08 Yaris 'S' Turbo Build

[scarsofcarma]

Thanks for the compliment ��

Yes I have owned a large array of vehicles. Mostly Mazda rotaries, but also Miatas, Supras, BMW's, Honda's, VW's, Porsche, etc. This Yaris is the most modern vehicle I have owned so far.

I think the Yaris does very well for what it is. The lightness of the chassis is what I originally found attractive about it. Compared to other fwd's I've built it can hold its own. My first car was an 81 Scirocco 'S'. I also had two Corrado's (both a G60 and a VR6), two EF Civic hatchbacks, an 89 Integra, two Accord hatchbacks and an 01 Prelude.

I won't say the Yaris suspension is as good as those Honda's in terms of adjustability and setup, but simplicity has its own appeal. Macpherson struts provide direct tire grip feedback to the steering wheel. If you know how to use the wheel like a rally driver (even on tarmac) you can use that to your advantage for greater confidence pushing it to the limit.

In most regards the Yaris reminds me of a VW in the way it handles, especially with the semi rear trailing arms. The Yaris needs a rear swaybar to combat understeer and get closer towards an instant neutral turn in response (which is what Miatas do best).

I opted for the TRD rear bar but I believe there are some beefier ones available. I wouldn't mind trying a bigger one. This Yaris still is prone to understeer at the limit, but it's predictable and correctable which is the most important thing. Mine being a sedan, it may be more prone to understeer than the hatchback (I haven't driven a hatchback yet), but the sedan may likely be more stable in terms of oversteer because of the longer wheelbase. So far I have not been able to get the rear end to slide at all whatsoever.

These Potenza RE-71-R tires are really nice. I used em on my last auto-x Miata build as well in the same exact tire size. I won't say the Yaris has the same level of outright handling as the Miata did, but it feels very stable and holds a surprisingly good level of grip.

Trying to keep up with those Miatas and the new turbo Civic Type R is the real benchmark in auto-x these days. I'm not close enough yet to challenge them with this Yaris but we'll see. I am still figuring out what to do with setup and modifications.

Despite the fact it has all this work put into it, this car was down for years while it was turbo'd and it hasn't been driven much since it was turbo'd. It is still a new learning experience. With more power, a lot changes in the way it drives, what it needs and how it needs to be setup.

I have new poly bushings ready to go in the front control arms. I want to upgrade the lower engine mount somehow (can't find a poly version) and I am interested in getting some additional bracing for the chassis. (strut braces, lower tie braces, fender braces, etc.)

And that's just for backroads and auto-X. If I want to take it on the track, I would also be thinking of getting rear discs on this car somehow. Can a Prius rear end bolt on???

As for your other questions, the Haltech is running in a parellel configuration with stock ECM. What the boomslang does is allow the Haltech to splice into the stock vehicle wiring harness saving the trouble of making your own. Forgive me it has been a few years since the Haltech and Boomslang were installed, but if I remember correctly when you order the Boomslang you have some options about which features you want for Haltech control and which ones you don't. It is a special order item that is customizable. So long as you order it the way you want it, no modification should be necessary (except how you decide to mount it in the engine bay).

Presently the only thing the Haltech controls is running the engine. All other vehicle functions such as ABS, gauges, wipers, buttons, switches, etc. work as usual based on their original modules and circuits. (Traction Control was not a feature in 2008 so far as I am aware. At least not for mine in the US market)

Some engine and alternator related functions (such as AC compressor or headlights) require that the Haltech be aware of that extra load on the engine so it can raise the idle up the way the stock ECM would normally do.

You can program that into the Haltech, but you have to be clever about which inputs you use for a trigger. To be honest, my setup has not been adjusted properly for the AC or headlights so I have to be careful sitting at a stop or the engine may stall unless I keep light pressure on the throttle.

This is something I will figure out, but first I have to familiarize myself with the Haltech to be able to adjust it myself instead of paying a tuner to do everything. I will get there eventually.

The Haltech Elite is capable of running variable valve timing, so yes that is fully functional and tuned for on my Yaris. Other versions of Haltech do not have that ability. The same goes with other brands of standalones. For example my turbo Miata had no variable valve timing so Megasquirt II was enough for that application.

My aftermarket efan is trigged by the stock wiring system, but you can easily run an efan trigged by a Haltech if you wanted. It's just a matter of using a sensor input into the Haltech to trigger an output from the Haltech to switch on a relay.

My efan feels too weak for my tastes so I plan on getting a bigger one and using a separate adjustable fan controller with its own relays and dedicated power source to beef up the amperage.