Ok I tried asking this in my other thread "beefy 2.9" but don't seem to get replies to this so I will ask here. I am looking to upgrade my 2.9 engine with some goodies, I can either A) add a '87 2.9 throttle body which was 58mm ('88 is 50mm) for under $30 (w/o new gasket) or B) add a 4.0L throttle body for under $30 (w/o new gasket). Which seems better? Also I think the 4.0 will bolt right on just making sure...

 

Either will help performance, any time you upgrade to a larger TB you will be able to flow more air into the engine. Just make sure you have a good intake system to go along with it otherwise the mod. is pretty much useless. Don't expect any miracles out of minor bolt-ons, its tough to get heavier vehicles moving if they dont already make large amounts of power (speaking from experience w/my 4.2). Don't forget the power to weight ratio. Even if you put on a mod. that adds lets say 15 rwHP, its not very noticeable with a 4,000 pound vehicle. How much does your Bronco weigh?
Also what is the size of the TB on the 4.0L? I'm sure you wouldn't see much of a difference between the two.

 

I've got the Bronco II, baby Bronco some say...It probably weighs alittle more then a ext. cab Ranger.
I have a K&N drop-in filter also. I'm not exspecting any real HP gains, just enough to be worth less then $30!
I am not sure how big the 4.0L TB is. I just found out from another member the 4.0 was based on the 2.9 besides being stroked and bored, so the 4.0L TB has to be a nice size, I was hoping a member who knew would tell me.

 

Hi 83,

Enlarging the throttle body will be worth about 3 HP on that motor, and that's certainly an OK bang for the buck ratio, about $10 per HP.

It's not a matter of if it was made for a 3.0 or 4.0, it's a simple matter of will it work with the linkage on *your* vehicle, and is it larger than the factory unit. Going 5-10 mm larger than stock on the throttle body for those motors is usually worth about 3-4 more peak HP. And that will show up regardless of if you are running the stock air intake setup or not.

In general, "airflow" mods are worth some power just by bolting them on, and worth more as you do further modifications to increase engine power further later on.

There are always plenty of things you can do to add more power to any computer controlled vehicle, in terms of the best bang for the buck that is generally optimizing the powertrain program with the Superchip, reducing restriction in the air intake tract, and then reducing restriction in the exhaust. From there it's on to things like underdrive pulleys & electric fans, headers, and so on. The only limitation to how much power you can add to that 2.9 Bronco II is your available budget.

Good Luck!

 

I'd love a chip, you make em for the 2.9 Mike?

 

WOW! 3 HP!
Do yourself a favor and get an entire intake system to go with it. Thats just my opinion if you want to even feel a difference. Good Luck.