Scion xA aero mods

[noahmckinnon]

I just bought a 4' x 8' sheet of black 4mm Coroplast (aka Cor-X apparently). Pretty cheap at <$15/sheet. However, a good look at my tires reveals they are indeed approaching their end of life so I might hold off cutting and adhering until I get a skinnier set (The previous owner put on a set of 195s - stock were 185). Might look into your flatter pizza pans too. I started noticing that the moon caps were making an annoying creaking sound, which at first I feared were cracked wheel bearings. A little googling resulted in a few suggestions that wheel covers can make this sound. I popped em off, sound gone (and $ saved!). Now I have them again and ignore the creaking when it's there.

I had automatically assumed that the RS2 alloys, just because they were "alloy" would be appreciably lighter than steels. But I suppose if the they made enough of a FE difference, Toyota/Scion would asterisk the mpg rating with another set of estimates for alloy wheels. Damn assumptions. Just out of curiosity, what do the RS2 alloy wheels weigh? I'll still take a look at some after-market alloys while shopping for new tires.

Gave a quick gander at that phlatprinter 3. Love the idea and hope to delve into DIY CNC and some point. On the to-do list at #1328

[NeilBlanchard]

Yes, the domed stainless steel wheel covers creak like crazy, and eventually, they may start to fall off; depending on the state of the roads you frequent. The right front is the most likely to end up on the shoulder and the right rear then may fall off, as well.

If you still have the stock plastic wheel covers, you can pop rivet 16" aluminum pizza pans (coupe style) and get better FE and hopefully not lose them...

Amazon.com: Winware Coupe Style Aluminum 16-Inch Pizza Tray: Kitchen & Dining

What are you RPM's at say 65mph? You might be able to get taller tires with a larger outside diameter and essentially raise the gear ratio; though you will also have to calibrate your odometer readings for accurate MPG's.

[chvycmmnslvr]

Hi there
I just joined this blog site and i am not too impressed with the fuel mileage results i am seeing so far ... i have a 1991 chevy crew cab 4x6 dually P/U ... I am currently gatting only 26.4 mpg but i have made trips with it as high as 127.5 ... i have not made any aerodynamic changes to it so far .. but i do plan on sheeting the undercarriage to eliminate wind drag ... i also have a 1992 toyota four-runner i installed a diesel engine in that is getting over 45 mpg .. it is also four wheel drive ... on my p/u i used an aux overdrive unit behind my five speed o/d dropping my engine to only 975 rpm at 65 mph giving me 33 mpg with my cummins diesel ... i then introduced 5 litre/minute hydrogen into the engine giving me 127.5 mpg ... this was figured on a 305 mile trip and only used 2.4 gallons of diesel ... i am currently doing an engine swap to a newer cummins engine and i am going to twin turbo the engine to increase effiency ... i expect to get close to 200 mpg when i get it finished ... I was going to include a photo of my truck but i cant figure out how to upload it from my computer ... any tips?

[Arragonis]

Originally Posted by chvycmmnslvr

Hi there... I was going to include a photo of my truck but i cant figure out how to upload it from my computer ... any tips?

Read this (by Me )

http://ecomodder.com/forum/showthrea...der-18279.html

You will need a few posts to get going though. 200 MPG is going to be a stretch, go for a realistic tank average first - measure what you get now fillup to fillup and maybe add 10% at first, and then a little more when you get that.

[noahmckinnon]

Originally Posted by NeilBlanchard

If you still have the stock plastic wheel covers, you can pop rivet 16" aluminum pizza pans (coupe style) and get better FE and hopefully not lose them...

What are you RPM's at say 65mph? You might be able to get taller tires with a larger outside diameter and essentially raise the gear ratio; though you will also have to calibrate your odometer readings for accurate MPG's.

Alas, I gave away the stock covers a few months ago.

At 65 mph, I'm probably turning ~3300 rpms. I'll check my Ultragauge next time I get on the highway to see how it compares to the dash. Regarding taller tires, the only taller ones I see available are 185/65 as compared to the stock 185/60 (I've only searched tirerack so far) and I'm still wading through all the brands and models. It's a bit overwhelming. Would I see an appreciable difference with a 65 versus a 60 considering I'm adding mass? In any case, what brand/model of all-weather tires are you running and at what pressure? I've got at 50 psi (max says 35). Might that be too much over the max?

Earlier in the thread, you mentioned possibly swapping the final gear in the gearbox after your warranty was up, but then you started focusing more on your CarBEN EV project. I haven't done anything more than replace a head gasket on a '78 Volvo. What's your assessment of the difficulty in swapping the xA's stock final gear with a compatible lower ratio one? I'm handy and like to fuss about, but I've never touched the workings of a clutch or transmission.

btw, Neil or anyone else, do you know if the Scions shut off the fuel injectors during coasting? If so, wouldn't that mean EOC'ing won't offer much benefit?

[SentraSE-R]

Here's a discussion of what's involved in the ring & pinion gear swap, with photos, from the Yaris side. It looks and sounds pretty difficult. I've done a lot with cars, but this is probably beyond my skill level. Too bad, as I'm ready to buy the parts ($400) or a Yaris transmission (available from $370 from junkyards). A straight transmission swap might be the way to do this.

I'm running 205-50/17s which are 25.07" tall, 5.31% taller than OEM. They lower my 60 mph engine rpms from 3096 with the OEM tires to 2931. The Yaris 3.722 final drive ratio (v. the xA/xB's 4.31) would lower the 60 mph engine rpms (with OEM tires) from 3096 to 2673. It's still higher than the 2545 rpm of the ATs.

[NeilBlanchard]

The sidewall maximum is 35PSI? That is pretty low -- most tires have a sidewall max of 44PSI.

I'm running Nokian tires in the summer, and I have Michelin X-Ice for the winter. You should check out the Nokian eNTYRE, which is a 51PSI sidewall max:

Nokian eNTYRE

Yes, the fuel is shut off when you use the engine to brake by lifting the throttle or downshifting. Your SGII should show 9999mpg when this happens.

If/when my clutch needs replacing, I will try to see about having the whole final drive case replaced with the 3.56:1 unit. My xA has a 4.31:1 final drive. You should check what your final drive is -- it may already be the taller geared unit. The manual shift cars have the short gearing because *if* you get cruise control, then you don't need to downshift. Automatics probably have the taller final drive, but since they are 4-speeds the overall gear ratio is only a little better than the 5-speed manual. Both 4th and 5th on my car are technically overdrive, but it spins at about 3,500RPM at 65MPH.

[SentraSE-R]

I missed where it's buried in this thread, but which Toyota car & transmission has the donor 3.56 final drive gears?

The xA/xB ATs have 4.15 diff gears. They combine those with a .7 4th gear to drop their cruising rpm to 2545.

[NeilBlanchard]

When I looked it up a while back, almost all the other models with the 1.5L VVT engine that is in my 2005 xA had the 3.56:1 final drive. I think they all had the same 5-speed manual transmission, with both the 4th and 5th speeds being overdrive (under 1:1).

[SentraSE-R]

? What I've seen is 4.05 final drives in Echos with the C150 transmission, and 3.722 final drives in Yarises with the C50 transmission, per Wikipedia. There's a C154 with 3.526 and a C551 with 3.55 final drives, but I can't find any US vehicles using either of these transmissions.

Wiki is far from authoritative (it lists our xA/xBs as having the 4.05 C150 transmission), but it has nothing about any Toyota 5 speed transmissions having a 3.56 final drive.