GeoMetricMoving

The say the reason for the tall deck is to allow different pistons with special ring heights, using a lot of boost and nitro can burn the rings.

GeoMetricMoving

The bore on the 427 is the same as the 454, so the walls are identical.

GeoMetricMoving

Lunati 44103SRK 441 C.I. LS
Stroke: 4.125"
Bore: 4.125"
Rod Length: 6.125"
______________________________

Lunati 45403SRK 454 C.I. LS
Stroke: 4.250"
Bore: 4.125"
Rod Length: 6.300"
______________________________

Lunati 42803SRK 428 C.I. LS
Stroke: 4.000"
Bore: 4.125"
Rod Length: 6.125"
______________________________

Lunati 41253SRK02 429 C.I. LS
Stroke: 4.125"
Bore: 4.070"
Rod Length: 6.125"

dirty_old_chevy

In the big block Chevy world, but not the lsx world.
EDIT: I didn't realize you were looking at a smaller bore/longer stroke 454.

6togo

iTrader: (13)

GM lsx454 motors bore are 4.185 stroke is 4.125 My 427 is 4" stroke by 4.125 bore 6.125 rods. There are lots of ways to get the CI up with bore and stroke combo's.

GeoMetricMoving

I'm kinda leaning towards the 441ci rotating assembly for my boosted motor, it balances stroke and bore.

GeoMetricMoving

Who makes the best pistons for boosted engines?

ayousef

how much do you wanna spend? that will answer who makes the best part

GeoMetricMoving

Funds will not be a problem

68 SS

iTrader: (23)

CP here very nice for the $ coat the skirts and tops and forget about them.

Unreal

Longer stroke just gives you piston support issues. I wouldn't do past a 4" stroke on a std LSX block for high HP.

Mine is a 4.125x4. On 18.5 psi, soft tune, 91+meth I made 1047rwhp/922rwtq last week. 21-22psi and 1100+ would have been easy. Keep some cylinder wall and keep the stroke reasonable and let the blower/turbos do the work.

JAX04

iTrader: (17)

Shearer posted some pics of some Wiseco Billet Slugs over on bullet...

GeoMetricMoving

Sounds good, I was debating wether or not to shorten stroke.

Unreal

You will get a more reliable motor with a better piston. I see no reason to run past a 4" stroke for what you want. Even if you wanted 1500hp I wouldn't sacrifice piston stability for a little stroke.

ayousef

lets assume on two similar blown motors a 427 and a 440 both limited by pump gas which for the sake of the argument means that in both motors you cant run more than 16psi of boost before detonation kicks in, you end up making more power with the 440ci engine, so you cant say there is "no reason" to run a longer stroke, if there was no reason id run a 1 inch stroke, yet its more of an educated sacrifice

Unreal

I disagree. Cylinder pressure will limit the max power. The 440 may make more low end but the heads/intake/blower/fuel will limit the power up top. I don't think think the .125" stroke which does make a big difference in piston support, ring lands, etc is worth it for a street motor. Race only that is going to get pulled apart ever 50 runs, sure, go ahead.

transam69230

iTrader: (49)

Sounds like he has his mind made up to be honest. They are soo many big shops and engine builders that would advise against anything more then a 4.0 stroke on a boost application due to pulling the piston out of sleeve soo far.

I am not really sure how times someone has to say this in this thread!!

oscs

iTrader: (19)

Same reason why I went with a 370 when building my engine. My car is driven on the street and I dont plan on rebuilding it anytime soon.

ayousef

My whole point wasn't the 440 vs the 427 discussion, I was simply stating that I can justify why the OP is trying to run as big of a motor as possible, because whether it be boost (in very similar motors) or cylinder pressure, you would be moving much more air at a given cylinder pressure in a big CI motor vs a small one (without adding any additional variables like blower, head and so on).

Blown06

iTrader: (32)

I gotta side with ayousef on this one. If your not trying to over power it, and your having to tear down the 440" deal every 50 runs, you need a new builder.

You can get a plenty good piston with a 4" stroke. I believe the lsx blocks use a longer cylinder than the 6.0 stuff. If I'm wrong please correct me.