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Old 09-19-2007, 11:29 AM   #1
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4.0L Engine Upgrades?

Alright, so I know that this 4.0L isnt exactly a huge power house. But are there any upgrades that can be done to help this thing breath a little better and possibly get some more tq / hp out of it with out spending gobbs of money on it (and still keeping the factory warranty. I get enough flack from this 4" lift that I have on here from the stealer-ship) so super chargers and v-8 swaps are out of the question at this point lol.

-K&N air filter?

-Bigger throttle Body?

-Bigger hose from the Air filter box? because it seemes like the engine is starving for Air above 3,500rpm and doesnt really do much in terms of speed while going up mountains. (usually im in second gear trying to maintain 50mph on I-70 @ 10,000+ ft on a 5% grade trying not to get hit from behind. Note location to the left) This is w/ the stock 30x9.5.15 stock tires and a 3.73 rear axle.

-After market plugs / wires? Hei DIST?

-Exhaust? Would a 2.25 or 3" mandral bent single exhaust? New Muffler / Cat? How efficient is the stock exhaust? I dont really hear many people doing this kind of swap hear more lift kits, bigger tires and re-gearing more than anything.

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Old 09-19-2007, 11:38 AM   #2
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all that stuff does nothing IMO.

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Old 09-19-2007, 11:44 AM   #3
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How can all of that stuff do nothing?
Is that just specific to the 4.0L motor or are you saying that in general?

Is this 4.0L a bad base to start with for bolt on performance, or is the stock OEM motor / parts about as best as this motor can get as far as HP / tq numbers are concerned.

In racing applications, all of those parts that I listed have made a performance gain. But then again they were bigger / different motors.

Currently right now its a 262cubic inch motor and producing 190hp. so its Cube inch / bhp rating is .793 bhp / cubic inch or ~47.5 bhp/L

If I could get it closer to a 1:1 ratio that would be much better. What could be hindering this? Heads? compression ratio?
I dont know enough about this motor to really have a scientific reason for it.
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Old 09-19-2007, 11:48 AM   #4
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Unless you're going to put the avenger supercharger on, theres not a lot you can do with the 97 and newer 2.5's and 4.0's. They are old technology in an emmission compliant world now.

Yes there are little things, but overall, other than making you happy cause yours is diffrent the result is the same.

A few horses a few TQ's but you're not going to see any real significant gain long term because the computer will adjust air/fuel ratio's to their optimum for spark advance and efficiency.

Combine AIr intake system with exhaust system and a hypertech programmer with premium fuel and a lower t-stat probably 20Hp guessing, But all that money, go out and cursh the exhaust on a stump or rock, added open air filter in water or extremy dusty trail contitions, and the added expense of premium fuel.

Or get the same equilivant of a regear for 700 800 bucks if you pay someone to do it, then you have none of those worries above and power all the time.

From www.allpar.com

“Compared with other contemporary engines, the 4.0 was strong up until the end - which will be/was when it was finally dropped from the Jeep Wrangler.”

As Jim Stone pointed out, the 4.0 “is descended from the ‘Typhoon’ 232 cid straight-six that came out in 1964. It may have inherited some elements from earlier Nash/AMC poewrplants, but it was essentially a whole new design in 1964.”

Bob Sheaves wrote:

The 4.0L was a strong performing engine, no doubt. There were a couple of issues with the basic design, including leaks; the oil pump was notorious for wearing out at around 145,000 to 155,000 miles, and the TPS (throttle position sensor) on the 1989/1990 models would fail if someone spit on the sidewalk.

The reasons the 4.0L went away [except in the Wrangler, so far] was due mainly to age of the manufacturing tooling, which was worn out completely. The long stroke engine was much harder to clean up the emissions of NOx, and NIH ("Not Invented Here"), in my opinion, also reared its head. To completely retool would have cost as much (almost) as the 3.7L v6 did, and the Dodges were going to use the 3.7 as a base engine. Logically, the engine group did what they were told to satisfy the dealers...."Make a modern engine, and junk the old ones." This statement is my opinion, based on conversations at the time.
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Old 09-19-2007, 12:36 PM   #5
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So basically to make a long story short, the 4.0L is based upon old technology from 1964 and has had very little modification / change since there. (Maybe adding injecors, lowering compression etc to make it more efficient and stay within standards of the wonderful emissions.)

But the thing that causes the biggest dramatic increase in HP /tq is going to be in the heads and compression ratio, cam etc has a little to do w/ it as well.

Are the valves too small causing the volumeetric efficiency to be very low?
The cam's lift duration not big enough due to emissions restriction the efficency of the valves?

Makes me wonder if I should have bought the new 2007 wrangler instead due to the new engine re-design that they had for the v-6 motor.
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Old 09-19-2007, 01:03 PM   #6
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Quote:
Originally Posted by EnigmaMan View Post
-K&N air filter?
I put on an AirRaid filter and noticed an increase in my '03 4.0L.

Quote:
Originally Posted by EnigmaMan View Post
-Bigger throttle Body?
Everybody I've talked to says that this is a waste of $$$. Many have tried it and removed later on.

Quote:
Originally Posted by EnigmaMan View Post
-Bigger hose from the Air filter box?
Bigger hose typically comes with the K&N or AirRaid kit.

Quote:
Originally Posted by EnigmaMan View Post
-After market plugs / wires? Hei DIST?
Dunno.

Quote:
Originally Posted by EnigmaMan View Post
-Exhaust? Would a 2.25 or 3" mandral bent single exhaust? New Muffler / Cat? How efficient is the stock exhaust? I dont really hear many people doing this kind of swap hear more lift kits, bigger tires and re-gearing more than anything.
I upgraded my exhaust and didn't notice any difference. Only reason I upgraded was to provide extra clearance for the articulation from the lift. Wouldn't bother honestly.

I'd have to say the biggest enhancement I've come across was moving from the stock clutch based engine fan to an electric fan. Noticed big perks after doing this. (Click Here)
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Old 09-19-2007, 01:04 PM   #7
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You bring up a good point on your 50mph example...

Are you sure your engine computer is calibrated for high altitude operation? Didn't I read you got your rig from Texas?

I live in a semi-mountainous area that has dramatic inclines and I have absolutely no issues maitaining 6% grades in 2nd gear with 3.73 gears and running 33's and keeping 70-80 mph.

IMO - I think you should check out your calibration. If your engine control computer was calibrated for sea level operations (as it was probably ordered for Texas) then you will have issues at high altitude.
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Old 09-19-2007, 01:27 PM   #8
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Description: in-line six, overhead valve (two per cylinder), flat-face followers, hydraulic lifters, cast iron block and head
Displacement: 3960 cc (242 cubic inches)
Bore and stroke 98.4 mm x 86.7 mm
Compression ratio 8.8:1
Redline: 5,300 rpm

Maximum power, Wrangler:

USA - 190 hp (142kW)@4,600 rpm; 235 lb-ft (319 Nm) @ 3,200 rpm



once you pass 3200 youre tq drops dramaticaly, its making HP till 4200 but its not a highperformance engine, its set up for idleing long periods and TQ from idle to 3200, for pulling and starting out on steep inclines and pulling.

I unserstand where youre going EnigmaMan but if you do all those performance mods youre going to shift the power band higher, yes makingm ore peak HP but reducung TQ down low, and the effects are goign to negate themselves.

If you really want to do those things look here.

The Insane Inline, Part 1
Golen Engine Service-built 4.6L stroker for power and longevity

http://www.jpmagazine.com/techarticl...ine/index.html




Here is exactly what youre looking for a comparision stock to mod to heavily modded to stroked comared.
http://www.jpmagazine.com/techarticl...ne_3/dyno.html

But note were all the gains are, at +4000 RPM's
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Old 09-19-2007, 01:29 PM   #9
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Yes u are correct, I did buy the jeep in Wonderful Dallas / Fort-less, Texas lol. My house here just outside of Denver is at ~6,017 feet above sealever and a lot of the 4 wheeling places are between 7500ft - 12,000 feet and get up to the occasional 14,000+ feet.

I do know that a N/A motor will loose between 3%-5% of its total output (in hp) for every 1,000 foot in elevation gain.

Supercharged / Turbo is ~1%-3% depending on the VE (volumetric efficency) of the motor, type of super charger, compressor etc. for every 1,000 ft in elevation gain.

With this calculation @ 8,000 feet I will loose ~32% (+/- 3%) or 60.8hp.


I have heard different points of view on this subject..

some say that the "MAF" should be able to comensate for this difference in pressure and calibrate the computer accordingly.

Some say that the MAF is only designed to handle a max height of 0-5,000feet due to relative pressure / air volume specs that it was origionally designed for.

Others say that it needs to be re-calibrated.

Is this something that I will need to take into the dealership or order a new MAF / ECU to compensate for this?
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Old 09-19-2007, 01:54 PM   #10
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Basicaly to reset the Learning mode of the computer.

Unhook both battery terminals, with a door open or other accessory on, thats not swiched by the key

Touch the positive to ground, or touch the cable ends together.

I usually leave mine ovrenight,

It takes something like 50 key cycles and over 160 operating temp for the computer to learn and adjust, basicaly just drinve normally and it will sort it out.

Im lookinf or the how to info now.

This is what i went by:
http://www.wranglerforum.com/tj-chat...-pcm-8050.html
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Old 09-19-2007, 02:01 PM   #11
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Stroke it.
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Old 09-19-2007, 02:04 PM   #12
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4.0 is a 242.

those mod's do not do a whole lot for the 4.0
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Old 09-19-2007, 04:20 PM   #13
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So basically to sum it all up, the 2.4L and 4.0L are pointless to upgrade and it would have mae more sense to install a turbo charged diesel motor in it (due to the low RPM Tq demands and excessive ideling). lol

So, aside from the ECU re-learning for the differences in altitude, there isnt much that can be done for it. (at least from an economical stand point).
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Old 09-19-2007, 07:11 PM   #14
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So basically to sum it all up, the 2.4L and 4.0L are pointless to upgrade and it would have mae more sense to install a turbo charged diesel motor in it (due to the low RPM Tq demands and excessive ideling). lol

So, aside from the ECU re-learning for the differences in altitude, there isnt much that can be done for it. (at least from an economical stand point).
Yes- without spending mad cash, what you got is as good as it gets. You either compromise fuel ecomomy for speed and power, or vise versa

The diesel on the other hand they say (government) that the CRD Diesel they sell in europe won't pass emissions here. (I read as - they dont want to)

ENGINE & TRANSMISSION
Cubic Capacity 2777 cc
Configuration 4 cylinders in line
Bore x Stroke 94.0 x 100.0 mm
Compression Ratio 17.5:1
Fuel Delivery Diesel direct injection
Maximum torque 295 lb ft @ 2000-2600 rpm
Maximum power 174 bhp @ 3800 rpm
Gearbox 5 speed automatic
Fuel Type Diesel

http://www.jeep.co.uk/jeep/vehicle.aspx?ID=270,2


if that isn't enough

Here have an 8.0L Wrangler
http://www.burnsvilleoffroad.com/Art...05_11_06c.aspx

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Old 06-09-2012, 07:38 AM   #15
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I fell into doing all those Mods when i was still learning. Spent plenty of coin trying to get the most out of my 4.0. Geared to 4.56 as well. After doing all the mods, my TJ was running like crap. emissions was bad, air/fuel all out of wack. This was after the hypertech chip as well. I backed off, went back to stock plugs/distr, went back to stock ECU settings. I ended up keeping the headers, exhaust, Cold Air intake, and "hotter" plug wires, and the 4.56. I tell ya, that 4.0 is running great now! Doing the gears was by far the best thing Ive done. no gained HP, just more fun to drive with a little kick in the ass on take off. (yes the front end comes up when I get on it) i can cruise at 100mph and she loves it! My advice, do the little things, let her breath a little better, and be happy with the small gains youll get. No magic formula. Its a good platform, dont try to do too much. (oh, my gas mil sucks!!!! but thats expected with my gear ratio)
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Old 06-09-2012, 07:59 AM   #16
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(yes the front end comes up when I get on it) i can cruise at 100mph and she loves it! (oh, my gas mil sucks!!!! but thats expected with my gear ratio)
Remember, just because you can, it doesn't mean you should. Jeeps and low speed accidents usually result in very little damage. Jeeps and 100mph accidents would be catastrophic! Imo you would have a better chance surviving a 100mph accident in most any car bigger than a Prius than you would in a Jeep. Just sayin....
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Old 06-10-2012, 04:45 AM   #17
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There is no arguement that you shouldnt just because you can. Just the mere point that the gearing was the best option to get the best out of the driving experiance of you Jeep.
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Old 07-30-2012, 12:19 AM   #18
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just to add my .02 i have been doing a lot of reading and trying to put my racing work into play. really that wont work. i did to my 04 was a volant cold air intake and a 2.5 catback. what it did for hp and tq im not to sure but seat of the pants dyne and fuel milage did go up. i picked up a throttle body with the computer (crs i can't recall the name) and driving up and down hills became easier without a change in fuel economy unless i got pedal heavy. i wanted the 4.0 because of its run long take anything reputation. after researching header, cam, stroking i decided that regearing when i put my 33's on is the best option. if i can get my hands on a supercharger ill probably do it just because for the last 10 years i have driven supercharged cars on and off the track. forced induction may help with a retune at high alt. my brother moved from shawnee co and had to have his f150 retuned for the drop in elevation when he moved to pa.

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