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Does anyone have any suggestions to get better mileage and HP from the 4.0L that actually work? I am looking for real info not the "I installed my new Cyclone and wow, for 3 easy payments of $39.95, it feels like I just put a turbo in!"

Air filters, exhaust, headers, throttle body, spacers, etc. I am looking for objective opinions. Thanks.
 
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On my old TJ I had Borla Headers, Cat Back and Gen II Air intake. I did notice some gains, however, I did not see any significant gains in MPG.
 

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Unfortunately you can't really use HP and gas milage in the same sentence.. :?

K & N is the only mod that I have done on my previous TJ and will do on my Rubi.
 

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On all my jeeps I did notice better perfofmence by removing the stock air box.. I had a Turboy city rocket on one and just transfered to the Rubi..Don't know if thier HP claims are true but it does make a difference..
Mike
 

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I was looking at a K&N filter.....I wanted the complete intake kit....the FIPK setup but I didn't see one listed on their site. They just list the drop in factory replacement filter. The stock air box is very lame....to restrictive and I have had my snaps pop off already (don't know why). Anybody try any other aftermarket air intake like the FIPK setup? I have looked at the AiRaid system....seems ok.
 

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Save yourself a ton of $$ and just cut off the stock tube at the end of the smooth part and stick a K&N on...

I will post the part # for you once I find it...... :?
 

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Did you do this mod yourself? Looking forward to the part number and maybe a picture or two.
 

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Here is a pick of the K&N...Note where it the stock air tube is cut.

K&N Part # RU6020

 

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NIce!.....Onboard air too. You used a different filter than I was expecting....Most of the ones I have seen have used the cone style filter.
 

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This is a pic of my Best friends JP. I am running the same system buy I have not Pics. :(


I am currently doing the same set up on the RUBI... :D

Works damn good and sounds sweet.............................

If you need more info let me know.
 
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Mods on my '97 were a Borla header to replace that damn factory manifold (LOTS of cracks), and a K&N drop in element. Header was a great change, with more HP and torque, as well as a slight increase in mileage. The new ('03) exhaust manifold has dual cats right off the head. This is gonna make it harder and more expensive to change to a long tube header. I have had some thoughts running in the back of my mind on a mod that I've not heard of anyone trying yet.......How about an aftermarket cylinder head? Maybe a little more compression, and an increase in port flow and valve size. I had seen one advertised, and would like to hear some feedback from someone who has done the mod. If I remember correctly, 30 to 50 HP gain........Sounds like a good change to me!
 

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The best performance mod I have ever found for most anything....less weight!!

Don't go bolting on huge heavy bumpers, full size spare tires, hard tops, every spare part known to man, long arm lifts, winches and racks and expect to have a speedy jeep.

There is a LOT to be said for keeping weight down when building on a jeep.

Beyond that....more air in...more air out.....with the right amount of fuel.
 

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Good question

Timely question because last night I decided to get myself a 4.0 and build it from scratch over the winter. I have built many race engines and other motors and because of the lack of many things in the 4.0's performance I figured I would try this. I am starting my search for cams, pistons and other components and am more interested in finding out what the end result is than the journey to it. The 4.0 seems like a motor full of potential however the only way to realize it may be a custom build. If anyone has done this and wishes to offer their expierences please speak up, I will be sure to post the outcome in the spring. I'll also post manufacturs or the performance parts I use, assuming of course someone out there makes them. Later, P
 

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http://www.rockcrawler.com/techreports/ ... /page2.asp

Bennie at Hesco`s motor

Hesco`s write up
My ’98 TJ needed a new motor and after considering all my options I decided to get the Hesco 4.6L stroker motor for a number of reasons (see article on stroker motors). Hesco is a very well known company that has an excellent reputation for high performance motors for Jeeps and many other makes as well. Their in house dyno facility tells me they know what will work for bringing out the horsepower and torque.

What is a stroker motor and how does it work? The stroker motor name comes from the fact a stock engine crank has been replaced with a crank that uses a longer throw or stroke. The longer stroke means that there will be more travel for the piston and more volume in each cylinder. The crank change combined with a little boring on the cylinders and some new parts and we will have an awesome motor that all fits in the same engine block of a 4.0L.

My motor was built up by Hesco and I considered building up my own motor until I looked at my calendar of things to do. I just didn’t have the time to build up my own motor anymore and with all my welding and grinding jobs going on in my garage, it was not the environment I wanted to build up a motor in. If you do have the space and time, Hesco does offer a full stroker kit and with a little machine work you will be able to put together your own motor or if you are lazy like me, just let the Hesco boys build one up for you.

The Parts

My stroker motor uses a 4.2L (258) crank shaft in a 4.0L block with custom ceramic coated pistons with moly coating on the skirts, custom rods with fitted wrist pins. The motor also has CNC machined heads with a 5 angle valve job with high performance valve springs and valve guides. The cam is a H264 for lots of torque and a double roller timing chain makes sure it turns the cam. To keep things properly oiled there is also a high volume oil pump and a high performance water pump to keep everything cool. Larger fuel injectors will be required to make sure this motor gets enough fuel and I am also using a ’02 intake manifold for a little more performance. This set up with Hesco’s machining work produced a 4.6L motor with 269 HP and a whooping 339 ft/lbs @3200 RPM on their dyno and its smog legal. The stock computer is kept and it will work fine on regular unleaded fuel.

The Install The install was a remove and replace job. For all outside appearances we are replacing a 4.0L with a 4.0L. All the brackets and engine mounts will fit perfectly as well as the electrical sensors and even hoses. It took friend and I about 10 hours for the swap with air tools, an engine hoist, one large pepperoni pizza and two orders of ravioli. It was a very smooth install and everything fits like a glove.

The Seat Time

The motor started up perfectly and the growl at idle was very nice. We let the motor warm up and checked for leaks. When all the hatches were secured I went for the test spin. It was a night and day difference. When the gas pedal was press the Jeep pushed back. The motor had plenty of torque at idle and it wanted to move even at idle. On a level surface I can ease out the clutch and get my jeep moving without killing the motor. On grades I can easily maintain my speed without having to downshift and my cruise control can keep up on the freeway now. One can easily exceed the speed limit without much effort and acceleration is a lot of fun. Off roading is now a lot easier because there is so much low end torque and it makes climbs easier and more controllable because of the gobs of torque without the higher RPM. It is very entertaining to have a fast TJ because speed and Jeeps is not something that most people think of.

Overall Evaluation

This motor is a dream come true, lots of horsepower, lots and lots of torque and I’m still running regular unleaded fuel. There is no check engine light, I passed my smog check fine and I have a smile every time I drive my TJ. Fuel consumption is about the same but there is a noticeable difference when I play Sunday school bus driver or if I play throttle monkey. I enjoy not noticing grades as much and it is very nice to know the motor has some punch left in it when I’m on the freeway. In my opinion the true test of how much you like something is would you do it again and that answer is a big YES with out a doubt.

Thanks to:

Bennie at Hesco for answering all my questions and the Hesco boys for a first rate job and service.

Tom at Jeep Specialist in San Francisco for all the last minute parts.

Mark Perez for the help with the install.

Duke Dog and Elsa Dog for the guard duty and food begging.

Contacts and info

Hesco

1200 2nd Avenue South, Birmingham, Al, 35233

205-251-1472

Ask for Bennie the Jeep motor guru.

Jeep Specialist

88 Shotwell St. San Francisco, CA 94109

415-241-0656




:wink:
 
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PJ

there is all kinds of aftermarket support for the 4.0.

Cams
cyclinder heads that have been ported, larger valves etc..
stroker kits
TB
superchargers
exhaust

etc......

here is a good website from dino over at JU on the spead freaks forum.

http://www.jeep4.0performance.4mg.com/

My suggestion.........

Stroke it, port the heads with larger valves, get the intake extrude honed, drop in an aftermarket cam, and throw on a bigger TB and a banks header. You could make 275-300 HP 330 or so LBFT torque.

Now build a low compression stroker and then put on a 8.5psi kenne bell supercharger. That engine would make an unbelievable amount of torque.
450+ I have no idea if the stock parts could hold it though.

Don't forget about engine management. Kenne bell might be able to retune your stock computer or you will have to go with an aftermarket stand alone system. You will need larger injectors and I would make sure the stock fuel pump and fuel lines/rail are up to delivering enough fuel.

Here is a good link that talks about the kennebell supercharger and the 4.0
http://www.kennebell.net/techinfo/dodge ... 40tech.pdf

It also explains why the 03 4.0s are so slow, look at page 2. Are engines are running too lean, even at WOT.
 

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Not going to give a parts list ,but you guys are on the rite track.
Think MOPAR!!!
lots of heads to chose from!!
and you can get the right cam also from Mopar Proformance.
Best of all you keep your factory warranty intact w/Mopar stuff.

See Ya on the Race Track
Robocon
 

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This is the cheapest fuel economy mod out there, always drive with the wind behind ya!!!
 

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I run a K&N and just recently had my muffler cut off and a tube put in it's place. Sounds better and a little more responsive. Cheap and easy just the way I like them! Mod's that is.

Adam
 
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