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Fuel efficient engine swaps???

HoosierDaddy

Contributor
Bronco Guru
Joined
May 29, 2006
Messages
2,773
Bottom line , get a Volkswagen TDI.
I tend to believe , from all that I have read here and from plenty of other sources over the years , our current motors are about peaked as far as making them efficent.
So ... build the motor to deliver a smooth torque curve and be as efficent as possible ( properly sized and designed headers, heads , intakes , cam , gears , short & skinny tires , no lift ...etc ) put your Mustang EFI on top , and you are pretty much at the top of what a gas motor will do for economy ... and you will probably still be under or just at 20 MPG in most cases.
Switch to a diesel and things start looking better , especially when you start running numbers like TLay and I do , 40 miles each way daily. But still a far cry from the 30 - 40 - 45 mpg numbers modern diesels encased in slippery silohettes are getting.

No matter what , fuel efficency is going to be tied to aerodynamics in a big way with these broncos.

If you REALLY want to get technical , there is an incredible post here , written by (iirc) an aerospace engineer or something like that. Tons of math and other solid info. that pretty lays it out that the number one thing we can do to increase fuel efficency is decrease the Broncos coefficent of friction.
In which case , you no longer have a boxy old truck , so you might as well pony up for the used VW TDI.
Found a short version : http://classicbroncos.com/forums/showthread.php?t=111757&highlight=coefficent+drag&page=2
 
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Dave

Contributor
Bronco Guru
Joined
Aug 25, 2006
Messages
2,190
IMO aerodynamic drag of the EB has been somewhat overstated. Its definitly not a showpiece of aerodynamic efficiency but when you compare it with many other vehicles such as the CJs etc, its not that much more of a box than many vehicles getting in the high teens and low 20s. I'm not saying that the EB will ever be a good candidate for a high speed daily driver but much of the pain seems to be comming fron guys getting 8 to 10 mpg. I put about 100K on a stock 73 Bronco (302 - C4) back in the 70s and got about 16 mpg on the highway. Also keep in mind that if you are seeing lousy milage on the trails and around town (below 40 mph), aerodynamic drag is not the culprit. Attention to weight and a smartly designed power train can go a long way toward less pain at the pump. I'm hoping to see about 18 mpg at 55-60 on my 70 conversion.
 

mavereq

Bronco Guru
Joined
Feb 19, 2009
Messages
2,092
Well then its not exactly stock now is it? Even if you consider it stock its not.

the longblock is stock and he isn't throwing boost or nitrous at it. i wouldn't call him a liar for calling it stock.
 
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