Knurled
Knurled UberDork
9/18/13 7:26 p.m.

Today, I tore apart my car's previous engine, which was a half bridge ported GSL-SE engine done on the cheap - 160k core engine that was given to me in pieces, so I did an experimental port on it (experiment: FAILED) and threw it back together with all of the old seals. The corrosion in the cooling system was spectacular so I didn't deem it worthy of new parts.

The last event the engine ran before the new engine was finished was a two-day rallycross, the 2012 Great Lakes Division National Challenge. I placed first in class. On my way home, I noticed that the engine had very little power at low RPM. 3000rpm at city traffic speeds, you could floor it and get nothing but intake drone.

First thing I noticed was that the JB Weld that I'd used to port-match the FC intake manifold (the primary ports sit a half inch lower) was rattling around in one of the intake ports. I'd never had it come loose before. It was only held in by the gasket and luck. If it entered the engine, it would have been a 1/2"x1.5" spear of death. None of it was missing, although there was a big curl of swarf ready to break off.

Upon cracking the engine open, I noted that the side seals were worn flush with the rotors, the corner seals had no pop, and the oil rings were shiny across half the face. End housings were FUBAR with grooving, a sign of dust ingestion. Apex seals had no springing left and they stayed stuck in the rotors. The center iron may be salvageable, which is fine because the end irons are crap anyway - 6 ports suck and I have a pair of 12A end housings on hand ready to make this a proper 4-port like my current engine.

But the rotor housings themselves? PRISTINE. Still no chrome flaking anywhere except for a small divot next to one of the exhaust ports, just like when I'd put it together. FUBAR everything BUT the rotor housings? On a 3mm iron seal engine? That's impossible!

The extra goodness is when I was picking the rotors apart. The backsides of the apex seals had deep gouges where the springs rode, another sign of dirt ingestion. Dirt gets in there and has no way back out so it laps everything, thus the lack of apex seal springing. Then I got to the third seal on the rear rotor - it came out in three pieces.

My exhaust ports are big enough that it SHOULD have lodged in the port and shredded everything related to the rear rotor. But, it didn't.

So, at least some of these runs: http://www.youtube.com/watch?v=0Pi6GlgWnjE were made on a broken engine....

amg_rx7
amg_rx7 Dork
9/18/13 7:54 p.m.

haha great story. the vid is cool. never realized how rough that sort of thing could be.

JtspellS
JtspellS Dork
9/18/13 7:57 p.m.

So the rotarys are unreliable right?

yj1D8nUekAVsXtP0KUDU3bbOa3Di14HH