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Squeezin pony's out of a 2.5


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I'm getting kinda tired of my AMC 2.5's lack of power, but I like the fuel economy. It's a low click motor, and still runs well. I don't think there are any blow by problems although it does need a valve cover gasket.

 

What can I do to get some more power out of it?

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Not much that you can do without spending more $$ than it's worth to do (read: forced induction). Others have cammed them, enlarged the exhaust, bored the TB (if MPI, not TBI) but HP gains were minimal. There's a guy over on NAXJA that went spazoo on his (MudDawg is his screenname, IIRC) and has a screamer, but dropped alot of coin to do it.

 

Keep it stock, and tuned, and gear it. My 2.5 TBI is anemic by most standards, and has almost 180K on it, with more blowby than a $10 porno rental....but 4.56's really woke it up. with 31's on it now, I can roll it on the interstate and not be so much of a target (tachs an even 2K rpm @ 65mph), and it's alot more peppy at low speeds too. THe poweband on the 2.5 is right around 2K, so if you can run it close to there, you'll really notice a difference.

 

Jeff

 

edit: I'm planning on adding an inertia ring when I swap trannies on mine, too. The biggest problem I have with mine is low rpm torque and engine stalling.

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Keep it stock, and tuned, and gear it.

X2 to about everything mjeff87 said. My son and I are getting ready to do a complete rebuild on his 2.5. Partly because it needs it and part because doing so qualifies as a "Senior Project", (A high school requirement out here).

We're also going to add a 9 pound inertia ring when it goes together. An old friend of mine competes in major rock crawling competition with a stock, ring-equipped 2.5. He does good.

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Thanks Guys. Gearing sounds like the way to go. My only concern is that I sit in hi-way traffic and roll in first for a good part of my drive every day.

 

It's an 87 AX5 2wd. Long term plans are to make it into a tow rig for my boat by dropping in an Small block, gm 5 or 6 speed tranny and probably an explorer rear end. Thats going to wait a while though, so I was looking for budget bolt on options.

 

Has anyone heard or seen these ebay inline turbo's. It looks like an electric turbine in some conduit that you just install with an open air filter in front. I'm pretty skeptical that they do much at all.

 

Here is an example. I've seen a few different versions of the same idea.

 

Ebay item Number 300136950807

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Thanks Guys. Gearing sounds like the way to go. My only concern is that I sit in hi-way traffic and roll in first for a good part of my drive every day.

 

 

gears can only make hi-way traffic easier to play in. cause the engine will turn faster to move the truck slower so you won't stall as easy and you might actually make it to second gear! :roll: (i feel you, i live near atlanta and traffic is terrible)

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I've got a 2.5 in my 1991 YJ, with a manual 5sp.

 

I put in one of those throttlebody spacers, (only cost $20.00), while it slightly helped my gass mileage, I didn't notice much of a difference with top end speed, or low end torque.

 

I must say though, In the winter I slap 235/70 r15 BF goodrich all terrains.

In the summer I put on 225/70 r15s, (whatever brand I get a deal on currently kelly navigators), I also have a set of 235/70/ r15 BF Goodrich Mud terrain tires that I through on every now and again.

 

With the larger tires, the old YJ has to work REALY hard to get up to about 75/80mph on the interstate, and thats about as fast as I can get it rolling.

But with the smaller tires, I have no problem doing 85-90, and it feels like it still has some more to give.

 

I'm sure the tread pattern plays a factor in this too.

 

Just something to keep in mind, If you put bigger tires, you need more power/torque from the motor, or better gearing.

 

But if you don't mind having standard tires, go with a smaller tire, like a 215 or 205. Won't look as cool, but you will notice the difference.

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remember, to compare apples to apples, tire diameter changes require speedo gear changes. I've currently got the correct factory gear installed for 4.56's with the factory 205's. It ran almost true with 235's on it, but is now registering about 5 mph slower with 31"s on it.

 

Not that it matters much to me, since I drive like a geezer according to my wife (who has several speeding tickets to my zero :D ). I just get in the slow lane and keep up with the majority of the traffic. There's enough vibrations/sounds/protests from my driveline that I know when I'm going 65, that I don't have to reference the speedo to know where I'm at LOL. I get there when I get there, eventually :chillin:

 

Jeff

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I'm getting kinda tired of my AMC 2.5's lack of power, but I like the fuel economy. It's a low click motor, and still runs well. I don't think there are any blow by problems although it does need a valve cover gasket.

 

What can I do to get some more power out of it?

One of best improvements for a 4 cyl. would be to replace the OEM type of spark plug wires with some high performance ones. Preferably a set with less than 1,000 ohms of resistance (per foot). You might also consider a new coil (performance one if available) along with new spark plugs.

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remember, to compare apples to apples, tire diameter changes require speedo gear changes. I've currently got the correct factory gear installed for 4.56's with the factory 205's. It ran almost true with 235's on it, but is now registering about 5 mph slower with 31"s on it.

 

Not that it matters much to me, since I drive like a geezer according to my wife (who has several speeding tickets to my zero :D ). I just get in the slow lane and keep up with the majority of the traffic. There's enough vibrations/sounds/protests from my driveline that I know when I'm going 65, that I don't have to reference the speedo to know where I'm at LOL. I get there when I get there, eventually :chillin:

 

Jeff

I know about speedo gears, unfortunately my speedo had never worked, so I'm not too concerned about it. Sometimes it would be nice to know how fast I'm going, especially when I'm the only guy on the road. For now I just judge by gear and engine sound. If it sounds like I'm going fast, I must be really gunnin it. jamminz.gif

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I'm getting kinda tired of my AMC 2.5's lack of power, but I like the fuel economy. It's a low click motor, and still runs well. I don't think there are any blow by problems although it does need a valve cover gasket.

 

What can I do to get some more power out of it?

One of best improvements for a 4 cyl. would be to replace the OEM type of spark plug wires with some high performance ones. Preferably a set with less than 1,000 ohms of resistance (per foot). You might also consider a new coil (performance one if available) along with new spark plugs.

 

I've done wires plugs cap and rotor, and the truck had a new coil when I got it, so I avoided that. I did find a noticeable difference after the ignition upgrade, but I'm always comparing it to my 4.3 vortec blazer, which isn't really fair to the ole girl. The blazer sure seems to have the balls though

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