trying to get a lil' more power

LilRhodyXJ

LilRhodyXJ

NAXJA Forum User
Location
South Kingstown RI
i have 2000 xj 4.0 with a k&n air intake, magnaflow hiflow cat, a flowmster 40, and rustys tail pipe.. it has pretty good power but i drive on the highway eeryday and i'm looking for a little more power to get me through the insane traffic of route 95...

i was looking at a banks or a thorley header plus a jeepers creepers bored tb.. wondering if they were worth it and any suggestions you may have for other power increases.. don't have he money to stroke, s/c, or boost my 4.0

thanks for your suggestions
 
Get lower gears, (numerically higher). 4:10s do good. That will give you the kick your looking for. It will lower gas mileage but will increase torque multiplication to the rear wheel giving you more power to the ground via higher rpms.

 
LilRhodyXJ said:
i have 2000 xj 4.0 with a k&n air intake, magnaflow hiflow cat, a flowmster 40, and rustys tail pipe.. it has pretty good power but i drive on the highway eeryday and i'm looking for a little more power to get me through the insane traffic of route 95...

i was looking at a banks or a thorley header plus a jeepers creepers bored tb.. wondering if they were worth it and any suggestions you may have for other power increases.. don't have he money to stroke, s/c, or boost my 4.0

thanks for your suggestions
Click to expand...

The Thorley header with a custom made 2.5" downpipe would be a worthwhile addition. You can get a 62mm bored TB cheaply from ebay. Don't bother with a TB spacer 'cause you won't have enough underhood clearance if you combine it with the K&N FIPK.
 
As long as you don't have the precats on the header the 99 will work. If you can fab up a mount for the coil packs you can get a 96-98 head. Have a valve job done on it, and yea haw.
 
so is this fast man throttle body the one to go with?... i've been lookin around and the RE one is rediculously expensive but the jeepers creepers one got a good write up and its only $115.... also will a bored tb kill my gas mileage?
 
I've never had any experience with Jeepers Creepers but reading this xj forum a lot of people have mentioned his name in a non positive tone.
 
The Jeepers & Creepers TB is a stock unit that has been bored out to a uniform 60mm. In other words, if you just remove the material below the blade on your own TB, you will have the same thing they sell on their site. The one above is a true 62mm bored out unit. It will be a flow improvement on over the stocker. The RE is considerably more pricey, but again its a true 62mm bore. Folks have adapted mustang TB's and tealcherokee has mated a massive Taurus SHO TB to his machine. That size bore will require milling of the intake manifold TB mount to accommodate the larger bore...
 
You shouldn't go any bigger than a 62mm throttle body on your stock cherokee. You can use a tb larger than 62mm of another car and adapt it to fit and modify your intake, but I think it would hender you more than it would help. You could try to find a local machine shop willing to bore your old tb out. There is a company that sells 62mm brass butterflys for the do it yourselfer, but for the life of me I can't think who it is.
 
i still have a couple of question but these tbs are startin to make sense
1.is this tb (the fastman) the one to go with?
2.will my k&n fipk still be usable?
3.gas mileage on bored tb better worse or same?
4.and back to the gearing comment... since i dont have boatloads of money could i regear my rear end to 4.10s and as long as i always have it in 2wd not damage the front end or do i have to do both no matter what?
 
LilRhodyXJ said:
i still have a couple of question but these tbs are startin to make sense
1.is this tb (the fastman) the one to go with?
2.will my k&n fipk still be usable?
3.gas mileage on bored tb better worse or same?
4.and back to the gearing comment... since i dont have boatloads of money could i regear my rear end to 4.10s and as long as i always have it in 2wd not damage the front end or do i have to do both no matter what?
Click to expand...

1. its the same as boring out your stock throttle body, which you can probably do yourself or at least have done for you, for considerably less money. So its up to you. Its cheaper than the larger bore TB's but does not offer the same inlet sizing.

2. yes, it should still be usable with either the 62mm or the fastman one (60mm), since both versions are bored stock versions. The OD of the inlet does not change size.

3. should be the same, except that you may become Prince Heavyfoot with your newfound power and will then work your jeep harder giving you worse mileage than before.

4. you can only regear the rear axle if you remove your front driveshaft. With no driveshaft in place, the axles can be geared differently. This way you can get one done and then save up to get the other done later. Don't drive with different gearing from front to back with both driveshafts connected.

HTH...
 
i have 31s at 3.5"of lift, looking to add two inches of lift and mayb go wih 32s.. soo lets say i put in 4.10s and got a header and d-pipe for a little more power would it be relatively faster... i kno that sounds weird but right now i have stock 3.55s with the 31s and its really not that bad, only difference is acceleration is slower and if i need to merge or go quick on the highway it will hit almost 3 grand before nailin' overdrive... im just lookin to get that extra oomf back... but i need it for highway use so 4.56 would not be smart..
 
Even if you have the ideal gear ratio for the tires your running you will still be slower than stock because big tires weigh more and have more "moment of inertia".

The "moment of inertia" not only makes it harder for the engine to accelerate the vehicle but it also makes the brakes work harder to overcome that extra interia to slow the vehicle.

Go for 4.10s.
 
what is a good company to go with for gears... on rocky-road outfitters they have us gear/yukon $159 for D30 and $185 for the 8.25...worth it??
also to i need a carrier for my front axle its an extra $49?
 
also kind of opposite from power i was wondering are the cross drilled rotors an d hawk performance brake pads worth it because im going to need new pads soon, was just wondering what u fellas prefer for brake upgrades
 
I got an extra TB and had it milled out to 60. What a difference! Throttle response was much better and Milage did improve except when.... Throttle response was much better!

I changed back after a year and a half when it would not pass emissions testing. The testing changed so I think I will swap and run it through again. The problem was that NOx and HCO was way over with the 60. Don't really know if this makes sense or not! Might need bigger injectors and hotter plugs. Oh yeah I alread talked about that today!:doh:
 
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