1996 Ford F150 4.9L (300ci) I6 5MT 4x4

[comptiger5000]

My Jeep has a 2 speed electric fan. It comes on low when the upper rad hose hits 210* (about 213* on the gauge), and high when the lower rad hose hits 210* (about 220* on the gauge).

Therefore, in normal driving, when the fan is off, it's no different than being fanless. Based on how the fan cycles (engine thermostat is 180*), I could never run without a fan in the city. Even in 30* F weather, if I get stuck in downtown traffic for 6-8 minutes of slow speed movement, it'll hit 213* and kick the fan on. In the summer, I could never survive without it, plus the A/C wouldn't work well at slow speeds either. With the fan, however, it has no trouble keeping cool, and the fan isn't needed at higher speeds.

Part of it is that the 360 produces A LOT of heat. The factory hood vents on the Grand Cherokee 5.9 aren't for show, they were added because they had trouble keeping the prototypes cool. That's also why it is rated to tow less than the 318.

[roflwaffle]

Originally Posted by Christ

Ok, next question (which probably should be in it's own thread)...

What injectors do I use? Does it matter where they come from, or are they matched to the pump, etc.?

These are all things I don't know for sure about diesel engines.

The fuel system is the (relatively) easy part IMO. What you have to do first IMO is have the block decked so the piston protrusion is correct and have the head machined in a way that provides the proper CR and proper amount of squish, which is really important make or break kinda stuff.

[Big Dave]

Converting a gas engine to a diesel engine is an ambitious engineering project. Remember the GM 350 diesels? They had a lot more engineering resources than you and made one small but fatal error. Those Corvette head studs were not big enough for the violent diesel combustion event. The things had horrendous head gasket leaks til just before they went out of production. The 1986 engines had real diesel (20mm) studs and a high percentage of the cars with the 1986 350 diesel are still on the road today.

A much easier project is to convert the truck to a Cummins 4BT3.9 engine. You may have to modify motor mounts but otherwise it should be a bolt-up. There is a whole community of people who have done this and there is even a website for it.

[Frank Lee]

I'd have to say, if I wanted a diesel I'd do a diesel swap. Even if the head studs and whatnot aren't an issue, I'd want the high C.R. of a "real" diesel, and I'd want the chamber/piston design for direct injection. Also I'd want the high-nickel block that I understand most if not all "real" diesels have, to enhance cylinder longevity under what has to be more stress. The mains bosses, crank, rods, etc. are tougher too...? A lower C.R. diesel conversion can likely be made to work but- speaking for myself- I don't think I would have the patience/resources/skillz to dedicate the R & D necessary to come up with an engine that matches a factory unit in efficiency and/or longevity.

Unless the homebuilt unit could easily beat gasser efficiency...

[Christ]

Originally Posted by Big Dave

Converting a gas engine to a diesel engine is an ambitious engineering project. Remember the GM 350 diesels? They had a lot more engineering resources than you and made one small but fatal error. Those Corvette head studs were not big enough for the violent diesel combustion event. The things had horrendous head gasket leaks til just before they went out of production. The 1986 engines had real diesel (20mm) studs and a high percentage of the cars with the 1986 350 diesel are still on the road today.

A much easier project is to convert the truck to a Cummins 4BT3.9 engine. You may have to modify motor mounts but otherwise it should be a bolt-up. There is a whole community of people who have done this and there is even a website for it.

I like torturing myself.

[Big Dave]

Check out www.4btswaps.com

In their "Showcase" forum they have a guy in Illinois swapping a 4BT3.9 into a F-150, just like Christ.

Its a proven, reliable, and efficient engine. This is a tough wheel to re-invent.

[Christ]

Originally Posted by Frank Lee

Unless the homebuilt unit could easily beat gasser efficiency...

I've been talking to some "people" about it. The design I'm working on is a pre-combustion type (for starters, might move on to something else later).

Regardless, it should be able to at least match, if not beat efficiency of the gasoline unit.

The engine math is already being considered, and I can't use the OE pistons anyway, so I'm thinking about having Arias or someone else mock some pistons from another engine to fit in the 4.9.

I can get rods for an old 240 I6 which bolt in and up the R/S ratio to 1.71, which will also up the compression a bit since the rods are .4" longer.

I still have to check clearances and deck the block a little, and then deck the head. Most of the compression (I'm looking for a static CR of ~17-18:1) will be had from the new pistons, though. Milling the head/block deck surfaces will account for whatever I can't get using the new slugs.

I've been working the numbers on this for about 5 years now... it's a shelf project. I touch it when I get ambition to beat myself up a little bit.

The crank and OE rods have shown to be good to - and maybe past - 400 HP/400TQ, and the OE pistons and gudgeons won't be used anyway. The gudgeons (wrist pins) are replaced with solid units bushed with brass in a slip-fit floating setup.

I'm still looking into piston designs, which is where Arias comes into play (unless someone else comes through first, but they're the ones I'm talking to right now).

[Christ]

Originally Posted by Big Dave

Check out www.4btswaps.com

In their "Showcase" forum they have a guy in Illinois swapping a 4BT3.9 into a F-150, just like Christ.

Its a proven, reliable, and efficient engine. This is a tough wheel to re-invent.

Dave -

I'm not suggesting I can do this over night, or that it will be any better or more efficient than some other setup. I'm doing only for my own purposes, as a learning exercise.

IMO, too many people read things and just assume they know, and knowledge isn't passed without experience.

Has anyone here ever tried to convert a gas engine to diesel? Probably not.

I'm sure many of us have thought about it, and many of us have probably even looked into it, but after reading 5 million posts about how it's impossible for one reason or another, the others have given up.

Regardless of what reasons anyone may have as to why it's not a good idea, I'm still going to do it.

While I appreciate your input on the situation, you should know upfront that trying to convince me otherwise just isn't going to get you anywhere. I see you're very fond of the 4bt engine (it shows up in just about every post I read from you), and while that's perfectly fine, it won't change my mind by any stretch.

Here's a point to ponder - I have 5 300 engines sitting around, doing nothing. I have access to about 14 more.

How many 4BT engines does that make?

The 300 isn't a big seller because most people don't understand how to properly operate it. They think that because it only has 140 HP, it can't be a good engine. Therefore, I would be wasting my time selling a 300 I6 to the public, which means that all these engines I have will either sit around, or something will get done with them.

If I can build one of these into a diesel, and get good enough prices on the parts, that I can build it for under $2000 (the average price of a 4BT swap that I've been able to find locally), I see no reason not to go ahead with it.

If it doesn't work, I've learned something, and I'll either try again, applying the new information, or I'll move on to something else.

[Big Dave]

After 35 years of engineering, I've found that Kelly Johnson was right.

"Keep it simple, stupid."

Do you have unlimited access to a good machine shop? You'll need a deck mill, a Bridgeport, line boring lathe, engine or turret lathe, and dynamic crank balancing minimum.

GM had all of that plus the experience of Detroit Diesel and still they made one critcal error on the 350, in a field very intolerant of error. Their 6.2 and 6.5 engines were better but they mismarketed them.

But if you have the time and the money, go for it.

My bad. I thought the purpose of the exercise was the vehicle.

[Christ]

For future reference, the ignition system in the 1996 F150 with EFI 4.9 employs a distributor that CANNOT be used to adjust base ignition timing (except a few degrees).

The ECM needs the signal from the hall effect sensor to determine TDC, and it's linked to the rotor. Advancing the hall effect sensor causes the ECM to over compensate with the timing, causing serious knock issues under any load.

I had to drive home using less than 20% throttle and keeping under 2k yesterday, with the bed loaded up with a few hundred pounds of scrap. SSSSSLLLLLLOOOOOOOWWWWWW.