JordanH

iTrader: (16)

I've got a set of forged Pistons for a 4" stroke and a 1.150 compression height. I was doing some figuring and I came up with two options; use some 4.8 genIV 6.275 rods and rebush them for a .927 pin size, or use a aftermarket 6.3 rod.. My math has the 4.8 6.275 rods right at 0 deck height with the 3.622 stroke and with the 6.3 rods and 3.622 the Pistons would be out of the hole .021.. Not sure how option two would work out? Maybe run a thicker head gasket? Anyways, I've never seen any builds use longer rods, besides the 4.8.. Most just seem to go for a longer stroke? What are the benefits to building a longer rod motor? From what I've read they seem to last longer and rev higher? Just curious as to why people choose bigger stroke and shorter rod combos over a factory 3.622 stroke and longer 6.3 rod setups?

I'm thinking about taking these extra parts I have laying around and building one just for the hell of it!
Piston compression height: 1.150
Option 1: 3.622 stroke, re-bushed 4.8 6.275 rods, and deck the block a hair
Option 2: 3.622 stroke, forged 6.3 rods, and run a thicker head gasket or mill a hair off the top of the Pistons?

RS/SS 4.8

iTrader: (13)

Those are some interesing pistons you got there. Most of the ones ive seen use a 6.125 rod like mine.

JordanH

iTrader: (16)

Well, they're for a 408 build... But you can make up for the reduced stroke length with more rod length. I'm really liking the sound of this setup the more I read on it! Seems like the longer rod length you have the more rpm's you can turn and the actual motor will last longer! No piston rock, overall better piston stability, and longevity.
This setup also produces a very good rod ratio, 1.74!

brandon6.0

iTrader: (26)

I know guys destroke a 6.0 by installing a 4.8 crank and rods. I think it makes like 322ci. guys are pushing that combo pretty far with turbo setups. reving close to 8k I believe.

but will the 4.8 crank be able to be used with those pistons? I'm thinking u would want more cubes than less anyways.

JordanH

iTrader: (16)

On those destroked setups they run the factory Pistons, which have a 1.340 compression height. These pistol s I'm using are a 1.150 compression height. I'm basically taking a piston setup for a striker motor, 4.00 stroke, but using the stock 3.622 crank with them and making up for the difference in rod length. Basically the same as a 4.8, but doing it with a bigger cube motor.

Sticking with the stock 3.622 stroke crank.. It's going to be a 370ci, but with a 6.275-6.3 length rod.
I was really curious why people don't do this more often? There are many positive benefits to building a motor like this, broader longer power band, and a lot less stress on Pistons and cylinder walls..... From what I've been reading.

Blown06

iTrader: (32)

Option 2 sticks the piston out a little further than I would feel comfortable with. I've seen/done stuff at +.005 deck height but no more than that.

My opinion, get you a custom set of rods made. I like long rod **** myself.

JordanH

iTrader: (16)

Well, I got another 6.0 block, genIII. If the stuff doesn't sell in a week I'll be buying a set of forged h beam 6.250 rods and throwing it all together... I think it'll be a pretty good setup!

Vortec350ss

iTrader: (20)

I like the long rod stuff as well... but you gotta have the deck height for it. I hate that 4" stroke pistons have the pin in the oil ring land. Its one of many reasons why 408's burn oil.

I'd keep it a little more conventional. I went down this road with hoped of building a bullet proof mini stroker at 383 or 390ci but at the end of the day I couldn't get comfortable with it.

George C....

not all long rod combos work out so well, a 5.4 is a long rod and they bust rods very commonly since their rod is so long...Thats why you dont hear many of them turning rpms like a LS motor does

JordanH

iTrader: (16)

The Pistons are a 1.150 CH, so with the 3.622 stroke and a 6.250, or 4.8 6.275 rods I can be right at zero deck with a 1.73 rod ratio. If I use the 6.250 rods I'll have to deck the block a little, but these Pistons would be a perfect match for some 60-64cc heads. I'll just build it and sell it or save it for a 3rd gen truck build down the road!