2.9L Reality Check: Highway capable?

[eightynine4x4]

1989 2.9 4x4 auto, 31x10.5’s, 4.10 limited slip, uncertain mileage

This last week I’ve gotten to put the ranger through some tests, one of them being I finally took it on the highway.

I have been planning to dig in a little bit with the engine and do some degree of cleaning and/or rebuild. But I’ve not really been able to comprehend what the engine would perform like vs how it currently performs.

I’ve already addressed a lot of peripherals in the air, fuel, and spark domains. I believe most of that performs as it should now, so I think any performance lacking is due to engine guts.

Unlike side roads, the highway adds some major wind resistance with all that open space. Granted, I have my fenders both off and my grill and bumper off. The front is like a brick wall or even worse. During long gradual uphills on the highway, I was simply pushed down to 40mph with zero ability to overcome it. Highway straightaways and downhills I could hang at 50 and the windy environment kept me to that. Needless to say I was a nuessance to other vehicles so got off the next exit. That was a long 30 miles though.

On side roads and less windy roads I can hang out at 55/60 and do 65 for stretches. I have touched 70 I think.

Again, all of this is with the non aerodynamic setup since so much of nose is missing.

But this has me thinking.. how much better should I be expecting even a fully rebuilt 2.9 to perform? With a rebuilt engine and the 1983-88 nose (I’m nose swapping), can this truck reach 70 mph on gradual uphills on the highway? Pipe dream?

Cause if that’s unattainable, maybe I’ll just enjoy the 2.9 as it is and start planning for a 5.0 swap some day.

I also am planning to get some 215/75/r15’s and have both on their own sets of wheels for quick swaps for whatever kind of trip I’m about to take. Maybe the smaller tires and proper aerodynamics will allow for an acceptable highway ride.

 

[RonD]

The 29" tires will help alot, 31x10 are pretty heavy and lower the ratio

2.9l makes best power/torque at 2,600rpms so you don't want rpms to drop much lower than 2,400 on a hill

In 3rd gear, 29" tires, 4.10 ratio at 2,600rpm you should be doing 55MPH, in 4th(OD) 70MPH

You can use a vacuum gauge to see how "fresh" the engine is, 18" to 21" is expected, the higher the vacuum at idle the better the compression

 

[gaz]

@eightynine4x4 ,
A good running stock 2.9l equipped vehicle should be able to roll over any highway mountain pass in the United States of America at 65mph with usable throttle remaining with just the following:
• K&N drop in air filter
• electric fan
• quality set of headers
• 2¼" mandrel bent exhaust, high flow cats, turbo mufflers or better
• Hypertech stage II CHiP for you engine/transmission

If you really want to learn it's full N/A potential, rebuild it in accordance with Sven Pruett's guide and expect all that and a 30%+ improvement in efficiency and fuel economy. The primary changes from stock are:
• flow bench port/polished heads to intakes
• free Floating valve train
• custom reground cam
• mill the heads 0.03"
• Ford 2.8l flat top pistons
• complete bottom end balance
• 2½" mandrel bent exhaust, high flow cats, turbo mufflers or better
• proper clutch or torque converter to get it to the ground

 

[eightynine4x4]

Thanks for the pointers everyone. I’m going to prioritize getting 29 inch tires on the cheap somehow and I am hoping that changes things. I wish I had a manual tranny so I could really ride the engine so to speak and make momentum adjustments as needed. I also wish i had manual just for the MPG.

I want to hook up a vacuum gauge to the intake manifold and have it sit in the cab so i can better monitor the engine while driving for a few days. I took a pic of a rusty hex/allen driven piece that’s in a spot on the drivers side near firewall. Maybe this is a good unused vacuum access point to hook up a gauge? I'd need to be pretty careful removing it but if successful it would be a nice ergonomic location to run a vacuum hose out of the way and into cab.

Also there are a couple mysterious threaded holes on the intake, and I’m hoping those are just external and aren’t leaking some internals somehow. Figure the smart thing is to post a pic of one here too just to see if I’m gravely overlooking their openness...? I mean you can see the back wall inside of it using the camera flash, but still I want to confirm there's not some sideways routing in there.

 

[Uncle Gump]

@eightynine4x4 ,
A good running stock 2.9l equipped vehicle should be able to roll over any highway mountain pass in the United States of America at 65mph with usable throttle remaining with just the following:
• K&N drop in air filter
• electric fan
• quality set of headers
• 2¼" mandrel bent exhaust, high flow cats, turbo mufflers or better
• Hypertech stage II CHiP for you engine/transmission

If you really want to learn it's full N/A potential, rebuild it in accordance with Sven Pruett's guide and expect all that and a 30%+ improvement in efficiency and fuel economy. The primary changes from stock are:
• flow bench port/polished heads to intakes
• free Floating valve train
• custom reground cam
• mill the heads 0.03"
• Ford 2.8l flat top pistons
• complete bottom end balance
• 2½" mandrel bent exhaust, high flow cats, turbo mufflers or better
• proper clutch or torque converter to get it to the ground

So what you're saying is... remortgage your house to drive your truck up a hill?

I can't wait to drive my 2.9L all stock... 33's with a 4.10. I'm thinking I'll be able to drive it about anywhere.

OP... you sure you don't have a bit of exhaust restriction going on...

 

[eightynine4x4]

So what you're saying is... remortgage your house to drive your truck up a hill?

I can't wait to drive my 2.9L all stock... 33's with a 4.10. I'm thinking I'll be able to drive it about anywhere.

OP... you sure you don't have a bit of exhaust restriction going on...

Hmm how do i check for an exhaust restriction?
My right side exhaust manifold is new, as is my cat and muffler and pipes down there.
My y-pipe is old, and there is a tiny leak as it enters the cat. I'm working on that repair in another thread here. I can see a smidge of exhaust coming out when the truck is warmed up and idling. I'm not sure that would draw down on any pep though, seems the opposite.
I can't take off the left manifold any time soon. It's a rust monster. It doesn't leak though, I did a leak test with some soap suds and a mild air blower into the tailpipe. Only leak is the spot at cat entry just mentioned.

I feel like i can learn a lot from a vacuum hookup to intake. I just posted a minute ago about that, above..

 

[Uncle Gump]

Right ON....

That vacuum gauge will tell you everything you need to know about restricted exhaust.

 

[Ranger850]

trying to improve your 2.9L? check out @PetroleumJunkie412 threads. He's done almost everything possible to that engine.

1988 Ranger Restoration - Keeping a Promise

Ok, so just a forewarning, this post is going to be heavily edited, re-written, and changed throughout its construction. This is being written as a post to document the restoration of a truck that was a terrible candidate for restoration, and to offer explanation to others that read my posts...

www.therangerstation.com

 

[Uncle Gump]

The real issue @gaz is the OP doesn't need to do any of that to drive that truck up a damn hill.

And you forgot a damn chip for the computer... add more money. And no way are you getting that exhaust for $350.

 

[gaz]

The real issue @gaz is the OP doesn't need to do any of that to drive that truck up a damn hill.

And you forgot a damn chip for the computer... add more money. And no way are you getting that exhaust for $350.

Uncle Gump,
In English, what the OP has stated is that his primary concern is maintaining highway speed on flats and during climbs, JFYI.

You are correct, I did forget to list the Hypertech CHiP and how the last one I bought was $12, brand new in box, never used on OCT2020.

WoW...you are correct. It costs less.
• $104, BORLA 2¼" SS turbo muffler, summit racing
• $80, 2¼" SS hi flow cat, summit racing
$139, 2¼" mandrel bent 409 SS tubing 8 piece kit, eBay ($250 from Summit).

$104
+$80
+$140=$324

 

[alwaysFlOoReD]

It looks like you can tap the vacuum tree right beside where you want to pull the plug. If I'm seeing clearly there is a cap on one of the outlets.

 

[gaz]

@eightynine4x4 ,
You can also install a boost gage to monitor your vacuum. Looks way cooler on the dash than a vacuum gage, though it is the same thing.

I put one in my daughter's car when she was in high school to help her learn to drive more fuel conscious. It worked great; she even wound up doing a term paper on how she was able to improve the fuel economy of her car and driving habits.

 

[fastpakr]

Most of the modifications gaz is suggesting will do nothing but lighten your wallet. Astounding waste of funds.

 

[Northidahotrailblazer]

All I have to say my ranger weighs 4200 pounds Its lifted, 35s 4.0 and 4.10 gears and it will not pull a decent hill at speed like at all really lol I know i need gears and they would help a lot but I'm guessing my 4.0 is on the weaker side of things. I live in northern Idaho so i know hills and mountains better than most. So I cant stress gears gears gears enough. but on the other hand you cant replace displacement! haha

 

[eightynine4x4]

Here's the truck in idle and with some quick rev's toward the end. This is after a drive. HG generally sits at 18 with some small range rapid vibration in needle.

HG.idle.mov

Shared with Dropbox

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Here is a drive up and over two moderate sized hills one after another on a 40mph road, in traffic. Video starts while already starting to accelerate but stuck in slow traffic, then picks up over first hill, then eases off a bit between hills, then accelerates over second hill and then slows down and so near the end you'll see that the HG returns to a higher state, that's when i'm slowing down approaching some traffic.

HG.Moving.mov

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Any thoughts? I have to do some homework on the readouts.