Thursday, May 29, 2008

I hate the inevitable. I've pretty much known for the last two years that the Experimental Chassis would need some major engine work sometime this year. I've also known that the obnoxious brattling in the trans bellhousing would involve a clutch change to fix. While I've been regularly verifying my diagnoses between waiting for stoplights, I've made no attempt to fix it. And now the inevitable has happened.

Last Thursday, the head gasket went at cylinder 3. I noticed milky blowby pooling in one of the elbows in the intake a couple weeks ago, so I should have been prepared for it. Instead I was stuck running K&W Head Gasket & Block Repair through the cooling system 24 hours before I needed to be in Massachusetts for Jennifer's graduation.

In retrospect, it was a pretty stupid mistake on my part. When I saw black puffs coming from the muffler and had pulled two fouled plugs out of cylinder 3 I should have noticed that injector 3 had a torn lower O ring. Instead I let the combustion chamber fill with gas as it sat at Metropark, and let myself blow out the gasket as I fired the car with one flooded cylinder. At least the K&W nanotechnology crap worked. Though I expected that. I accidentally stuck my hand in the mixture at one point, and I could swear I could feel the nanites crawling on my skin.

The head gasket in a bottle stuff held up well enough to get me the 230 miles to Springfield Friday evening. Then about 200 miles into the trip back, I lost all feel in the clutch pedal on 287. On first sight, it looked like the metal portion of the cable adjuster had pulled itself out of the plastic knob. But when the pedal didn't come back after I rigged a fix, I realized that the clutch had gone. Good thing I didn't refuse that tow home.

Turns out that incident was my fault too. When I torqued down the clutch pressure plate, I didn't torque everything back in the correct order. The resulting vibration knocked off one of the clips holding the throwout bearing to the clutch arm. That caused the disc to warp, which allowed two out of four clutch springs to break free of their retainers and pop right out of the clutch. Whoops.

So what have I learned from all this? Judging from the fact that I'm running with 3 crossmember bolts (there are supposed to be 4) and I have a keychain ring holding my clutch cable to the transmission, not a whole lot. At least I have a package coming from Courtesy Nissan, with which I will waste 2 hours of my weekend doing nothing but correcting my own mistakes. God I hate the inevitable.

Thursday, May 29, 2008 9:42:57 PM (Eastern Standard Time, UTC-05:00)  #    Comments [0]
 Friday, May 09, 2008

Saturday was the first 2008 Test and Tune for both me and the Experimental Chassis. We headed over to Pocono East (well, I did at least) with the usual crew, with the usual plan: Driver shakedown, suspension test & tune, and a quick go around with an instructor to check my work. Unfortunately, a massive cloud of thick Pennsylvania fog beat us to the track, which limited our running to about half of what we normally get. At least I got lots of sleep in.

Thankfully the car hasn't changed much since October of 07. The only major modifications are the newly track-revalved Teins, ride height changes, and a small adjustment to the front bump steer adjusters. This worked out surprisingly well. The fundamental flaws of the B14 chassis' suspension geometry are still there, but by shifting more static load rearwards and making the rear end handle more of the roll force, I think I've succeeded in making the car respond more naturally across corners of all speeds. By making these changes and running the rears at 34psi (down from 36.5 psi from last October), I estimate with some confidence that the Experimental Chassis could be consistent for maybe 3 or 4 laps on at 10/10. I'd say that's pretty decent progress, considering I used to fade all of its consumables after a single fast lap.

Of course, no successful test would be complete without something going terribly wrong. About five minutes into the second afternoon session, I noticed a small dip in the power delivery between 5500 and 6000 rpm. No ticks, no pings, no clunking, no CEL. Just a little flat spot in the power band. A quick look under the hood revealed nothing, so I just kept going and pointed the queue by as they caught me on the back straight. Back at home, a quick compression test confirmed my worst fears. Down to 155 150 155 160 from 175 175 177 175 on July 2007 (and way down from the stock optimum figure of 199 across all four cylinders). A squirt of oil test revealed no change in any of the cylinders, indicating some sort of top end wear. My guess is that there's a couple burnt / bent valves from either me overrevving it or when I let the thing suck up just a bit too much Seafoam when I cleaned it out last winter.

If the problem does turn out to be the valves, I'm just going to replace the entire head with a reman unit. If it's the piston rings, I'll give it a shot of Xado, possibly followed by an engine swap to a rebuilt GA16DE. As expensive and inconvenient as it is, this could turn out to be a blessing in disguise. A 20% loss of compression in an engine of this size comes out to be a loss of around 8hp. Doesn't sound like much, but when you only have 91hp to the front wheels 8hp is pretty substantial. This might be just enough to get me in contention with the midpack ST5 race machines at some of the smaller tracks in this area - and at the top of the ST5 TT group.

Ah well. It's progress.

Friday, May 09, 2008 7:22:19 PM (Eastern Standard Time, UTC-05:00)  #    Comments [0]