4.0 engine swap or modify

[isaiahpowell]

I have a 1997 mazda b4000 with a 4.0 v6 engine. The truck is modified to be a pre runner but I am not liking the lack of power and speed from the engine. I have a tuned diesel and a turbo charged st so driving this is not as exciting as driving my other vehicles. I'm thinking about swapping to a ls or maybe going carburated 302. I'm on a budget with the engine build and want to do alot of it myself for learning purposes. What have people found to be the best for these vehicles? Is there anything I could do to pull alot more power from the 4.0?

 

[19Walt93]

Usually budget and power both increase at the same time. One change that would make an immediate difference is deeper(higher numerical) rear end gears. If you have 4.10 gears those tall tires would make it feel like running 3.00's. I'd consider 4.56's or even 4.88's with those tires.

 

[isaiahpowell]

@19Walt93
Yes sorry I forgot to mention I have a custom rearend floater with 4.88 gearing. It works great for take of but drastically loses the power come 2and gear

 

[19Walt93]

I think the 351 will correct the power situation in my 93. NH has OBD II emissions testing on everything under 8500 GVW that's 96 or newer, would a carbureted V8 swap be legal in Texas?

 

[isaiahpowell]

That does look nice. I had a bronco with the 351 and loved how it pulled. Just didnt go fast. Is there alot you can do to the 351 to get the speed out of it.
I dont believe I have emissions where I'm at in the county. I have to do some checking but either way I'll find a way around it. I have a drivers license for Colorado and they only do emissions for the city of denver.

 

[PetroleumJunkie412]

I'm not as serious an offroader as most of the truck builders here, but be wary of a carburetor and offroad. Fuel delivery and heat both become issues quickly. There's a few articles on this in the tech section.

Have personally seen guys with more extreme builds convert to propane/LP to mitigate said fueling issues.

 

[PetroleumJunkie412]

Or, if I'm going to be my normal jackass self:

 

[Dirtman]

Plus propane has the wonderful advantage of being able to run even if the truck is upside down.

 

[isaiahpowell]

I dont think I've ever heard of a propane ran offroad vehicle. I'll have to look into it. I know alot of people that go to dunes and drive keep away from carburated due to all the sand.
What causes the carburated engine to over heat? Is there any mitigations that can be done to make it work?

 

[Dirtman]

Carburetors run on low pressure. Low fuel pressure has the inherent problem of vapor lock. A condition when the fuel in the line vaporizes and since the fuel pump cant push vapor the engine dies until the lines cool back down. Extremely well insulated lines solve this issue but any way you look at it EFI is simply a more effective system in efficiency, power, and reliability. Carbs are simplistic and don't require additional sensors or controllers so its much easie and cheaper to build a carbed engine though. Its very easy to convert a carbed engine to propane which increases the efficiency and reliable and eliminates vapor lock issues. Its popular with rock crawlers that are often at extreme angles. Propane is also a very high octane so you can build the engine with a much higher compression ratio. More compression = more power. It also burns insanely clean so carbon buildup is almost none existent.

 

[isaiahpowell]

How hard would it be to put a fuel injected 5.0 into my truck? I'm not wanting to have to change every piece of the truck. I've heard with putting an LS you have to change just about everything.

 

[Dirtman]

Not hard at all. You can get a 5.0 from an explorer and its almost a direct bolt in replacement in a ranger since they are practically the same truck.

 

[isaiahpowell]

Would I want to upgrade the transmission? Or can the stock one be modified to handle more horsepower added?

 

[JOLENE_THE_RANGER]

my prerunner with a ohv 4.0, 5.13 gears and 35s TUNED made 100 wheel HP.
a stock explorer 5.0 makes 150 wheel hp. add your big tires to that mix and that number will drop so imo that swap is not worth the work in anyway.
if you have the money go LS base engine 100% theres no easier or more cost effective way to get 250-300 wheel hp
a stock 6.0 LQ9 engine and 4l80e transmission (or turbo400) is the go to combo for pretty much everyone racing or playing in the desert. but that needs all new wiring, mounts, gauges, management.

I recently did a 4.0 sohc swap into my truck with out changing almost anything. used the old wiring computer trans and even engine mounts. im expecting somewhere around 180 wheel hp after a tune. i havent gotten the tune yet, but i have been driving it around a few days and i will say its ALOT more exciting to drive and way faster.

EDIT: the stock trans will not bolt to any other engine listed above.

 

[Dirtman]

Would I want to upgrade the transmission? Or can the stock one be modified to handle more horsepower added?

Auto or manual. The m5od manual can be bolted to the 5.0. The automatic cannot.