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Fuel Efficient High Torque 5.0 HO Build Advice Please

9K views 39 replies 14 participants last post by  Leadsled Coupe 
#1 ·
Engine is slated to swap into a 1989 F-150 2wd short bed base model with a C-6. 3.08 rear gears. No AC, hand crank windows, rubber floor mat, 1 small 12 gallon fuel tank--so, pretty light for a truck.
It has the 300/6 in it right now and gets pretty bad fuel mileage. I'm not a fan of 6 cylinders and I figure if I'm going to get bad mileage anyway, I might as well have an engine I like.
The truck is a daily driver, won't be used for towing or any heavy loads.
Would like to get as good of fuel mileage as possible with the combination at hand. Plans include to swap to a T-5 in the future as well as maybe a Fitech fuel injection set-up. It will be carbureted for the time being.

Any input is greatly appreciated.
 
#2 ·
Do you currently have the 5.0?

Since it's a truck, and if you don't, why not locate a 351 - there are still roller cam 351s out there with the ability to go carb'd.

This will give stump pulling torque with few mods
 
#3 ·
Thanks for the response, Top Heavy.
Yeah, I have the 5.0 engine but I'm certainly not against going with a 351 Windsor. In fact, I was looking for one on CL when I found this 5.0. It needs a complete rebuild as it has had water sitting in a few cylinders due to sitting outside exposed to the weather with no upper plenum. :frown2:
I only gave $60.00 for it so I wouldn't be out much if I could find a 351.
 
#5 ·
The other thing to do is to clarify your goals. You said you want better gas mileage, but you also said you want an engine that you like. What is kind of implied by saying "I want better gas mileage" is actually "I want to save money."

If you spend $1000 swapping a new engine in and you go from 13mpg to 15mpg, at 10,000 miles a year and $4/gal for gas, it will take you 2.5 years to make up for the project cost. If you decide to get a new cam for better torque/mpg, you get some new injectors so they flow well, get a really good tune or a standalone to dial in the highway fueling and timing for better economy, you're probably spending $2000-3000, which means it will take 5-7 years to make your money back.

And that assume you get any mpg benefit at all. Your truck was rated at 13 city/15 highway. A '96 351W with the four speed auto was rated at 11 city/16 highway. Depending on your mix of city and highway driving, it might get worse.
 
#7 ·
"An engine I like" referring to a V-8--I'm not a 6 cylinder guy.
I won't have much money invested as I'm going carbed for now. I'll do all the engine assembly, swap etc.
No pick n pulls anywhere around me, unfortunately.

Or look at the casting number. F4TE is a roller block. But even a non-roller engine can run link bar roller lifters and the roller cam of your choice.

I've never known a 351W to be especially "fuel efficient" in a truck (or car for that matter). And I would NEVER put a T5 in a full size pickup. Just not the right transmission for the job.
Have you ever built one to be fuel efficient, or known someone who has?

I use this truck as a car that can haul things. That T-5 will work great for what I want.

Thanks for the responses, guys. :cool:
 
#11 ·
Keep the I-6 and work on the V8 stuff later on as you can.

The 4.9 I6 is one of the best engines ever made. Not real powerful; but they do respond to light mods. They are torquey.

You can use the dual outlet exhaust manifold from the later 93-97 F150's, helps some. Also, if it's a manual transmission, you can get better fuel economy with it as opposed to the automatic (C6 eats up quite a bit of power, which=parasitic loss=drop in MPG). Dual outlet manifold is available at junkyards, and inexpensive. The trans can come from about any of the later F150's that had I6 engines, best to get everything (pedals, slave, master, lines, everything). I've had a couple of them and they are more desirable than the 5.0 V8 was in its' day. Got decent MPG too, as I recall I was seeing 21mpg on the highways with no load on it (reg cab short bed 5 speed w/3.55 8.8, 1995).

A 5.0 just doesn't make that much low end torque unless it's forced induction, it's just got 3" stroke. If you need torque, look into a 5.8 stroker but they aren't known for good MPG. Of course one could get crazy and drop in a 3.5 EB and have both, but that....ain't gonna be cheap.

I have had 4 or 5 of the OBS trucks, from 1980 through 1997. Most were stockers that I used for transportation (and they did great for that purpose). One was an 83 that I did a 460 swap into, then later after a problem went to a 514". Torque? No traction. Pulled great. MPG? Hahaha.....never bothered to check it. The 466 (original engine) had DOVE-C heads, 10:1, small cam, C6, 2.47 8.8 and it managed 16 mpg on average. One of the '95's was a 5 speed 5.0 and it honestly didn't have the torque as the 95 4.9 did, but it did get a little better fuel economy (19 vs 17). By comparison to the '83, both were SLUGS. 5.0 was a little better from 2500 RPM and up, but the big six outpulled it from idle to 3000-by far. By 3500 it was done and that's where the "mods" come in. You can open up the intake & exhaust a little and extend the power up to about 4200 or so, but you can't get crazy with RPM, it just doesn't need it.

Another thought, a 5.0 but use gears to your advantage. With low 1st gear ratio you get the "feel" of torque. Say, 5:1 first gear or better (didn't some of the 4 speeds have a 5.90?).
 
#13 ·
Okay, let's get this out of the way, I am NOT a 6 cylinder guy. I don't care if this 300 made 500 horsepower and got 30 miles to the gallon, it's not staying in my engine bay. lol.

My original questions were fuel economy and torque for the 5.0 I have now, that's what I'd like to concentrate on, or maybe a 351. It's staying carbureted for now.

I used to have a '79 F-100 that I drag raced and was my daily driver. I had a 460 with D0VE heads, Crane sft cam, C-6 with a 3000 stall and a 9 inch with 3.89 Detroit locker. Truck was a blast. Now THAT was less than stellar mileage. lol.
It weighed 3900 lbs full interior, all street trim.

I can't imagine this '89 weighing more than the '79.
I think the T-5 will be fine.

Anyhow I was hoping for maybe some tips on cam, heads, intake, exhaust for mileage and torque/throttle response.
Will the stock E7s be fine? Stock HO cam?

Thanks again.
 
#18 ·
I can't imagine this '89 weighing more than the '79.
I think the T-5 will be fine.

Anyhow I was hoping for maybe some tips on cam, heads, intake, exhaust for mileage and torque/throttle response.
Will the stock E7s be fine? Stock HO cam?

Thanks again.
I have a low mileage 89 GMC full size 1500 truck with a T5 and I have pulled plenty of weight with it and no issues, how you drive it makes the difference.

Get some GT40 heads for a 302 or 351, use a stock HO cam, a used dual plane intake, some HO headers and you should be happy for your goals
 
#15 ·
I'll bet your buddys Lightning had AC, power windows, power door locks and all the electrical and plumbing associated with it--that stuff adds up. My truck has none of that.
You're absolutely correct, the truck will not pass smog with a carb. Fortunately, we don't have annual or biannual checks where I'm at. The vehicle only needs to pass smog when changing ownership, so I'm good.
 
#20 ·
You mentioned the $60 302 needs a rebuild as it has rusted cylinders. That means bore and new pistons. Soooooo if you want tq and have to bore it anyway, I'd go with a 347 rotating assy. Summit has them pretty cheap and since you aren't looking for max hp and max rpm, the cast crank will be fine.
Yes you can use your E7 heads on a 347. It won't have power but will have tq. You really should put better heads on it though. Those old E7's are going to need to be gone through, new springs, valve job, mill or resurfaced - gets expensive fast. Look for some ready to use heads or some that have already be gone through. Guys here can suggest some cheap alternatives for ready to run heads.
A stock HO cam would be fine also. It is hard for guys here to realize not everyone that builds and engine wants or needs max power. Stock HO exhaust headers would also be fine - unless you "want" full length aftermarket headers and have the cash for them...
Carb dual plane intakes are pretty easy to find. You also mentioned in the future maybe getting a Fitech.
I recommend a Holley Sniper EFI system. I have one and am very happy with it. My car would get 18 mpg on freeway with a carb. It gets 21 with the Sniper :)
Yes as mentioned recuperating the cost for all of this with fuel mileage savings will take forever. That is your decision no one else's. If you want and You are paying for it, do what you want to do - it is your money not theirs.
Another option is find a running 331 , 347 or even 351 that someone is selling. You can always put in a small cam, don't have to run what cam they used. Run a carb intake and carb, drop in your truck and enjoy.
There are many ways you can go. All you can do is look at all the options, come up with a goal, make the game plan and carry it out. Good luck and keep us posted.
 
#22 ·
A 4R70W is an electronic shift trans. What shift controller do you recommend and how much does it cost? How much is a 4R70W, converter and flexplate?
I'm curious what all of this costs...
 
#23 ·
You can source a 4R70W with the SBF bellhousing from a 2wd 5.0 Explorer or a later 3.8 V6 Mustang. car-part.com shows a ton of V6 Mustang transmissions in the $150-200 range. Baumann makes a standalone programmable controller for it, costs about $600.

This thread has a good post.

A 4R70W with a stock 235/75-15 tire and your 3.08 rear would hit 59mph at 6000rpm in 1st gear and would run 1755rpm in 4th at 70mph.

A T5 with the 3.35 1st gear would do 50mph at 6000 in first gear. It would feel a lot peppier than the tall 4R first gear. Closer gear ratios mean you stay in your powerband better. And it would do 1705rpm at 70mph in 5th gear.

Any four speed auto is going to suck for gas mileage, they're heavy (135lbs vs. a T5 at 75lbs), 3 gallons of ATF is heavy. The converter sucks power and efficiency. It wasn't until the last 10-12 years and the advent of more efficient 6 speed auto transmissions and tighter OEM trans controls that autos have been able to meet/beat manual efficiency.
 
#27 ·
GT40 heads stock-for-stock flow about 9% more on the intake and about 18% more on the exhaust than the D0OE 351 heads.

https://www.fordmuscle.com/archives/2000/05/heads/index1.php

You could port the D0 heads to meet/beat a stock GT40, but you could also port a GT40 head to do even better.

If you're taking your current 302 to a machine shop, you're immediately spending $1000 and probably more on pistons, crank, and all of the supporting bits and pieces.

You're probably better off just getting a running Fox or SN95 5.0/T5 dropout and slapping that in place.
 
#28 ·
Thanks for the link.

I enjoy building engines. No matter what I have laying around or something I pick up--running or otherwise--will be pulled apart and rebuilt.
My friend owns the machine shop I go to so I'm not too concerned with machining costs. Doing all of my own work and finding deals on parts when I can keeps costs at a minimum.

Thanks.
 
#33 ·
I did a stock HO roller cam conversion from a foxbody in my 91 f150. I did the cam swap, 1.7 rr’s, mild port work Match to the stock heads And Intake manifold. It completely changed the truck. It felt like a dog before with the stock flat tappet cam. After the roller conversion the truck revved up faster and had more torque down low. Oh I only spent $80 for the cam, lifters, pushrods Distributor etc. I found someone on this forum selling it for cheap. I had maybe $200 into it. I also did 4.10 gears to help with my offroad capabilities.
 
#34 ·
Fuel injected or carb? Reason I ask is you will need to decide either “speed density or mass air”. If you do speed density you will be limited on cam options etc because speed density can only handle so much cam. Mass air you have more options but you will then need to worry about doing a mass air conversion... best bet is to get a roller 302 from a bronco for pickup from I believe1992- beyond. You can get the ECU engine harness etc and it will be mass air. That’d be the most cost effective way. You can also find yourself a 4.10 rearend from an explorer to help with the getup and go which will probably help fuel mileage in the city quite a bit. There is gold out in the junkyards... you just gotta look! ??
 
#36 ·
Well, I picked up a complete 5.8 out of a '95 F-250 2wd. All the front dress, complete from fan to flexplate, all the wiring harness with the ECM and Mass Airflow Meter. Also got the frame to motor mount mounts.
Would really like to come up with a set of GT40s and maybe use the stock HO cam out of the 5.0 I just disassembled.
I'm pretty stoked. I think this will be a fun little truck with a spunky 351w and T5.
 
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