My rebuilt motor arrived from X-Factor as part of a group buy. I decided it would be a good idea to run a Mazda Motorsports baffle. It is a steel sheet that sits in the bottom of the oil pan to help oil stay down at the oil pick up. It doesn't add any power, it simply helps prevent oil starvation. Seems like decent insurance to me. I ordered one from Mazda, except it never showed up. Turns out the person taking the order messed up the credit card order and never bothered to communicate that. Well by the time I figured this out, I couldn't wait any longer. I remembered having something in my original motor, and thought fine, I will pull it from the non-leaking motor and transplant it. So the refurbished motor had the oil pan pulled off. The old motor had its oil pan pulled off, then only to find out this was all for not, as it did not have the baffle! Ugg…clean, re-RTV, new gasket, and re-assemble, kick myself for burning up an entire Saturday afternoon.
The motor gets installed, and the very first time it gets fired up and sounded HORRIBLE! So much so, for a few seconds I thought it might be a rod knock. I have dealt with a number of cars over the years that have had bad lifters, I’ve installed fresh lifters before. I have heard lifter tick many times, and usually it goes away in short order. Not this time. I had two friends come by and give it a listen and confirm that after a 2nd heat cycle that it didn’t sound good. Oil pressure using 5w-30 with a water temp of 180 degrees was about 13psi (oil pressure gauge goes from “0” to a halfway mark, then 25psi so, not the most accurate.
We pulled the entire subframe to get the oil pan off. FYI with a Miata to get at the oil pan one has to pretty much remove the motor from the car, or remove the oil pan to get the oil pan off. Everything looked fine; the pickup tube was clear, the pick-up tube gasket was indeed there. Ugg…clean, re-RTV, new gasket, and re-assemble. Pulled off the valve cover, check that all of the hydraulic lifters seemed fine and had good spring tension. No issues found, add assembly lube to all the cam lobes, fill with 10w-30. Let it run for a bit, the noise is better, but not great. The following day, it sounded perfect! I have never owned a Miata that was quiet and smooth.
Come back the following weekend to find a puddle of oil on the floor. <sigh> Pull the transmission out, replace the rear main seal and the rear “half-moon” oil pan gasket. Reassemble, let the RTV cure for six hours, let it do a heat cycle, a short test drive, and all seems well!
Here is a diagram of the Miata oil pan. The two "half moon" gaskets circled in red at each end of the motor, the factory windage tray indicated by a blue arrow, and the whole thing is sealed with RTV. A silly design in my opinion.
The following week load it up on the trailer, and let it idle, and notice oil drops on the trailer. <sigh> Get to HiTech in Elk River for dyno tuning. Their tailpipe sniffer wide band oxygen sensor was being all sorts of wacky, and my AEM wideband was also doing its own thing. So I have invalid air/fuel numbers to go by. The dyno operation was either having a bad day, is generally just cranky, or hates Miatas? I got four runs, and settled on 14ish degrees of timing and 40lbs of fuel pressure. Resulting in 122whp and 119tq, which is 8 more HP than the previous motor, which doesn’t sound like a lot, but percentage wise is a decent chunk.
Friday was a test day at Brainerd International Raceway. I ran the first session, short shifting at 6500 rpms. Came in and checked the car over to find the bottom of the car covered in oil. <sigh> The transmission was pulled again! A fellow Miata racer pointed out that sometimes there can be a ridge on the crankshaft where the main seal rides from wear. The proposed solution was to install the main seal 1/16 of an inch proud (or sticking out) vs. having it flush. Thus the seal will ride on a part of the crank that is not worn down.
The next morning we finished the reassembly, ran the practice session. Everything seemed fine. Changed out the oil used for “break-in” for a mix of Schaeffer's 10w30 & 20w50 Series 9000 racing oil. My qualifying session was cut short as on the 4th lap the exhaust separated where the down pipe meets the exhaust. I used up my last spare gasket, and borrowed one from Jenkins Racing. FYI the 1.6l and 1.8l gasket are not the same, but I made it work anyways.
Twice I had the igniter wire fall off of the starter. I can tell you getting all buckled in to the car, all the accessories hooked up, then the calls to grid come over the PA, then the car doesn't start; it doesn't do any good for ones mental state!
The first race I had a phenomenal start and finished okay. Oil pressure at wide open even towards the end of the race was always around 30psi. However when back in the pit, the motor had a horrible lifter tick even after letting the it idle for a few minutes with the radiator fan running and the water temp sitting at 180 degrees.
Sunday, practice, qualifying, and the race went okay. The best lap time I could do was a 1 minute 50, which is good for me, but still a second off of my best lap time. The wind was quite strong all weekend, but I still would have expected to best previous lap times with the extra power.
photo credit Kris Eshenour
I struggled with putting the power down coming out of turn 13. I still chronically over break for turns 3 and 7. Turn 12 still continues to be a pucker factor for me. After each session I would wipe off a couple of drops of oil from the bell housing of the transmission. So I am unclear if that is residual from the previous leakage, despite cleaning it pretty good or if it is still leaking.
HUGE thankyous to Geoff, George, Jenkins Racing for helping and not letting me throw the towel in (SEVERAL TIMES!). Also to my wife and Andy Nash.
More photos and videos to come...
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