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-   -   MPG vs Performance (Yaris) (http://www.fuelly.com/forums/f8/mpg-vs-performance-yaris-14402.html)

GasSavers_BEEF 10-05-2012 09:19 AM

MPG vs Performance (Yaris)
Been a while since I posted and so just wanted to get some people talking.

I bought a yaris a little over a year ago. I have been trying to decide what direction to go with the car and have been doing some small performancy things to it.

My original idea was that it was going to be my daily driver after my Cavalier dies but I have actually made other arrangements there.

I have done the following things to it:

-stiffer springs (~1" drop)
-rear sway bar
-Short Ram Intake (SRI)
-heat wrapped Tri-Y header (stainless steel)
-shift extender (3" extension)
-short shifter
-OEM armrest
-OEM rear bumper protector
-OEM cruise added

I just ordered a mandrel bent 2" exhaust from the resonator back. that should be here in about a week or so.

I am seriously considering a supercharger that is relatively popular in the yaris community.

I have heard that the S/C actually doesn't hurt mileage when it is off. The S/C kit actually has a clutch pulley so you can have it on or off. That was kinda neat.

The stock hp of these cars with a manual is 90whp (106hp as per manufacturer). I have heard that with the supercharger you can achieve 120-135whp depending on what other stuff you have on the car.

I am just curious of any thoughts that anyone has about all this. I know this isn't a typical discussion for this board but hey, I'm trying to liven up the place.


andyrobo 10-05-2012 01:48 PM

That's interesting to learn that the S/C can be disabled. That's a great way to switch from a fuel efficient ride to something quite a bit more peppy. Have you ever ridden in a Yaris that had one installed?

GasSavers_BEEF 10-05-2012 07:26 PM

I have not but have heard good things about them. The power is reliably there and the boost level is well within the limitations of the stock internals.

I have heard that the pulley is situated like an A/C clutch pulley and can be cut on and off. It has a selector switch for low/medium/high which is actuall throttle position. low basically means any throttle and it's on. high is only at WOT. there is actually an off position as well.

the S/C is expensive so it is more of an idea I have been throwing around for a while. I think even with the upgrades I have done so far and several WOT runs I have made, I am still in the 40mpg region.

DRW 10-05-2012 10:00 PM

Interesting, If you manage it correctly you should be able to maintain the same FE while improving power.

I've had fun with my car; improve power a little, then make sure it doesn't hurt FE, then do a mod or two to improve FE. It's a never ending cycle that pushes the envelope in both directions.

andyrobo 10-06-2012 10:20 AM

Out of curiosity, how much does the super charger run?

GasSavers_BEEF 10-06-2012 12:05 PM

They have come down a bit. It was originally right at $4000 but is now around $3400. That is for the entire kit and includes management (piggy back fuel controller). It is completely plug and play.

There are turbo kits out there but they aren't complete and you have to tune them yourself. There are too many stories of guys blowing motors because of running lean.

I know it is a lot but it is not that popular of a car to supercharge so the price is high. if it were a honda civic or a mustang, the price would probably be less than half.

kracka 10-07-2012 10:41 AM

Forced induction did me well. My passat got me around 32mpg mixed driving while able to have some decent power and response. Supercharging most likely will never recoup the savings in gas mileage though if you tried to save some gas with it. Tuning is what matters the most.

I would never spend 3-4k on mods that give you a 20-30whp difference either.

JanGeo 10-08-2012 02:02 AM

If you get 145 whp that's a 50% increase - wow that thing will really move! I wonder what the price is for the eCycle electric driven SC ? Would give you boost without engine loading off a 12 volt battery.

GasSavers_BEEF 10-08-2012 09:41 AM


I had issue with the HP gains as well but if you look at it from a percentage standpoint, it's pretty significant. The price point is what has been keeping me from ordering it. I have been contemplating it for about a year now. There are other options (turbo) that make more power but there is not a known plug and play tune for it. every car is different and a lot of guys go lean and pop motors. I was actually told that a good dyno tuning session (note: tuning session) usually runs around $700.


there are a few boosted guys (turbo guys) that are making killer power. the biggest drawback is that there is a hard threshold around 200whp where you have to change internals because the connecting rods can't handle it.

One guy has a Scion xA (same drivetrain) that is running under a 12 second qtr. I think his time was 11.95 or so. he is running something like 28psi though. He has more money in his engine than I even want to think about. most turbo kits for these cars run 8psi (as does the supercharger).

JanGeo 10-08-2012 10:53 AM

That's about half an atmosphere so it sounds about right that you almost get 50% increase. Turbos put more strain on the exhaust and heat the oil more to keep things cool and you can't turn them off easily. That's why the supercharger is a cleaner power booster. Need to do some math on the cfm needed to get the boost at high rpm but you should get plenty at low end. Looks like about 174cfm at 6500rpm for the 1.5 liter engine NA so it is not big enough unless you get a 24 volt battery to power it and you will get a little drop in boost near redline.

Low Voltage Electric Supercharger | eCycle, Inc.

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