A Nissan Sentra Forum banner
21 - 32 of 32 Posts

·
Registered
Joined
·
657 Posts
Discussion Starter · #22 ·
no one supports the MR20. I mean shit, the MR16DDT has a whopping 2 people supporting it and thats factory turbo lol

I have the engine sitting on a stand. I have 3 engine builds happening right now, so the qr has taken a back seat. My buddy bought the car itself off me, and he wants to do a high comp NA build, so we have the parts here for that already. Down the road we will do high comp turbo, but for now its all just sitting. He is having me build him a 500 whp juke, so that needs to get done first.
 

·
Administrator
Joined
·
6,922 Posts
I think I still have a light weight crank pulley for that motor series.

Any updates?

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?

Sent from my Pixel 4a (5G) using Tapatalk
 

·
Registered
Joined
·
52 Posts
I’m late to the party, but there were some manual transmissions in some of the x-trails. There aren’t that many on eBay at the moment, but they go for $400-$600 right now if you can find them.


It’s a 6-speed and bolts up to the QR25 so it may come from the same RS6F51(A orH) platform. According to Wikipedia “The X-Trail's All-Mode 4x4 transmissiontransfer case enables the driver to select between 2WD, 4WD or 4WD Lock through an electronic switch on the dashboard.”
I’m not sure what the real transmission model number is for these or if their gearing is in any way similar to the spec V or Maxima 6-speeds because there’s not that much info out on these trannys since they weren’t available in the ol’ USA. I’ve been playing with the idea in my head the past couple weeks, but the time, money, and effort spent to get everything working is way beyond my wheelhouse of capabilities.
 

·
Registered
Joined
·
645 Posts
According to Wikipedia “The X-Trail's All-Mode 4x4 transmissiontransfer case enables the driver to select between 2WD, 4WD or 4WD Lock through an electronic switch on the dashboard.”
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.
If you were to use the Xtrail transmission in the Sentra you would probably have to remove the pinion and blank off the opening it was mounted in. If you want pics I'll find some and put them up for you.
 

·
Registered
Joined
·
52 Posts
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.
 

·
Registered
Joined
·
645 Posts
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.
 

·
Registered
Joined
·
52 Posts
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.
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.

This is why most of my ideas end up dying in my head lol, it’s fun to think about though
 

·
Registered
Joined
·
645 Posts
The 80kph limit is on the wet clutch only. If you could extend the driveshaft and somehow modify the rear diff to take the driveshaft directly without the wet clutch between then there would be no speed limit and the gear ratios already in the diff would match the transmission and pinion.
 
21 - 32 of 32 Posts
Top