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Dear Dave


Dave Coleman
Oct 1, 2007
0710_sccp_01_z+dear_dave+funny_pic Photo 1/2   |   Dear Dave

Direct 'Dear Dave' Tech Letters To Dave@Eyesoreracing.Com. Coleman Will Share Mind-Numbing Details, Earth-Shattering Revelations, And Technical Nerdisms In This Space Each Month.

Q. Post-Graduate Economics
After many years, I have finally graduated college and will soon be working in a fairly lucrative field. I've never owned a vehicle manufactured post-1995 and the most fun ride I've had was a '92 Daihatsu Charade. I'm in the market for a new(-ish) vehicle. I can't find an Evo IX MR, so it looks like I'll be defaulting to a 350Z. This will serve as a daily driver/weekend track machine. These are the few mods I've decided on: ARC radiator, oil cooler, Quaife ATB, BBS wheels (18x9.5 front, 19x10.5 rear,) and Michelin PS2s. I'm leaning towards natural aspiration and in that vein am looking at Cosworth heads, 11:1 pistons, and intake manifold (as soon as it's available).

I'd also add a low-restriction air intake, headers, cats, and exhaust, as well as a lighter flywheel. There are several stroker kits on the market, but I don't want to hurt my redline or throttle response. Now for the questions: do you anyone who makes titanium connecting rods for the VQ35 or blah blah blah blah blah... (cut off by impatient geek). Caleb CoxPrivate, Idaho

Here's your answer in only three words: buy a Miata.You, my friend, need to face some hard facts. First, you can't drive. If a Charade is the best car you've had so far, you have no business getting on a track in a Z until you've learned some skills in something balanced, rear-drive and underpowered.

Second, using the same car for a daily driver and a track car is asking for unemployment. Your lucrative new employer probably won't appreciate it when you can't get to the office because some throttle monkey rear-ended you on the track after upgrading to a Corvette from his own Charade. Or when your car is down for six months instead of six weeks getting its perfectly reliable engine torn down and rebuilt with titanium bits. Or when you miss a shift and scatter those same titanium bits all over the track.

Shit happens on tracks-plan for it.

Don't get me wrong, go ahead and buy the Z, but use it as a daily driver while you learn to drive the Miata to its surprisingly high limits. The Miata is so inherently good as a track car that all you'll need is some streetable track tires (Toyo RA-1s, Kumho Victoracers, etc.) a pair of Racing Beat anti-roll bars, a Hard Dog roll bar and an oil change. A Miata in this trim (assuming you were smart enough to buy one with a factory limited-slip diff) has amazing grip, perfectly neutral handling balance and can withstand years of track flogging with no mechanical consequences.

And the whole car will cost about as much as that set of Cosworth heads you want for the Z.

By the time you've burned about halfway through your second set of Miata tires, you should be passing newbies in 350Zs. That's when you'll know you're ready to step up.

If you haven't done the arithmetic yet, it's worth thinking about just how much of your new lucre will be sunk into this Z engine. All the radiators, oil coolers, and LSDs you're dreaming about are absolutely necessary if you want the Z to withstand track flogging as well as your $4000 Miata did, so consider that money spent.

Then there's that built, naturally aspirated set-up you're leaning toward. Cosworth heads, pistons and rods, four Tomei cams, a pair of stainless DC sports headers and an AEM intake will set you back over $9700 in parts alone. Then you have to pay someone you trust to pull the engine, tear it down, machine it, assemble it, put it back in, figure out an engine management strategy and, finally, actually tune it properly.

By comparison, a $7000 JWT turbo kit suddenly looks cheap, considering it can be installed without removing the engine and comes with all the engine management headaches already solved.

Odds are very good that the cheaper solution is also the faster one, which will come in handy when you learn the next hard lesson. This is just my personal experience talking here, but careers seldom turn out to be as lucrative as expected. If I'm wrong, the Cosworth bits will complement the turbo kit quite nicely.

0710_sccp_02_z+nissan_240sx+side_view Photo 2/2   |   Dear Dave

Q. Pre-Graduate Economics
I currently own a 1995 S14 240SX and I want to make several suspension modifications. I followed the progress of Project Silvia with great interest, partially because my understanding is that any information on modifying the S13 is relevant to the similar S14. I have a substantial list of parts I want to get in the near future, including coilovers, shocks/struts, anti-roll bars, bushings and strut bars. Because I'm in college and tuition sucks, I'm definitely on a budget for this stuff.

I was digging through back issues the other day to find your '1g/12-sec. quarter-mile on the same day' set-up. After that, I started looking at JIC coilovers and discovered they're at the high end of the market. I'm curious as to whether you can suggest a cheaper alternative for those parts specifically. I found that Ground Control makes coilovers for the 240 and SCC always seems to have good things to say about them. But even if

I order them with the same spring rates as the JICs you decided on, will performance be comparable? Evan GreeneBuckhound, Montana

While the JICs are absolutely brilliant on a smooth track, like Laguna Seca, they have proven to be a little on the skittish side on bumpier tracks like Streets of Willow. The source of both their smooth-track strength and rough-track sensitivity is their unusually stiff damping, even on the softest adjustment.

In more recent Silvia projects, I've tried softer Koni Sport dampers (Ground Control's own valving up front, with Koni's 300ZX valving in the rear) with similar spring rates (300lb/in front, 250lb/in rear) with reasonable success. Ride is substantially better, while still firm and well controlled, and track performance is quite good. Unfortunately, being installed on two different S13s, it's impossible to compare them directly.

I'm incredibly hard to satisfy when it comes to damping, so still not perfectly satisfied with the off-the-shelf Koni valving, but it's a good place to start. And all Koni Sports are re-valvable. Eventually, when I'm finished getting them valved to my liking, you'll be able to send yours back to Koni and say: "Valve mine like Coleman's."

On your hot dog-and-ramen budget, I'd recommend the Koni Sports (at around $560) and the stiffest, tallest lowering springs you can find. Eibach Pro-Kits (Sportlines are lower, so stay away) will set you back about $230, so you're in for $790 so far. There may be stiffer, taller springs available, but nobody publishes their spring rates. Pair those with Progress anti-roll bars (stiff, adjustable, and the front bar is designed to clear any conceivable oil pan you may end up with) at about $400 for a set, and you're in for about $1200.

Later, when you enter a fairly lucrative field, you can put Ground Control coilovers ($400) over those same dampers and add some Ground Control camber plates ($300). By then, you will have spent nearly as much as the JICs, (the JICs still need the Progress bars) but you will have spread out the cost over a few different summer jobs.

By Dave Coleman
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