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Old 03-23-2015, 06:52 PM
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2.5L Engine options

Hi guys I was wondering if there is something that can be done to the 2.5L engine to get some extra power out of it? Would it be worth getting some cold air feeds and throttle body spacers put on would they make any difference?

It's a 98 TJ if thats any help.

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Old 03-23-2015, 06:54 PM   #2
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Best thing to do is have it re geared. All the CAI and TB spacers will not gain you anything on a TJ

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Old 03-23-2015, 07:01 PM
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Best thing to do is have it re geared. All the CAI and TB spacers will not gain you anything on a TJ
Ok thanks for that. Is there any links on what I'd need to do for the re gearing?
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Old 03-23-2015, 07:48 PM   #4
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If you are running stock size tires, then regearing is not going to help. Its when you go to 31"+ tires that regearing makes sense. Typically in the USA it costs about $1200 to regear both axles ($600 parts, $600 labor) by your local axle/transmission shops.
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Old 03-23-2015, 07:54 PM   #5
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Here's a good few minutes of reading to get you started -

Jeep 2.5L 4-Cyl Power Mods
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Old 03-24-2015, 12:06 PM   #6
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Lot of miss information in that article. Author starts by saying he was having trouble on a 7% grade above 11K feet. Of course he was. If he tried walking he'd be having trouble too. Air is starting to get thin that high.

Throttle body spaces do nothing - zero - zip. They were effective under a carb or a TBI system. CAI and Cat back systems can give a very slight power increase - at wide open throttle. If you are usually running at 5000 RPM you might see a difference. I don't know of anybody that uses that range though.
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Old 03-24-2015, 12:37 PM   #7
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That's what 2.5 owners want to hear. Most of us go through it all on our own and see for ourselves. But there's one thing in that article that people always miss, he doesn't advocate any of the solutions but he does advocate all of them working together, and is very upfront about the results you can expect. I know from all the things I've tried that the one mod that does save some of your available power is an electric fan, for me on 33"s and 4.10s it was the difference between being able to use 5th gear at 7k ft and not being able to.
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Old 03-24-2015, 12:54 PM   #8
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Google some of the right ups on installing Ford injectors , x2 on the electric fan swap!
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Old 03-24-2015, 03:37 PM   #9
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Aside from a VERY (think the smallest amount possible) small gain from an electric fan, re-gearing is your only option.
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Old 03-24-2015, 03:43 PM   #10
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Aside from a VERY (think the smallest amount possible) small gain from an electric fan, re-gearing is your only option.
You don't gain anything from the conversion to an electric fan, it allows the available power to go to the wheels instead of turning a 5 blade propeller.
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Old 03-24-2015, 03:59 PM   #11
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I did them all except the TB spacer. The regear is by far the best single option to get more power. The others do add, but only a little, power. Electric fan, larger throttle body, CIA, and exhaust header help in power DELIVERY in my opinion. Its run up the RPM scale and running over 3k RPM is much smoother than stock. The engine doesn't fee like it's going to fly apart at 3k rpm as it does it stock form. They also improve throttle response, which can be a liability off road when you're trying to ease over or through an obstacle.
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Old 03-24-2015, 05:03 PM   #12
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You don't gain anything from the conversion to an electric fan, it allows the available power to go to the wheels instead of turning a 5 blade propeller.
Gain in performance....
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Old 03-25-2015, 02:54 PM   #13
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How are y'all's electric fans set up? Are they thermostatically controlled, or just run all the time?
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Old 03-25-2015, 10:14 PM   #14
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Run it through a temperature switch and have a manual on/off.

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