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Repairing A Jeep Engine In Denver

Good morning. I’m Saul Reisman here at Saul’s AUTOTEK, and today we’re gonna talk about a vehicle that we really love here, and that has one of the most reliable and durable engines ever built.

You’ve heard us talk before about straight six engines and how they can be the most longevity, improved motors that we see on the market today. By that I mean, they might be in the market in the same vehicle for 20, 30 or 40 years with virtually no improvements or differences simply due to how efficient they are.

Jeep and BMW have both done this for the past several decades. The engine we’re looking at today is the Jeep four liter straight six. Now, this particular four liter started being produced in the mid-80s. The original block was a 4.2 and a 3.8 variant of the same engine all the way back to the 60s in original AMC cars. Now, this particular four liter came out of a 1991 Jeep Comanche pickup truck. A relatively rare vehicle but it uses a pretty common Jeep engine. There’s absolutely nothing wrong with this engine at 393,000 miles. The only reason we’re removing it, is the owner put a little bit left, little bit bigger tires and wanted a little bit more power. So as much as we love and appreciate this guy, and we’re gonna use him as a good car to make a builder, there’s absolutely nothing wrong with this one 25 years down the road.

Let’s take a look at what we’re putting in and why we’re doing it, and taking this great motor right back out. The engine that we’ll be replacing it with is the same engine block but we’ve used different internal components. We put in crankshaft and connecting rods from the older 4.2-liter engine which use a longer stroke and a smaller diameter bore, in this engine which has a larger bore but conversely smaller stroke. What that will effectively do is, as that piston is traveling up and down, we’ll be able to get longer displacement out of it. So instead of this being a four liter 242 cubic inch engine. This will be approximately a 285 or about a 4.7-liter engine. Effectively taking us from around a 177 horsepower to about 220, and from about 224 pounds to well over 300.

In the off-road world, we all know that torque is really the answer. While horsepower’s fun, smoking the tires doesn’t get us anywhere. That torque is really what’s helps push us through the rocks and crawl up and over obstacles. So in the case of this vehicle that’s modified for some pretty serious off-roading, we wanna make sure it is as capable and has plenty a torque to get the job done.

Even though that factory motor was still performing, it was definitely getting tired after a quarter of a century, and traveling to the moon and back twice. We’re pretty happy to say that this 4.7-liter stroker that we’ll be replacing it with will definitely be able to last several hundred thousand miles as the original did. We back these with a three year, one hundred thousand mile ourselves. They’re built here in house and we guarantee their performance supported with a dyno sheet on every single one of them.

So if you’ve got a Jeep four-liter engine in your vehicle and you’re looking to getting a little bit more power out of it? Little more skoot in the boot but at the same time you don’t wanna make that commitment and go to a different engine, different setup, you wanna keep it simple? Give us a shout. Let’s talk about how we can use the same design, squeeze as much power out of it while still keeping you reliable, and keep you on the road as efficiently as possible.

Give us a shout here at Saul’s AUTOTEK at (303) 919-7769. We’d be happy to talk to you about your Jeep and keep you on the road making power.

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About the Author

Picture of Saul Reisman

Saul Reisman

Saul Reisman has been helping the residents of the Centennial State with their automotive needs for over ten years now. He finished his Associate Degree in Physics at the Community College of Denver. Saul is an active member of the Specialty Equipment Market Association and a board member of the Young Executives Network. He undergoes constant educational training through GMC, MOPAR, Ford, Snap-On, Borg-Warner, and Ozark Automotive, with an emphasis on diagnosis, repair, and improvement.

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