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Technical Questions and Answers - Tech Q&A

Aaron Bonk
Mar 2, 2013

We Say 'Bypass'!

Q: I'm about to install a throttle body on my '94 Integra GS-R and it doesn't come with the connections for the fast idle thermo valve. Do I need this or can I just bypass it? Also, do I have to port-match my intake manifold or will it still make power without doing that?

Albuquerque, NM

A: The fast idle thermo valve is one of those niceties that Honda thinks you need, like an eighth cup holder or AM radio. It bumps up engine idle for a quicker warm-up, but after that all it does is heat up the intake charge. Heating up anything that'll eventually end up in your intake manifold is bad. If you can deal with a slightly longer warm-up period, then ditch the valve altogether. The trade-off is cooler intake air temps, which can lead to better performance. As for port-matching, whatever gains you make by removing the fast idle thermo valve will be lost by not port-matching your intake manifold. The bore difference between the throttle body and the intake manifold opening makes for a nasty step that'll disrupt airflow and could actually make things worse.

The Choice Is Yours

Q: I'm looking at coilovers for my Scion tC and noticed that different coilovers offer different ways to adjust ride height, either by compressing the spring or by shortening the shock body. I mostly want to slam my car but I also want it to handle better and ride like stock. Which is better?

Redmond, WA

A: Coilover suspensions that'll slam your car, make it handle better, but ride like stock make about as much sense as an all-cupcake diet. By their very nature, performance coilovers feature stiffer springs, which are what'll keep you from bottoming out once you're slammed. There are two ways you can lower cars with coil-over-shock suspensions like your tC: shorten the springs or shorten the shocks. Entry-level coilovers typically only allow you to reduce ride height by pre-loading (compressing) their springs, which isn't necessarily a bad thing until you've gone too far. Problem is, you'll almost always go too far. If you're not looking for a major drop and won't be spending much time at the track, these types of coilovers will get the job done. More expensive, double-adjustable coilovers also feature adjustable lower mounts, which allow you to essentially shorten or lenghten their shock bodies by screwing them in or out. This'll let you reduce ride height independent of spring pre-load, resulting in better performance.

My Way or the High Way?

Q: I've got about 140,000 miles on my '93 Accord and want to start modding it. Are these too many miles for me to be thinking of upgrades and making more power? Should I rebuild the engine before doing anything else?

Riverside, CA

A: It all depends on what sort of condition your engine's in. Try doing a compression test followed by a leak-down test. The results will tell you whether or not there are any underlying issues with your piston rings, head gasket or valves. You want to be within 5-10 percent of whatever Honda says you should be at. If you're not, that doesn't mean that your engine's about to give birth to a rod, but keep in mind that excessive high-rpm use or any sort of increase in cylinder pressure, whether it's from high-lift cams or forced induction, will speed up the chances of you encountering engine trouble. If everything checks out, then just be sure that you're up to date on maintenance and that your engine's free of any major leaks.

All That or All Hype?

Q: I want to start doing more to my Evo, but I'm not sure which companies' products to use. I've heard JDM parts are better, but what about products that are made in the U.S. or other places, like China? JDM parts are pretty expensive so I'm looking for alternatives but without sacrificing quality.

Via email

A: Twenty years ago, spending the extra money on Japanese-made parts made a whole lot more sense. Most American companies didn't understand what the sport compact crowd wanted (Where do you think bumper grilles came from?). Things have changed, though. Twenty years later, what matters more is how something's made rather than where it's made. Because of our global economy, many "JDM" parts are now manufactured in Taiwan and China, and more than a few "American" manufacturers outsource overseas as well. Instead of narrowing your search to a product's supposed manufacturing origin, go online and see if you can learn more about the company's manufacturing processes, quality control measures, and warranty policy. If your favorite company outsources, do they at least do their own R&D and inspect their own products upon delivery or are they nothing more than a glorified trading company?

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By Aaron Bonk
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