92 Fox Notch Build: Stock, Light And Sticky..what Next..

EZE183 · Mar 19, 2014

Hi-

I hoping to get some advice and direction on my project. I scored a stock 92' notch a few years ago and I decided to build a fun that gets great gas mileage so I took a different direction than most builds. I basically left the engine stock and modified the suspension and drivetrain to be strong and light. This is also my daily driver so I'm keeping it comfortable with stock interior and air conditioning. I'm guessing I'm at around 2800lbs / 220 rwhp and I don't want to sacrifice any hp for efficiency. The car feels really stong now and a lot sturdier and sticky than it did stock.
I'm currently getting 20city and 26-28mpg highway. Speedo corrected for gears, 3.73, stock wheel height and stock t5. I drive like I would a normal manual car to get those figures but I try to keep below 4000rpms.

I'm not sure what else to do to break 30 mpg. I'm thinking computer, throttle body, MAF, tranny's final gear...

Here is what I've done so far...

Suspension:
UPR tubular k-member w/ A-arms
UPR coil overs
Steeda aluminum control arms w/reinforced torque boxes
Stock rear springs with airbags

Engine:
SVE aluminum radiator
Electric fan
BBK aluminum underdrive pulleys
Walbro 255-lph pump
Aeromotive adjustable fuel regulator
Stock TB and MAF with C&L inlet pipe
Stock filter housing with k&n drop in filter
BBK longtube headers / H-Pipe / flowmaster american thunder
Smog delete
Advance timing 14*

Drivetrain:
FRPP aluminum driveshaft
Superior 31-spline axles
Disc brakes all around
Eaton posi
FRPP clutch and p.plate
3.73 gears
Stock t-5

Body:
Fiberglass hood (stock appearing)
Fiberglass trunk lid
Weld draglite wheels

Thanks for any help.

A5literMan · Mar 20, 2014

Looking for over 30mpg...buy a Prius. Lol. Jk. I'd swap out the 3.73 gears to 3.08's. You seem to have lightened about everything reasonable so there isn't really anything to be done there. I wouldn't spend a lot of $$ to gain a few mpg at this point. You're about at the limit of every 5.0 fuel efficiency IMO. Why are you running a 255 pump for 220rwhp? In theory a smaller more efficient pump "might" get you better mpg. There's a lot of fuel flowing back to the tank that you're not using. Possibly heating the fuel etc. This is all a semi weird concept for me worrying about mpg with a fox body.

madspeed · Mar 20, 2014

Save a few bucks and buy an older nissan sentra that gets 40 mpg

mikestang63 · Mar 20, 2014

Is this the Prius thread? Mustang and economy are like Pizza and Sushi. Both are great but don't go together.

7upstang91 · Mar 20, 2014

I believe 30mpg on the highway can be done, however with a push rod 5.0 you may be at your limits. One, you could do a Coyote swap, but the car is your daily driver so unlikely.

Right now the last couple things you could do are first off, I don't see tune done at all? The tune will help with efficiency. As stated, a different set of gears such as 3.08 or 3.31 (2.73 but that would be a major step backwards in my opinion.) Lastly, I believe a 6 speed swap along with the proper gearing could get you over 30mpg on the highway.

Obviously, these are only my opinion.

Grabbin' Asphalt · Mar 20, 2014

No way I'm taking 3.73's out for better fuel economy, that's helping your 225hp a TON right now but it would certainly do the job if you did it
I like how you went light first, power to weight ratio can do great things. I have a DD also so I know the desire for good fuel economy. I just took a trip from Atlanta to Nashville and got around 23~24mpg and I was Super Happy about it
I'm around 280rwhp_320rwtq also. If I had a different cam, I would break 300rwhp but my fuel economy would probably take a big hit.

tannerc91gt · Mar 20, 2014

Where do you get 220 wheel from a set of headers and a fuel pump?
I guess I just don't get why you build a fox for fuel economy. Everything you're suggesting is just taking the car further from what it is supposed to be.

You'll have to excuse me I'm gonna go tow my boat with a smart car

Grabbin' Asphalt · Mar 20, 2014

He's got pullies, smog delete, electric fan, long tubes etc, ....IMO from my electric fan and pullies I think he is there. Made a huge difference in my seat of the pants car.

tannerc91gt · Mar 20, 2014

Grabbin' Asphalt said:
He's got pullies, smog delete, electric fan, long tubes etc, ....IMO from my electric fan and pullies I think he is there. Made a huge difference in my seat of the pants car.

Pullies (IMO) are more trouble than theyre worth. The smog delete is nothing but a weight savings and an electric fan is negligible. Not arguing just giving my opinion. I just don't think the car picked up 50fwhp from longtubes on an otherwise stock car.
But I suppose that aspect is somewhat irrelevant in the grand scheme when he's only looking for MPGs

NIKwoaC · Mar 20, 2014

Actually smog delete may have hurt your fuel economy more than anything. Depending on where and what speeds you drive, the 3.73s probably aren't doing you any good either.

Tune is going to be the big thing. Go quarterhorse or something like that and try to lean out your part throttle/cruise fuel tables.

Other than that, you should try running thinner oil. If you're running 10w30, a logical first step is 5w30 (5w30 is arguably better anyway).

Or you could can all this stuff and do a 4 banger. Or a Prius.

7upstang91 said:
I believe 30mpg on the highway can be done, however with a push rod 5.0 you may be at your limits. One, you could do a Coyote swap, but the car is your daily driver so unlikely.

Right now the last couple things you could do are first off, I don't see tune done at all? The tune will help with efficiency. As stated, a different set of gears such as 3.08 or 3.31 (2.73 but that would be a major step backwards in my opinion.) Lastly, I believe a 6 speed swap along with the proper gearing could get you over 30mpg on the highway.

Obviously, these are only my opinion.

While the gearing of a 6 speed on paper might seem beneficial for fuel economy, the additional weight and parasitic losses of a T56 would probably actually hurt more than help.

FoxMustangLvr · Mar 20, 2014

I understand people wanting their passion vehicle as a sensible daily driver. Not everyone has room and money to have a sensible 35+ mpg DD, truck for hauling and playing and the "hot rod" in the garage for Sundays.

IMO he's maxed out the economy. It is what it is and anything too expensive to achieve 1/2 mpg more you'll never get back in gas savings.

Sounds like a fun car though already but I have to agree the longtubes and 255 fuel pump (could feed a super charger) seem to be overkill for an economical daily driver.

Grabbin' Asphalt · Mar 20, 2014

IMO cause I've done it, Pullies and Electric fan are 20rwhp, add long tubes to it and darn close to 220-230. Smog delete hurts fuel enonomy for sure, hp wise it free'd up the added pullies addition for a couple more hp's, ...IMO.

FoxMustangLvr · Mar 20, 2014

Grabbin' Asphalt said:
IMO cause I've done it, Pullies and Electric fan are 20rwhp, add long tubes to it and darn close to 220-230. Smog delete hurts fuel enonomy for sure, hp wise it free'd up the added pullies addition for a couple more hp's, ...IMO.

Anyone not see that his 220 rwhp is A GUESS just like he's guessing his car weighs 2,800 lbs. He has not dyno'd it so why all the debate over a guess?

Also, i'm assuming he misstated the smog delete. I'm thinking he meant smog pump (thermactor) delete.

EZE183 · Mar 20, 2014

Thanks for all the replies. I know a few of you don't get my approach to my build and some do, it's a little different than most. I think having what I THINK is a low 13sec fox with above average fuel economy is sweet! I would have to go quite a distance to find my closes track so I have no real quarter mile ETs. I can get on a scale but haven't yet I was just guessing and yes I've probably spent what it cost for a new Prius but it NOT, it's way better! Haha
I got that fuel pump real cheap..it is overkill I may rethink that. I took the smog pump off but I still have it I can put it back on. I forgot to mention my speed limit is 55mph so I cruise at 60mph and I don't wanna get rid of my 3.73, it really woke the car up.
I guess what I'm asking is what kinda tune should get or stay away from. My TB and MAF is factory should I change?

FoxMustangLvr · Mar 20, 2014

EZE183 said:
Thanks for all the replies. I know a few of you don't get my approach to my build and some do, it's a little different than most. I think having what I THINK is a low 13sec fox with above average fuel economy is sweet! I would have to go quite a distance to find my closes track so I have no real quarter mile ETs. I can get on a scale but haven't yet I was just guessing and yes I've probably spent what it cost for a new Prius but it NOT, it's way better! Haha
I got that fuel pump real cheap..it is overkill I may rethink that. I took the smog pump off but I still have it I can put it back on. I forgot to mention my speed limit is 55mph so I cruise at 60mph and I don't wanna get rid of my 3.73, it really woke the car up.
I guess what I'm asking is what kinda tune should get or stay away from. My TB and MAF is factory should I change?

I love how you're modifying your car. Handling and economy and just enough HP to keep it fun & reliable.

You should go back to stock or a 110 fuel pump. Do you have Catalytic converters on your car? I'm assuming you don't. If you don't have Cat's then you don't need the smog pump (they work together). People thought you removed your EGR which can result in losing a couple MPGs.

tannerc91gt · Mar 20, 2014

I think you're 3,000lbs race weight and 210~hp.
I'll give you the 220 wheel and still can't call it a low 13s car. I'd love to be proven wrong though

Bullitt347 · Mar 20, 2014

All synthetics in the engine, trans and rear diff will help. Next time you do a clutch, install a aluminum flywheel, less overall weight, but more importantly less rotating weight = less HP required to spin. Make sure all tires are at optimal tire pressures, research different tire makes/sizes for a weight savings as well. The wheels are already light enough, especially compared to stock. . May pick up some mpg with a good ignition system, optimizing plug gap with a quality plug wire.

Grabbin' Asphalt · Mar 20, 2014

No debate just what i think, it's all gravy

90lxcoupe · Mar 20, 2014

If i were you id look into making the car more aerodynamic, and making the car move easier, if you put the car in neutral and lean on it, it should start rolling right away. Think of it like a racecar in terms of chassis efficiency.

Bullitt347 · Mar 20, 2014

90lxcoupe said:
If i were you id look into making the car more aerodynamic, and making the car move easier, if you put the car in neutral and lean on it, it should start rolling right away. Think of it like a racecar in terms of chassis efficiency.

Exactly.................minimize pinion angle, minimize front end alignment angles such as toe and camber, make that sucker want to coast easily. After all your just cruising for mpg, right? So throwing it into a corner is not the primary concern, same with launching the car, you are not winding it up and dumping the clutch, so you don't need the pinion angle that helps the car hook.

92 Fox Notch Build: Stock, Light And Sticky..what Next..

EZE183

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A5literMan

At least it is lumpy...

madspeed

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Grabbin' Asphalt

tannerc91gt

This last 25% is foreign territory at this point

Grabbin' Asphalt

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I have been doing it wrong this whole time

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92 Fox Notch Build: Stock, Light And Sticky..what Next..

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