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XJ performance upgrades?

yea thatll work as a really good air dam in an intake which you are trying to make more free flowing.

please do your jeep a favor and save things like this for hondas
 
LOL I wasnt going to buy it I was looking online and came across that site and had no clue if it worked.

Im new to moding a Jeep well hell any car this is my first. Im looking for tips, I wanted to do intake, chip, exhuast for now
 
intake/exhaust are good first upgrades, beyond that searching will be your friend and your flame suit, welcome to the boards man
 
Welcome to the boards.

My suggestion is to stay far away from Jet chips. I ran one for a day and it nearly fried my computer, it made all my sensors go nutty. I've heard other horror stories with them too.

If I were you, I'd start with a bored out throttle body, and a cat-back kit.
 
First things first - what year are you working with (it makes a difference,) and what is your plan? Doing a performance buildup as a batch of discrete mods can work (you tackle the project stepwise,) but if you're not working toward an ultimate goal, you're not really going to get anywhere. Besides, if you don't know where you're going, how will you know when you get there?

A bored throttle body is mainly going to show as crisper part-throttle response - in the case of both RENIX (1987-1990) and HO (1991-2001,) the OEM throttle body can support maximum airflow rates for the production engine, and even all but the most exotic strokers.

Unless you're building a street racer, you are likely going to want to work to maximise low-end torque output (vice high-speed horsepower,) and that's going to want to start with modifying camshaft timing and valve opening events. Even with forced induction (a real supercharger or a turbocharger,) you're going to want to swap a better bumpstick in and get your fuel delivery and ignition timing all sorted out - you can drop a blower onto a stock engine in good condition and notice a gain in performance, but it won't be all you can really get if you do the job right (from zero, in other words.)

But, I'm going to start with the same advice I was given years ago (before I started building bracket engines, mild pulling engines, and other fun stuff...) and that I started giving a few years after: Sit down with three pieces of clean paper. Label one "ideal", another "minimum", and the third "acceptable". Write down what you really want on the "ideal" list, what you'll take as a minimum on the sheet so labelled, then you'll write a compromise on the third. Will you get everything you want? Probably not, as most people in your position have eyes bigger than their stomachs. As you learn more about how an engine works and what makes it work better, you'll be able to set more realistic goals (within the limitations of platform and budget.) Will you get more than the minimum? Quite likely - and it will be a learning experience for you. Most people I've guided through this have ended up getting their "acceptable" level or slightly better, so the idea does work. But, if you are new to modding like this, you're going to need to learn a lot before you can really understand what you're doing, and why it works.

For those "electric superchargers?" Don't bother - the ones that are cheap won't push enough air at enough pressure to matter, and the ones that can/will will cost you too damned much to bother (better to start with the cam swap.) Either plan on a supercharger (driven by the crankshaft via a belt) or a turbocharger (driven by exhaust gasses and wasted heat energy from the engine.) Both will give you a parasitic drain on power output, but it's more than made up for with the boost you get from the increase air intake (and the fuel delivery increase that had damned well better accompany that air!)

Nitrous oxide will work in a similar fashion - note that nitrous doesn't make power on its own! Nitrous is a compound of nitrogen and oxygen that dissocates at elevated temperatures, increasing the availability of oxygen to combine with fuel. Therefore, there had better be extra fuel being delivered - at flash temperatures in the chamber, it's quite likely that the oxygen will find something else to combine with - like the aluminum pistons. Oops.

By now, I'm sure you can see some of the pitfalls you're likely to run into. Probably the best way to increase power output of a naturally-aspirated engine (no boost) running just air (no nitrous) would be to swap out the camshaft, as the OEM cam is a compromise between power, economy, and "making the thing run smooth" (NVH, or "Noise, Vibration, and Harshenss".) Ever hear an old built musclecar idle? Sounds rough, right? That's because the camshaft timing has been altered - wind it up a bit, and it smooths right out - but it has a hard time holding an idle (try getting a rumble like that out of a rice rocket!) That's going a bit far, and it's damned difficult to do with computer-controlled engines, but you can get the idea - the big high-torque engine has trouble idling because the valve opening events overlap so far that it has a hard time holding the fuel-air charge to compress it. Once you speed the thing up, inertia settles the whole thing down and it holds onto the fuel-air mix, compresses it, burns it, and makes power as a result.

Why do I get the feeling I'm going to have to print a few more copies of my book?:laugh::rof::eyes:

As you can probably tell, I've been learning quite a bit more about this subject (you should see the bookshelves in my office!) and I'm still working on "translating" most of it into layman's terms - so you won't need a good deal of understanding of thermodynamics, fluid dynamics, petrochemistry, physics, or other abstruse subjects to understand it...
 
In order, I'd go:
2.25 - 2.5" diameter downpipe (from manifold to cat)
Get your TB bored out (search google for "gojeep")
99+ Intake
Some sort of header upgrade
Check this site:
http://www.angelfire.com/my/fan/

NO need for the 99+ intake I have a 2000 XJ. Im looking into the mustang 70mm throttle body got the idea from that site. same measurements as the one mentioned.

Thanks for the tips
 
First things first - what year are you working with (it makes a difference,) and what is your plan? Doing a performance buildup as a batch of discrete mods can work (you tackle the project stepwise,) but if you're not working toward an ultimate goal, you're not really going to get anywhere. Besides, if you don't know where you're going, how will you know when you get there?

A bored throttle body is mainly going to show as crisper part-throttle response - in the case of both RENIX (1987-1990) and HO (1991-2001,) the OEM throttle body can support maximum airflow rates for the production engine, and even all but the most exotic strokers.

Unless you're building a street racer, you are likely going to want to work to maximise low-end torque output (vice high-speed horsepower,) and that's going to want to start with modifying camshaft timing and valve opening events. Even with forced induction (a real supercharger or a turbocharger,) you're going to want to swap a better bumpstick in and get your fuel delivery and ignition timing all sorted out - you can drop a blower onto a stock engine in good condition and notice a gain in performance, but it won't be all you can really get if you do the job right (from zero, in other words.)

But, I'm going to start with the same advice I was given years ago (before I started building bracket engines, mild pulling engines, and other fun stuff...) and that I started giving a few years after: Sit down with three pieces of clean paper. Label one "ideal", another "minimum", and the third "acceptable". Write down what you really want on the "ideal" list, what you'll take as a minimum on the sheet so labelled, then you'll write a compromise on the third. Will you get everything you want? Probably not, as most people in your position have eyes bigger than their stomachs. As you learn more about how an engine works and what makes it work better, you'll be able to set more realistic goals (within the limitations of platform and budget.) Will you get more than the minimum? Quite likely - and it will be a learning experience for you. Most people I've guided through this have ended up getting their "acceptable" level or slightly better, so the idea does work. But, if you are new to modding like this, you're going to need to learn a lot before you can really understand what you're doing, and why it works.

For those "electric superchargers?" Don't bother - the ones that are cheap won't push enough air at enough pressure to matter, and the ones that can/will will cost you too damned much to bother (better to start with the cam swap.) Either plan on a supercharger (driven by the crankshaft via a belt) or a turbocharger (driven by exhaust gasses and wasted heat energy from the engine.) Both will give you a parasitic drain on power output, but it's more than made up for with the boost you get from the increase air intake (and the fuel delivery increase that had damned well better accompany that air!)

Nitrous oxide will work in a similar fashion - note that nitrous doesn't make power on its own! Nitrous is a compound of nitrogen and oxygen that dissocates at elevated temperatures, increasing the availability of oxygen to combine with fuel. Therefore, there had better be extra fuel being delivered - at flash temperatures in the chamber, it's quite likely that the oxygen will find something else to combine with - like the aluminum pistons. Oops.

By now, I'm sure you can see some of the pitfalls you're likely to run into. Probably the best way to increase power output of a naturally-aspirated engine (no boost) running just air (no nitrous) would be to swap out the camshaft, as the OEM cam is a compromise between power, economy, and "making the thing run smooth" (NVH, or "Noise, Vibration, and Harshenss".) Ever hear an old built musclecar idle? Sounds rough, right? That's because the camshaft timing has been altered - wind it up a bit, and it smooths right out - but it has a hard time holding an idle (try getting a rumble like that out of a rice rocket!) That's going a bit far, and it's damned difficult to do with computer-controlled engines, but you can get the idea - the big high-torque engine has trouble idling because the valve opening events overlap so far that it has a hard time holding the fuel-air charge to compress it. Once you speed the thing up, inertia settles the whole thing down and it holds onto the fuel-air mix, compresses it, burns it, and makes power as a result.

Why do I get the feeling I'm going to have to print a few more copies of my book?:laugh::rof::eyes:

As you can probably tell, I've been learning quite a bit more about this subject (you should see the bookshelves in my office!) and I'm still working on "translating" most of it into layman's terms - so you won't need a good deal of understanding of thermodynamics, fluid dynamics, petrochemistry, physics, or other abstruse subjects to understand it...

What he said.
Listen to this guy, Dr Dino, a few others - they've been there and done that, better results than most.
 
where do you get a DP? custom made at the exhaust shop? mine has a nice dent in it

That dent is there "on purpose" - it's to provide operating clearance for the front driveshaft at stock height, at full stuff. Don't eliminate that unless you've lifted - I think the consensus is at least three inches to have a stock size downpipe with no dent.

As far as "where" - you can probably have it bent up by any competent exhaust shop. Take your old one in, and tell them you want one without the crimp because you've lifted the vehicle (a good shop will ask you about it if you don't tell them - especially if they do a lot of Jeep work.)
 
5-90 i want your brain, i know most of that stuff i just wish i could convey my knowledge better
 
First things first - what year are you working with (it makes a difference,) and what is your plan? Doing a performance buildup as a batch of discrete mods can work (you tackle the project stepwise,) but if you're not working toward an ultimate goal, you're not really going to get anywhere. Besides, if you don't know where you're going, how will you know when you get there?

A bored throttle body is mainly going to show as crisper part-throttle response - in the case of both RENIX (1987-1990) and HO (1991-2001,) the OEM throttle body can support maximum airflow rates for the production engine, and even all but the most exotic strokers.

Unless you're building a street racer, you are likely going to want to work to maximise low-end torque output (vice high-speed horsepower,) and that's going to want to start with modifying camshaft timing and valve opening events. Even with forced induction (a real supercharger or a turbocharger,) you're going to want to swap a better bumpstick in and get your fuel delivery and ignition timing all sorted out - you can drop a blower onto a stock engine in good condition and notice a gain in performance, but it won't be all you can really get if you do the job right (from zero, in other words.)

But, I'm going to start with the same advice I was given years ago (before I started building bracket engines, mild pulling engines, and other fun stuff...) and that I started giving a few years after: Sit down with three pieces of clean paper. Label one "ideal", another "minimum", and the third "acceptable". Write down what you really want on the "ideal" list, what you'll take as a minimum on the sheet so labelled, then you'll write a compromise on the third. Will you get everything you want? Probably not, as most people in your position have eyes bigger than their stomachs. As you learn more about how an engine works and what makes it work better, you'll be able to set more realistic goals (within the limitations of platform and budget.) Will you get more than the minimum? Quite likely - and it will be a learning experience for you. Most people I've guided through this have ended up getting their "acceptable" level or slightly better, so the idea does work. But, if you are new to modding like this, you're going to need to learn a lot before you can really understand what you're doing, and why it works.

For those "electric superchargers?" Don't bother - the ones that are cheap won't push enough air at enough pressure to matter, and the ones that can/will will cost you too damned much to bother (better to start with the cam swap.) Either plan on a supercharger (driven by the crankshaft via a belt) or a turbocharger (driven by exhaust gasses and wasted heat energy from the engine.) Both will give you a parasitic drain on power output, but it's more than made up for with the boost you get from the increase air intake (and the fuel delivery increase that had damned well better accompany that air!)

Nitrous oxide will work in a similar fashion - note that nitrous doesn't make power on its own! Nitrous is a compound of nitrogen and oxygen that dissocates at elevated temperatures, increasing the availability of oxygen to combine with fuel. Therefore, there had better be extra fuel being delivered - at flash temperatures in the chamber, it's quite likely that the oxygen will find something else to combine with - like the aluminum pistons. Oops.

By now, I'm sure you can see some of the pitfalls you're likely to run into. Probably the best way to increase power output of a naturally-aspirated engine (no boost) running just air (no nitrous) would be to swap out the camshaft, as the OEM cam is a compromise between power, economy, and "making the thing run smooth" (NVH, or "Noise, Vibration, and Harshenss".) Ever hear an old built musclecar idle? Sounds rough, right? That's because the camshaft timing has been altered - wind it up a bit, and it smooths right out - but it has a hard time holding an idle (try getting a rumble like that out of a rice rocket!) That's going a bit far, and it's damned difficult to do with computer-controlled engines, but you can get the idea - the big high-torque engine has trouble idling because the valve opening events overlap so far that it has a hard time holding the fuel-air charge to compress it. Once you speed the thing up, inertia settles the whole thing down and it holds onto the fuel-air mix, compresses it, burns it, and makes power as a result.

Why do I get the feeling I'm going to have to print a few more copies of my book?:laugh::rof::eyes:

As you can probably tell, I've been learning quite a bit more about this subject (you should see the bookshelves in my office!) and I'm still working on "translating" most of it into layman's terms - so you won't need a good deal of understanding of thermodynamics, fluid dynamics, petrochemistry, physics, or other abstruse subjects to understand it...


Thanks..That was a lot to type....(glad I didnt have to)

Im looking to increase low end torque for off roading. I noticed a lot of the power kicks in around 3k rpm. I got a tight budget right now (no job) (school). I have a 2000 XJ with a 3 inch lift and 31 inch tires bone stock engine
 
5-90 i want your brain, i know most of that stuff i just wish i could convey my knowledge better

Heh. I'd be happy if I could download it, defrag it, clean it up, back it up, and upload the revised copy. It would make some things so much easier...

Why do you think I've started writing? I can't follow someone else's schedule anymore, so I work for me. Part of what I do is mail-order, I do some odd jobs, and I work on my books (working on the second now. Good response to the first.)

Besides, why learn so much if you don't teach it to others? I'm willing to teach damned near anything I know - there are a few things I won't teach outside of family, and even fewer I won't teach at all, but the rest of that is pretty open.
 
Yeah, forgot to mention that : The downpipe would need to be EXTREMELY close to the block / oilpan to clear the driveshaft at full stuff. Mine doesn't. It's irritating and liable to contribute to my header's demise some day.
 
Thanks..That was a lot to type....(glad I didnt have to)

Im looking to increase low end torque for off roading. I noticed a lot of the power kicks in around 3k rpm. I got a tight budget right now (no job) (school). I have a 2000 XJ with a 3 inch lift and 31 inch tires bone stock engine

OBD-II will make your job a bit more difficult (if you change something too much, it will throw codes at you...) and I don't know what the smog regs are like in NYS. Can't be as bad as here in CA, tho.

The good news is that more "bolt-on" parts are going to be available for you than for me (I have RENIX, which is pre-OBD and there aren't an awful lot of "California-approved" parts available...) but the gains from them are going to be minimal. However, they should complement a cam swap easily - and I've used Crane, Comp, or Isky cams on various engines with good results. I'm sure Crane and Comp make cams for the AMC six, and there's an outfit called Lazer (found them when I was researching the Power Manual) thta have promising numbers.

Recall that an engine is little more than a large air pump that generates power, and it needs less power to run than it generates. What's left gets split three ways (cooling system, exhaust, motive power) and all you're trying to do is make more power. It's still going to get split - but you're going to move up.

How do you make more power? You need to burn more fuel. In order to burn more fuel, you'll need more air - which means that most engine power adders are going to be concerned with helping the engine move more air through itself - by opening up the exhaust, opening up the intake, and then altering camshaft timing.

What I'd do? Find a #0630 (1996-1998/1999) or a #7120 (1991-1995) cylinder head, and get ready to bolt that on. Both heads will have more exhaust flow than your #0331 head, and the #7120 also shows a marked increase in intake flow (since your intake manifold and throttle body will support the flow, the cylinder head port is the next restriction that needs to be eased.) You'll need an adapter for the exhaust manifold - but there's a thread around here somewhere for someone who has designed a plate and is selling them - for #0331 to #0630 conversions, but it should be able to be made to work with the #7120 head as well. Keep your later intake manifold - it flows better. You'll also need to fabricate bracketry for the coil rail pack you have - the #0630 and #7120 heads don't have the mounting bosses for it - but that shouldn't be too much work.

If you've lifted, get a new downpipe made. If you haven't, you may not need it unless you're building a stroker anyhow. Either way, get a more free-flowing muffler (you don't need a glasspack, but I've heard good about the Flowmasters and the like. I've actually been using Walker Turbo II mufflers - about twenty bucks at the local - and I've been happy with them. BD - Butt Dyno - does show a slight increase in power, they sound nice, and they're cheap.) Next thing to tackle in the exhaust is the catalytic converter - I've had good luck using BBChevvy "universal" converters on my RENIX rigs, but I'm not sure how well it will work with OBD-II - it should tho - since I've not failed a California emissions check using them. Your 2000 likely has "pre-cats" and main cats - see what you can do there (I haven't done much research.) Make sure you can replace the HEGO sensors in the manifolds; the bung is a standard size, and if the part you're using doesn't have them, any competent exhaust shop should have a boxful and can drill and weld them wherever you need them.

As I said earlier, you don't really need the bored throttle body - the main thing you're going to notice there is part-throttle response, rather than an increase in torque output. So, save that for later (and note that you can usually get away with using later Ford small block throttle bodies, making them easier to find.) Essentially, if you "blip" the throttle with a bored throttle body, you're going to see the effective opening open up faster - which is what makes for faster response. It's a simple swap - you don't need to do it, but if you want quicker response, it's an idea.

Once you've sourced your replacement cylinder head, have the ports cleaned up and polished (it's a "dry intake" setup, so you don't have to worry about fuel puddling. You don't want a mirror finish, but you don't really want the "sand-cast" finish either.) to improve airflow. Do not change the profile of the port - just clean up the surface. Don't do anything to change the profile of the port unless you have a flowbench - it's painfully easy to screw this job up! Standard Abrasives has an excellent writeup on their site to do this very job, and they're also a good supplier of abrasives for the job (you'll find an air-powered die grinder to be best for the job, believe me.) Smooth out the cast surface of the combustion chambers as well, and be sure to "break" (gently!) the sharp edges where the machined surface meets the cast bowl - this point is a heat riser, and breaking this will help to keep detonation down. Don't remove a lot of material - feel it before you start, gently hit it with the abrasive, and feel it afterwards. All you really want to do is round it off slightly - that's it!

Once you've done with the airflow bits, go over the head and make sure you don't have any flash from mould parting lines anywhere - heat risers, again. Cleaning casting flash up will help to improve heat rejection. All parts should have casting flash cleaned off of them.

If you take the head in for work, specify a "three-angle" valve job (which you should get anyhow) - a "five-angle" is more work than you need, and more money than you want to pay. Don't bother changing the size of the valves - it's also more work than you need to have done.

That should be enough to keep you busy for a little while. Let me know if you need more...
 
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