nevrenuf

I am building a stroker and it is ready to assemble.. At the last minute, the a 4.250" crank/rods/piston package (lunati) is available and could be installed instead of the 4.000 I had previously selected..

I was doing 4.100 bore x 4.000 stroke for 422 ci

4.100 bore x 4.250 would be 449 ci.

My concerns are about how far out of the bore the piston skirts/wrist pin must travel with all that extra stroke. I am also concerned about the extreme angle that must exist between the piston and the rod at the bottom of the stroke.. It seems that the piston would be exposed to much more sideways forces as it begins up the bore and thus wear the bore faster.

Any thoughts?

I'd love the extra cubes though.. "no replacement for displacement!" comes to mind..






[Modified by nevrenuf, 4:49 AM 10/11/2001]

AVETTE

Tom, Tom, Tom, I'm really suprised you are asking this question :jester You of all people know that it is 'nevrenuf' right. Go for the 4.250, if it breaks you have 30 grand in snap on tools to fix it, right :D :cheers: :lol:

MattG

What do you want to do with the car mostly? If you are looking for an engine that doesn't mind reving high and puts out some great power up top for the drags I would stick with the 4.000" stroke. If you are looking for a torquey street machine that you dont care to rev past 6500rpm, then I would go for the big cubes and get the 4.250" stroke. If you want something in between, go for the 4.125" stroke and make it into a 432ci, which is what my plans are for this winter.

The thought of beating the hell out of a 4.250" crank at high RPM on the dragstrip spraying nitrous scares me.

MrEracer

Without going into a lot of engine theory, there are a few problems with the long stroke 454 LS1. 1st, the piston becomes so short that very little skirt is available to support the side loads... This is a much greater problem than the rod ratio which is not unreasonable in this combination. 2nd the compression height is so short that there is very little room for the ring set. This drives the top ring very close to the (hot) top of the piston and the wrist pin must intrude under the oil ring. This will be a real problem for a NX application. 3rd, the LS1/LS6 fully ported heads, as good as they are, will not flow enough to support the displacement requirements of a 454... This leads to a situation of diminishing returns... Not much gain to show for a lot of money spent in conjunction with the problems with the short piston and ring pack mentioned above... Also compression ratio goes beyond streetable limits unless a dished piston is used... It goes on and on... I would recommend a shorter stroke for a streetable engine which brings a much more favorable piston/ring pack configuration and then you can make up additional HP requirements with NX...
My own preference is a 427 CID (another great Corvette number) with a 4.080" bore, 4.080" stroke, and a 6.125" rod length... BTW, for you or anyone else that may be interested I have a great Excel spread sheet that calculates every critical engine building dimension including CID, C.R., rod ratio, ring pack distance and much more just by inputting the basic information (bore/stroke/rod length etc)... I'll send it as a file attachment to anyone that provides his email address to me... And since I created it, I can assure you that it will be virus free...
Shirl