Putting a decomp plate in the way
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Senior Member

Joined: Dec 2008
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From: Floating around the AUDM
Vehicle: X3 Sprint, S-Coupe Turbo
Just a thought
The beta has pretty nasty geometry because of that diesel-length stroke. One of the problems that it creates is the rods have to be rather short so the engine isn't tall as f*ck. Then having short rods means that they end up taking lots of bending load, especially at high revs. Look up rod/stroke ratios if you want a better explanation, it makes for interesting reading. Anyhoo, engines like the B16, 4AGE and 4G92 all have R/S ratios around 1.75, this is definitely a desirable target ratio.
I was thinking about improving the R/S ratio by using a 1.8 crank in a tall 2.0 block with custom longer rods, but that only does so much. What about using a decompression plate to lengthen the block? I know they are usually used to lower compression; ie the piston never crosses the boundary between the plate and the regular block... I wonder whether the rings would care or what? I made a picture to illustrate my point:

I would like to hear your thoughts.
The beta has pretty nasty geometry because of that diesel-length stroke. One of the problems that it creates is the rods have to be rather short so the engine isn't tall as f*ck. Then having short rods means that they end up taking lots of bending load, especially at high revs. Look up rod/stroke ratios if you want a better explanation, it makes for interesting reading. Anyhoo, engines like the B16, 4AGE and 4G92 all have R/S ratios around 1.75, this is definitely a desirable target ratio.
I was thinking about improving the R/S ratio by using a 1.8 crank in a tall 2.0 block with custom longer rods, but that only does so much. What about using a decompression plate to lengthen the block? I know they are usually used to lower compression; ie the piston never crosses the boundary between the plate and the regular block... I wonder whether the rings would care or what? I made a picture to illustrate my point:

I would like to hear your thoughts.
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Joined: Sep 2001
Posts: 10,795
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From: Pflugerville, TX
Vehicle: 2000 Elantra
The rings would be chewed to pieces unless you did something very expensive to the joint between the plate and the block, or you did something VERY expensive with the pistons.


