What is the most fuel efficient engine for FF Roadster Mk4

[panayaces]

I'm from the Philippines and am planning to build a FF Roadster in the U.S. and when completed ship it to my country. I'm retired and plan to drive the FF Roadster on weekends cruising the countryside.... no racing. Can you recommend a small block V8 engine that would give me the best fuel economy. Thanks.

Albert Enriquez

[wallace18]

5.0 Ford is the best IMO.

[Jeff Kleiner]

IMO your best fuel mileage potential will be an EFI 5.0 windsor or 4.6 mod motor.

Jeff

[Mike N]

What's your budget? If you can afford it you might want to consider the Ford Coyote crate motor, plenty of power and great mileage. On the other end of the cost range a good 5.0 EFI donor motor will give you similar gas mileage but about half the power.

[tirod]

Power vs fuel mileage is a classic conflict. It's been very difficult to arrive at a motor that gets respectable figures in both categories. The engines that do are sometimes not what we would expect.

The Ford Ecoboost turbocharged V6 is another possibility. 400 hp, 26 mpg. The major obstacle is that nobody has done it yet, it would require remodeling the intercoolers to work under the hood. Factory stock, parts would be available from Ford sources and the aftermarket without resorting to a hot rod industry that doesn't even want to recognize the motor's existence.

Conservatively, the Ecoboost would deliver 25% more mileage vs any Ford V8, at the cosmetic expense of not looking like the traditional motor. And the notoriety of being the first might not be fully welcomed. Nonetheless, somebody is going to do it. It's just a matter of time.

Just keep fingers off the boost adjustment and it would last 100,000 miles with virtually no maintenance beyond the factory recommended oil changes, etc. Many here can't report getting that - their custom built motor will need a significant repair long before.

[skullandbones]

Your best investment is a refreshed 5.0 pushrod engine like a 302. You said best fuel efficiency so the price of the engine factors in and affects the price per gallon of gas. That's why a Prius is not as good a deal as some give it credit. Plus your maintenance of this engine will be easier as it has the most after market availability and a good selection of cheap OEM parts. I don't know if you have an Autozone in the Philippine but it wouldn't surprise me if you did. Good luck. You're going to love your ride. WEK.

[SStrong]

One guy I know has a stock 5.0 and gets about 27 mpg, combined, and will outrun most cars on the road. I am ready for paint, so I don't know what to expect (375 to 400 hp) mileage wise. Remember these are very light cars, and they are very quick with even a stock 5.0. Mine scared me the first time I had it out as I couldn't go from start without spinning the tires. So be prepared. Your mileage shouldn't be terrible unless you get really radical.

[Bob Cowan]

For a very few years, Ford built the Mustang SVO, with a turbocharged 4 cylinder. Although not the fastest car on the road, it was pretty darned fast, and could easily be tweaked to be a bit faster. And the engine is very light. I think the engine was a bit overwhelmed in a 3500 pound Mustang. But in a 2,000 pound Cobra, it would be fast, unique, and very fuel efficient.

The same turbocharged engine was also available in other front wheel drive cars. To make it a rear wheel drive, it just needs a different bell housing.

I was seriously considering this set up for a '66 Mustang.

[68GT500MAN]

Any of the above as long as you keep your right foot under control!
Doug

[Mustang Man]

Not to dilute the thread, but for possible future engine searches...

Bob, where have you ever seen a 2.3 EFI turbo in a FWD application? The 2.3L EFI turbo was only used in the Mustang, Capri, Thunderbird, Cougar XR7, and Merkur Xr4Ti, all RWD...

Mark

[Jason Lavigne]

Hey guys - all great ideas. If you're looking for a bolt-in solution, I do think a 4.6L modular or the 5.0L Coyote would be your best bet. Final gearing in the rear axle is a huge factor, and you just need to be aware of what the tradeoffs are when you do things like running a tall ring & pinion ratio (great cruising RPM, but poor torque to the ground).

If you want to discuss anything in further detail, give us a call at 508-291-3443 or email Tech@FactoryFive.com.

thanks!

Jason @ FFR

[rich grsc]

I think it would be great if more responders would 'read' OP request, weekend cruising, no racing. Why so many suggestions for 400-500 hp engines? A stock 5.0 engine with the right gearing will easily get you in the 22-25 mpg range. I think for a bit more money the 4.6 will also do that, maybe even better.

[Bob Cowan]

I thought the Merkur was a FWD? If it isn't, that's even better.

[bwwooster]

I'm getting better fuel economy in my (3500 lb.!)'08 Bullitt than I am in the Mk II, which has the 340hp crate Windsor. I'd go with a stock 4.6 right out of an SN-95 car.

Another (big) factor is cam profile. Most high performance cams have longer duration, move the power and torque curves up the rev range and gobble up fuel. Relatively lower duration, higher lift cams might make the powerband feel more like that of a truck, but it'll help you keep it near the torque peak and save on fuel.

The Merkur XR4ti was RWD with ~175 hp, but it used the Ford Type 9 transmission. I have to figure there's some way to bolt a T-5 onto it, though.

If the V-8 rumble isn't that important, here's my choice for "the next one" I want to build:
http://i157.photobucket.com/albums/t47/johntennyson/loglisci01.jpg (http://s157.photobucket.com/user/johntennyson/media/loglisci01.jpg.html)

Alfa V-6-- and it should get pretty good fuel economy, too!

Anyway, what about the availability of spare parts in the Philippines? Which makes are the most popular over there? You might want, say, the engine and transmission from a Toyota truck or a Nissan Z-car. I teach at a school where a lot of the kids either came from or have relatives there and they carry a lot of stuff back and forth, so maybe the Ford bits might not be so hard to get a hold of, but it would be a drag to have to wait for a relative to come over to get that MSD distributor-- and hope it's the right part when it gets there.

[panayaces]

Thanks for all your inputs.... they bring me closer to getting my dream machine. I might be flying to the U.S. in a couple of months or so and will be staying either in LA or NC. Once there, the next question would be to do the project or get one that's already built. About spare parts, I guess close to none would be available in the Philippines but you're right, friends and relatives fly to and from the U.S. quite a lot and there's always the USPS.

[Mustang Man]

Sounds like you have a plan! And since I didn't really answer your original question, a stock 5.0L pushrod V-8 with a T-5 five-speed and 3.08 gears will still be a nice spirited weekend driver and pull down mid-20s in the mpgs...

And Bob, yes, the Xr4Ti was RWD. 2.3 turbo, non-intercooled with a German five-speed (or A4LD auto) and IRS. I put a LOT of T-5 conversions in those. The Merkur Scorpio sedan was the German 2.9L V-6 and RWD as well. Quirky cars, but I loved working on them and was Merkur certified when I worked at the dealer many years ago.

[MPTech]

I spent 6 months in Manilla in 2011, if you want easy spare parts, grab a Jeepni motor! :cool: these things are like cockroaches over there, all over the place! I also remember the gas was kinda high, so I understand your requirement for good mileage.


I'd have to ask, what HP are you looking for? and what's your budget? My experience was that HP isn't going to do you any good unless you are out in the country, because the city traffic SUCKS. You'd never get over 20mph!! Even in the country, we ran into a lot of Jeepni's and scooters/sidecars, but some of the mountain roads would have been a blast! I remember thinking how fun it would be to cruise my car over there!

I'm running a warmed up '93 EFI 302 and got 22mpg on a recent hiway trip with close to 300hp at the wheels. This is a pretty good compromise, but I'm sure if I wanted better gas mileage at the expense of HP, a few more mpg's could be squeezed out. Now if you put your foot in it, all bets are off, gas mileage drops significantly.
I would agree, a Coyote would probably be better for mpg and HP, but it's going to cost you more and limit your footbox room considerably.

I'd also suggest a good dyno-tune after you complete the build and ship it over, to squeeze out every mile and have it running optimally.