Technobabble (blog) – Help Us Help You Avoid Tetanus!

Frankenmiata's compression doesn't look good

Technobabble (blog) – Help Us Help You Avoid Tetanus!

by Dave Coleman
 
Frankenmiata
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Frankenmiata molly maid
Frankenmiata Batmobile
Frankenmiata Alice In Wonderland
Frankenmiata Enterprise Miataprise
6 themes, 9 races, over 150 hours on the track, and our bucket of bolts is only now starting to show its respect for physics. Won't you help us help you by donating your sad old Miata engines to the cause?
The stats are astounding. The FrankenMiata's engine was built (from the least-destroyed parts of 4 blown engines) and turbocharged (with a rusty Mexican Dodge turbo and some obsolete tuning parts) for less than $200. It should have blown up on the first dyno pull, but it didn't. It should have blown up on the first track test, but it only started making a slightly funny noise. It should have blown up in its first race, or the subsequent weekend of flogging and non-stop hoonassery at Mazda Raceway Laguna Seca. Instead, the noise just got loud enough to justify a slight teardown and a $40 set of new rod bearings. 
 
After that, it continued not blowing up through 7 more 15-hour 24 Hours of LeMons races and a 24-hour ChumpCar race. In total, it has run more than 125 hours in competition, and another 30 or so in test days. Few proper race engines would perform this long, but then again, few proper race teams define “perform” as loosely as we do.
 
Over the last couple of races, the exhaust note has been slowly developing an off-beat Subaru warble. At first I suspected a strange resonance in my helmet, or some acoustic side effect of the 7-foot wooden disc on our roof, but a compression test this weekend revealed the sad truth.
 
There is, it seems, a limit to how much a Miata engine will endure. After starting life with compression readings of 180/190/190/175, the compression actually improved after a race's worth of ring seating, peaking at 185/200/206/185. We then stopped checking for a long, long time. This weekend, our latest numbers came in at 175/160/160/125. Cylinder #4 is going down, and fast. 
 
Or maybe not that fast. Since we haven't tested the compression in at least 5 races, we really don't know how quickly our #4 cylinder is failing, but we're going to find out. We'll be testing the limits of junkyard Miata endurance by trying to squeeze a tenth race from our venerable lump, but after that, something will have to be done.
 
We built our last engine by scrounging free blown B6 carcasses from the backyards of friends and acquaintances and using the parts that weren't actually all that broken. It was a win-win for everybody. We got an engine, and they no longer had to worry about keeping their tetanus shots up to date. 
 
Well, now its your chance to get that rusty, greasy old lump out of your back yard. Got a 1.6 Miata engine you're tired of tripping over? Is it in Southern California (or at least on the way back from Thunderhill)? Leave your generous offers of free engine parts in the comments and Eyesore Racing will be eternally grateful.
 
-Dave Coleman

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