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how to add as much horsepower without buying a new engine


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new cam

replace head with edelbrock alumn performance head

up-grade to larger valves

Change rockers to lighter weight and or better ratio.

replace the exhaust system  (header)

replace intake manifold with ~2001 or so.

larger Throttle body

4 hole fuel injectors ( or high flow if other mods support the flow)

modify the CPS to advance timing (or remove adjustment tabs on distributor  and rotate that)

remove factory belt driven clutch fan, add all electric fans

modify intake to bring in cold air (most aftermarket CAI for the jeeps are actually Hot air boxes) I modified factory air box to get cool air from cowl. 

Change the thermostat to lower ~180.

plug in programmer to change fuel

 

changing gears will give your engine greater leverage on the tires, making the engine feel stronger. (it's like using a ratchet with a longer handle)

Also using smaller tires will give the feeling of more power. reducing rotational mass helps too. 

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  • 3 months later...

If you have a '91 or '92, you can buy a high performance chip for the ECU. It increases power, but you have to run high-test gas with it.

 

No, there is no chip available for the Renix years.

 

Depending on the chip and how it's programmed, your compression ration ratio, and other factors there is no regulation or requirement for running high-test gas with it. I ran a Unichip for years and never ran high test nor did I need to. There was no preignition or pinging problem. The Unichip is on the intake heat shield in the pic below. It did work quite well until it developed an intermittent internal short.

 

http://www.jeepstrokers.com/forum/viewtopic.php?f=5&t=387&hilit=unichip

 

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Don, still have the Unichip?  I just read your other write-up, didn't realize that it made such a difference.  I'd be willing to take a chance on finding that short.

 

Also, intake has just moved up to the top of the to-do list.  A/C can wait a little while longer! 

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No, don't have it anymore. I had it wired in for about four years and it did great, then the engine started dying randomly. When I jumpered the Unichip out of the system, no more cotouts. So I sent it to Unichip in Hillsboro, OR to check it out. A tech mapped it for his BMW and drove it for two months with zero problems. He sent it back with the Jeep map and it still caused engine cutouts. I'd had it and sold it on Ebay to a guy in Brazil a couple of years ago for more than I paid for it who's still running it on a racing BMW with no problems.   :dunno:

 

It did well when installed on my rig. The Unichip program allows you to vary the MAP, TPS, CPS, and IAT outputs to the ECU for the best dyno numbers.

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How much money do you have to play with?   No matter what option you go with, and a wide variety of factors, to add any notable power to said vehicle is going to cost you at LEAST $2000, and that is being generous.  That would be using used parts or finding great deals and finding creative solutions while doing all of the work yourself.

Otherwise, there are small bolt-on things that can be done, depending on the engine, that won't really net you a whole lot for your money.

Ironically, the easiest and most affordable way to get more power from your 4.0L is to build a stroker like somebody else mentioned.  That requires replacing your engine.  :thumbsup:  

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