28 MPG Highway?

Disclaimer: Links on this page pointing to Amazon, eBay and other sites may include affiliate code. If you click them and make a purchase, we may earn a small commission.

Dolsvt00

Member
Joined
Jun 29, 2011
Messages
39
Reaction score
12
Location
SC
Somebody else try this, I want to know I'm not loosing my mind.

About me, I am a SCT Tuner I work/own a performance shop. I have 3 fords, a Mustang GT, a 2nd gen lightning, and a 10 SHO. I build Mod motors, and modify them, My lightning is over 700 rwhp and 900 ft lbs of tq, the mustang has spray on it and is every bit of a 500 hp car on the gas. I'm no stranger to modified cars.

The story: Although I am an Advantage III tuner I have not tuned my SHO, mostly because I haven't had time and the wife drives it so there's really no point. So, this is biased on a stock tune.

What I did: I was changing the oil and plugs and doing normal maintenance, I'm **** so i refuse to take anything to a dealer and don't want anyone touching my stuff. I got all that done and made it to the air filter, I found a K&N at the local parts store and although i'm not a big fan of their stuff It was cheap and reusable unlike the stock paper crap, and virtually the same price.

when I popped the top off the filter box I noticed dirt collecting around the edges of the box seal, I know it has a scoop up front but dirt collecting up at the seal means one thing "vacuum". So I had this lightbulb, back in the days of the early lightnings if you cut the bottom of the stock box out it was good for a pound or two of boost, I got to looking at the SHO boix and I seen a pretty good area on the side facing the fender well where a big hole could go. I grabbed a 3" hole saw and cut a hole in the box.


Thinking nothing of it, I put it all back together new oil and filter, new plugs, new drop in filter. I reset the MPG avg and took it down the road, first thing I noticed was I could hear boost now, not what I was trying for but ok, and I can hear the recirc valve bleed boost when I let off. Everything was fine and I thought nothing of it.

I know the MPG AVG takes time to develop, so I just completely forgot about it for a month or two, well my wife takes a 400 mile trip and says "Wow, what did you do to the car?" I was like "what do you mean, normal maintenance?" She says, Its getting 28.6 MPG avg, I said huh?

So when she got back I decided to drive it around town for a while, sure enough It said 28 MPG when I got in it, and now after a week of in town its 26 mpg.

Somebody else try this and make sure I'm not crazy or my MPG gauge is not working properly.
 

rubydist

SHO Master
Staff member
Super Moderators
Joined
Jun 25, 2007
Messages
7,521
Reaction score
3,399
Location
Denver
it would not be the first time that Ford reduced performance in the name of reducing engine noise...
 

Dolsvt00

Member
Joined
Jun 29, 2011
Messages
39
Reaction score
12
Location
SC
it would not be the first time that Ford reduced performance in the name of reducing engine noise...

Oh yeah I'm well aware of that, they castrated the 13 gt500's in the means of db reduction.

But 4 MPG? The car averaged around 23-24 at 75-80 before on the highway..

I think there's something wrong with the gauge.
 

SHOrod

Torrie Tuned
Joined
Jan 1, 2006
Messages
1,193
Reaction score
532
Location
Cedar Rapids, IA
Twice now I've taken my SHO on a 400 or so mile road trip with a week's worth of luggage, a 12 inch bicycle in the trunk, and my daughter's 20 inch bike and my 26 inch full suspension (ie: heavy) mountain bike hanging off the Thule in the receiver hitch, air conditioning blowing the whole trip, and averaged 28.5 mpg both directions 1 week apart. My son rode with me on the return trip, but since he was only 4 last summer, he didn't add much weight, or cause me to ease up on the throttle. I didn't have very many 80 mph stretches, but mostly 70-75 mph. I took a lot of 2-lane highway so there were a few aggressive passes on that drive as well. I don't think the gauge in your wife's SHO is broken or unrealistic.

-Rod
 

Dolsvt00

Member
Joined
Jun 29, 2011
Messages
39
Reaction score
12
Location
SC
Yours is tuned though right? I'd expect that from a proper tune.
 

Leadfoot1

Member
Joined
Feb 27, 2013
Messages
35
Reaction score
13
Location
eastern PA
Oh yeah I'm well aware of that, they castrated the 13 gt500's in the means of db reduction.

But 4 MPG? The car averaged around 23-24 at 75-80 before on the highway..

I think there's something wrong with the gauge.

To verify the increase in MPG was due to the cutout, you could temporarily cover the hole to see if the mileage drops.

possibly the gas stations were switching to the summer blend at the time the hole was cut. Normally the summer blend is good for 2-3 MPG.
 

Dolsvt00

Member
Joined
Jun 29, 2011
Messages
39
Reaction score
12
Location
SC
This is the first I have heard someone call a 650hp engine 'castrated'.

Drop the resonator in front of the throttle body out and delete it (yes it gets louder) and adjust the throttlebody in the tune to open 100% and it will make over 620 to the tires, and its alot louder.

To verify the increase in MPG was due to the cutout, you could temporarily cover the hole to see if the mileage drops.

possibly the gas stations were switching to the summer blend at the time the hole was cut. Normally the summer blend is good for 2-3 MPG.

Since I baught the thing its never gotten better than 25 no matter what time of year, I make frequent trips to Florida in it Its got over 50k on it now and this is the first time since new ive seen over 25.
 
Last edited:

EcoBrick Bob

SHO Member
Joined
Mar 13, 2010
Messages
1,682
Reaction score
253
Location
Clear Lake, IA Naples, Fl
My Flex would love to get 25 MPG... I would be delighted with 22... I get about 20 driving 79 mph on I-75, and this has been consistent since new to 53K... Small, light wheels & tires that are 8% smaller vs stock heavy tires... Actually do better with the wheels/tires that are 80 lbs lighter than stock! Plus it really stops quick with my lighter wheels and stop tech/ power slot brake combo.
 

SHOdded

SHO Member
Joined
Dec 25, 2011
Messages
9,045
Reaction score
4,390
Location
Maryland
EBB, have you changed out your PTU/differential fluid? I read somewhere recently that it helps restore/increase mpg.
 

EcoBrick Bob

SHO Member
Joined
Mar 13, 2010
Messages
1,682
Reaction score
253
Location
Clear Lake, IA Naples, Fl
I haven't... Will do when I get up north. At 54K, I suppose it's time to finally change my oil too.... (LOL) My mileage hasn't gotten worse. It's pretty much stayed the same since break-in completed. I do have a tendency to lead the pack out of stoplights, and go fast, just under the radar on Interstates!
 

bill1

New Member
Joined
Dec 31, 2010
Messages
12
Reaction score
1
Location
texas
mpg

In theory restrictions are more noticable as the intake air vs HP increases crusing along the total CFM through the motor is quite low and restrictions shouldn't get noticed. I often get 28 mpg on the road, on one 180 mile trip to Dallas I squeeked 32 mpg out of the SHO. (tail wind in winter no AC lots of coasting). Daily 10 mile commute to work nets 19.
 
Back
Top