Random questions, how much power can a mr20 engine take, and who makes internals for it? I like the layout of that engine. And...what transmissions mount to it?
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That selection is actually done by a wet clutch mounted infront of the rear diff. The transmission in the Xtrail has a pinion gear to allow the drive through a tailshaft out to the rear.
Ok, pardon my ignorance if I say something stupid lol, I’m just trying to understand how this system works. So blanking off the opening would just keep it front wheel drive. Since the 4x4 system is controlled by the rear end of the x-trail, the pinion on the transmission is always spinning under load. So if I could magically make a rear end for the Sentra with a rear differential then I would need to replicate the x-trail’s wet clutch system to switch between FWD and 4x4, or I could use a “regular differential” like an LSD and have 4x4 all the time.
I wonder what the next weak point is after the wet clutch, it doesn’t seem worth trying to reuse the x-trail rear end for a 4x4 Sentra if the 4x4 is limited to 80kph. That is unless you wanted an off-road capable Sentra, but there’s much cheaper and easier ways to have that kind of fun. You’d probably be better off trying to source a center and rear differential and figure out what gear ratios would work best to distribute power to the front and rear for highway or track driving. If you can get to that point after fabricating everything necessary, then you’d still have to find out whether the transmission and pinion in particular can handle the increased load on it. You’d probably want a modded or built QR25, or VQ swap as to make it not feel sluggish.Yes, the pinion is always driven by the crown gear in the transmission housing so blanking it off would leave it front-wheel drive only.
The Xtrail 4x4 system has 3 modes of 2WD where the wet clutch is disengaged, AUTO where the controller changes the amount of torque transmitted to the rear wheels by varying the current sent to the solenoid on the wet clutch and 4WD LOCKED where full current is sent to the solenoid to split the torque 60:40 between front and rear wheels.
The wet clutch is not rated for full-time use so the AUTO mode disengages the rear drive after 80kph and the 4WD LOCKED mode reverts to AUTO mode after 40kph.
I would say you could have the tailshaft drive a standard rear diff for permanent all-wheel drive with standard differentials on front and rear but putting an LSD in the rear might cause problems.
You would need the rear diff to have the same ratio as the Xtrail otherwise your rear wheels will be at different speeds to your fronts and cause all sorts of transmission problems.