Frankenmiata's compression doesn't look good

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

by Dave Coleman
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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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Sunday, July 25, 2010 6:08 PM
How about a discarded Hayabusa engine? Then add in a prototype Miatabusa kit and build a Lemons Miatabusa. What better way to show off the merits of your design then that?
Monday, July 26, 2010 1:59 PM
I've got 4 Honda B-series, an L28, some gardening equipment, zip ties, and JB Weld - I'm sure you could make it work :-P
Dave Coleman
Dave Colemanlink
Monday, July 26, 2010 4:08 PM
Hmm, what kind of gardening equipment?
Monday, July 26, 2010 4:09 PM
I do have a bunch of SR20 parts if you need them. If you can get a spare block and a piston and rod, I've got everything else. I've even got a trans that will work if you replace the input shaft. I'd be happy to donate my leftover bits to the project if you want them. I'm in DE, but shipping shouldn't be that bad.
Tuesday, July 27, 2010 3:41 PM
I have a low-port SR20 fuel rail and injectors. just pay the shipping from orlando FL and its yours. feel free to email me if your interested Dave
Thursday, July 29, 2010 2:24 AM
Too bad Mazda can't just help out on this with a crate motor mysteriously appearing in someone's back yard... ;)
Wednesday, October 20, 2010 3:02 PM
Hey, I just signed up so I could post this. I am sure you are aware of the horrible cooling design of the miata. I believe that to be the cause of the #4 cyl to be going out quicker. I think it is getting way to hot. I melted piston rings in a 1.6 engine for the same reason (blocked heater core not allowing coolant flow the the back).

I know you guys have some friends that do machining, you should make your own coolant re-route.
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