Darky
NAXJA Forum User
- Location
- 29 Palms, CA
Power is power. Search Street and Performance, there's lots of info on power adding there.
Also, dump some Badger Milk in the tank.
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Motor Mods
- Thread starter joejeep92
- Start date
Also, dump some Badger Milk in the tank.
robsjeepxj
NAXJA Forum User
- Location
- North Jersey
Then in that case sell your first born and get a 4.7 stroker with a race cam, roller rockers, aluminum head, stainless headers & 2.5" high flow exhaust, a belt driven super charger, 60# injectors & throttle body and you should be have enough HP to blow out the trans, transfercase and rear in a few weeks if you don't snap the unibody in half first.
jeeperjohn
NAXJA Forum User
- Location
- Temecula, CA
Honestly, I'd be looking to upgrade from the 35 before doing any performance mods.
joejeep92
NAXJA Forum User
- Location
- Beloit, KS
Well I have the possibility of a set of Dana 44's out of a 89 Grand Wagoneer. Not sure on gear yet...
- Location
- Southern Maryland
Basic starting point is that an internal combustion engine is essentially just a self-motivated air pump with a lot of leftover power--it pulls air into the pump, mixes it with gas and sets it on fire, and then pushes the spent air out of the pump. All of the power for the pump comes from the combustion process, and the leftover power is then directed to the transmission. Only the leftover power is available, and any power that is consumed elsewhere will not be available.
In a four-stroke engine the process is
1) piston pulled down draws air and fuel into the chamber from the manifold
2) piston pulled up compresses air and fuel
3) spark ignites compressed air and fuel, forcing piston down
4) piston pulled up expunges spent air and gasses
The only part of the cycle that produces power is the explosion, the rest of it consumes power that is made from an explosion in some other cylinder. Thus the two basic strategies available are to either make a better or bigger explosion that produces more power, or reduce waste in the engine itself so that more of the power that already exists can be sent to the transmission.
If you want to make significantly more power then you need a bigger combustion chamber with more fuel and air. There's no replacement for displacement. This is $$$ but it works.
Low-dollar mods will not cause your existing engine to produce significantly more power, and instead all they can do is make it run more efficiently, meaning less waste, so that more of the existing power is available to the transmission. For example a high-flow air intake allows air to be pulled into the combustion chamber with less resistance so less energy is consumed on the dead downstroke, while a high-flow exhaust allows air to be expunged from the combustion chamber with less resistance so less energy is consumed on that upstroke. If both are installed then the air pump will have much less drag and there can be substantially more power available to the transmission but you will only be using the power that is already there. Another big thing to do here is get a more aggressive cam that will hold the valves open longer so that the engine can breath better.
Ignition mods that help to ignite the air/fuel mixture sooner or more fully can help to produce a cleaner/fuller explosion that motivates the piston better. The best you can do here is use good spark plugs, wires and distributor parts to get cleaner and fuller spark to the combustion chamber. Our engines do not have adjustable timing in the traditional sense and you have to monkey with the sensors to advance the spark. Indexing the spark plugs to produce fuller ignition will help sometimes. Higher grade gas can help with the combustion process too. Better oil lubrication will reduce resistance on the moving parts. Etc.
One of the biggest things you can do is get rid of engine accessories. On my engine the biggest jump in responsiveness came when I replaced the mechanical fan with an electric. The mechanical fan is always partially engaged, and so it is always dragging on the crankshaft and consuming energy that could otherwise be directed to the wheels, while an electrical fan with a temperature switch only produces drag on the alternator when it is needed. Likewise the A/C compressor, power steering pump and water pump can account for significant drag, and switching out old parts can free up some ponies (one of the articles I remember said their biggest gain was from switching out a nasty power steering pump).
There are a lot of good suggestions in the street forum but that should give you some ideas. Just think about how a mod will affect the engine performance and will it allow more power to the wheels or not.
joejeep92
NAXJA Forum User
- Location
- Beloit, KS
Thanks ehall. Lot of stuff I hadn't been thinking about...especially the fan and pump stuff.
oblivion_twister
NAXJA Forum User
- Location
- Rio Rancho NM
put a wing on it
I tripled mine and cut a hole in the hood so I could mount a filter onto the TB... :jester:
IMO, running 235/ATs with an 1.5"-2" lift is just right for a DD that gets to explore the backroads on occassion... :sunshine:
You would definitely benefit from the combination of a CAI, 62mm TB, and CatBack with 2.5" pipe or muffler w/turndown.
Is your exhaust manifold cracked yet? You might consider replacing it with a header if you're going to be doing the other stuff.
I'd hold off on the e-fan. Done them before, makes a difference, but you could mess up your cooling performance if you don't do it right.
jeeperjohn
NAXJA Forum User
- Location
- Temecula, CA
The biggest concern when choosing mods for an engine is bang for the buck. Most manufacturers will make claims that their parts are good for X horsepower. Well that may be true if there are other mods involved and the engine is tested under controlled conditions but generally speaking you will not see the gains most companies claim. There is not much room for improvement in the 4.0 at a cheap cost. Most mods that make a difference only do so when accompanied by other mods. See where this is leading? If you have a fat budget then there are certainly ways to get more power, but it ain't gonna come cheap. That being said, improving the flow of air through and out of the engine will give some modest improvement. You can get a good flowing header for a little over $100 online. A cat back will help some for a couple hundred bux. More efficient fuel injectors help some and can be had at a fair price on e-fence or craigsfence. Don't waste any money on ignition parts beyond all copper cap and rotor and quality wires and plugs. The factory ignition is more than adequate for the 4.0. The consensus seems to be that Champion truck plugs are a good choice. Using an electric fan can free up some horsepower but electric fans don't move as much air as the engine driven fan. Good luck.