TeamSwift
http://www.teamswift.net/

over 60 miles per US gallon with 3 cylinder
http://www.teamswift.net/viewtopic.php?f=34&t=39285
Page 3 of 3

Author:  cbx_kim [ Sat Nov 01, 2008 8:00 pm ]
Post subject:  Re: over 60 miles per US gallon with 3 cylinder

Trevor, this convertible is 32 miles East of San Francisco. I use the car all around and there is a lot of mixed driving with freeways and 30% around town. My 94 Caddy had a digital fuel mileage readout and I was always horrified to watch it read 0 mpg, 2mpg in traffic. So I can see why hitting every red light messes with my mileage. There are some long steep hills but I always use the backside to coast. I am still happy getting 9+ mpg with the XFI cam and same driving habits, though.

The top is almost always up, windows closed in the cooler weather. My son NEVER puts the top up with his convertible and 39mpg is the norm for him. He likes the feel of the XFI cam and might put one in.

I may try blocking the front end air flow, up the tire pressure, and play with heating the fuel and find a way to regulate 110 Deg F air into the inlet. We'll see. This is my daily driver so I don't want it out of service too long. Besides, I have to go up to Nevada and work on the diesel Metro. Donner Summit not only kills people but gas mileage suffers severely!

Please!!! How many teeth are on the pinion and on the crown gear on your New Zealand gears??? When you get the old tranny apart can you please post the same info for the stock gear set? Thank you much...Kim

Author:  TrevorHeath [ Sun Nov 02, 2008 10:30 am ]
Post subject:  Re: over 60 miles per US gallon with 3 cylinder

Kim,

All the info on Metro / Swift transmissions is on this page written by Rick Thompson (http://www.metroxfi.com

http://metroxfi.com/2008/04/metro-trans ... formation/

A 3.52 final drive is is 21/74

A convertible is 4.39.....wow. How many rpm at 60 mph is that?

Regards,

Trevor

Author:  cbx_kim [ Sun Nov 02, 2008 6:13 pm ]
Post subject:  Re: over 60 miles per US gallon with 3 cylinder

Thank you Trevor. So 3.52 ratio is 74/21 teeth. The 3.79 should be 72/19 teeth by calculation.

My convertible runs 3400 rpm at 60mph, tires are Bridgestone 165/65R13. The rolling radius ground to mid hubcap is 10-1/8 inches.

Author:  TrevorHeath [ Sun Nov 02, 2008 11:13 pm ]
Post subject:  Re: over 60 miles per US gallon with 3 cylinder

Kim,

165-65R14 comes out to 21.445" dia

These calculators may help you decide what ratio is best for your car.

http://wildcatent.freeyellow.com/zookmods/calc.htm

3400 rpm at 60 mph is certainly a major reason why a vert suffers on MPG

Sorry....I made a typo (now corrected in previous mail)l. The XFI standard gear ratio is 3.85

With 175-65R14 tires and a 3.85 final drive my car turns 2600 rpm at 60 mph

I'm not sure how to calculate the expected rpm with a 3.52 gear set using the same tires.

TH

Author:  cbx_kim [ Sun Nov 02, 2008 11:36 pm ]
Post subject:  Re: over 60 miles per US gallon with 3 cylinder

Woops, I have 13" tires on the convertible. I believe they came with 165/65 R13 stock. I have some 14" rims in the garage and some 12" ones as well...but the 12's don't fit as the brake rotors interfere and the lug studs are smaller. Maybe I'll try the 14" fender scrapers on for a tankful and pump them up to 40psi.

The 10-1/8" measurement is the actual distance that the ground is from my front axle centerline and provides the loaded radius of the tire. The OD is a rougher measurement and comes to actual 20-3/4 inches, meaning the weight of the car is crushing the bottom of the tire body 5/8". No wonder rolling resistance is low with higher tire pressures. This has me curious as I watched the rim rise farther from the ground with each psi of pressure until I quit at 32psi on all 4 corners(up from 24psi as it had been running). ...Kim

Author:  TrevorHeath [ Sun Nov 02, 2008 11:53 pm ]
Post subject:  Re: over 60 miles per US gallon with 3 cylinder

Kim,

My typo (again) 165/65R13 is 21.445" dia

This thread deals with changing a car from a 4.39 to a 3.52 transmission.

http://ecomodder.com/forum/showthread.p ... n-107.html

Trevor

Author:  TrevorHeath [ Fri Nov 07, 2008 7:02 pm ]
Post subject:  Re: over 60 miles per US gallon with 3 cylinder

Hi all,

Made the 380 mile round trip from Port Orchard, Washington to Wilsonville, OR a couple of days ago.

Temp was 48-50F with some rain showers. Virtually all freeway, I held the car to a steady 60 mph

279.5 miles, 6.114 gallons = 62.07 MPG

TH

Author:  bigblue [ Tue Nov 11, 2008 1:28 pm ]
Post subject:  Re: over 60 miles per US gallon with 3 cylinder

Mine MPG has dropped miserably. I was hitting over 60 pretty regular the past couple of months, now I am hitting 50 to 52 no matter what I do. I just changed gas stations which sells "real gas" and is not oxygenated. My regular fuel station went from real gas to oxygenated and won't go back to real gas. See ya. We'll see what this gas does.

I also re-installed my stock intake, but routed the plastic snorkel that normally attaches to the inner fender, and routed it to the back of the radiator fan. (Note to self - zip tie it, or you may lose it!). I am only getting a 15 degree rise in inlet temperature. I'd like a 30 to 40 degree rise, so my head is hurting pretty bad from all the brainstorming. I might make a mod to come off the exhaust pipe...

Hey to Johnny Mullet!

99metro

Author:  1995Firefly4dr [ Tue Nov 11, 2008 2:06 pm ]
Post subject:  Re: over 60 miles per US gallon with 3 cylinder

TrevorHeath wrote:
Hi all,

Made the 380 mile round trip from Port Orchard, Washington to Wilsonville, OR a couple of days ago.

Temp was 48-50F with some rain showers. Virtually all freeway, I held the car to a steady 60 mph

279.5 miles, 6.114 gallons = 62.07 MPG

TH


do you imflate your tires to max psi (40) ?

Author:  cbx_kim [ Tue Nov 11, 2008 2:24 pm ]
Post subject:  Re: over 60 miles per US gallon with 3 cylinder

I was thinking of mounting a heater core in a box behind the right headlight. Then regulate the coolant to a constant 115 deg F and allow the inlet to breathe through the core. The resulting flow of air should be nearly constant from idle to full throttle with far less fluctuation than trying to regulate temperature from the exhaust pipe or radiator. The radiator temp fluctuated wildly I found out... Some bunny find me a thermostatic adjustable water flow valve with 1/2 inch inlet and outlet ports please.

OK, REAL CHEAP TEST of pre warmed inlet air....cut a 2 1/2 inch hole in the firewall above passenger feet and route your air inlet thru a flex hose to suck air from inside the car by your heater outlet. Just remember not to roll the windahs up all the way.

Author:  TrevorHeath [ Wed Nov 12, 2008 1:10 am ]
Post subject:  Re: over 60 miles per US gallon with 3 cylinder

Hi all,

I run my tires at 50 psi and have done for a year.

The difference in "seat of the pants" rolling resistance between 35 and 50 psi is amazing.

I tried to run warm air induction last summer and simply could not. The car just "pinged" even on the flat. My point? there is a limit as to how much one can warm the air.

TH

PS My last tank of fuel came in at 58.2 mpg. It though included some three person miles and, a visit to congested Seattle from where I drove home at 65 mph after sitting behind a wreck for almost an hour.

Author:  cbx_kim [ Wed Nov 12, 2008 11:17 am ]
Post subject:  Re: over 60 miles per US gallon with 3 cylinder

Good point about pre ignition. Maybe try it now that the weather is cold. Even raising induction temps to summertime levels is bound to help.

Obviously at 50 psi the tire footprint is smaller. Do you have any noticeable issues in handling or stopping? Does it rattle the car like an old pickup truck?

Author:  TrevorHeath [ Wed Nov 12, 2008 10:00 pm ]
Post subject:  Re: over 60 miles per US gallon with 3 cylinder

Kim,

Warm air induction has been back on the car since October 1st. I am convinced that it and keeping the engine warm 24/7 are the reasons my mileage remains high whereas other have seen a loss.

Generally speaking I'm very happy with the interior noise of the car using 50 psi in the tires Occasionally the road surface will generate interior noise of too high a level but not often. No issues with braking or cornering.

TH

Author:  bestgassipper [ Fri Nov 06, 2009 5:19 pm ]
Post subject:  Re: over 60 miles per US gallon with 3 cylinder

untill i read through this thread, i was happy with an average 47 mpg, high 51 mpg. Now im dissapointed. thanks alot guys! :(
http://www.bestgassipper.com

Author:  xrw44 [ Sat Nov 07, 2009 5:40 am ]
Post subject:  Re: over 60 miles per US gallon with 3 cylinder

bestgassipper wrote:
untill i read through this thread, i was happy with an average 47 mpg, high 51 mpg. Now im dissapointed. thanks alot guys! :(
http://www.bestgassipper.com

well there is a lot of info in the forum you can do.
The way we drive is the biggest factor -- go for low rpm and light acceleration.
keep the tire press. up -- 100-110% if under 3 yrs old -- safety 1st
when my mpg dropped I replaced the plugs and rotor and got back 5mpg. So $15 in parts saved $100 per yr. The old plugs didnt look too bad but came with the car so I dont know how old.
I also find the car is sensitive to cargo wt. -- 100 lb is worth several mpg.
I use 15% larger diameter front tires.

I seldom get flat road for more than 2 min. -- going up hills at constant speed eats a lot of gas. I do keep to the right on freeways and pull off to let others pass on 2 lane roads. People used to honk so perhaps their attitude is changing. MPG is for the smaller US gallon.

4 to 5 cents per mile now. In 1973 my small 4 cyl car cost 2 cents per mile which is around 20 cents in todays money. Most things cost 10x more now. Too bad wages didnt keep up!

Author:  Woodie [ Sun Nov 08, 2009 10:20 am ]
Post subject:  Re: over 60 miles per US gallon with 3 cylinder

TrevorHeath wrote:
Sorry....I made a typo (now corrected in previous mail)l. The XFI standard gear ratio is 3.85


Why does this myth keep coming up? Like zombies resurrected from the dead every couple of weeks. XFI and GEN3 four cylinders have 3.79, never was a 3.85 that I can find. I've seen 3.61 and 3.87 as available automatic final drives, maybe that's where it comes from.

Here's a direct quote from the 94 sales brochure, there's nothing special about this one, I've got almost every years brochure and they all agree:

"XFI's axle ratio of 3.79, coupled with a specially programmed Electronic Control Module, provides maximum fuel economy. Base Metro Coupe and Sedan models have a 4.10 axle ratio that provides a combination of excellent fuel economy and snappy performance."

Author:  993cc [ Thu Sep 12, 2013 11:20 am ]
Post subject:  Re: over 60 miles per US gallon with 3 cylinder

I read this as if we have to go about 3000 rpm at about 55% engine load.

55% engine load means about 0,5 bar vacuum?
Edit; About 55nM or 70% load

Attachments:
geo-1L-bsfc-chart-reconstruction.gif
geo-1L-bsfc-chart-reconstruction.gif [ 17.07 KIB | Viewed 3902 times ]

Author:  90LSI [ Thu Sep 12, 2013 12:51 pm ]
Post subject:  Re: over 60 miles per US gallon with 3 cylinder

Yes. But another way to look at is if you have to drive at a given condition say 60 mph on a flat road and say that condition requires a road horsepower of 20 hp so you must consider what options you have to drive with 20 hp output. In the plot the thick line is the 20 hp line and as you can see decreasing the engine rpm and increasing the load(up shifting) dramatically improves efficiency down to about 2000 rpm.

Attachments:
BSFC20.jpg
BSFC20.jpg [ 48.63 KIB | Viewed 3895 times ]

Page 3 of 3 All times are UTC - 5 hours
Powered by phpBB® Forum Software © phpBB Group
http://www.phpbb.com/