Why the Porsche 911 (996) & Boxster (986) blow smoke when driven hard, and how to fix it.

While doing an engine teardown, we walk through the reasons the M96 engine can often blow heavy blue smoke, especially when driven hard, and when the throttle is lifted after heavy acceleration. 

[@captainkai9989]

awesome content ; keep sharing please

[@mikepetersen3]

Sorry, have been so busy, not enough time ;-(

[@robmeador8971]

Hi Mike, do you have any updates on this? I have a track day coming up and Id like to see your results as I too get smoke in hard turns.
Thanks!

[@earthlingtheaaron21]

Is the deep sump and Accusump enough to keep the engine from starving in high G loads? I’m trying to make a plan of action for making a boxster a reliable track car.

[@mikepetersen3]

I have an Accusump on the car. It works fine, but does run dry occasionally in longer high G turns. Video is here: th-cam.com/video/lp-PJr1aPtA/w-d-xo.html. Im also now adding a 2qt deep sump from LN Engineering. Im not impressed with the design but I have not had it on the track yet. I just posted that video here: th-cam.com/video/qSS12Sr4QCU/w-d-xo.html. I will post more info this summer after I have tracked tested them with pressure gauges accusump discharge indicators. Neither is perfect, but I THINK the deepsump may be the better option.

[@Anil-bg5se]

Thanks for the video Mike! When you put a filter to the AOS, isn't it going to cause a vacuum leak even if we plug the intake side?
Also, have you thought of adding an oil catch can between the AOS and the filter in case oil passes AOS?
If this works well, air/fuel ratio is going to be better as well since there is no unknown air to the engine, right?

[@mikepetersen3]

Hi Anil, Hope this helps...
Q: When you put a filter to the AOS, isn't it going to cause a vacuum leak even if we plug the intake side?
A: No, the crankcase will now have a small positive pressure, and it will force the crank gases gases out of the AOS into the filter, similar to how crankcases have been vented in cars for many years through PCV's.
Q: Also, have you thought of adding an oil catch can between the AOS and the filter in case oil passes AOS?
A: The AOS already has a built in "catch can" and the caught oil flows directly back into the block. If you look at the AOS there are three connection points, one for the LH head, one for the RH head, and one for drainage into the block.
Q: If this works well, air/fuel ratio is going to be better as well since there is no unknown air to the engine, right?
A: It will lean out the A/F mixture. Based on dyno testing with a wide band sensor installed, this car is already running slighter richer than optimal, so this may help lean it out to the ideal ratio. That said, we are making other mods to the car and we will dyno/test the car with all the changes and then determine if A/F adjustments are necessary on the tune.

[@Anil-bg5se]

@@mikepetersen3 Thanks for the detailed explanation! I will do this to my 986 after passing the smog test.

[@mikepetersen3]

You may want to want for a month until we have dyno results and a little more insight.

[@Anil-bg5se]

@@mikepetersen3 Sure, I am looking forward to for Dyno results. I read in forums that long term fuel ratio doesn't like it but not sure why. In any case, I will experiment with my car too and check myself how long term fuel ratio changes over time.