max mpg from 300 in a lightweight vehicle.

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deere114
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max mpg from 300 in a lightweight vehicle.

Post #1 by deere114 » Sat Dec 02, 2017 8:45 pm

Been thinking lately about building a very unconventi daily driver....... a model T coupe or closed cab pick up. Using the model T body and more modern drivetrain and suspension components. Mustang II suspension, 7.5" rear axle and a 300 six backed by a t5 or m50d. The goal being build something small, light, dead simple and reliable while getting great mpg. If a 300 will do 18 mpg in my 4x4 f150 and 22 in my brothers 2wd f150..... how good do you guys think it would do in something that only weighs 2000lbs or less? figuring a carb'd 300 with header, 252h cam, light head work, and a carter yf with duraspark 2 ignition. 30mpg out of the question? Also considering a 250 CIA small block six, a 302, carb 2.3 turbo, or some sort of small diesel. I like the 300 best though. Enough rambling, what're your guy's thoughts?

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THE FRENCHTOWN FLYER
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Re: max mpg from 300 in a lightweight vehicle.

Post #2 by THE FRENCHTOWN FLYER » Sat Dec 02, 2017 10:19 pm

Depending on your driving habits you could get near 30. But aerodynamics plays a big role and the bodies you mentioned push a lot of dirty air. So experiment with the sweet spot speed wise and keep the gearing very tall, tires skinny and rotating pieces as light as you can make them.
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Re: max mpg from 300 in a lightweight vehicle.

Post #3 by deere114 » Sat Dec 02, 2017 10:38 pm

A model t body is about as aerodynamic as a bill board. definately not helping me. I'm usually comfortable cruising at 65mph on the highway around here. I plan to keep the stance of the car reasonably low on a 28" or so tire and do whatever I can to clean up the aero under the car. Thinking nice light centerline wheels, and a 3.08 rear gear with the t5. Should put me around 1500rpm @65. I would think a 300 with a 252h cam would be comfortable under those conditions. Thinking 87 octane gas here so I'm pretty limited on compression with that short of a camshaft. You have a 300 in a lightweight car if I recall? Probably more of a hot rod oriented engine but have you ever checked mpg?

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Re: max mpg from 300 in a lightweight vehicle.

Post #4 by pmuller9 » Sun Dec 03, 2017 12:20 am

You are looking for engine efficiency.
The EFI head with the high swirl combustion chamber would be your best bet.

Use the stock cam which has a long advertised duration so you can keep the compression ratio near 9:1
Comp cams for the Ford 300 are detonation prone because of their short advertised durations and forces you to either drop the compression ratio, run rich or back off the ignition timing none of which will help with MPG.

Switch to the 1.73 ratio pedestal mount Scorpion roller rockers to reduce friction and increase valve lift for extra torque.
https://www.summitracing.com/parts/scc- ... /overview/

Use the EFI Hyper pistons that have metric rings for reduced cylinder friction.
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MSD 6A ignition #6201
Use it with the Duraspark Ignition system.
I tried the MSD as a stand alone but it does not trigger at the zero crossing point of the trigger signal.
Instead it triggers as soon as it sees voltage which advances the timing. When you turn the distributor to correct the timing the rotor phasing is way off.
I let the Duraspark unit trigger the MSD and it worked perfectly.
Big difference in spark intensity and low rpm spark duration. It should let you run a leaner mixture during cruising.
I also ordered directly from MSD to prevent buying a counterfeit unit.

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Re: max mpg from 300 in a lightweight vehicle.

Post #5 by worken2much » Sun Dec 03, 2017 6:05 am

How about an early Falcon? They came with little sixes. I'd think a trans upgrade to something with overdrive would be a big move in the right direction. Pick a trans that uses atf not 80/90 wt gear oil. Run synthetic lube in differential.

The gently rounded Falcon body would have less drag than a T or 30's pickup cab. Not as cool though.

I had a 1973 Maverick Grabber with 302 & 3 speed column shift. Carefully driven it would return low twenties mpg.

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Re: max mpg from 300 in a lightweight vehicle.

Post #6 by Wesman07 » Sun Dec 03, 2017 8:13 am

T bodies are cool but I think you would see your best mpgs at around 45 mph.

Would increasing the rocker arm ratio increase lift enough to push the valve past the shoulder in the EFI head? Or enough that it would hurt the swirl effect?

I remember xctasy talking about a "learn burn" motor... maybe this is the project for it?
86 f150 300 efi with advanced stock cam. Np435, Dana 60/ 10.25, 35" BFG's, four link front suspension with 12" travel fox coil overs, custom deaver leaf pack in the rear.

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Re: max mpg from 300 in a lightweight vehicle.

Post #7 by deere114 » Sun Dec 03, 2017 8:40 am

There are definately other bodies that offer better aero. Your right though, not near as much cool factor. That 65 mph I mentioned is more of a max cruising speed. I generally don't drive on any roads day to day that have a speed limit any faster then 55. Most of them being 30-45 mph zones. I just need to build this to be comfortable at 65-70 for the once in awhile I go somewhere involving rt84. I was wondering about the efi cylinder head. Since I'm limited to stock valve sizes to keep swirl high I wonder how much power the efi head can support with such a small cam. Stock efi's made 150hp. Wonder if 200 is out of the question? I'm really leaning toward the t5 trans because it's light, takes atf, and offers a pretty tall overdrive gear. 1.73 roller rockers with the stock cam advanced seem like good fit. I'm leaning toward the 300 over other engines because even built for max economy it should make enough torque to be pretty fun to drive in such a light vehicle. I don't have a t body to measure anything yet, but I assume I'm looking at major fire wall modifications.

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Re: max mpg from 300 in a lightweight vehicle.

Post #8 by deere114 » Sun Dec 03, 2017 8:45 am

Good info on the msd 6a. I run one in my f150. During the tuning process for megasquirt I found it had no issues lighting off the mixture as lean as 17.1 age. That truck seems to get its best mpg cruising at 10hg of vacuum with a 16-16.5-1 afr. One thing about that efi cylinder head, it doesn't like a lot of ignition timing. I'd have to refer back into my laptop to see where I left it during cruise but I remember it liked a lot less then I initially thought.

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Re: max mpg from 300 in a lightweight vehicle.

Post #9 by THE FRENCHTOWN FLYER » Sun Dec 03, 2017 8:58 am

deere114 wrote:... You have a 300 in a lightweight car if I recall? Probably more of a hot rod oriented engine but have you ever checked mpg?

Yes. My '33 Willys gets around 16 mpg but it has twin 2100s with direct linkage and retarded spark to live at 11:1 CR and a wilda**ed cam. Plus, when I take it out for a ride, MPG is the farthest thing from my mind - I just want to take it through the gears with authority and blow off steam.
We never checked the MPG on the 240 '48 Anglia. Both those cars weigh in the 2300 - 2500 lb range.
The drag roadsters get about 1/3 gallon of 112 race fuel per run. Not bad considering.
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Re: max mpg from 300 in a lightweight vehicle.

Post #10 by GPGoverMPG » Sun Dec 03, 2017 10:38 am

You'll probably want a wide ratio transmission to use all the big six's torque. Light cars get thought the RPMs quick.
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Re: max mpg from 300 in a lightweight vehicle.

Post #11 by deere114 » Sun Dec 03, 2017 10:54 am

That's the thing about this build. I want good mpg when driven daily, but I want it to be quick enough to be fun to drive when when I get that itch. The wide ratio trans might move the car down the track faster. But I'm thinking the close ratio t5 will help me keep the motor in the sweet spot for mpg around town, plus I like how a t5 feels to drive. I do have a tko-600 I can use, but I really don't think it's needed in such a light weigh car. I've thought about running a draw through turbo set up, I know how fun to drive my turbo 4.9 efi f150 is to drive. But I'd have to compromise on compression and cam timing to make that work on pump gas. Building an engine exclusively for e85 use is an option. (My turbo truck burns e85) but I don't think I can get the same mpg out of it.

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Re: max mpg from 300 in a lightweight vehicle.

Post #12 by GPGoverMPG » Sun Dec 03, 2017 11:11 am

If you don't plan on hooking it up a t5 would be ok. They get fragile in my experience when you apply the amount of torque a 300 is capable of. I have not seen torque numbers on a boosted 300 bet they are amazing.
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Re: max mpg from 300 in a lightweight vehicle.

Post #13 by GPGoverMPG » Sun Dec 03, 2017 11:16 am

E85 seems great however, it's octane isn't regulated. Hard to tune for with it's inconsistancy.
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Re: max mpg from 300 in a lightweight vehicle.

Post #14 by deere114 » Sun Dec 03, 2017 11:46 am

I've broken 4 t5's in my fox mustang. But that's a 300 or so hp 5.0 @3000lbs with drag radials and good suspension. I'm hoping with the lighter weight and street tires it will live happily in this application. That 300 makes some torque for sure. As far as the turbo 300 goes I've never had it on a dyno. But it'll spin both back tires from a 40mph roll in 2nd gear at 2200 or so rpm (it's got 2.73 rear gear) and stay sideways until I lift to grab 3rd. It's just a stock 4.9 efi with an hx35, eBay intercooler pipes and blow off valve, decent fuel system for e85, and megasquirt controlling it. I'm convinced the same combination with 4.10 gears in a 1 ton would tow better then my 7.3 powerstroke or 460 truck could.

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Re: max mpg from 300 in a lightweight vehicle.

Post #15 by deere114 » Sun Dec 03, 2017 11:50 am

As far as tuning pump e85 goes, I tuned my turbo truck on winter e85 figuring that's worst case senerio, so the tune is plenty safe on higher % e85.

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Re: max mpg from 300 in a lightweight vehicle.

Post #16 by Haywood » Sun Dec 03, 2017 10:06 pm

My vote on the transmission would be the 4 speed overdrive used in the 4.9 87 F-150, I have one of those and with a 3.08, and a later F-150 4.9 M5OD with a 3.55. Frankly the 4 speed is more of a joy to drive, it is smooth and accurate, and better matched to the 4.9 torque curve than the 5 speed. The M5od seems way too short in first, you have to be on your toes to not wind it too tight, yet it is too tall in second to just ignore 1st and treat it as a granny gear. Those 4 speeds are a heavy oil transmission, so probably wouldn't contribute to mileage, but I believe it generates more smiles.

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Re: max mpg from 300 in a lightweight vehicle.

Post #17 by pmuller9 » Sun Dec 03, 2017 11:09 pm

The stock EFI head intake valve size will produce high velocity flow for low rpm torque and high swirl with the proper attention to the port and cam selction.

The 300 cylinder is relatively large and will draw lots of air through the port but the main restriction is the valve guide boss that sits right in the area of the greatest air pressure in the port.

The job is to eliminate most of the boss and contour the remaining part to direct the airflow around the valve stem.
Nothing else needs to be done to the port exept a cleanup.
Here is my head which is on the extreme side because I used undercut valve stems.
https://www.dropbox.com/s/xklz27x77cvgh ... 3.JPG?dl=0
Here is an EFI head without undercut valve stems and less radical work around the valve stem.
https://www.dropbox.com/s/c2wxpsuq25rp1 ... 3.jpg?dl=0

The other factor in making a high torque 300 is valve lift.
The Scorpion rockers with the stock cam will give you .430" lift but .500" lift would be better with the port work described above if you are looking for more power.

Example: A Jones H67300 has 268* .006" duration like the stock cam, 210* .050" duration and .519" valve lift with the Scorpion rockers.
You would need to use the pre-1987 valves which are .060" longer than the EFI valve to keep the valve retainer from smashing the valve stem seal.
You will want to use the longer valves anyway so you can get the correct installed spring height.

This should give you well over 200 HP along with good gas mileage.

If you run E85 then you can use a flat top piston with 11:1 compression ratio.
If you stay with pump gas what octane would you want to use?

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Re: max mpg from 300 in a lightweight vehicle.

Post #18 by deere114 » Mon Dec 04, 2017 9:43 am

Being the main goal for economy I'd like to run 87 octane for pump gas. I wonder which would make more power and or economy. High compression e85 or low compression 87....

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Re: max mpg from 300 in a lightweight vehicle.

Post #19 by deere114 » Mon Dec 04, 2017 9:44 am

As far as transmission goes I'd like to stay with something running atf for better economy. I think the t5 close ratio will help me keep the motor in its sweet spot for mpg over a wide range of speeds. It would probably be faster and fun to drive with a long torque curve and wide ratio trans though.

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Re: max mpg from 300 in a lightweight vehicle.

Post #20 by wallen7 » Mon Dec 04, 2017 10:31 am

I think a T5 would be a good choice myself as I have thought about this before. You can get a higher torque rated gear set for a T5 now.
I also like the Ford AOD in the automatic.

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Re: max mpg from 300 in a lightweight vehicle.

Post #21 by Haywood » Mon Dec 04, 2017 1:08 pm

deere114 wrote:As far as transmission goes I'd like to stay with something running atf for better economy. I think the t5 close ratio will help me keep the motor in its sweet spot for mpg over a wide range of speeds. It would probably be faster and fun to drive with a long torque curve and wide ratio trans though.

I will add, that the M5OD equipped one becomes the one to chose, if serious weight is added. When I pull my all steel 18' car trailer, even empty, the ratios in the 5 speed suddenly become ideal. The 4speed is out of its depth with the trailer, 1st gear seems way too tall, 3rd becomes the highway gear unless pointed down hill. It will do it, & has for years, but enjoyable it isn't.

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Re: max mpg from 300 in a lightweight vehicle.

Post #22 by deere114 » Mon Dec 04, 2017 3:57 pm

I can second that. My brothers trucks tows just about every day with a granny 4 speed. Has been around 12,000 lbs gross combined on a somewhat regular basis. While power is really no issue, certain road conditions would make a few in between gears very usable.

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Re: max mpg from 300 in a lightweight vehicle.

Post #23 by bubba22349 » Wed Dec 06, 2017 7:25 am

Another choice for a trans for your light weight T if you can find one is the heavy duty 3 speed with overdrive (first used about 1957 these had the stronoger R11 overdrive unit) They have good ratios and you can split shift them, the later models made in about the mid 1960's up are all Sinc. Too. Good luck :nod:
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Re: max mpg from 300 in a lightweight vehicle.

Post #24 by Haywood » Wed Dec 06, 2017 12:10 pm

bubba22349 wrote:Another choice for a trans for your light weight T if you can find one is the heavy duty 3 speed with overdrive (first used about 1957 these had the stronger R11 overdrive unit. They have good ratios and you can split shift them, the later models made in about the mid 1960's up are all Sinc. Too. Good luck :nod:

That is a very lovable transmission. I'm pretty sure that is what came in the Willys Overland wagons. My Dad had several of those, and they were a joy to use. Around town in 2nd it was like an automatic, shifting back up and down depending on speed and grade, in 3rd just lift and it would up shift, floor it and it would shift back down. 1st to second didn't require the clutch, since it would freewheel below 30mph, and would glide right in. I was a child when all this was going on, but I still remember my fascination with that wonderful transmission. I see a couple on Ebay for a little under 2k, that seems steep, but they are fully rebuilt.

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Re: max mpg from 300 in a lightweight vehicle.

Post #25 by THE FRENCHTOWN FLYER » Wed Dec 06, 2017 1:20 pm

My drag racing neighbor had one in a '60 Ford Starliner w/ a HiPo 352. We did 110 mph in second gear OD. Impressed this kid.
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Re: max mpg from 300 in a lightweight vehicle.

Post #26 by MechRick » Wed Dec 06, 2017 1:36 pm

deere114 wrote: I wonder which would make more power and or economy. High compression e85 or low compression 87....


E85 would make more HP, economy would go down a bit. Megasquirt offers a dual table mode so you can run both (dual fuel).

Consider a TT instead....

http://topclassiccarsforsale.com/ford/1 ... c-cab.html

I think enough panels exist in the aftermarket to build one from scratch. Frontal area isn't bad until you get to that billboard windshield...

The tough part would be finding vintage-looking but yet practical wheels...
1994 F150, 4.9L/ZF 5 speed, C-Vic police driveshaft
EFI head w/mild port work, 3 angle valve job
1996 long block, stock pistons, ARP rod bolts
Stock cam installed straight up (aluminum cam gear)
Hedman header, full mandrel bent duals, crossover, super turbos
viewtopic.php?f=2&t=73244
Bronco II with a 2.3L swap viewtopic.php?f=13&t=72863

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Re: max mpg from 300 in a lightweight vehicle.

Post #27 by Haywood » Thu Dec 07, 2017 8:54 am

MechRick wrote:The tough part would be finding vintage-looking but yet practical wheels...

Chrome reverse is about as classic hot rod as you can get. https://www.wheelvintiques.com/gennie-chrome.html

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Re: max mpg from 300 in a lightweight vehicle.

Post #28 by deere114 » Thu Dec 07, 2017 9:19 am

The TT and AA ton trucks seem to be cheaper, cleaner, and less modified so I may go that route. There's an AA for sale locally for $1800. That TT is pretty fair priced to. Even though I love megasquirt in the two trucks I have it in I'm thinking carb'd for simplicity on this naturally aspiriated build. I do like those wheels.

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Re: max mpg from 300 in a lightweight vehicle.

Post #29 by MechRick » Thu Dec 07, 2017 1:23 pm

That's a great price for an AA, especially if it's complete with wheels...

AA's are cool!

https://barnfinds.com/reader-find-1929- ... -aa-truck/
1994 F150, 4.9L/ZF 5 speed, C-Vic police driveshaft
EFI head w/mild port work, 3 angle valve job
1996 long block, stock pistons, ARP rod bolts
Stock cam installed straight up (aluminum cam gear)
Hedman header, full mandrel bent duals, crossover, super turbos
viewtopic.php?f=2&t=73244
Bronco II with a 2.3L swap viewtopic.php?f=13&t=72863

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Re: max mpg from 300 in a lightweight vehicle.

Post #30 by deere114 » Thu Dec 07, 2017 4:21 pm

It has the wheels, $1800 isn't bad at all, it's not near as nice as that TT you posted. That's almost too nice, I'd have a hard time changing the motor in such a nice original truck.

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Re: max mpg from 300 in a lightweight vehicle.

Post #31 by Haywood » Sat Dec 09, 2017 11:24 am

I'd like to say what a pleasure this thread is. Really good exchange of ideas. Only thing is; now I'm longing for that B/W T85N / R11 overdrive. I suppose it isn't entirely practical, but the driving experience would be worth the hassle of scaring one up and getting it the required shifter, electricity, cable & driveshaft. Probably no trailer puller, but an amazing boulevard cruiser. Inertia will probably save me in the end, as another shiny object draws my attention away.

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Re: max mpg from 300 in a lightweight vehicle.

Post #32 by THE FRENCHTOWN FLYER » Sat Dec 09, 2017 5:46 pm

I read an article about them a while ago and they said rebuild parts are now pricey and some parts are getting hard to find.
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