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221, 260 or roller 302 for best mpg?

25K views 16 replies 10 participants last post by  PSIG 
#1 ·
I'm wanting to build a Ford V8 for best mpg. My thinking was to start with the smallest one, the 221. I've been studying on the best recipe like highest possible compression (this article in Popular Hotrodding is great- Engine Compression Ratio - Tech - Popular Hot Rodding Magazine), free flowing heads and exhaust, torquiest cam, mild intake and small carb. I know roller engines are more efficient and that Crane Cams has the retrofit setup to turn a non-roller into a roller.

I already have a 260 out of a 63 Comet. Dad has a 221 in a 63 Fairlane that I might be able to talk him out of. My questions about the 221/260 are;
1) will late model heads like the GT40 or GT40p heads bolt on easily or is there a better choice of heads?

2) Will a mass air EFI off of a donor car work for this setup or is the small carb the better idea?

3) I think this 260 has a compression ratio of 8.8 to 1. I would like to bump that up to about 9.5 to 1 but there is nothing but stock, cast pistons available and they have no valve reliefs in them. How do I handle this?

4) Should I just quit thinking about the non-rollers and look for a good roller? I figure that the 221/260 will cost a little more, but if it works better for mpg, I would like to try it. Any of your thoughts would be greatly appreciated.
 
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#3 ·
What are you going to put it in? What drive train? I have gotten 32.9 MPG 302 in a 4000 lbs 87 Grand marquis. Just for availibilty of partrs would lean towards a 302. Have put bigger heads on a 260 back in the day it wanted lots of RPM to work not much low end. Dont remember the MPG could get regular for 11 cents a gallon back then.
 
#7 ·
Thanks for the responses. Right now my idea is to put it in a 51 Ford 2dr sedan which I think is about a 3000lb car. That would be the easiest option. I also have a 27 Model T sedan body I could build or a 77 Triumph Spitfire or a 73 Opel GT. Those would all be lighter than the 51 which I know is important.


It sound like I should go ahead and just store the 260 and get the EFI 302. Which EFI should I look for, the Crown Vic or Mustang? Which is the most tunable for mpg?

What heads should I look for? Would GT40/GT40p heads be too much head. I know I need free flowing heads, but is there a limit that would start to hurt my mileage?
 
#8 ·
It all comes down to BSFC at part throttle. You want to make the most power for the least fuel, and also select gearing that puts your efficiency peak right at cruise RPM.

Contrary to popular belief, lower is not always better for cruise RPM - there is such a thing as too low. While frictional and pumping losses increase with RPM, especially with 8 cylinders, fuel atomization and burn efficiency drop off with decreasing intake flow speed.

Like David said, higher overlap cams will rob you of part throttle, and large heads will reduce flow speed at low RPM, so make sure to size everything appropriately. Maximize your squish for lots of chamber turbulence if possible (flat top pistons, small combustion chambers). Tighter clearances mean you can run a lower viscosity oil, so I'd recommend hypereutectic pistons. The lighter your engine components, the less fuel it takes to accelerate them.

Low tension ringpacks, minimize your valve seat pressure, blueprint the entire engine including your oil pump. 4-2-1 headers give you a little torque boost down low versus 4-1, as well as an H-pipe. Don't go crazy with the exhaust, 2.5 will be more than enough.
 
#9 ·
I have wanted to try somthing like this myself, just havent found the time yet. i am not sure if the GT-40 heads (valves) will clear the bores in a 221 or 260. I have a set and will measure tonight. If you go with the early block you should be able to fit the stock ford roller gear in with some drill and tapping, If the lifter bores are tall enough. The GT-40 heads will not be to large for your build, the ports are actualy still pretty small. You could get your self a good roller block and stick a 289 crank in it. Then you lose some CID and keep all the good stuff like 4" bores, 6 bolt bellhousing, factory roller setup, might even be able to get good results with a factory HO cam.
 
#11 ·
I am getting ready to build another 87 Grand Marquis for economy DD so I can park my other one as its built for open track, auto cross now.
This time instead of ported E7 heads going to pocket port some E6s that come with the original LOPO in the 87. Ported lower, ported lopo upper, 60mm TB, shorty headers, some other mods to improve milage.
The engine in the other Grand marquis that got 32.9 / 22 in town pulled 280 RWT @ 2400 RPM peaked around 300@ 3500 RPM.
Cam will depend on air flow of the heads. Possibly just stock LOPO. Gear to start will be a 2.73 but guessing a 3.27 in my case would be best. Other car had a 3.55. Tires were 275 50 15s front and 295 50 15s rear. New set up will be like 235 60s or so (should hep economy). Trans a stock AOD.
Exh will be 2.5 necked down to 2" stock muffs it what the other had.
Possible might convert to mass air mark VI ECM. Havw a set of 1.7 Cobra rockers. Going to base line it as is then ad stuff piece by piece and check mileage one change at a time. Hope to hit in the mid to high 30s. Doing it just to beat my 32.9 my best so far with a 302.
 
#12 ·
Should I forget about the 221? It seems small enough that it should have good potential in a lightweight car.

I have an 88 LX Mustang with 5.0 and automatic. It's basically stock. I get 19/city and regularly 25 and 26 on the highway. My best it's 28.3. I used to get 21 and 22/city before we started running the E10 gas. I know the potential is there.

Dad has a 69 Falcon wagon. It has stock 302 2bbl with 3 speed. It would get 27 mpg. I think what helped it was no power anything, just engine under the hood.
 
#13 ·
my old '93 hatchback Mustang ran right around 29 mpg. 3.55's and a T5z. Decently built 5.0-but I paid attention to MPG from the start of the build, right down to light pistons, narrow rings, cylinder wall finish, crankshaft windage control, etc. Did what it was supposed to and as a side note, dyno'd 423 HP at 6400. 306 inches; not a 347 or anything. AFR165 heads.


As good as it ran, and as much fun as it was to drive, I really had no place to work on it. Traded it for a '04 Mustang V6-which has been a good car so far; although the MPG is pretty sorry. 29.3 is the best I've seen, with a typical average of 25.7. And 1/4 the power/torque that the '93 had, unfortunately. But it runs smooth, doesn't have to be worked on much (yet), and my girlfriend can drive it (automatic).

The EFI 5.0's can be built to make good MPG....and good power, IF you build it correctly from the get-go. When they were produced at Ford originally, they had to deal with emissions (not just exhaust emissions either....they had noise emissions, etc), NVH, and a ton of other issues to work around. If WE build it, and we're outside of mexifornia, we can do it the way we need to-for the most part. The '93 met 49-state emissions just fine-had it tested just for giggles.
 
#14 ·
I'd forget old school on this and take advantage of all the tricks Ford has learned over the past 2 decades or so: low tension rings, EFI, long runner intakes,, the list goes on. I think about the best 302 to start with would be the last Explorers to use the 5.0. The GT40p heads they used are supposed to be the most efficient factory head made. It has small valves and ports, yet modern design made them the best flowing, plus the combustion chamber design is far better than any other head. They run best with less timing than other heads, indicating their efficiency-less timing means less 'negative work' by the piston. Those Exploders also had a weird tube header type exhaust that also enhanced low RPM torque (needed to get those heavy barges moving, good for more MPG in your situation).
 
#15 ·
Thanks for all the replies. There is alot of good info here. I will put the 260 in mothballs and start looking for a GT40p engine to work with. Should I run the Explorer computer or is there a better choice?
 
#16 ·
Run the Explorer computer since the heads don't need as much spark advance. I forgot to mention that. This way you will have a completely stock setup, made to work well together. If you're going to run an automatic, you'lll need one from a 2WD Explorer or similar that is compatible with the computer as it controls the shifting. If manual, you'll want a 5 speed overdrive to better keep RPM in the most efficient range.
Then later, if you want to experiment further, you can play with chips, tuners, different headers, even camshaft, etc; then be able to go back to stock if your ideas go the wrong way. If you start with a highly modified 221 or 260 and it gives poor mileage, you may not know what to do first to improve it, and end up wastng a lot of time and money.
 
#17 ·
Agreed - you could start with the GT40 ECM (PCM), and if you get really serious, pop $400-$500 for an aftermarket ECM with much better and easier fine-tuning, and ability to make direct use of stuff like AFR tables,using wide-band O2 sensors, auto-adjust cruise timing advance,etc. Also, just skip using the factory ECM for auto tranny control. Guys have lost almost all their hair trying to get them to work well with any combo other than bone stock. Yes, they functioned, but not very well - and these were some very smart and experienced hombres attempting it. An aftermarket controller ($250 DIY to $750 ready to fly) seems the best solution out there currently. And, yes, I agree overdrive and appropriate rear gearing would be very strongly suggested for this effort.
:tup:
David
 
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