4.25" strokers??

[Skip FIx]

Anyone using a 4.25 stroker crank? With as many BBC as there are out there sems like someone would try it. It stil would not even be "square" with the big 09 bore! I don;t know if the heads would flow enough though.

[Skip FIx]

Since I posted taled to a friend in Tampa that is involved in one. Using aftermarket rods to help clear.

[JimKwiatkowski]

Skip flx,I did a search on 4.25"stroker.Aubrey wrote this in engine chracteristics in a post in a Dan Miller thread on 7-28-04.I think Aubrey should know if you can install 4.25"crank in a 09.If your interested I'd e-mail him
(quote by Aubrey)
As for the super long strokes ( over 4" ). I don't know of anyone who's done it. 4" seems to fit pretty easily. However, I AM contemplating trying to do a 4.125" stroke with a .060" bore for my 1 ton tow rig. This is where bigger IS better !

[Skip FIx]

Jim. Our "regular" BBC bretheren have doing it to 454 block regularly even in car blocks and they have a smaller bore. When you start looking at bore/stroke ratios it is still less than "square" with a 4.3125/4.25. My 455 Pontiacs even have a bigger stroke than bore(4.151 bore/4.21 stroke), they have a longer rod to get a better rod/stroke ratio. They are torquey motors also.

As you said bigger is better when it comes to torque. With head flow and cams as a limiting factor(our '09s can't flow with a BBC esp a Big Chief/DART head) it just shifts the torque band down lower in the rpm band, but lots of it. The 4.25 cranks are plentiful in the aftermarket as are the 4.0 cranks.

Some of the '09 guys I have heard are putting BBC 4 bolt main caps and boring the block mains to BBC size. Main bearing sets cheaper and more available!

[64ss409]

Jim. it is still less than "square" with a 4.3125/4.25. My 455 !

That is "over square" isn't it?? Or am I having another senior moment :? Or just the regular never ending CRS??
Ron

[RedSled]

The heads will not flow enough to support the displacement. It would have to be built as a torque motor, and then exactly how much torque can you reasonably use??

[oil4kids]

.

Some of the '09 guys I have heard are putting BBC 4 bolt main caps and boring the block mains to BBC size. Main bearing sets cheaper and more available!


yes this is a better way to go since cutting the 396 bbc crank to 409 mains to 2.5 results in cracks in the webbing area

Im not sure how Lamar Walden is putting in a 454 crank in the stock 409 block however his new aluminum 409 block is really a BBC block with the deck cut at 74 degrees and redrilled for 409 heads

Just send Lamar $50G wait 6 months and get a monster 409

[Skip FIx]

Mark from what I've heard cutting counter weights down around .125 to fit in the block.
Got any pictures of your twin turbo?

I always heard "oversquare" to describe a bigger stroke than bore.

[oil4kids]

Skip

cutting the counter weights is a must then rebalance

but the long throw of 4 inch crank stroke makes difficult to prevent the connecting rods from hitting the sides of the bottom of the block generally you have to grind the block but with larger strokes you will go into the water jacket - the block is not that big-
thats why lamar started using aluminum 454 size bbcs because the bottom end has much more clearence