I have a 92 325i NV swap in my e30 (m50b25.right?) and recently killed it. This means turbo build time. It was a swap finished about a month ago with 175000 miles and this was always in the plan so the early demise just means more money wasted sooner lol. I have experience with turbo tuning and access to both engine and rolling dynos, but have questions about the m50 builds and internals in particular. I know the b25 has 135mm rods (5.315 inches), and that the vanos went to 140mm (5.512 inches) rods. I'd like to employ carillo rods for this build and want to use the straight H-beams as opposed to just the h beams. I have access to a set of the straight H's that are the 140mm length and not the 135mm length. Can these be used without interference? I know that the NV motors had more lift and am concerned about interference. I plan on running custom JE pistons obviously to lower compression and can probably eliminate this problem with those, but was just wondering if the rods are interchangeable and what the resulting outcome would be. My instincts tell me the shorter rods will be stronger and like high RPM more but my patience to wait for custom rods is not good. Give me your opinion.
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faint in, throttle out. -
The shorter the rod the more power you can put down, but also places more stress on the cylinder walls because of the increased angle. If you are getting custom pistons then 135mm or 140mm rods wont matter, I don't think.
Personally if it is just a toy for the weekend then I would go for a shorter rod and more power. But this is also if you are going to push the tune to the limits of the engine. If not then yeh 140mm will be all you need.sigpic
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