Another thread got me to thinking about the 2.5 SE's and engine performance mods. THAT got me to cruising the interwebs in search of information and ideas. (Sorry folks, I'm layed up at the moment and have too much time on my hands)
So here is my pain killer enhanced stream of consciousness...it's Oregon right? The snowflakes seem to be rubbing off or something.
The basics: The Jeep 2.5 liter I4 has a long and illustrious history of pushing lightweight rigs around on and off road. It's simple, not a lot of moving parts. Oil changes, tuneups and etc are slightly cheaper than the 4.0. It adds up over time. It's lightweight and compact, shaving a couple of hundred pounds or so off the I6 and AX15 combo. Lots of room to maintain and repair it under the hood. It falls on its face with heavy rigs and big tires. It can be miserable to drive on the highway if it's set up wrong. Heavy loads and hills can make you pull your hair out if you aren't Zen about it. (I'm not having issues there, third gear is my friend)
Browsing out on the interwebs, specifically ebay, results in numerous "turbo kits" for the 2.5 that promise results that range from the ridiculous to the sublime. Some are just piping kits and others are the full meal deal. All of them that include the turbo seem to be based off a hybrid T3-T4 turbo. Some of them have air to air intercoolers. All of them seem to be boost adjustable from very low ranges, say a few pounds boost, up to 30 - 35 pounds boost. Most require the use of premium fuel, and all of them require premium at higher boost levels. The advertised power gains? The average seems to run in the 40% increase in HP and torque range. Congratulations. You just converted your 2.5 to a 4.0 in other words. And made it half again more complex, using parts that may or may not be available when they cack a hairball because the company that produced them may or may not still be in business. Or they may have decided that hot rodding 2.5 TJ's is a money loosing proposition. AEV or OR-Fab anyone? I'm sure you understand what I'm saying.
Now lets say that you've found a turbo kit manufacturer that swears on their mother's grave that they will be around at least as long as you own your TJ. Parts will be available forever! The installation instructions are clear and complete. Everything bolts right up, and the default piggy back controller programming doesn't cause your 2.5 to have an unplanned disassembly when you fire it off. Now comes the interesting part. The piggyback programmer is generic. It needs to be programmed for your specific setup and conditions. That means plugging it into a laptop with custom software on it. Once it's plugged in and talking, then you need to create a custom fuel and spark advance / retard mapping. The "Tuner" guys do it all the time, or at least have a shop handy that knows how to do that. I can see the conversation now though, when you take your TJ SE in to get mapped. "Howdy, I need a custom computer tune for my TJ. I'd like to keep the power and torque bands in the same general areas they are now, or possibly move the max torque peak 500 RPM lower if you would." You could reasonably expect that request to be followed by a blank stare and laughter.
Then there is the knock-on drive train mods required. Specifically the AX5, if you have one of those. (I don't do automatics, so I'm not even going there) Everything else can be easily addressed, the Dana 30/35, the transfer case. But that AX5 is going to bite you, hard, eventually. They work reasonably well behind a stock 2.5 with a little care, but hook them up to a 4.0 equivalent and it will grenade in short order.
Alrighty then, lets beat this subject to death. What's your thoughts?
So here is my pain killer enhanced stream of consciousness...it's Oregon right? The snowflakes seem to be rubbing off or something.
The basics: The Jeep 2.5 liter I4 has a long and illustrious history of pushing lightweight rigs around on and off road. It's simple, not a lot of moving parts. Oil changes, tuneups and etc are slightly cheaper than the 4.0. It adds up over time. It's lightweight and compact, shaving a couple of hundred pounds or so off the I6 and AX15 combo. Lots of room to maintain and repair it under the hood. It falls on its face with heavy rigs and big tires. It can be miserable to drive on the highway if it's set up wrong. Heavy loads and hills can make you pull your hair out if you aren't Zen about it. (I'm not having issues there, third gear is my friend)
Browsing out on the interwebs, specifically ebay, results in numerous "turbo kits" for the 2.5 that promise results that range from the ridiculous to the sublime. Some are just piping kits and others are the full meal deal. All of them that include the turbo seem to be based off a hybrid T3-T4 turbo. Some of them have air to air intercoolers. All of them seem to be boost adjustable from very low ranges, say a few pounds boost, up to 30 - 35 pounds boost. Most require the use of premium fuel, and all of them require premium at higher boost levels. The advertised power gains? The average seems to run in the 40% increase in HP and torque range. Congratulations. You just converted your 2.5 to a 4.0 in other words. And made it half again more complex, using parts that may or may not be available when they cack a hairball because the company that produced them may or may not still be in business. Or they may have decided that hot rodding 2.5 TJ's is a money loosing proposition. AEV or OR-Fab anyone? I'm sure you understand what I'm saying.
Now lets say that you've found a turbo kit manufacturer that swears on their mother's grave that they will be around at least as long as you own your TJ. Parts will be available forever! The installation instructions are clear and complete. Everything bolts right up, and the default piggy back controller programming doesn't cause your 2.5 to have an unplanned disassembly when you fire it off. Now comes the interesting part. The piggyback programmer is generic. It needs to be programmed for your specific setup and conditions. That means plugging it into a laptop with custom software on it. Once it's plugged in and talking, then you need to create a custom fuel and spark advance / retard mapping. The "Tuner" guys do it all the time, or at least have a shop handy that knows how to do that. I can see the conversation now though, when you take your TJ SE in to get mapped. "Howdy, I need a custom computer tune for my TJ. I'd like to keep the power and torque bands in the same general areas they are now, or possibly move the max torque peak 500 RPM lower if you would." You could reasonably expect that request to be followed by a blank stare and laughter.
Then there is the knock-on drive train mods required. Specifically the AX5, if you have one of those. (I don't do automatics, so I'm not even going there) Everything else can be easily addressed, the Dana 30/35, the transfer case. But that AX5 is going to bite you, hard, eventually. They work reasonably well behind a stock 2.5 with a little care, but hook them up to a 4.0 equivalent and it will grenade in short order.
Alrighty then, lets beat this subject to death. What's your thoughts?
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