

Longer rods have advantages and disadvantages. I think the engineers can well explain them. The most obvious downside is where they force the piston pin to be in the piston. Longer rods force the pins toward the piston crown, crowding the area where the rings live. Jamming all this towards the piston crown can lead to the pistons rocking in the bore....

All that said, I think the best compromise is to use a 5.85" rod which changes the thrust force angle but leaves enough room for the ring pack....

 

Ok thanks, was just curious about all of it n didn't want to make a mistake and be pulling it right back out anytime soon. Also I plan on spraying 150-200 if that makes any difference as far as where the pin sits on the piston.

 

If your running nitrous, you want nitrous pistons. They will have a heavier crown. They will have the ring pack dropped down to get the top ring further from the heat, and strengthen the ring land. Even on my 381 with 5.85" rods, the pin is in the oil ring and required ring rails. With the stock stroke, you might even want to stick with stock rod length.

 

Ok thanks Fred, I'll have to check into some nitrous pistons. Glad to know there's a difference. I thought long as they were forged they were ok. I was looking at the mahle power pack.

 

I'm very conservative, and listened carefully to the guys that built the engine. They had some incredible LT1 builds to their credit, and extensive nitrous experience.

 

Only "nitrous" pistons I can find are domes and the compression would be thru the roof with 54cc heads. Looked at je and diamond n both were domes

 

Nitrous loves high compression...which helps explain the CR of the aftermarket pistons....

 

How much nitrous do you plan on using?

 

No more then a 300 shot and that's if I go with the direct port. If money runs out n I just go with a plate kit no more then 200

 

No reason to not run a 6.0" rod with a 1.250" comp height piston. A standard 2618 piston will handle a 300 shot no problem as long as the tune is right, doesn't matter what piston you have if the tune is bad.

JE Auto piston #130974

That's a standard series -14.5cc inverted dome piston that should put you at 10.5 with a 9.0" deck and LT1 chamber. If you'll run race gas or good fuel, you can easily go higher if you can find a 2618 piston with an 11cc dish.

Call Total Seal and have Keith Jones set you up with the right rings, an AP steel set might be right, #CSL3690 with a Napier 2nd ring subbed in would be nice.

On the original question, no, I would not use a 6.125" rod with a 9.0" block unless it's a no nitrous road race application where piston weight is important for the rpms being run.

 

When you say good fuel are you referring to race fuel or 93 pump gas? And the nitrous kit will have a stand alone fuel system with race gas. Don't want to risk leaning put the intank pump.

 

You could go past 11:1 if running 93

 

That's all I run in it is 93. Thought I had to cause of the tune and extra compression form the le2's and impala head gaskets