LSx vs 5.0 MPG; all in the trans?

I have a distant hope of finagling the household toward something really fun in a novel eco-nut kind of way for an around-town DD (think Leaf, Th!nk, etc, though this isn't the central point), leaving us wanting something else for longer trips (several times a year, but not that much).

I want a Volvo 240 wagon with V8 power. Maybe 740, but that's also not the central point.

Either engine in the topic will provide plenty of power for this car. It's not a racer, it's just for fun. But since we'll be driving it significant distances, I am interested to some extent in fuel economy.

Now, I know, sticking it in a brick isn't a great first move... But.

Is the remarkable fuel economy that I hear about from LSx engines mostly down to a tall overdrive on the T56? Is there a T5 version that'll get me something similar? Or is it down to something about the engine itself of the engine management? If the latter, how much would I be losing with a modern intake arrangement and Megasquirt, tuned well?

Let's hope Mazda brings us the Skyactiv-D 6 wagon or VW fixes the high pressure fuel pump on the TDI and saves me from this ill-conceived idea...

choose your rear differential carefully and I'm sure you could get decent fuel economy. You'll just be giving up some acceleration.

It's mostly double overdrive transmission, plus using fuel injection and not carbs.

LSx head design is nice and aluminum heads let you run more timing with the same fueling, some good aluminum heads on the 5.0 would make it a contender though.

If you go Ford get the T5 with the. 63 overdrive it is a huge step from the 1:1 4th gear, works in my 3.9 Mazda diff with the 5.0

Most of the fuel economy is in the engine not the transmission. Even the automatic models, which did not have mega-massive-overdrive, got absurdly good fuel economy. I've heard of 30-31mpg with automatic C5s.

The LS1 only needs something like 26-28 degrees of timing to make best power, proof of a very efficient combustion chamber. The ports are wind tunnels that need only mild cams in order to make good power, and the base engine is stiffer than a Ford engine could ever hope to be, so it stays dimensionally true, so the clearances can be tightened up for further efficiency gains. (Don't need a massive oil pump, and so forth)

Let's face it, the LS1 is a modern engine while the 5.0 isn't much different from what you could get in 1962.

I should point out that I am a Ford guy. There's no denying, however, that the LS1 is a finely engineered piece of work. I make myself feel better by the thought that Chevy just designed the ultimate Windsor

The great fuel economy is also due to aerodynamics. The Corvette has an amazingly low CD and frontal area. The box will somewhat...suffer.. in this regard.

How much are the 2010 Mustang V6 engine's going for now? More than an LS1? Those had 310 HP while putting out 30+mpg if I remember correctly.

In reply to sobe_death:

It's true; I'm certainly not expecting to match the numbers hit by vehicles with the same engine/trans and a shape not made up entirely of angles and ledges with some external gutters for good measure.

I need to borrow my dad's '86 240 sedan and just remind myself what that sounds like in terms of wind and road noise at 70 mph before I build something we'll be sitting in all day at that speed...

http://www.astroperformance.com/product_info.php/manufacturers_id/29/products_id/865

T-5 performance rebuild with a .60 to 1 fifth gear ratio. So a T-5 could offer the same legs as a T56 if you wanted to go that route.

I think Knurled is right on about the cylinder heads on the 5.0 leaving much to be desired vs. the LS family from GM. I'd like to think the aftermarket has options to improve on that situation quite a bit but then that's money out the door again.

An aluminum 5.3 LS-type truck motor with a mild cam swap and the A-5 I've linked to here would probably be a great bet for mileage & performance.

In reply to Enyar:

That's an excellent question, though that's a bulkier DOHC engine, even if it's a cylinder shorter F to R, yes? For wedging into a Volvo engine bay, I think that would be at a minimum annoying, and quite possibly a no-go.

In reply to Enyar:

And they do it with a car roughly the size and shape of a Volvo (larger, even) and port injection. Good call!

Car-Part says 3.7L V-6s from the Mustang and F-150 are going for about $1800-2500. The MT-82 manual is going for $1800-2000.

Gearing is also important with the Mustang. The best I can get from my 3.31 and summer-only tire-equipped 2013 is 26mpg. The 2.73 models with gas-saver all-seasons are the ones that can make it to 30mpg.

don't forget most of the MPG is gained by tuning the nut behind the wheel. with a custom ems you could have a switch to go from lean burn to high performance

As for dimensions, I posted this in an earlier thread about the Cyclone:

I got some rough dimensions for my Mustang's engine. It's about 23" wide by 24" long by 28" tall.

Here are some Chevy dimensions for comparison.

I measured across from one valve cover to the other, from the back of the valve covers to the pulleys, and from the skid plate to the top of the intake manifold (minus 1" for the space between the skid plate and oil pan).

The second post here is close to what I got and the poster claims the engine weighs about 330lb. He didn't mention long- or short-block, though.

RexSeven wrote: Gearing is also important with the Mustang. The best I can get from my 3.31 and summer-only tire-equipped 2013 is 26mpg. The 2.73 models with gas-saver all-seasons are the ones that can make it to 30mpg.

I wonder how much of that simply is the tires. My fuel economy dropped about 10% by going from 215/70 allseasons to 235/45 snow tires. (Yes, a rim diameter change occured at the same time, kept tire diameter roughly 25.5") You can really feel the extra load on the engine, to boot.

Comparing apples and granola bars, here, but never discount the effect that higher rolling resistance has on fuel economy. Heck, I've noted a significant drop in fuel economy just from driving in the rain.

RexSeven wrote: As for dimensions, I posted this in an earlier thread about the Cyclone: I got some rough dimensions for my Mustang's engine. It's about 23" wide by 24" long by 28" tall.

So here's a pic of a 760 engine bay with an [EDIT: 5.0. the photo was captioned LS1. then I finally noticed the Trick Flow intake ] in it. This engine is about 4" narrower than the Cyclone [EDIT: I get the impression that the 5.0 and LS are similar in size, but 4" was based on the mislabeled photo and thinking it was an LS], though I'm not sure how much of that might be overhang from the cam covers, since the biggest concern is room for the headers.

It doesn't look completely terrifying, but again, this isn't some racecar dream, and I don't want to build something that requires double joints and five u-joints to work on. This is a semi-DD. Hrm...

I recently looked into swapping a v8 into my 245. Also just got back from a 14 hour roadtrip averaging around 75 mph.

The swap would make an already excellent car even better. Please do it, I was too afraid of starting something I wouldn't finish....

Also, from my research it seems the 5.0 is a MUCH easier swap due to sub frame clearance, also cheaper with basically free ford exploder engines available.

Looks more spacious than the engine bay on my SN95 with a 302 under the hood...

I've got a 245 with a 5.0 and T-5. Its been off the road a while for rust repair so I can't test mileage. It cruises pretty relaxed with the stock rear ratio (3.9 IIRC?) at 70 or 80 but I dont remember ever calculating MPG's. Most of it has been around town not being particularly easy on the throttle.

Its got GT40P heads, shorty headers, Cobra Intake and E303 cam. If I get it back on the road anytime soon (fingers crossed) I will go ahead grab some figures for you. Shoot by the time you are looking to build I might be looking to sell.

Oh. and a 240 is a much better receptacle imo. I believe it has a larger engine bay and less extra crap that probably won't work anyway (climate control, power seats, etc). Better looks too.

In reply to Greg Voth:

Hrm... Spectate at $201x Challenge, drive home (literally) cross country?

I definitely have a bunch of other stuff going on between now and when I'd be after something like this, but let's just let that percolate...

In reply to Markde:

Jeez, I hadn't even thought about HVAC. It's one of those things I don't normally care about that much, but on a car which exists mostly for us to be in for extended periods, A/C may not be optional...

Mine has functional AC :)

The Rx5.0 gets about 27 mpg when driven as a regular car would be, somewhat less when driven like a RX7 with a 5.0 and manual.

Aluminum heads, mild cam, Holley systemax, and much more, 309 hp at the wheels(around 370 at the flywheel) with 3.9 Mazda rear and Tremec with the long overdrive.

No AC or PS for weight sake.

20lbs over stock weight.