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Old 10-30-2012, 10:38 PM   #1
bigjae1976
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Non-M FI and track duty...not a good mix?

I run a stage II twinscrew with w/a injection, a zionsville radiator and oil cooler. As some may know, I had to get a new (used stuff) engine put in back in May. I've been to the track quite a bit, 19 days to be exact. Probably about 90 sessions mostly in 90-100 degree heat. I've had some misfore issues but replaced the bad coil pack and continued to go. During my last weekend, I was flogging it pretty hard and it didn't feel right. I pulled the plugs and they were gray/white from burning water wetter and coolant.

So my shop pulled the head and found that the exhaust valves were cooked, head gasket no good, the head was lifting, a cam bearing broke, the O2 sensors were cooked, and the insides of the headers were cooked as well. The valve stems where white as well. So obviously I was getting a LOT of heat, fire and maybe detonation. There is some debate about when this all went wrong but I am pretty sure it started early on back in June/July.

Now here's the theory. Apparently the MS45 DME monitors the differential between two air temp sensors between the MAF and the intake manifold. What AA (and I believe ESS) does is allow the temp sensor in the intake manifold monitor ambient temp to avoid throwing an SES light because the air after the compressor would be much hotter, engine would pull timing and throw a fault. This is OK for the street since you might get 1-2, maybe 3-4 good pulls and then you run into traffic or run out of road. On the track, you basically do a dyno pull coming out of every corner. While in the corners, I have the revs pretty damned high as well. This NEVER allows the intake charge to cool and heatsoaks quickly. The air temps go up and up but the DME cannot compensate because it is reading the mani air temps from the ambient temps of the engine bay. So the compressed air gets hotter and hotter and eventually detonates. Engine pulls lots of timing suddenly then the mixture is too rich and then shoots flames through the exhaust ports.

I've been tracking my 330 since 2008. My plugs were always black and I don't think I experience this heatsoak issue because I wasn't driving the car nearly as hard as I do now. Now with the new engine with the oil cooler, I see the oil temps top out at about 260 degrees and then the coolant gauge never moves past halfway.

I've done some asking around and apparently ESS does monitor intake temps but puts the mani air temp sensor before the compressor as well so you will probably run into the same issue.

Thoughts? Opinions? This could be a potential issue for any FI'd non-M that sees long term track use. This is a serious issue for me because this is about 2 months away from becoming a track car. I'm considering an S54 or LS swap but I would really like to keep this FI'd engine because its pretty damned fun and cool.
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Last edited by bigjae1976; 10-30-2012 at 10:42 PM.
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