Any ideas on improving the 4.0 OHV's reliability?

[Project91Jp]

The title sounds dumb, right? The 4.0 is a very reliable engine. Well, the ohv is anyways. Why fix what's not broken? That I can't really answer. I picked up a 94 explorer. Now I gotta tinker with it.

At first, I wanted to build a fast explorer with the v6. I read hundreds of pages about cam swaps and port n polishing all the way to turbos and superchargers. And the results I read... were disappointing.

So now I'm interested in what would make this engine run smoother. Obviously, leaving it stock is the best answer... but is it? It's been 30-ish years since it was engineered. Surely, some improvements can be made. Lighter weight parts? New lubricants? Thermal coatings? I read some on improving oil flow and balancing pistons, but I feel like I'm still missing some stuff.

Any ideas are appreciated and thank you for reading my rambling.

 

[RangerX]

Interesting point about it being designed 30-40 years ago, and maybe there’s new improvements.
But my 93 went to 370,000 without any engine work, save new intake gaskets. I just changed the oil fairly on schedule, every 3000-4000 miles.

 

[Fix4Dirt]

sohc hypereutectic pistons and 95tm heads can improve performance iirc the 95tm hewds are leas ausceptoble to cracking as far as relaibility iirc

 

[DaSovietPotato]

Synthetic oil, high volume oil pump, and reinforced cylinder heads just to name a few off the top of my head.

 

[Josh P]

sohc hypereutectic pistons and 95tm heads can improve performance iirc the 95tm hewds are leas ausceptoble to cracking as far as relaibility iirc

Plan on running E85 if you do this. Flat top pistons and the smaller chamber heads will get you close to 13 to 1 compression. I started on a build like this but the 0 mile brand new block I bought from a member here was a 30 over used unit so I got a bunch of parts that don't fit.

 

[Mbrooks420]

Pre-oiler kit. Bypass oil filters. You might be able to get low drag rings, but it’ll consume a little oil the way newer commuter cars do.

 

[410Fortune]

Run smoother? A properly running ohv runs smooth as glass

More
Reliable? I’ve had some of these engines still passing emissions with 487k miles on them

Cannot get more reliable then the pushrod 4.0 unless you get into a diesel

Looking for more power? Consider a drivetrain swap…. A 91-94 ohv does not respond well to power adders and the cost to do so is about triple what it would be for a v8

Your weak link would be the transmission, not your engine

You may check and see what ring and pinion gears your truck has, a jump in gearing may get you the performance you are looking for

 

[Josh P]

That means you need a 351W

 

[Project91Jp]

Interesting point about it being designed 30-40 years ago, and maybe there’s new improvements.
But my 93 went to 370,000 without any engine work, save new intake gaskets. I just changed the oil fairly on schedule, every 3000-4000 miles.

These engine are pretty strong that's for sure. Mine is at 240k right now. I wanna reach 300k if I can help it.

sohc hypereutectic pistons and 95tm heads can improve performance iirc the 95tm hewds are leas ausceptoble to cracking as far as relaibility iirc

Like Josh P said below, the compression would be too high for me. I might can do one or the other if I go that route. It'll be a difficult choice though.

Stronger heads vs lighter pistons. Hmmm...

I did see hypereutectic ohv pistons that got me curious.

Synthetic oil, high volume oil pump, and reinforced cylinder heads just to name a few off the top of my head.

Keep em coming lol. I'm using synthetic now. The high flow pump will go in if/when I pull the engine.

Plan on running E85 if you do this. Flat top pistons and the smaller chamber heads will get you close to 13 to 1 compression. I started on a build like this but the 0 mile brand new block I bought from a member here was a 30 over used unit so I got a bunch of parts that don't fit.

I definitely want to avoid detonation lol. It killed one of my trucks. RIP little s10. It barely had 200k miles.

Pre-oiler kit. Bypass oil filters. You might be able to get low drag rings, but it’ll consume a little oil the way newer commuter cars do.

The pre-oiler idea is neat. I saw one of the sohc guys postpone his tensioner issues with it.

I'll have to look into bypass filters. I read mixed reviews before.

I wish I could find low drag rings for the 4.0. Apparently, 50% of engine friction revolves around the pistons.

Run smoother? A properly running ohv runs smooth as glass

More
Reliable? I’ve had some of these engines still passing emissions with 487k miles on them

Cannot get more reliable then the pushrod 4.0 unless you get into a diesel

Looking for more power? Consider a drivetrain swap…. A 91-94 ohv does not respond well to power adders and the cost to do so is about triple what it would be for a v8

Your weak link would be the transmission, not your engine

You may check and see what ring and pinion gears your truck has, a jump in gearing may get you the performance you are looking for

Yea. I might be overkilling it. If I cant make it fast, I'll make it last.

You're right about my transmission being the weak link- the dreaded a4ld. Unfortunately, my 94 is a 2wd automatic. I gotta beef up the cooler and research other upgrades.

According to my door sticker, I have a 3.73 ls rear end. Which might be optimum for going 65-70 mph around Tennessee hills.

That means you need a 351W

I can dream lol.

I have pondered, though, of a 2.0 or 2.3 Ecoboost build. It'll bolt right up to a ranger's manual transmission. But that's for another time...

 

[Josh P]

I have pondered, though, of a 2.0 or 2.3 Ecoboost build. It'll bolt right up to a ranger's manual transmission. But that's for another time...

that would be a cool build. I'd spend the coin on that over doing a performance 4.0 build.