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4.0 high output performance overhall

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4.0 high output performance overhall

Old 08-14-2010, 09:33 AM
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Year: 1992 Laredo
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Default 4.0 high output performance overhall

I'm trying to get more power out of my 4.0, I've added a cold air intake and a flowmaster, I've gottin some gain but feel there more i can do, I've thought about a throttle body spacer and was wondering if anyone has used one and if so did it work? Any suggestions about HP gain would be helpful.
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Old 08-14-2010, 05:01 PM
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Throttle body spacer, to me, seems specious at best.

Bored throttle body will increase part-throttle response (giving the illusion of more power,) but doesn't actually increase power. The OEM throttle body will even support a stroker without trouble.

How much work are you willing to do? Without going to forced induction, you're going to see the greatest net effect with a camshaft change and/or cylinder head work (since you've already opened up the intake and exhaust systems.

By the by, there's a huge difference between "horsepower" and "torque" - and, with a truck, you really want torque output. Horsepower increases don't really become noticeable until over 3500-4000rpm anyhow, while the torque from an inline six is noticeable off-idle. Horsepower and torque are mathematically related, but torque will always exceed HP until 5252rpm, then HP takes over and surpasses torque output.

It would really help for you to be more specific about what you're trying to accomplish - I went through this same thing with my two boys, they just had non-specific "more power" goals. Once they were able to figure out just what they wanted, we were able to accomplish those goals. "More power" isn't really a goal...
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Old 08-14-2010, 11:16 PM
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99+ intake
screamin daemon coil / wires / distributor
raise the plug gap
neon injectors
nice cold air intake
headers
2.5" exhaust
make sure the exhaust/intake gasket is tight and torqued correctly so no mis-fires
getting it custom tuned will make the biggest difference after you do all these. I did all the said upgrades to my xj, and it dyno'd out at 251 tq/230hp. I had a shop custom tune it to all the mods I have done / motor specs, and re dyno tested it and came up with 268 tq/ 239hp. This was done with stock 225 tires on 15" jeep steelies, 3.55 gears

It costs a lot of money, but you never said anything about being on a budget.
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Old 08-15-2010, 10:07 AM
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to be honest i'm just trying to get it tip top for hunting, wheeling, camping, etc. it seems like there really isn't much i can do. I know a bored out throttle body to 62mm helps alittle but i dont want to go extreme but would like to get the most out of the 4.0. This is my first 4x4 and first jeep so I'm learning as I go. iam on a budget but i'm not scared to do the work myself but rather injoy it.
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