Gas mileage in my Ford Zetec modified:

Wowee !! Nice ride ! The mileage however , seems unusually low . My Ford Explorer at 4300 lbs , V-8/auto and FTFWD gets 20+ on the highway . I think you have a lot of potential for way better mileage

 

20-25# Tire Pressure, Front To Rear.

 

My 6.0L 345hp Denali gets 17 on the highway... you should be getting a lot better than 20.

 

cool looking modified!! who cares what ya get for milage if your having fun.it's always nice to get good milage but thats not the reason ya drive a hotrod.

 

Gas Pumper (Frank) I am going to try the grease on the bushings i can see it is a great idea. I also have pretty stout spring clamp on the rear springs to make every thing stay together, I am going to take some out of it also.

One of the things that I want to try with the engine is to lenghten the inlet air ram tubes. I would guess that from the tip of the inlet tube to the inlet valves is probably less than 12 inches. My plan is to buy another set of 2 inch ram tubes and add around 6 inch to them this should really help the mid range and probaby work better with my headers which are 32 inches. The idea being to try to get the inlet ram frequency and the exhaust to be around the 2500 rpm range. It feels like it is around 4000 now.

Thank you all for your interest in my roadster.



Rex

 

I knew your car had some small modern engine in, I took a lot of pics of it.
You should challenge yourself to get the best mileage out of it.

 

hmmm....my bbf 514 powered dodge got 15 or more on the way to Paso 2 years ago.

 

I'm currently building a modified (21 T truck chassis, 27 T body). That was intended to have a Zetec in it but I got all traditional and ended up with a 1957 347 Pontiac engine.

The figures you have quoted are fairly common over here for Zetecs in Lotus 7 clones - especially those running webers instead of fuel injection. There are lots of Zetec and Duratec engined kit cars in the UK so you might wish to try one of the Westfield or Locust forums for tips on setting up your engine.

 

What was the original donor car for the motor? I would investigate its gearing.

Is the Hilborn electronic fuel injection known for providing good gas mileage?

gary

 

rex,
that is one cool car that you have there!
dan

 

were did you get the bell houseing for the motor ???

 

Is the backpack apporatus removable?

 

i have a speed racer,a comp coupe thats got a pretty slick aero package,one day at maxton we decided to run it without the front sheet metal,the complete front end just slides off.
with a 4 litre engine we run 171 with the body work complete.
with the same engine on the same day,without the front sheet metal we ran 140mph.
those big tires on the rear of your car and the front tires stuck out in the wind kills mileage and speed.

 

Don, I may be able to give you an MPG report in a couple weeks.
Got a swap +$$ for my 4.57 Detroit Locker.
Going to a 3.00 in place of the 3.70's.

Right now I'm running 16-17 mpg on the highways and if I'd quit rolling the throttle on . . . firmly . . . ok, hard, on the on-ramps it should be touching on 17-18 mpg.

Timing seems to be about right, carb is an Edelbrock 750 tuned two stages lean according to the Edelbrock manual.
Runs great here at 3300' altitude and runs just as good down at the river at 500' altitude.

From what I understand, new Edelbrocks and Holleys come jetted/rodded about 5% rich for the expected engine size.
IE: 600 cfms for 350's etc.

I have run a shorter tire than the 30" ones, about 3% shorter, but mileage didn't seem to be any different although I have no figures in this configuration.

This is a real guess, more of a gut feeling than anything else, but I think your full fendered roadster is somewhat more aerodynamic than my highboy.

 

Neat car.
Nice to hear some real-world mpg figures.

You're at the fun part now.
A little tinkering and tuning should get you to where you want to go.

Why not put a top on it for trips?
It makes a big difference over a long, bright and sunny day.

Simple top irons are easy to build.

Another way out would be a Bikini top like the Jeep guys use.
A lot of those around here (N/W Arizona).

A simple 4-point roll bar for the rear and something to connect up front.


I know, some of you are thinking, Geez, it's a roadster.
Ok, but how many who are thinking like that have ever spent the day/or days like Rex and his son have?

Tops lend their own bit of personality to the car and for me, makes a roadster a four season car.

Then again, there are mornings at the donut shop (16 degrees F) where the coupes stay home and there are a couple of roadsters sitting out front....

 

That is a really nice looking car. I didn't see in the thread if you mentioned highway RPMs. I'm curious to see what the engine's turning around 60mph

 

This is what i'm thinking, too. When I had mine on jack stands this winter and was running to check for driveline vibration, the wind off the tires was unbelievable. The wire wheels pump a lot of air. And nothing is aero on these little cars, there's got to be a lot of drag from everything hanging out in the breeze.
At least I have 7" headlights.
Also the bias plys get warm, they are out in the breeze getting cooled off and they still are at 120* when I stop (on 80* days).
A lot of ineffeciency there, too.

Frank

 

that's a spiffy little ride you have there!

but yes... something isn't jiving though... i'll speculate the combination of gears, tall tires and some tweaking with the air fuel ratio should bump that up a bit. was the engine lugging at all? i'll venture to guess once you've dialed it in it should deliver mid-high twenties.

just throwing out some numbers I scrounged up here... not certain of your total configuration... mileage may vary

2002 Ford Focus 2.0 4V M/T 195/60/15 (24.2") tires and 2550lb dry weight shows 22 city/31 hwy under the new EPA rating standards. It has a c/d of 0.36
http://www.fueleconomy.gov/feg/calculatorCompareSideBySide.jsp?column=1&id=17551

couldn't find the trans and final drive ratios I was looking for on the same car but did come across this on a google search...

MTX-75 trans
Gear Base Ratio 4 Cyl, 3.83 Final Drive Ratio
1st = 3.42
2nd = 2.14
3rd = 1.45
4th = 1.03
5th = 0.77
Rev = 3.42
Final Drive = 3.83

 

Which T-5 Gearset do you have? IIRC the O.D. ratio can be as high as .63 or as low as .82 (I believe I have a .68 in the Model A). With just a .75 O.D. you knock the 5.20 down to a 3.90. If it's a .63 it goes down to 3.27.

FWIW I'm cruising in the A (w/ a warmed up SBF) at about 5 1/2 inches of vacuum at highway speeds (2080 = 65), so the power enrichment is ON (and I get crummy milage so far, absolute best of 17.5 MPG with 12 being more routine). I have a 3.70 now, I'm looking at 4.11 or perhaps 4.30, currently with 27.8" tall rear tires to get the RPMs up (and the vacuum too, and to stop lugging the crap out of it).

 

Nice modified....but I would be expecting a better gas milage than that.
Like blackjack says check out some of the kit car fourms from over here fo help get it set up right.
as a comparison I have an all steel, fendered A roadster, ZZ4350 with 700R4...15mpg round town and 25 on a run.....20 or so towing a trailer!
My daily is a Mitsubishi Shogun Pinin with permanent 4wd and that's averaging 27mpg and is shaped like a brick!

 

Just a quick catch up on some questions;
I got the adaptor for the Zetec to T5 from Quad 4 Rods out of Denver, John Erlach is the guy.

The "back pack apperatus" is really a dual roll bar that is removable, we needed some place to put some gear and the roll bar work out well.

RPM at 65 mph is almost exactly 2500 rpm. The final drive ratio in 5th works out to be around 3.9 just as someone else has calculated.

I have thought about a little top but that is a winter project.

It does look like I will drive it to B'ville so I am going to try to incorporate some of the great ideas you have all posted

Thanks!

Rex

 

No matter what else may be said, it is one of my fav modifieds.

 

Yes, rex that little car looks great.

 

Honestly, I'm still having a hard time wrapping my head around the idea that your modified would be less aerodynamic than the HHR, and you also have less weight.
Could the headlights and tires really drag that much? I'm building a 29 A Sedan, and was figuring on hitting 25mpg with a Focus engine.
I certainly do expect a brick / sedan to drag more than a modified.

 

1950 Chevy,
When I go to B'ville in August I am going to really make an effort to not exceed 65 and see if this along with a couple of other changes makes a difference to the milage. Even 5 mph can make a big change in the air resistance.
Rex

 

I was surprised to learn that roadsters have very high drag, the numbers are often much different than you might guess... there is a good article on auto drag coefficients at http://en.wikipedia.org/wiki/Automobile_drag_coefficients
The Caterham/Lotus Seven is the worst of all by far....

 

Its all about how much you disturb the air.
My '94 Roadmaster wagon daily driver with a 350, 2.90 gear, and 700r4 gets 20-24mpg on the hwy. My dad's highboy roadster with a 283, 3.0 gear and 700r4 gets 20-22mpg. I would bet my wagon is more aerodynamic even though it weighs more than twice as much.
Edit: just did a quick search...
the Cd of a 94 Impala SS is .34
The Thacker and Shine A-V8 started out at .52 in Bonneville trim with headlights before aero tuning. Very interesting.

 

hmmmmmmmmm makes me think the '50 Burb will get better mileage than the Sedan.
keep us posted, Rex.

 

I've always read the windscreen is the worst of that. I wonder what they work out to with the competition 'bug deflector' instead (and a toneau maybe?)? Unfortunately Wiki doesn't list it that way (didn't see any Cd's in the Lotus / Caterham specific section either).

 

Wow!
Jeez, Louise, as bad as a bus?
Great site, alarming CDs, especially as I'm leaning on 7 stuff for my
next hot rod! It must be all the stuff sticking in the wind, eh, as the
cross section would seem to be small given how low and narrow those cars
are. And enclosed hood and sides will have to go on my build list.
Do you think better shrouding / ducting of the radiator / under hood air
would help? A full or partial belly pan?
Heck, I was thinking of fenders, too... I guess they would also trap
air, eh?
Later, Gary