4.0 performance mods

I've done the Windstar intake and 4 port injectors. My exhaust is also 2.5" all the way. I don't believe my Jeep is any faster than any other that is in good repair.

Like everyone else who has done it, the regear made the only difference that didn't require convincing myself that I might have accomplished something.

2003 Rubicon
 
skrelnik said:
Does a cold air intake have a refrigerator attached to it?

I would guess that a less restrictive exhaust, with cats removed, and an ECU tune will add more power. Most of the other stuff mentioned above does nothing noticeable.

As others said, just buy a new engine to drop in...or realize this is a jeep and go buy yourself a 2000 BMW or Audi and tune the crap out of it.
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Can't tune the jeep ecu, so you are stuck with a piggyback chip (questionable results) or a full aftermarket ecu (mega bucks)

—
There must have been a time
when we could have said no.
 
Drizit said:
Can't tune the jeep ecu, so you are stuck with a piggyback chip (questionable results) or a full aftermarket ecu (mega bucks)

—
There must have been a time
when we could have said no.
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I don't believe that is as true as it once may have been. I've got a 01 PCM on it's way back to me from a tuner here in SoCal that converted it from a manual PCM to an auto and disabled the fault code for the TCC when used with an AW-4 swap. I've also used the Split Second piggyback with very good results on a supercharged TJ 4.0 and it's user tunable.

I don't know what his full tuning capabilities are yet but he doesn't seem to have too many limitations on what he can do. We'll know more as we do some testing. I do know he has a PCM in a YJ that has a TJ 4.0 with the coil on plug rail in it and it's being run with a YJ PCM that has been tuned for a stroker without a piggyback tuner in it.
 
jjvw said:
I've done the Windstar intake and 4 port injectors. My exhaust is also 2.5" all the way. I don't believe my Jeep is any faster than any other that is in good repair.

Like everyone else who has done it, the regear made the only difference that didn't require convincing myself that I might have accomplished something.

2003 Rubicon
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We have a client with a 97 with the 4.0 and manual trans. He was bragging about how fast it was. I let him drive my 04 TJ Unlimited on 32's with the 4.88's in it (N/A) so he could see what re-gearing does for you. My rig is quiet since it has a newish soft top, auto, and all the carpet. The 97 has a soft top, no windows, only front carpet, and 33's. He came back and said his was much faster. After he left, my helper and I took them over to our "dragstrip" just to see. The heavier Unlimited beat the 97 3 out of 3 times.
 
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mrblaine said:
I don't believe that is as true as it once may have been. I've got a 01 PCM on it's way back to me from a tuner here in SoCal that converted it from a manual PCM to an auto and disabled the fault code for the TCC when used with an AW-4 swap. I've also used the Split Second piggyback with very good results on a supercharged TJ 4.0 and it's user tunable.

I don't know what his full tuning capabilities are yet but he doesn't seem to have too many limitations on what he can do. We'll know more as we do some testing. I do know he has a PCM in a YJ that has a TJ 4.0 with the coil on plug rail in it and it's being run with a YJ PCM that has been tuned for a stroker without a piggyback tuner in it.
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Now THAT would be very cool. I look forward to your results as it would really open things up.
mrblaine said:
We have a client with a 97 with the 4.0 and manual trans. He was bragging about how fast it was. I let him drive my 04 TJ Unlimited on 32's with the 4.88's in it (N/A) so he could see what re-gearing does for you. My rig is quiet since it has a newish soft top, auto, and all the carpet. The 97 has a soft top, no windows, only front carpet, and 33's. He came back and said his was much faster. After he left, my helper and I took them over to our "dragstrip" just to see. The heavier Unlimited beat the 97 3 out of 3 times.
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I think the ass dyno always favors the stick even if at the end of the strip it's actually slower. That direct lockup of the clutch just "feels" like it should be faster. 4.88s and 32s should haul the mail.

—
There must have been a time
when we could have said no.
 
mrblaine said:
We have a client with a 97 with the 4.0 and manual trans. He was bragging about how fast it was. I let him drive my 04 TJ Unlimited on 32's with the 4.88's in it (N/A) so he could see what re-gearing does for you. My rig is quiet since it has a newish soft top, auto, and all the carpet. The 97 has a soft top, no windows, only front carpet, and 33's. He came back and said his was much faster. After he left, my helper and I took them over to our "dragstrip" just to see. The heavier Unlimited beat the 97 3 out of 3 times.
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Sorry but two wranglers racing just put a picture in my head of two fat kids running a race, or two skinny dudes in an eating contest.

But remember, the Client is always right!
 
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skrelnik said:
But remember, the Client is always right!
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Not here. In fact this client is about to get his walking papers. In the 6 times I have dealt with him, he has not once been on time and is rarely less than an hour late. Normally that isn't an issue but the last time he had an issue with the lights being wonky and called me at 7:30 on a Friday evening. I told him I'd be glad to take a look at it and he wanted to swing by right then and he lives almost an hour away.

WTF??? No, not tonight and what kind of an asshole even asks that? Knowing his propensity to be late, I offered to look at it the next morning provided they were here on time. He asked what time to be here and I told him it was up to him, pick the time and stick to it. They were still an hour late. He has been relocated to the miserable user category.
 
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mrblaine said:
Not here. In fact this client is about to get his walking papers. In the 6 times I have dealt with him, he has not once been on time and is rarely less than an hour late. Normally that isn't an issue but the last time he had an issue with the lights being wonky and called me at 7:30 on a Friday evening. I told him I'd be glad to take a look at it and he wanted to swing by right then and he lives almost an hour away.

WTF??? No, not tonight and what kind of an asshole even asks that? Knowing his propensity to be late, I offered to look at it the next morning provided they were here on time. He asked what time to be here and I told him it was up to him, pick the time and stick to it. They were still an hour late. He has been relocated to the miserable user category.
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Wow! That's crazy.....yeah, I can see why his about to get his walking papers, I don't blame you. You put up with it longer then I would have.
 
mrblaine said:
Not here. In fact this client is about to get his walking papers. In the 6 times I have dealt with him, he has not once been on time and is rarely less than an hour late. Normally that isn't an issue but the last time he had an issue with the lights being wonky and called me at 7:30 on a Friday evening. I told him I'd be glad to take a look at it and he wanted to swing by right then and he lives almost an hour away.

WTF??? No, not tonight and what kind of an asshole even asks that? Knowing his propensity to be late, I offered to look at it the next morning provided they were here on time. He asked what time to be here and I told him it was up to him, pick the time and stick to it. They were still an hour late. He has been relocated to the miserable user category.
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Yeah, I hate that as well, when someone is consistently late. One or two times, whatever....and to call you on a Friday night wanting light help, ugh. Frustrating, but hopefully he pays you on time.
 
Mike Jolley said:
I have my eyes on the Banks CARB approved turbo with intercooler. Supposed to be pretty easy to bolt on. The turbo is little over $3k, the intercooler is a little under $2k. I’m guessing it’s a weekend install. I have a 30k mile complete 4.0 sitting in the corner of my garage. I’ll probably do the swap first since I feel better about turbocharging a motor with 30k vs one with 123k... I chose 4.56 gears over 4.88s with a turbo in mind.
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Asking because I honestly don’t know, but will that net more gains than stroking the engine? You can get a brand new crate stroked engine for 3-4k.
 
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You can add all the intake and exhaust pieces you want. If you do not address fuel delivery, you aren't getting anything useful, especially for the cash outlay.
 
talianslyr said:
So why would I pay 3k for a kit when I can get a new stroked engine for 1k more. And then I'll have 2 engines?

Sent from my SM-G955U using Tapatalk
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You can have them assembled and shipped in long block form with or without fuel injection. That was merely an option thrown into the fray.
 
Only mods which make a significant difference are the super charger or turbo mods. But they are mostly only noticeable on the highway or if you are towing.

For everything off road, gearing, low range, 4WD are all you need. The 4.0L is an awesome power house for what it was built for, crawling thru ditches and over rocks.
 
zip04 said:
Asking because I honestly don’t know, but will that net more gains than stroking the engine? You can get a brand new crate stroked engine for 3-4k.
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According to Banks you get a 40% torque and 40% HP increase. 0-60 time stock 12+ seconds, with the Turbo, 9+ seconds. Flat out turbos and superchargers are the easiest ways to make big power boosts.
 
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