More HP from the 4.0

[P1atinum]

When I built mine, I took a 98' 10kmi. 4.0l motor, added the larger intake, 24lb mustang injectors, 62mm with the spacer, aftermarket TJ airfilter re-locator (cooler side of engine), K&N big cone, MSD 6al with a blaster 2 coil, MSD fuel pump, header, 2 1/2" flowmaster.

I no-longer wanted a v8.

Still don't.



XJR:us:

I always thought/heard that the stock ignition was pretty strong. Why go with the MSD 6a? Did you see much gain from it?

 

[chaser9478]

I have the "live wire" ignition setup, but I have had my eye on the jacobs system. I may get that with the money I save by doing my own TB. I found an intake on E-bay, there is one here in a jy but the guy only will sell the whole engine......

Talyn You should checkout GWNF. Where do you go? I am always looking for folks to go with.

 

[XJRubicon]

I noticed smoother ecceleration through the powerband with the 99+ intake, but not much else. It can help in conjunction with other mods. Didn't notice anything when I bored out my TB either. TB spacer is useless as well.

Free flowing exhaust(get rid of the crimped factory down pipe at the header collector).

An intake is useless without routing it somewhere other than in the factory spot. It'll just suck the hot manifold air, so something to the other side of the engine bay would work best.

Larger injectors wont do much if the engine doesn't demand more fuel. Stock ones are rated at 23.6 or so anyways.

A teardown of the engine with a cam replacement, headwork, more compression, ect.. can land you more power numbers but will result in emptying your wallet.

No bolt ons that are cheapish will net you huge gains in power numbers(exc. NOS, its cheapish).

I guess different people have different results with things.

I believe that every item has a purpose and if used outside of its requirements will not yield much if any improvement, maybe even hurt.

Example: Adding a beefcake cam to a stock setup.

An aftermarket cam is designed to work with a more free flowing intake and exhaust, you can actually lose power by over camming a motor. choking up the combustion chamber with unburnt fuel or exhaust.


Example: Adding larger injectors to a stock truck.

While they are capable of delivering more fuel per hour, your ECU is going off the O2 sensors to determine how long to open them each cycle to produce the most efficient burn. Its not going to dump more fuel in for no reason. The ECU will regulate them to give the engine what it needs, that is all.
In order to need a larger injector, there must be more demand for fuel.
Used in combination with other items.


There are also Items that can be solely responsible for an improvement in power and or economy.

Example: MSD ignition.

Multiple Spark Discharge. Instead of 1 spark per trigger, MSD delivers a steady stream of spark for up to 20 degrees of crankshaft rotation under 3k rpm. This can improve your bottom end torque, power for the trail and fuel economy on the highway.


I am all for different strokes for different folks, but some things remain the same. That being said, I don't believe the 62mm TB is for high rpm HP.
I have noticed it on the low end throttle response while crawling and the lack of downshifting on the highway to pass in 5th.

Most things you can do to improve power work with each other. You may not see an improvement adding a single 62mmTB and spacer, but when used with a K&N, a high flow cat, a magnaflow and 2 1/2" exhaust, you really notice a difference with out it. I love mine.


Its best to look around, ask some questions, and come up with a plan when trying to gain HP. It can get spendy quick, or you can keep it fairly cheaper by just addressing the bottlenecks. Trick is knowing what that is.

XJR

 

[XJRubicon]

I always thought/heard that the stock ignition was pretty strong. Why go with the MSD 6a? Did you see much gain from it?

I keep it setup to run the stock ignition if need be. (AKA: MIGHT SUDDENLY DIE) They are known!

But yeah, my first 6al that was in my powerwagon I have never had a problem with, its in my jeep now.

I bought the MSD Offroad for my XJ, thinking it would be better. Well It died first trip to Moab, I had to beat it with a 1/2" breaker bar to get it to fire then it would be good for a few days. it did it a second time I went to stock for the rest of the trip. When I got home I put my trusty 6a in there, have not had a problem since... That was 03'

That being said as cautionary advice, I love my MSD for crawling slow it is a must have. I will run them in all my trail rigs. I want one in our daily driver for better fuel econ.

MSD changes the exhaust tone, increases throttle response and causes one hell of a rasp that makes wild life flee for miles when pissed off.

MSD for life
XJRubicon

 

[chaser9478]

I keep it setup to run the stock ignition if need be. (AKA: MIGHT SUDDENLY DIE) They are known!

But yeah, my first 6al that was in my powerwagon I have never had a problem with, its in my jeep now.

I bought the MSD Offroad for my XJ, thinking it would be better. Well It died first trip to Moab, I had to beat it with a 1/2" breaker bar to get it to fire then it would be good for a few days. it did it a second time I went to stock for the rest of the trip. When I got home I put my trusty 6a in there, have not had a problem since... That was 03'

That being said as cautionary advice, I love my MSD for crawling slow it is a must have. I will run them in all my trail rigs. I want one in our daily driver for better fuel econ.

MSD changes the exhaust tone, increases throttle response and causes one hell of a rasp that makes wild life flee for miles when pissed off.

MSD for life
XJRubicon

How do you piss off the MSD to make the wild life flee? LMAO

 

[XJRubicon]

How do you piss off the MSD to make the wild life flee? LMAO

Threaten stock setup!

 

[chaser9478]

How funny.....Guess your right. My dad has a 2003 TJ. I should swap the intakes. He would be PO'd, unless he didn't find out........ I think from what I have been hearing it is worthwhile to switch to the 99+ intake. Its a shame because I just replaced a cracked header last month. It would really make my 4.0 shine though, because I have a nice intake and exhaust...

 

[chaser9478]

I have so many parts waiting to go on. I am waiting for the shock hoop from cross before my jeep goes in the fab shop. They are going to install my air bumps. I have brand new fox 12in shocks sitting on my table. I am probably going to plate the uni body next month. Every month it gets pulled apart to get something done. My wife always wants to know when its going to be done. In the midst of the other work I want to get as much power as I can for the last 50K miles.