Hi guys new to the forum and its looks great loads of great info. I did search for a couple hours couldn't find a similar thread so I thought I'd ask....
I have a 2001 2.5 v6 with a seized crank, rather than mess about striping and rebuilding I can lay my hands on a 3.0 v6 easily, what I don't know is, would this be as easy as a direct swap or do I need to change ecu's, injectors etc etc?
Any body on here done this upgrade or possibly point me to a thread of a previous 2.5 to 3.0 swap.
Thanks
Justin

 

its not an upgrade

 

Hello Dennis, thanks. what is it then?

 

Justjus, from our experience, the 2.5L motors and 3.0L motors move the car along at about the same rates. Yes, the 3.0L motor does it a little bit quicker, but the 2.5L motor is no slouch. You get the 2.5L motor wound up and it will get you where you need to go. Where the 3.0L motor is more of a slower revving motor and you don't have to have the tranny shift as much (ie, dropping to a lower gear) to get the car to accelerate.

As for making a 3.0L motor work in a car that was originally designed for the 2.5L motor, a lot of the harness and whatnot will convert over as the blocks are essentially the same. They just use a different crank. But, you will need to swap out the ECU to the 3.0L variant to make sure that the fuel maps are correct for the engine. Hate to see you blow up a new engine because you were running it lean.

 

Isn't a bigger engine with more torque and power always an upgrade?

I'd imagine the difference is more significant in a manual gear box car, because then you can actually use the extra power in normal situations (1500-3000 rev range) while the autobox would just shift down and start yelling at you.

 

Aon, in most cars, that would be a true statement. But, as we have found with our cars, more power leads to more TC issues. So, it could be seen as a problem as an upgrade too.

As for the manual gear box, yes, a 3.0L motor would be a bit easier to drive if you like to drive sporty. The 3.0L motor makes a fair amount of torque down low. So, shifting is not needed. I would love to get a manual tranny in my Jag, but finding a manual is pretty tough here in the US. OH well, may have to custom order my next Jag to get what I want.

 

Too bad they don't have any manuals currently.

I know that more power can decrease TC life, but doesn't that only really apply if you abuse car (drop the clutch, or constant 1st gear full throttle take-offs)? In normal driving, the extra torque down low would just make it easier but the extra strain in using that is insignificant compared to abusing it with the 2.5.

 

Aon, Some of the members have found that their TC's failed with normal driving with an Auto tranny. From discussions here, part of the problems stemmed from improper loading of the bearings in the transfer case. So, any additional loading from the torque of the engine can lead to bearing damage. The more torque, the more damage that can occur. It is a double edge sword.

 

Hmm. Is there any statistics data on the causes of failures?
To my knowledge there are at least...
1) leak in rear output seal -> oil leaks out
2) case flexes under stress -> crack -> oil leaks out
3) case flexes under stress -> temporary change in interior geometry -> cogs & stuff are damaged
4) viscous coupling overheats -> silicone fluid leaks out of it

No idea of the other modes of failure nor how common each is. How does the improper loading affect things and can it be remedied by replacing bearings? I'm no engineer, just throwing questions in the air

 

thank you for the info guy's, quite interesting to understand why

 

Aon, if the bearing is properly loaded, it would be pushing on the casing, trying to essentially rip it apart (think 10 pounds of stuff in a 5 pound sock). Now, you add in the stress of the transfer case having torque applied to it and the gears sliding side to side as a result of the torque being applied, that can be enough to essentially rip the transfer case apart.

If you have the case flex, the gears do not mesh the same way. This causes the gears to wear differently. The different wear tosses metal particles into the lube. These metal particles get into the bearings and causes pits. The pits start making the bearings bounce around and that causes the bearings to fail. This is why if you ever have new gears put into the rear end of a car, they highly recommend that you run the vehicle for around 50 miles with minimal load as the gears are under going a lot of wear and they will be tossing lots of particles into the oil and will be running very warm and then changing the fluid to remove all these particles and and damaged fluid due to heat.

 

maybe a dumb questions.....why does the case flex in this car?

I would suspect an faulty designed motor/tranni/gearbox mounting set up vs. the actual casting of the t-case. Perhaps flex from old and worn out motor and tranni mounts are to blame vs the t-case. Then the seal leaks finish it off...