So tell me about these engines....

[Kiba]

Hi all. Have a '99 2.5l I4 paired with a stick, and I love it. However, there isn't much out there to tell me how to get the most from this little engine.

I come from a motorcycling background and there are usually plenty of details on where the "sweet spot" for power, economy, or engine life is, projected engine life with a certain kind of use, minimum and maximum rpm, shift points, cruising rpm, etc.

Right now I'm driving like an old man in the city; my shift points are between 1800-2200 in city traffic. On the highway I shift at 2400-2700, 3000 only if merging. Maximum cruising speed is 85 indicated (90 IRL) in overdrive, turning 2700 rpm. Also keep it in fourth up to 55 sometimes at 2600 rpm. Never had it above 3k.

So, my question is, what is the sweet spot for this motor? What's the highest cruising RPM which it can sit at for a long time without stressing the motor, what's a comfortable shift point for quick acceleration that doesn't stress the motor, etc? What's the ideal RPM for fuel economy (for reference, it's not always the lowest), both in normal gears and in overdrive?

I've seen graphs showing the power peak at 4500 rpm and the torque peak at 3000, pretty normal for a four-cylinder but I'm not sure this motor likes revs that much!

Also curious on what affect minor intake/exhaust modifications (such as a K&N type intake, slightly more open exhaust) have on the life of the motor. I'd like a little more power, and a little more exhaust noise (nothing excessive) but do not want to shorten the life of the motor at all. I want 300k out of this truck!

For reference:

Right now I have 188k on the motor, not sure of the rear-end gearing but I believe it's stock.

I have a small tachometer installed to keep track of revs when I take long trips. Tested to +/- 5% accuracy with a real shop tach.

Running the 30" tires that were on the truck when I got it, which gears it up.

GPS verified, speedometer reads five mph less than actual speed over 60mph- ie if my speedometer says 80mph, my actual speed is 85-87.

 

[RonD]

Welcome to TRS

The Lima engine was first used in mid-1970's in Ford Pintos, it was made at the Lima, Ohio Ford engine plant, hence the Lima name, but it was originally called the "Pinto Engine", and still is by some.

It came as a 2.0l, then bored out to 2.3l, some say 2.0l is under-bored 2.3l, your choice, lol
The 2.3l was given a longer stroke in 1998 to get 2.5l, and the 2.5l was used in Rangers until mid-2001, when Ford switched to the 2.3l DOHC Mazda L engine, Ford brand is 2.3l Duratec engine.

Switching to an electric fan vs engine driven radiator fan is a good option, Ford did this in later years, frees up some horse power and is better all around in warm and cold climates.

Fuel injected Rangers all came with Cold Air Intakes(CAI) and have almost 200% rating on air cleaner, i.e. engine can only use 1/2 of what air cleaner housing can provide in air flow at maximum RPM, this allows air cleaner filter to get a bit dirty with out effecting performance, but to each his own, the sound after changing intake air flow is often worth a few horse power in the drivers view point, real or imagined .

Yours will have a tuned exhaust, but tuned for mid-RPM power.
Tuned exhaust means someone sat down and calculated the exhaust flow velocities in different pipe sizes at the exhaust ports.
The velocity when exhaust hits the larger collector pipe determines the "scavenged" power saved and at what RPM you save the most power.

Power savings is because the Tuned exhaust causes a lower pressure at the exhaust valve ports, when one cylinders exhaust hits the larger collector pipe it causes a pressure drop at the other 3 exhaust valve ports.
Normally the piston uses power to push out the exhaust, if you create a lower pressure at the exhaust valve then piston uses less power to push out exhaust, so you save power to use at back wheels.

You can get "headers"(tuned exhaust) for low-RPM power, mid-RPM power or high-RPM power, this doesn't add any power, unless you have home-made exhaust, lol, it changes when you get the lowest pressure at the exhaust valve ports so gain the most power savings to pass on to back wheels.

People that have tried home-made exhausts, "free flowing" is often the term used, will often notice that they lost power with this new exhaust system, which is true, that is where the MYTH of "some engines need back pressure" comes from.
The free flowing exhaust lowered the velocity so they lost the scavenged power the original exhaust provided.
No 4-stroke engine runs better with back pressure.

You are a motorcycle guy and maybe know about 2-stroke engines, they DO need back pressure so they don't eat gallons of fuel, lol, and they used tuned exhaust by necessity, building higher pressure when needed and then reducing it when wanted.
In my day we called it "on the pipe" when you were in the best RPM range for best power output for that engine.
"on the pipe:" these days means something completely different.


have a look here: http://www.therangerstation.com/tech_library/axle_codes.shtml
Look at your door tag to see rear axle ratio and original tire size, larger tires will cause your speedometer difference

 

[YungICY]

As far as longevity for these engines I am definitely the wrong guy to give pointers there but my 2.3 loved anything over 3k rpm. At 3k it would kick in almost like a two stroke but that was probably due to my "home-made" exhaust. I have heard from many others that are much more experienced than myself that these motors do like the upper rpm range. If I were looking for longevity out of it though I would say you're safe as long as you regularly keep her under 4200 rpm.

I just rebuilt one of my 2.3's and the blocks are pretty bullet proof. This motor had around 120k on it and still had cross hatching in the cylinders. The heads are pretty bullet proof as well but if one of the oiling holes for the lifters gets plugged it won't take long before you're replacing the cam and lifters.

For power increase I would do a cam. Comp cams makes some good cams and when I rebuilt my motor the guy at the machine shop said that's what he would use every time for his personal 2.3 rebuilds.

Sent from my LGMS345 using Tapatalk

 

[Kiba]

Thanks much guys!

RonD,

I appreciate the info, very interesting. Makes sense why the valve cover looks so old-school; it's really from the 70's!

You're right too, I have had a couple of dual-sport two strokes, although I never did get into four stroke exhaust tuning that much as my bikes tended to keep their stock pipes, thanks for the detailed explanation.

Excepting the Duratec (which I assume can flow better with its DOHC), am I right in thinking that the 2.5 is the best performing four banger of the bunch?
Basically a bored and stroked 2.0 with a cold air intake out of the box?

If so I may just have to be willing to drive it a little harder, or change the gearing often via the wheels (have two sets, one big for top end one small for acceleration). If so I'd like to get some nice old-school looking wheels to put smaller diameter tires one, like from an old Falcon or something, but that's probably another thread.

Any suggestions for getting just a tad more noise out of it? Don't want loud, just a pinch. Also not ricey if possible. Alot to ask from a four banger, I know. But I can barely hear the motor over the ubiquitous Ford power steering pump whine until I rev it above 2500. And I hate to just stick on one of those fake-looking tips from autozone.

Also, I heard about turbocharging but I don't think it would get me the low-midrange power that I want.

YungICY,

Yeah, one of these days I'm just going to have to rev it a bit more... at 3k it did seem to have a little kick just before I let off to shift. I just want to be sure I'm not messing with my chance to get long life from the engine by taking it above X rpm like with certain motors.

Cam sounds good... actually should be relatively simple, should just involve taking valve cover off, loosening belt, resetting timing right? Or maybe my motorcycle experience is fooling me. Are these guys shim-under-bucket or do they use rocker arms like old Honda OHC motors?

 

[YungICY]

For the most part that's all that's involved with a cam change. Here's a pic of what it looks like under that cover.

For making that motor last, if you just treat it nicely and keep up on maintenance she should last a while. I'm really hard on mine cuz I'm a go fast desert racer guy and the thing that finally did mine in was coolant in the oil because I didn't change it after I did a head gasket. Otherwise it still would've been chugging along even with my abuse.

For getting a little louder exhaust, when I first bought mine it had flowmaster on it. I don't know which one it was but it might be about what you re looking for. It gave a nice little rumble but wasn't loud unless I was really working the motor. If you're gonna have a shop do the exhaust I would just pop in there and tell them what you're looking for and I'm sure they could get you set up nice.

Sent from my LGMS345 using Tapatalk