Someone can drop in here, and correct me if I'm wrong, but I don't believe our 4.0's benefit much from just dropping in a cam, or bolting on the latest CAI, or whatever kids are doing these days.
I see a lot of people on here get excited about bolt-on "horsepower mods this, and boost that" and while this enthusiasm is understandable, consider this:
These are not SBC's or exotic OHC fanboy ricers.
Without running over to Wiki to sift through mountains of technical text,
From what I know these motors are of "undersquare" design, and benefit from torque over RPM?
Sure they can be stroked, and deck height tweaked etc,
But just how much HP is gained to justify the cost?
Don't get me wrong, if one can afford to do this, then why not?
It can never hurt to have more HP.
However, bolting on a TB spacer, or CAI etc, and expecting worthy-of-cost increases in performance seems like a step in the wrong direction.
My first order of business when modding a stocker, would be to gear it.
Gear it deep.
And spend money on things that you can't live without like a winch, and armor.
(haha and yes this is all coming from the guy that ran out and bought a K&N stock filter replacment when I was a mere noobling)

Just an observation, nothing more.
Feel free to offer your opinions and technical experience.

 

I think a lot of bolt on mods have practicality. motor mounts can help get a little more power to the wheels. cowl intake is on my list as well because there is so much dust where I wheel. it's not even water I'm worried about. loud exhaust starting with an APN header for strength. all preventetive measures to preserve my engine and surrounding components as I beat on it. any HP upgrades that happen to come with it are welcome but there are more reasons than HP for certain engine mods


things like 99+ intake manifold or fuel injectors. not my style. I'm not gonna go fishing for +3hp

check out my Horsepower Myth link in my signature. somewhat interesting read

 

I don't think most people do injectors for power though, or at least I didn't.

Atmos pretty much summed it all up there. If you want power a stroker is the name of the game.

 

Yeah I agree. Those items you mention are beneficial in regards to preventative maintenance. Stock motor mounts are terrible, and I replaced my header as well, because it was cracked.

I did the injector mod for MPG gain. That turned out to be a myth.
It runs smoother though. And also my new header helped provide a smoother feel to the motor during acceleration.
I would consider these things a benefit, but not a major HP gain.

 

When I replaced the 4.0 in my 91, I bought a performance package with the engine including a bigger cam. I saw a really nice performance increase, but my MPG (naturally) went down. These engines are really better suited to making useful torque rather than useful HP.
That being said, almost any mod you do to increase performance is going to hit you in the wallet both at the time of purchase and at the gas pump. You just have to consider what your primary purpose for the vehicle is. If it spends an overwhelming portion of its time on the street, I would shy away from trying to make a lot of power or torque. Keep the engine efficient and reliable (and legal)
A trail rig? Go for it if you have the $$. But, make smart choices and get the best bang for your buck AND be sure it's reliable enough to get you back.

All this from a guy with a 350 under the hood.

 

There's nothing wrong with some simple breather mods. No, an aftermarket exhaust header paired with some slightly larger piping and a freer flowing muffler won't stun the dyno but it will increase throttle response, power efficiency and offer up a subtle increase in horsepower and torque. Any "older" engine can benefit from the holly trinity of bolt-ons i.e. header, exhaust and intake.

I will agree with you about more in-depth modifications going to waste. Mostly because it's a rare day when I read a thread regarding a stroker engine not having to be rebuilt a second time due to "something."

 

From stock to where my engine is now was worth the money, however I waited until a good deal for things as they came by or made them myself.
Mechanical fan delete
99+ intake
Bored TB
K&N filter and snorkel
Higher flow exhaust
All cost me less then $200 and it was worth it to me the slight mpg gains as well as some seat-of-the-pants feel on acceleration.
Practicality of these mods is quite high imo, but the doing these mods for "performance" or "hp" gains aren't worth it

 

Just dyno'ed one of mine with all the bold on's-
Volant CAI
62mm TB
ported '99 intake
Perf Dist ingition upgrade
Harland 1.6 roller rockers
'Revolver' clone headers
2.5" front crossover pipe
2.5" high flow cat and muffler
2.5" exhaust throughout
synthetic oil
oops-forgot the 784 injectors

auto, 2wd, 3rd gear pull on Mustang Dyno -->> 150rwHP 191rwTQ
that's the best you can get with the stock, poor flowing head.

 

Tire size? Gearing?

 

2WD, auto, 3rd gear, 3.55, 265/35-18 mustang cobra wheels

 

Hm, thats depressing... with my mods and 33's i can't be putting down much more then 110hp and 150tq... Cam and Turbo here i come i guess...

 

Which is why I wrote - and will keep revising - the Power Manual.

I feel that the AMC six (or sixes in general) got left out in between the "Big 3 V8" market and the "tooner" market...

 

you guys have to consider most every engine in stock form (with exception to na 4 bangers) will make more tq than hp. I think these engines are held back so much by the terrible intake design and poor flowing head. if these 2 items could be addressed and improved mods like headers and cai setups would be more potent.

with that being said. there's no reason more power can't be made hand in hand with efficiency. bc that's really all that is happening. you are making this air pump more efficient so more power is made. mpg shouldn't suffer unless you're wot all the time. these engines don't have carbs on them. keep the afr in check and it will be fine.

 

Our heads actually flows pretty decently although it could be improved (Looking at an HO head). The earlier model year engines suffered from poor cast quality as well as a few other restrictions. If anyones interested in reading more about how to make your head flow better, then this is a thread you want to read as its the only work that is backed up with proof on a flow bench. http://www.jeepstrokers.com/forum/vi....php?f=5&t=226
I also saw a post regarding strokers commonly failing, I have seen a few builds that have failed but thats mostly due to someone overlooking a step in the rebuild, having a reused worn part fail or a problem the machine shop has caused. Some of the issues are even easily fixed. (You definatly better know your stuff before you take your block to a shop). I have also seen strokers that were built years ago that are still running reliably today so take what you will. But MPG and reliability wise i've seen quite a few guys getting better gas mileage than stock and some builds even using 87 octane. (18-20 mpg average vs. 15-16 average stock). They can definatly be put in a daily-driver because passing emissions shouldn't be a problem since its the same engine just with more displacement. Just remember not all strokers have to be rebuilt constantly like those that are meant for high rpm uses. It all depends on what you want your engine to do. But this thread isn't about strokers necessarily I just wanted to show their are some cheaper stroker options that are just as reliable as our engines are stock. Bolt-ons such as you all are talking about definatly shouldn't be thought of as major sources of hp, because realistically they just aren't but you can't deny all of these mods are improvements over stock.

 

more displacement = more air + more fuel

more fuel = decreased mpg?