Piston Slap: Compact Tunerz Edition

TTAC Commentator Heath writes:

A couple of months ago I got the SVT suspension for my Focus. Not want to blow the budget any more I left the 205/50/16s that the Focus came with and there is a unhealthy amount of sidewall flex with the 50 (Pirelli P6). The SVT had 215/45/17.

My question is when its time for new tires, should I go for 40 or the 45. I’d like to stay on the 16″ rims as don’t really want to get new 17″ rims as well.

Sajeev responds:

If you stay with 16″ rims and go for a lower profile tire, the change in circumference messes up the speedometer, gearing (lower profile means more gear and less economy) and increases the unsightly gap between the tire and the body. We did this for TTAC’s entry for the 24hours of LeMons, and the gearing advantage was totally worth it. On a street car? I doubt it.

If you compensate by fitting a wider tire (225/45/16, for example) on a stock wheel, the tire’s outer tread blocks will not meet the road, and it’ll look like the back end of a steroid-injected baseball player. Which is phat. Except when its not.

So I don’t recommend this. I’ve never seen anyone recommend it. Here’s my question back to you: don’t you want a more responsive tire with more grip? One of my cars still has 60-series tires, and its quite good. I run the stickiest summer tires and their level of precision is even more appealing than keeping my cosmetic tire-to-wheel-to-body ratio in check.

Kevin writes:

Sajeev, I need some more speed in my Astra XE 5MT. It’s new to the US I know but lots of them sold in EU, Brazil and elsewhere since it was introduced in 2005. Isn’t there a 1.6 L turbo version in some markets? Or could I get some GTC parts somehow?

Sajeev responds:

From what I’ve read, you can swap an Ecotec 2.0T or its successor (in Europe), the 1.6T. I would join the appropriate forums to learn the differences between the 2.0 T in the Cobalt SS and the Astra. If the 1.6L is better, find a parts supplier in Europe and ship it here. I’m hoping the 2.0T from the Cobalt works because it’s a well-known package for stateside tuners and finding parts will be a breeze.

Either way, slap the turbo motor in, get a higher flow exhaust, custom tune on a chassis dyno and you should be good to go. Also check the differences between the turbo clutch and yours. And getting a limited slip differential will certainly help the massive torque steer you’ll encounter.

I applaud your creativity, but take it from the guy with a one off, 6-speed, Mercury Cougar: you’d better love that car. Nobody in their right mind will pay anywhere near your final tab for this tweaked Saturn. Not to mention that you (and me) can probably buy a far superior performance car for the same price and much less effort.