Best mpg with your festiva?

[TominMO]

Are you guys adjusting your speedometers for the different tire sizes? Or have you figured which tire sizes have the same circumference?
'91 1.3 5sp stock 220+?miles best=44mpg no EOC or surge and coast.

The whole point is to have tires with much greater circumference, for higher gearing, so we have to calibrate our speedos by driving. If we are going 60 mph, it should take 60 seconds to get from one mile marker on the hwy to the next. I keep adjusting my speedometer speed until I hit that 60 seconds/mile, then I know that 60 mph will be x mph on my speedo. With a 165/80x15, an actual 60 will probably be about 55 indicated on the speedo.

[bolokid]

I am able to purchase ethanol free gasoline at the local Conoco stations. Using ethanol free gasoline my Festiva purrs and gets 41-42 mpg. Using the ethanol/gasoline mix it routinely gets 38 mpg.

[Pu241]

Are you guys adjusting your speedometers for the different tire sizes? Or have you figured which tire sizes have the same circumference?

That's why we have a GPS.

[Pu241]

I am able to purchase ethanol free gasoline at the local Conoco stations. Using ethanol free gasoline my Festiva purrs and gets 41-42 mpg. Using the ethanol/gasoline mix it routinely gets 38 mpg.

No surprise, ETOH free gas has higher BTU content.

[TominMO]

OK, just went out and fit the 15" space-saver rim/tire to my Festy, with Capri front brake swap. The only issue I see there is strut clearance, again, due to the design of the rim. A 10mm spacer should take care of that. And no, the rim can't be mounted backwards, in case you were wondering.

On the rear, same issue for the same reason. Needs a spacer. And BTW I have Aspire Monroes on the rear. If you did mount these rims with 165/80x15 tires, front and rear, it would provide about a 2" lift over the stock 12" tires.

[mikeyjd]

OK, just went out and fit the 15" space-saver rim/tire to my Festy, with Capri front brake swap. The only issue I see there is strut clearance, again, due to the design of the rim. A 10mm spacer should take care of that. And no, the rim can't be mounted backwards, in case you were wondering.

On the rear, same issue for the same reason. Needs a spacer. And BTW I have Aspire Monroes on the rear. If you did mount these rims with 165/80x15 tires, front and rear, it would provide about a 2" lift over the stock 12" tires.

I've been thinking about this swap a bit. A few different things have been going through my mind in regards to the net efficiency gain. One concern about doing the swap is that it raises the bottom end of the gearing across the board. At this point I shift into 3rd at 15mph, into 4th at 25 and 5th around 35. I'm wondering if the extra time spent in the lower gears, especially in town and on back roads is enough to cancel out any significant gains for me, in times of limited highway travel. If a person were to spend the vast majority of their time on the highway then the gains would be bound to be more distinct. Another issue I'm seeing is that with the taller tires you're also going wider, which will increase rolling resistance and frontal area. The increased rolling resistance is also bound to be more noticeable in city/non highway driving, but the increased frontal area would show up more on the highway. And thirdly, the increased weight of the larger tire, will also have a small impact in stop and go situations.

From a strictly fuel economy standpoint I think it's only likely to pay for itself for mostly highway drivers. But from an increased tire option and safety standpoint, it's probably worth doing even if it made no positive impact on FE. thoughts?

[TominMO]

The tires I will buy for these space-saver rims will be 165s, so not very wide. You are correct that the 15" steelie and tire will increase weight, which will have an adverse effect on stop-and-go city driving. For the city you want the lightest tire/wheel you can get, and drive in 4th whenever you can. For this, the 12" tires are perfect. I plan on using these tires primarily on road trips, but first I will experiment with them in the city to see how big a hit I take in mileage. I suspect not that much if at all, since all my driving tends to be city/hwy combined. In that case I may just leave 'em on all the time.

Raising the car 2" will also increase undercarriage turbulence, so I will create some sort of cheap (but hopefully not too cheesy) air dam for the front, and probably side skirts too. But my first MPG test will be with no aero mods.

[mikeyjd]

The tires I will buy for these space-saver rims will be 165s, so not very wide. You are correct that the 15" steelie and tire will increase weight, which will have an adverse effect on stop-and-go city driving. For the city you want the lightest tire/wheel you can get, and drive in 4th whenever you can. For this, the 12" tires are perfect. I plan on using these tires primarily on road trips, but first I will experiment with them in the city to see how big a hit I take in mileage. I suspect not that much if at all, since all my driving tends to be city/hwy combined. In that case I may just leave 'em on all the time.

Raising the car 2" will also increase undercarriage turbulence, so I will create some sort of cheap (but hopefully not too cheesy) air dam for the front, and probably side skirts too. But my first MPG test will be with no aero mods.

Or you could do what I did and create a full under belly panel out of 4x8 sheets of 4mm coroplast

festy1.jpgfesty2.jpgfesty3.jpgfesty4.jpg

[Aaronbrook37]

No wonder you average 57MPG! That looks awesome. Only complaint I have would be that it's white other than black, but it's still pretty awesome all the same!

[mikeyjd]

No wonder you average 57MPG! That looks awesome. Only complaint I have would be that it's white other than black, but it's still pretty awesome all the same!

The grill block and underbelly tray added 7.9% fuel economy in similar driving situations. While the trial is somewhat anecdotal and not at all a controlled test, it does seem to show significant improvement in drag and noise reduction since the mods

[Pu241]

mikeyjd, TominMO and I can atest to the noise reduction via the upper grill block.
And it does seem to warmup quicker.
TominMO has gone one step further and has done a partial lower grill block as well.
I see you've done a lower grill block, I suspect you can also do an upper grill block on yours as you have made provisions
for the fan pulling air through the radiator, if it needs to.
You also might want to do a mod which I discover by accident.
The temp indicator becaomes some what a poor temp indicator as the connection corrodes between the copper line, connector , and sensor.
I soldered the copper line directly to the sensor, and enjoy greater range and sensivity of the OEM gauge.

Good work on the under bodybelly tray. Was thinking of using a 323 engine bay tray to start.
Should fit with a few mods here and there, but it seems by the time they reach the JY they are gone.
Besides that isn't as nice as a whole under belly pan.
How did you handle the cat converter and exhaust pipe in general as coroplast is polyethylene or sometimes Polypropylene, neither have very high HDT?

[mikeyjd]

mikeyjd, TominMO and I can atest to the noise reduction via the upper grill block.
And it does seem to warmup quicker.
TominMO has gone one step further and has done a partial lower grill block as well.
I see you've done a lower grill block, I suspect you can also do an upper grill block on yours as you have made provisions
for the fan pulling air through the radiator, if it needs to.
You also might want to do a mod which I discover by accident.
The temp indicator becaomes some what a poor temp indicator as the connection corrodes between the copper line, connector , and sensor.
I soldered the copper line directly to the sensor, and enjoy greater range and sensivity of the OEM gauge.

Good work on the under bodybelly tray. Was thinking of using a 323 engine bay tray to start.
Should fit with a few mods here and there, but it seems by the time they reach the JY they are gone.
Besides that isn't as nice as a whole under belly pan.
How did you handle the cat converter and exhaust pipe in general as coroplast is polyethylene or sometimes Polypropylene, neither have very high HDT?

Check again full upper grill block already done in black Gorilla tape. Stealth mode keke.
The cat and pipes are rapped in 2-3 inches of fiberglass insulation. Check page 1 to see my full list of mod's.

[Pu241]

Check again full upper grill block already done in black Gorilla tape. Stealth mode keke.
The cat and pipes are rapped in 2-3 inches of fiberglass insulation. Check page 1 to see my full list of mod's.

Somehow missed your mod list, thanks for pointing that out!

The fiberglass usually has a sizing agent, you didn't have any issues with it smoking for a period of time?
Did you wire it in place or used a wiremesh then wire it in place?
Like the idea!

[mikeyjd]

Somehow missed your mod list, thanks for pointing that out!

The fiberglass usually has a sizing agent, you didn't have any issues with it smoking for a period of time?
Did you wire it in place or used a wiremesh then wire it in place?
Like the idea!

Hmm. I didn't notice any smoking at all. I just wrapped it in place and zip tied it on so that I could get the coroplast on without it trying to come off. I assume the zip ties melted and the insulation might come off if I take the panels off but I wasn't sure if I wanted it on there permanently when I was doing it. So far I haven't had a reason to take the coroplast off and its been well protected from the heat up to this point.

[TominMO]

OK, yesterday I went and picked up some tire irons/spoons, one 30-inch and two 18-inch. Today I spent about five minutes less than eternity removing one of my space-saver tires from its 15x4" rim. I broke the bead by jacking up the Festy with the tire's sidewall as the base for the jack. Festy didn't go up, tire went down, as planned/hoped. Had to go mostly around the tire to git 'er done. Then had to do the other bead, but this went much quicker.

Then to work with the irons. I've done this on bicycle tires, so I understood how to do it. Just a matter of scale. Long story short, from start to finish I probably took about an hour, maybe a little less.

Went back inside and saw that my wheel adapters came! I just ordered them on Monday. Went out and put one on, then mounted my other space-saver, which still has air in it even. Really fills up the wheel well. Plenty of clearance from the strut now. I'll have to see how it goes with the fender liner. Took pics, but photobucket is acting even weirder than ever. Can anyone recommend a good site to upload pics to?

BTW the label that identifies my wheel as a space-saver wheel peels off very nicely, if you are patient. Then a little Goof-Off or Goo Gone or WD40 will get off any remaining glue.

Diameters:
155/80x12 = 21.8"
165/80x15 = 25.4"
An increase of about 15%, i.e. your motor is turning 15% slower at hwy speeds with these tires. So 50 MPG at a given speed should be 57.5 now.

If you have the Aspire swap and use these wheels, you need to carry an extra spare with this bolt pattern (4x114.3). Or you could just do a front Aspire swap, add the wheel adaptors, and carry only one spare. Or you could have a dual-bolt pattern spare. Or have a prybar or equivalent handy so you could remove the adapter when you put the spare on. (Assuming you are alone when you get a flat, there will be no one to press the brake pedal for you to immobilize the brakes so you can get the adapter nuts loose. Hence the prybar, which you wold place between two studs and have the other end touch the ground, to immobilize the adaptor so you could remove the nuts holding it to the hub.)

Also bear in mind that since this tire is much taller, you might want to have a 2x4 or two handy to put under the stock jack.