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Upgrades for towing

J

J1MB0B

NAXJA Forum User
Location
Tacoma
My engine is out for some work. I will be towing a small trailer, 1500 lbs max.
What should I do, if anything, to upgrade the engine? Its a 2000 XJ with a cracked head and a spun bearing.

My plan so far is to use a 95 head, casting no. 7120. My exhaust manifold won't work, so I was going to use an aftermarket header. What should I do as far as head work?
Should I do anything to the intake?

A buddy said to use an RV cam but I was reading that an RV cam would hurt my top end performance on the highway.

What about the exhaust? It already needs to be redone anyway.

Other than that, all I was going to do was add electric trailer brakes and a trans cooler.

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You're on the right track to junk the head, but don't think you can use the 95 head without major mods. 00-01 are coil on plug and the manifolds are different. IIRC you need a TJ head from 03+. Don't quote me on that but it's different than the older ones. The 4.0 isn't really a builder power house and most of the things that can be done are $$ for little gain. Gears are going to be the best upgrade that truly will help. Unless you want to build a stroker I would mess with the engine a whole lot. Trans cooler will also help.
 
From the I found, the only thing I need to do on the 95 head is fabricate brackets to mount the coil rail and use the 95 valve cover. And the exhaust manifold.

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The exhaust ports on the 00/01 heads are different from the earlier years.

If you have the Cali emissions package with the precats under the intake, you will have to keep them to pass a smog check, which means keeping the current exhaust manifold, and that won't line up with the earlier head without some additional parts and labor. Specifically you need an adapter plate and (probably) both old and new style gaskets to sandwich the adapter.

If you don't have the Cali emissions then you can switch to an earlier exhaust manifold that matches the exhaust ports.

Or option C, get another 00+ head and keep the exhaust.

Nothing easy, some options are less expensive than others though.
 
ehall said:
The exhaust ports on the 00/01 heads are different from the earlier years.

If you have the Cali emissions package with the precats under the intake, you will have to keep them to pass a smog check, which means keeping the current exhaust manifold, and that won't line up with the earlier head without some additional parts and labor. Specifically you need an adapter plate and (probably) both old and new style gaskets to sandwich the adapter.

If you don't have the Cali emissions then you can switch to an earlier exhaust manifold that matches the exhaust ports.

Or option C, get another 00+ head and keep the exhaust.

Nothing easy, some options are less expensive than others though.
Click to expand...
Smog is not an issue. I'm already planning on using a header. An 00+ head is not an option because they are prone to cracking.

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J1MB0B said:
Smog is not an issue. I'm already planning on using a header. An 00+ head is not an option because they are prone to cracking.

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Click to expand...

Not fully true, it's the 03+ TUPY 0331 found on WJ/TJs head that is a direct replacement that fixes the cracking issue. It was recast and addressed the issues with that.

Even without smog you still have your O2 sensors that need to go somewhere. You can weld in bungs but again more work. When I was contemplating doing a similar swap I scrapped it. Way too much work for really no gain.
 
I used a 7120 head on my 2000 with cali emissions -- I just used the adapter plate and gasket sandwich -- been 6000 miles now and seems to work fine

I also opted to get rid of the coil rail and used the Viper coil -- just search "viper coil mod" and you should come up with results
 
I'm not worried about a little work. Welding in bungs and bending brackets is too easy.
158459c4ce3c2d1283856b7be8c08556.jpg
783428c161e0ee63ac388b36ad7b905f.jpg


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More air flow is all the 4.0 should get. Cowl intake or some cold air variant and bigger exhaust. Done. Does pretty well in stock form and doesn't really improve until you stroke it or throw serious money and parts at it. Cam is even pretty good like it is.

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My 2001 XJ has a 7120 head, using a Banks header and coil brackets, like the one shown by J1MBOB. A Banks header will cover the exhaust ports of the 0331, 7120 and 630 heads.

With the stock air box and hose used, it looks stock. My 01 just passed California's biennual emission testing and inspection. This may not be a consideration for the OP but those who live in stricter inspection states need to know this.

If you are towing, install the largest transmission cooler you can fit, the AW4 is a heat generator, make sure the fan clutch is new or in good shape.
Same goes for the radiator.
 
lazyxj said:
If you are towing, install the largest transmission cooler you can fit, the AW4 is a heat generator, make sure the fan clutch is new or in good shape.
Same goes for the radiator.
Click to expand...

^^^^ This is the key! When I did my stroker I used a CCH 0331 head made into a 0630 by Russ.
P1080516_zpsybaiiwn0.jpg
 
1500 lbs isn't much. Even most little econobox cars can tow that kind of weight. Past getting a good transmission cooler installed there's not much else to do.
 
devildog0 said:
1500 lbs isn't much. Even most little econobox cars can tow that kind of weight. Past getting a good transmission cooler installed there's not much else to do.
Click to expand...
I agree with this. If you're on big tires with stock gears going up hill, I'd say change out your gears. Otherwise, you should be fine.

Having said that, a bigger trans cooler never hurts.
 
I used to tow a 3,000lb boat and trailer with my XJ. Relatively stock (Specs in signature) except for Ford Explorer trans cooler, and upgraded brake pads. It would do it but was at the upper limits of its ability. I don't think 1500lbs would be an issue with the right upgrades and care.
 
I towed my 1500lb trailer with my 98 when it ran 31's and 3.07 gearing, and later with 35's and 4.56 gearing. With either scenario, it didn't really affect the rig performance, if you drive with common sense. Mine is manual - no cooler needed.
 
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