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Originally posted by RoninEclipse2G
I'm gonna have to disagree with you there Kirby. on a stroker crank the rod journals are moved farther out from the center to increase the distance between TDC and BDC thus increasing the stroke. to move the piston farther away from the head at TDC you would have to move the entire crank away from the head (multiple headgaskets, taller deck height) or de-stroke the crank (move the rod journals closer to the centerline of the crank) you may have been a lucky case with larger valve reliefs on your forged pistons or my guess is that when your tensioner took a shit the belt didn't shift enough to get everything into place where it will contact. I'm leaning towards the second option (belt not shifting) because I had the same thing happen to me. The tension and idle pulleys both went bad and shat the bearings all over the place. luckily the belt never skipped enough teeth to have anything hit at ~4000rpms
You are absolutely right on the rods being offset further from the center line. And you are correct in the pistons travel making the increase in displacement. However there is one thing you are missing. If you move that rod journal and keep the same rod length (The 2.2L uses stock length rods) what would happen? If it's coming further down in the bore it will also go further up into the bore. How do you solve that problem? Shorter Piston (by moving pin locations or changing shape or height). This is also one way to lower the comp. on a piston, think dish vs. dome... As for the belt I assure you that there was no belt on the cam gears at all, and the engine was out of time when I went to fix it. I am not saying it is impossible to get lucky and not smash something, I am just saying that I am NOT that lucky...LOL
Originally posted by ez
Yea I gotta agree with the other Erik. Kirby, what you described with the piston being at a lower spot in the cylinder at TDC, would essentially mean you have a smaller compression ratio. Reducing the compression ratio can be accomplished with low comp pistons, a thicker-than-stock head gasket, but I don't think that it's necessarily inherent with a 2.2 or stroked motor (unless the wrist pin was moved higher on the piston than the stroked rod is longer.)
You are right as well. The compression is lower than stock on this motor as well, so that does factor in here also. Your last point here is a good one, since the rod length remains the same it is the pin movement that comes into play here. It may not be inherent to every stroker motor, but I believe it is to this one based on it's design.
Originally posted by cougar694u
Happy belated, meant to post about it on Monday, but was wore out from the track day and forgot. A stroker kit increases the stroke (distance a piston travels), thus creating more displacement, it doesn't change the distance from the head. Since displacement is a calculation of bore (cylinder diameter) & stroke (piston travel), increasing both will give you more displacement.
Also correct. This is what I was trying to say with the part about moving the top and bottom of the cylinder to increase volume (displacement). However we still have to remember that the rod length is the same so we are not taking into account the shorter piston that makes it work in the first place. If you have a fixed length item that is rotating at a fixed travel, and you modify it so that it is further down at BDC it will be higher at TDC. So you have to shorten it up in some way, otherwise the valves and pistons would self-clearance in one rotation. (thanks for the phrase Corbin) It is the rod length remaining stock that throws things off here fellas. So I can not provide the super secret design or get into technical clearances and piston sizes because I don't have Gary's secrets. But I am assuming that he does have those bits of info that would cause him to clue me in to the fact that it is a non interference engine.
Corbin made a great post about this here: http://forums.2gnt.com/dcboard.php?az=show_topic&forum=5&topic_id=103574&mesg_id=103574&listing_type=search
I edited to the wiki!
Originally posted by DR1665
NOTE TO SELF: Go commando to wedding. Scar the Irishman for life.
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