F150 vs 7.3IDI

[kc0stp]

I hate to be "that guy" but been using my dads 2010 F150 (4.6 24valve) to haul my car trailer to the races (24' est weight of 7-8k) and while the truck is capable of handling the trailer its at near max capcity (trucks rated to tow 9.8k at sea level but Im a mile up which kills NA power...). Based on my budget a 7.3IDI is my only option (or a 6.9 but havnt found any locally) however comparing stock specs the 150 has pretty much equal power figures (7.3 has 60 more torque 4.6 has slight HP advantage) While some of the dynos on the modded trucks look impressive I dont really have the budget to drop $4k on mods in addition to buying a truck. Ill be the first to admit that I dont know of any real world info on the 7.3 except the occasional dyno sheet and what Ive read on here. Found a 93 7.3idi for sale locally thats tempting figuring the body is in decent shap (205k miles, F350 dually, "newer" trans for $2500) however I have no idea how this would compare to my current truck (and any hills Ive towed my current trailer over are a couple hours from this guy and doubt he would let me hook up a trailer to compare...) but if the 7.3 would be about equal (slightly better torque but if Im right the 7.3 has a 4sp vs the 6sp in the 4.6) Im not sure itd be worth the extra $$ to buy a truck + the added maint costs.

I belive on the aftermarket side youve got the turbo option (+~80tq), intake, exhaust, fuel tuning and a typ4 cam (anyone ever compare that to stock?), moose pump+injectors and a splitter for better tranny ratios (might also do a 5spd swap as Im not a fan of 4spd autos with an overdrive...) any ideas on cost/gains with that? Im gonna make an assumption (slightly educated) and think the 7.3 would get 9-11mpg towing? If so thatd be an improvment over the 4.6 for sure (8-9mpg) but with the added cost of diesel might be a wash. And for the record yes I have diesel experience just not on an IDI (mainly school buses, DT466, 6.0PSD, and assorted others from Thomas and older blue birds) but thats all factory and nothing aftermarket.

Footnotes: Hows the 7.3IDI compare to the 4.6 24valve gasser)

 

[The Warden]

Welcome aboard!

First, if I'm reading your post correctly, the truck you're looking at has a E4OD 4 speed automatic...if that's the case, I would be wary. That tranny is nicknamed "E4DOA" for a reason As far as transmissions are concerned, the best tranny for your application depends on what you prefer and what you want.

If you'd rather have an automatic, the C6 3 speed (available with the IDI between the engine's introduction in '83 and '89) is the most bulletproof; however, you don't have a torque converter lockup or an overdrive gear, so you're going to be spinning high RPM's at freeway speeds, especially if you have 4.10 gears. The E4DOA (available from '89 until the IDI was replaced by the PSD in '95) is essentially a ticking time bomb...it is possible to do a quality rebuild-strengthening, but you're looking at spending a good amount of money on this...Gary (icanfixall) is the resident E4DOA expert on here and can give you more good information.

Personally, I would vote strongly in favor of a manual transmission, especially since you said your main use is for towing. The Borg-Warner T-19 is the strongest transmission that was available behind one of these trucks from the factory (between '83 and '87), although it's a 4 speed with no overdrive gear. The ZF S5-42 is almost, but not quite, as strong and has an overdrive gear...for towing, I would recommend the ZF.

As to towing...I can give you a bit of a comparison. I've never towed with a 4.6l, but I put about 1,000 miles on a 2011 Ford Expedition EL towing a Jeep crawler on a U-Haul car carrier from the San Francisco Bay Area to Moab, UT about 7 months ago. This had a 5.4l and probably the same transmission your F-150 has. This was actually the first time I had towed a significant load with a gasoline engine, but I've put thousands of miles on my diesel F-250 with a trailer strapped to it over the years. Wikipedia says that the 5.4l as used in the Expedition's rated at 310 horsepower and 365 ft-lbs of torque. Compared to my diesel, I was very surprised at how much the 5.4l bogged down with the weight...it would get up to speed just fine (55 mph speed limit in California when towing, and the rig started getting squirrely at anything above 70 mph once I got into NV and UT, even though the speed limit was 75), but it felt like the engine was getting wound-out in the process. I couldn't really accelerate without the engine spinning up to 4500 to 5500 RPM

Compared to that, I've pulled heavier loads with my truck countless times and felt more comfortable doing it from a power-band standpoint, even though my engine puts out lower power numbers than that 5.4l did. I have a 6.9l, but it's essentially similar to the 7.3l IDI (IIRC something like 10 hp and 25 ft-lbs difference stock)...I added a non-wastegated turbocharger and I have a ZF 5 speed manual. I've never had any major complaints about power...with a heavy load (in the 7 to 8K range, whole rig weighing about 15K), she'll accelerate slower, but she'll hold speed just fine. I'm generally downshifting and slowing down because the pryo's getting too warm before the engine actually runs out of power. I've never put my truck on a dyno, but with a non-gated turbo, I probably didn't add THAT much power...I MIGHT be at 185 hp and 350 ft-lbs of torque if I'm lucky, and that's being generous HOWEVER...you pointed out that your truck has lower power at altitude; that's going to be true in spades with a diesel, and I would strongly recommend investing in some sort of turbocharger system, since you're at high altitude and plan to tow. The forced air from the turbo will essentially negate the altitude air density differences.

BTW, in terms of fuel mileage, I averaged 11 mpg on that trip with the Expedition (thank goodness I wasn't buying the fuel ), whereas since adding the ZF5, I've never gotten below 14 mpg with my truck regardless of what was hooked to it, and if I'm empty, driving on the highway, and being easy on the pedal, I can meet or even break the 20 mpg barrier

Hope this helps a bit...good luck!! There's quite a wealth of information to be had on this board...personally, I'm of the opinion that, particularly when towing, diesel is the only way to go

 

[Wyreth]

The 7.3 isn't going to feel as powerful. However, the 350 will tow SO much better. You will wonder if there's anything back there. My SRW 250 simply does not notice less than about 5000lbs. It prolly also has 4.10 gears, which is going to dramatically increase it's towing capability. Also, well cared for, these idi's are easy 400,000 mile motors. Running somewhere near 20k gross weight, I was still hitting 14mpg. (granted I was babying it @ 55) But realistically I think that once you have it sorted, 11mpg will be the lowest you will see towing. Diesel here, is about 6% more than gas. 9 vs 11 mpg is almost a 19% increase. More than enough to offset the fuel cost. Granted however a diesel costs more to maintain. So really cost is pretty much a wash. Unless you burn alternative fuels, which isn't that ******* these IDI's.

Something you're not taking into consideration with your # comparison, is power band. A diesel hits it's max torque before a gasser understands what "torque" means, and hit's it's max HP just as the gasser decides to start moving. Also, 60 more torque is a HUGE #. Horsepower is pretty much acceleration. Torque is what keeps you going, and is much more a factor when towing.

As for mods, figure a fuel system replacement. Just to be safe. (350-400 for injectors, and 5-600 for a quality stock rebuild pump) You can get a complete turbo kit for around $500 if you look. So for 1500 you will be seeing 150hp 300ft/lbs at your rear wheels easy. The 24v modular is good, but it's not that good.

If you're going to tow, or haul heavy. Diesel is the way to go in my opinion. The things I've done to this truck would have killed a gasser.

 

[justinray]

^This guy

 

[kc0stp]

Also, well cared for, these idi's are easy 400,000 mile motors. Running somewhere near 20k gross weight, I was still hitting 14mpg. (granted I was babying it @ 55) But realistically I think that once you have it sorted, 11mpg will be the lowest you will see towing. Diesel here, is about 6% more than gas. 9 vs 11 mpg is almost a 19% increase. More than enough to offset the fuel cost. Granted however a diesel costs more to maintain. So really cost is pretty much a wash. Unless you burn alternative fuels, which isn't that ******* these IDI's.

Something you're not taking into consideration with your # comparison, is power band. A diesel hits it's max torque before a gasser understands what "torque" means, and hit's it's max HP just as the gasser decides to start moving. Also, 60 more torque is a HUGE #. Horsepower is pretty much acceleration. Torque is what keeps you going, and is much more a factor when towing.

As for mods, figure a fuel system replacement. Just to be safe. (350-400 for injectors, and 5-600 for a quality stock rebuild pump) You can get a complete turbo kit for around $500 if you look. So for 1500 you will be seeing 150hp 300ft/lbs at your rear wheels easy. The 24v modular is good, but it's not that good.

If you're going to tow, or haul heavy. Diesel is the way to go in my opinion. The things I've done to this truck would have killed a gasser.

Milage wise it confirms what I knew/learned/suspected that the motors will last forever (I was thinking closer to 500k+ but close enough) Id love to be getting 11mpg right now only taken the current setup to 2 weekends worth of racing so far (1-1.5hours each way) and highest ive gotten is 9.2 and that was with drafting a semi most the way. Figured the overall cost might come out to a wash but at least it wont be to much higher (if any) and hey I can brag about my improved MPG

Where are you finding turbo setups for $500? Havnt looked to hard at used yet but 2 setups Ive found currently avalible (admitidlly new) are $1.5k+ (banks and hyper).

Welcome aboard!

First, if I'm reading your post correctly, the truck you're looking at has a E4OD 4 speed automatic...if that's the case, I would be wary. That tranny is nicknamed "E4DOA" for a reason As far as transmissions are concerned, the best tranny for your application depends on what you prefer and what you want.

If you'd rather have an automatic, the C6 3 speed (available with the IDI between the engine's introduction in '83 and '89) is the most bulletproof; however, you don't have a torque converter lockup or an overdrive gear, so you're going to be spinning high RPM's at freeway speeds, especially if you have 4.10 gears. The E4DOA (available from '89 until the IDI was replaced by the PSD in '95) is essentially a ticking time bomb...it is possible to do a quality rebuild-strengthening, but you're looking at spending a good amount of money on this...Gary (icanfixall) is the resident E4DOA expert on here and can give you more good information.

Personally, I would vote strongly in favor of a manual transmission, especially since you said your main use is for towing. The Borg-Warner T-19 is the strongest transmission that was available behind one of these trucks from the factory (between '83 and '87), although it's a 4 speed with no overdrive gear. The ZF S5-42 is almost, but not quite, as strong and has an overdrive gear...for towing, I would recommend the ZF.

As to towing...I can give you a bit of a comparison. I've never towed with a 4.6l, but I put about 1,000 miles on a 2011 Ford Expedition EL towing a Jeep crawler on a U-Haul car carrier from the San Francisco Bay Area to Moab, UT about 7 months ago. This had a 5.4l and probably the same transmission your F-150 has. This was actually the first time I had towed a significant load with a gasoline engine, but I've put thousands of miles on my diesel F-250 with a trailer strapped to it over the years. Wikipedia says that the 5.4l as used in the Expedition's rated at 310 horsepower and 365 ft-lbs of torque. Compared to my diesel, I was very surprised at how much the 5.4l bogged down with the weight...it would get up to speed just fine (55 mph speed limit in California when towing, and the rig started getting squirrely at anything above 70 mph once I got into NV and UT, even though the speed limit was 75), but it felt like the engine was getting wound-out in the process. I couldn't really accelerate without the engine spinning up to 4500 to 5500 RPM

Compared to that, I've pulled heavier loads with my truck countless times and felt more comfortable doing it from a power-band standpoint, even though my engine puts out lower power numbers than that 5.4l did. I have a 6.9l, but it's essentially similar to the 7.3l IDI (IIRC something like 10 hp and 25 ft-lbs difference stock)...I added a non-wastegated turbocharger and I have a ZF 5 speed manual. I've never had any major complaints about power...with a heavy load (in the 7 to 8K range, whole rig weighing about 15K), she'll accelerate slower, but she'll hold speed just fine. I'm generally downshifting and slowing down because the pryo's getting too warm before the engine actually runs out of power. I've never put my truck on a dyno, but with a non-gated turbo, I probably didn't add THAT much power...I MIGHT be at 185 hp and 350 ft-lbs of torque if I'm lucky, and that's being generous HOWEVER...you pointed out that your truck has lower power at altitude; that's going to be true in spades with a diesel, and I would strongly recommend investing in some sort of turbocharger system, since you're at high altitude and plan to tow. The forced air from the turbo will essentially negate the altitude air density differences.

BTW, in terms of fuel mileage, I averaged 11 mpg on that trip with the Expedition (thank goodness I wasn't buying the fuel ), whereas since adding the ZF5, I've never gotten below 14 mpg with my truck regardless of what was hooked to it, and if I'm empty, driving on the highway, and being easy on the pedal, I can meet or even break the 20 mpg barrier

Hope this helps a bit...good luck!! There's quite a wealth of information to be had on this board...personally, I'm of the opinion that, particularly when towing, diesel is the only way to go

Ideally if I could find one locally (for a half decent price) Id love a ZF with 4X4, as far as manual vs auto goes personally (for a tow vehicle) I just go with what performs best, with the E40D(A) having only 4 speeds and one being an overdrive (making it IMHO worthless when towiing as its geared for economy) that means when it comes to hill Id either be in 3rd or 2nd (or 1st..) especially since 98% of autos are geared for max economy vs performance. The ZF at least gives me 1 more gear to use and is geared closer together. Oh and for the record if/when I upgrade Id mainly use it for towing the car trailer unless we get 1'+ of snow and Im not sure my Miata can make it to work (hasnt failed me yet but has been interesting some days)

Figuring the excursion and F150 share trannies (I know the F150 has tow/haul mode but not sure if thatd warrent a diffrent tranny or just diffrent programing or if both have it) then the 5.4L and mine are the same tranny (cookie cutter drivetrains..diffrent motor same everything else) and I can relate to the rpms, on flat ground with no/minor headwind Im sitting at 2k-2.5k rpm @65 and 4k-5.5k on the hills and occasionally foot to the floor to maintain 60-65 (once again figuring no headwinds...had one occasion where it was easier on the truck going up the hill then down due to winds) which is the main thing that kills my gas milage beyond the aero on the trailer.

Any idea how the power loss at altitude compares gas to diesel? I know the gassers are affected (if NA) by enough for the butt dyno to tell but otherwise...(I love it when on the rare occasion our vehicles see sea level, feels like someone installed a turbo when we wernt looking)

Oh and one final question... what are the 7.3 IDIs going for? Im just assuming the $2500 is a good price as thats the cheapest Ive seen yet (locally). Trying to keep it to mid 85+ (cant have the tow vehicle be older then the race car after all ) along with being a non commercially used vehicle (Ive seen how our drivers treat the trucks...) but can be talked into them in good shape just inspect them closer

 

[DragRag]

If you really want the mpg's, descent power, and super engine reliability I would also consider a 1989 to 1993 12v cummins truck also. They get the best mileage of the big three diesel. I mainly have all idi in my fleet due to mass amounts of them for sale cheap around these parts. But if I were to have one truck, I would seriously consider a dodge cummins also. The mpg's are super good, like 22mpg freeway, and they run forever. Let's face it, they sound cooler to. Problem is they are much farther and fewer between to find, and they usually fetch a premium. Keep your ear to the ground and you can find a deal on one. The ford is a great choice to though also, they just don't get the mileage, and the after market is much much better supported on the cummins to. I just picked another cummins up myself this weekend after years of not having one. Simply couldn't pass up a good running super cab 92' cummins 4x4 for $1700. Overall I am happy with it, and it even came with a lift gate to sell off of it.

 

[kc0stp]

Biggest concern is power, already got a truck capable of my needs just want one that struggles less but since it sounds like the 7.3 can do that fine then next step (being broke..) is cost, a good truck does you no good if you cant afford to use it

 

[rjjp]

The 7.3 isn't going to feel as powerful....

I know that my IDI when stock felt more powerful than our farm truck (05 F250 5.4 Triton).

As for the towing, I'm just going to say that there's a reason my IDI can legally haul more than the 05.
GCWR 18,800 (my IDI)
GCWR 16,000 (05 F250 5.4)
Empty the 92 weighs 1000lbs less.

As for hauling in the bed, I put 2,600lbs in the bed of the 05 yesterday, truck could hardly accelerate, had to be over 2500rpm at 50 in the flats. I've had over 4,000 (steel adds up fast) in the bed of the IDI only time that it ever grunted was accelerating up hill.

 

[TWeatherford]

I don't know if the IDI is better than the gasser, as I've never even driven one that new.

My truck was on its second engine when I got it with 250k on it, it is now on its third. They can go 400k but its not exactly common. I have replaced the entire fuel system and clutch, and obviously an engine. The first engine got 17 mpg empty, which dropped to 12 with a 3000 lb horse trailer (NA engine at that time). Now with a 1st gen banks on a 6.9, I haven't seen above 15 empty, I don't even want to know what it will be towing. There are plenty of threads on here with people getting 12-14 mpg out of their IDI and calling it the best it can be. Maybe I have less patience than most, but I'm at 270k and about ready to turn this one into rebar, and drop in a cummins, or just get a whole cummins truck. Or I will go with a 5-6 liter gasser and call it done. I guarantee you I have spent more money, not to mention time and frustration, maintaining this truck than I would have ever spent in fuel. For the amount of towing I do (not much) I don't need a diesel anyway. I have the diesel because I want it, and the IDI because I could afford it.

I'm currently in a bit of a low point with the truck. Having trouble getting it running again after an injector swap (cross threaded an injection line nut - long story) and was about ready to scrap it. So take what I say for what its worth. I'll probably drive this one for a few years yet.

 

[Iowa 73]

If you are wanting a cheap truck to tow with, and can't find a good used IDI, you can probably find a 460 out there pretty cheap. Stock for stock, they tow pretty much the same, and the 460's last pretty good too. I have an '88 with the 460/C6 with 250k+ miles and it still has plenty of grunt. Fuel mileage would be the trade off, but gas is cheaper than diesel now, and a 460 truck will cost you a few hundred less. Just an option for consideration.

 

[Old Blue]

I've never driven the 4.6, but I have my dad's 5.4L Super Duty. It will pull every bit as much load towing as my (and his old) IDI. The key difference, and I mean key, is the HP and torque numbers at your highway cruise RPM's. Take a quick look at this dyno chart for the turbo IDI's, and then this one for the 4.6L, it's the same basic story as the 5.4L. The old 460 on the other hand makes its power numbers lower, and is more comparable to driving the IDI in a towing situation. These newer small displacement gassers all make the HP and TQ up high - you get less than 100 RWHP and 200 TQ at highway cruise RPM on the 4.6. It's probably because I grew up with diesels, but I hate downshifting or winding out a motor to pull even the smaller grades, it just seems unnatural!

That said, buying any truck to tow with instead of using your dad's (free) truck is going to cost you more money in the long run. If you want a truck, buy a truck! If you decide you want a truck (seems like you do), buy the one you want and need! If you buy a truck, especially an older one, it's gonna be hard to keep your hands off the upgrades down the road no matter what you buy, period. Plan on spending the extra dough at some point, don't look at it as additional up-front cost. Just pick a truck you know you'll be happy spending money on in a few years. The IDI is great, because you get a stout platform with a stout, long living engine that has plenty of headroom for upgrades at a low purchase cost. The IDI (and first gen Cummins) injection systems are a lot cheaper and simpler to fix/replace/maintain than newer diesels AND like the alternative fuels a lot better if you're into that, too. Plus, you'll belong to the diesel owner's club, which automatically gives you extra cool points in general, redeemable at stop lights, parking lots, and drive thrus nationwide.

 

[Wyreth]

Where are you finding turbo setups for $500? Havnt looked to hard at used yet but 2 setups Ive found currently avalible (admitidlly new) are $1.5k+ (banks and hyper).

There is a marketplace here. There's even a factory kit in there right now, might be sold by now tho. http://www.oilburners.net/forums/showthread.php?56809-For-sale-idi-turbo-kit
Members tend to post craigslist/fleabay finds. Aslo, Gingrass179 likes to post things like this. http://www.oilburners.net/forums/showthread.php?56839-ats-088-kit-for-sale
Hang around a bit, you will see them.

I know that my IDI when stock felt more powerful than our farm truck (05 F250 5.4 Triton).

Granted I never hauled anything with the shop150 at my old job, but empty to empty... it made my 250 feel like it wasn't moving. And the she-devil isn't slow.

 

[bjprk]

Here's my two cents: If you are going to tow 7 to 8K get a 3/4 ton truck with a diesel or the largest big-block gas engine you can find. Regardless of what the specs say a half-ton truck is not going to last under that load. As an example, a very good friend of mine is a vintage racer and his car and trailer never total more than 4.5K. He has a 2010 F150 with the larger V8 and it did a decent job taking him to the races until 66,000 miles when it pitched a rod through the side of the block - he was not pleased. After three months of the truck sitting at a dealer and not-very-friendly discussions with Ford they gave him a re-man engine and all labor for free. The late model trucks from all the manufacturers are engineered down to the last molecule of materials, unlike the old-school trucks on this forum, which can routinely carry frightening amounts of weight.

Having said that, if you're going to buy an old truck you're primary consideration should be the condition of the truck, not the manufacturer. As an old-time racer I can guarantee that if you have to concentrate on your tow vehicle instead of the race you are going to lose, period. It also helps if you can actually get to the race track. At the next race go around the pits and see what guys in your class are using to tow with - watch to see who is working on the tow vehicle and who is working on the racer. Go with guys working on the racer ....

One of these old Ford diesels can make a great tow vehicle, but you will need to fix all the known issues with it before you hook up your trailer or you will regret it. Also, since you are in Colorado, don't even think about an NA diesel truck, get a turbo or don't buy one.

Good luck and good racing....

 

[redmondjp]

Good advice above!

Speaking as somebody who was looking for a diesel truck but ended up with a 460 gas, I'll second the advice to consider the engine and vehicle's condition more than gas vs. diesel. I bought my gasser truck because it was in excellent condition (after a 3-year fruitless search for a diesel CC in similar condition) and I don't regret it. As stated above, the 460 makes its torque down low and I certainly drive it like a diesel! I often upshift when I hit 2K rpm and the engine doesn't care at all. Sure, I am taking a fuel mileage hit over the diesel, but I seldom drive my truck so that's really a non-issue. In my area it's not hard to find a 460-powered truck in good condition with many less miles than on the 7.3l diesel trucks out there (most of which have 200-300K miles on them already), and for a reasonable price (esp. with the rising fuel costs).

 

[RANOVRU]

3/4 ton or 1 ton will be much more stable/safer towing that kind of wieght than a 1/2 ton. Even if you get an underpowered older diesel it will still tow better and be less of a strain on the truck. I would stay away from small blocks in those trucks though. Either go big block or diesel.

And for what its worth not all gas engines wind out that much. A bigger gas engine will have a powerband much closer to a diesel. For example my new rig (Magnum V-10) makes its peak torque (450) at 2,2k rpm. Albeit no gas engine will get premium MPG, diesel would be the way to go if youre really after milleage.