brakebias

Tons of different perspectives on this topic but a lot of the older threads are on A8s or pre-2017 M7s. I have a '18 M7 - what's the consensus for solutions on heat soak/timing pull for this model year that do not involve cutting the front bumper? I'd imagine the car would be much harder to sell with a cheek cooler mod.

I know G-Speed has a no-cut solution but it's fairly expensive. Is that the only way or are there more inexpensive routes. Thank you in advance.

Bill Dearborn

Not really heat soak as power varies and doesn't necessarily vary with temperature. The key is making sure the intercooler is bled. Too much air in the intercooler leads to misfires in cylindres 7 and 8 which will knock about 200 HP off at peak power point. Sometimes the car will be down on power all day even on cool days and sometimes the power will drop off after a few good laps and then come back 7 or 8 laps later. It varies. Getting the air out seems to reduce the issue greatly.

The A8s had an engine overheating problem that wasn't due to heat soak. The A8 tends to keep the engine at an average higher rpm than drivers using M7s which can cause the engine to overheat. Cutting the front fascia and adding cheek coolers and replacing the oil to coolant cooler with an oil to air cooler increases cooling capacity by removing heat load from the engine cooling system thus reducing the overheating problem.

I see heat soak as something that happens after the engine has been run hard and then shut off (like in the staging lanes at a drag strip). Heat soak doesn't happen on a car that is running at WOT, high rpm at triple digit speeds.

Bill

brakebias

Interesting, so losing power/pulling timing is mostly a function of the intercooler bleeding as opposed to high fluid temps on '18 and '19 M7 cars and I don't need extra cooling for track? Is there a way I can check whether cylinders 7 and 8 or misfiring?

Took my car out to NJMP Lightning yesterday in ~65 degree weather running 1:12 pace, engine oil got up to 265 degrees, coolant got to 223 degrees and transmission fluid got to 235 degrees. Do these temps seem normal given the ambient temperature? I had telemetry but there was so much traffic that I couldn't tell if I was ever losing power. But to your point, an improperly bled intercooler can lose power even on cool days.

cabinInTheWoods

I'm dealing with the intercooler bleeding issue, myself. Some track days nothing happens. Other track days, like last week, the engine completely loses power but I have no limp mode warning or engine light/code.

Going to vacuum bleed this week and see if I can get the reservoir level to the near-full level.

9sec

I dropped 30* in everyday traffic red light stops and see a faster drop in temps after sitting by draining the entire system flushing it thourghly and replacing the fluid with distilled water and 1 pint of water wetter. with my extra expansion tank and double le row heat exchanger im at 2 gals 1 pint in the system. this is what a proper cooler bleeder bleed looks like compared to what most people will see if they look at the oem tank

ZMC2001

I'll try and post up a thread soon about it, but I was in the same position as you. I didn't want to cut up the front bumper and wanted to run cooler. I did a 2.5gal tank replacement to the OEM tank and then did another 2gal engine bay tank. I added a new high flow pump as well and used all -16an lines to route up the whole system. I also did a Dewitts 70mm radiator as well. In 75 degree weather, idling for an hour, manifold temps never got above 120 and the coolant held at 160-165. This system seems to be extremely promising, but I won't have more data until after I get the car tuned as I also did SPI for the ability to run full E85. I would be happy to try and get you some pictures or info on what I did if you are interested before I get around to writing a thread about the whole ordeal.