[Thecastle]

No, this hasn't been beaten to death.

I have a 2016 BMW 550i xdrive (N63TU). I race it at open road race, and may do speed week in Bonneville. In this environment I may run at 145+mph for 130 miles in 100+ degree heat on maybe okay 91 octane out there. Lots of full throttle pulls for 15-20 seconds at time. Its very different environment than what the typical tuner targets which is a couple of carefully controlled dyno pulls and said yup, nothing blew. Most customers do a 1/4 mile pull once or twice on the freeway then let things cool of for a while, so my use case is different than what most off the shelf tunes are designed for which is just a quick thrill.

I'm looking to accomplish 3 things really. Eliminate the top speed limiter on my car, increase the max cruise control speed to beyond 110mph, add some more power for fun (stage 1 91 octane).

BM3 my indy see's multiple engine failures monthly with their tunes and has 3 in the shop right now with blown engines. These are guys are just doing freeway pulls when their engines pop. Indy says don't do it. Some of this maybe folks are customizing the OTS tunes and blowing their engines.

MHD said nope, we don't recommend our tunes under those conditions, but would do a stock tune to lift the speed limiter. I appreciate their candor. I lean towards them, stage 0 speed limiter lift.

Who would you guys recommend for my use case? The engine has gotta stay alive for the 1500 mile round trip drive to the race, and through 130 miles of actual high speed racing. My N63TU is highly maintained, 100% stock (other than coil packs) and has 96K miles on it.

[Unspec]

Stock tune with vmax off.

To be clear, there is no safe tune for those conditions. There's a reason why popping engines is part of the game. However, stock tune will at least minimize it as much as possible.

[Thecastle]

thank you. I'm getting that impression with the BMW tunners, that none of them are "safe" or tested for sustained high speeds in high temps.

There were quite a few C8 vettes at the race that had to shut it down due to limp modes in the tranny for overheating so even stock some cars have trouble. None of the unlimited cars completed the race.... All of the BMWs and Mercedes made it.

Know anyone who can lift the cruise control speeds beyond 110? I ask is part of the race is to lock in to a specific speed, and using cruise control in the last 6 mile straight helps.

I remember when I had a highly modified GTI that APR would take their stage 3 (i had one) cars out to bonneville and run them to test their tunes. They destroyed a few engines in the process, mainly due to overheated spark plugs causing the engines to diesel / detonate due to hot spots. They ran even colder plugs and dialed back boost (heat) and increased fueling. Its possible to tune an engine for these conditions.

Racing improves the bread and helps tuners get to actual safe tuning.

[badblack550xi]

N63tu engines popping is very rare usually connected to very poor maintenance i think I've seen or heard about maybe one in past 5 years of tuning them. The car was a co part purchase and most likely was already damaged. Stage 1 91 octane should be fine and safe as long as you do 5k oil changes with oils like Redline 5W-50, lower temps with oil cooler, thermostat and lower temp radiator cap to help you fight heat soak.

[Thecastle]

Thanks what tune do you recommend? Most of the tuners I've personally contacted do not recommend even stage 1 for the kind of racing I do. I'm not talking a street pull or a quick dyno run. I might just remove it for race day and do stage 1 for fun. Ideally I'm trying to find a tuner that has a race proven tune, thats safe, and can raise my cruise limit above 110mph and remove vmax. What concerns the tuners is high temps 100+ and sustained high load, 91 octane, and altitude. The tuners don't think their tunes are safe for those conditions and have said so when I talk to their tech department. You might sit with your car idling for 5-10 minutes waiting to pull up to the start line before your run, and you leave with a full throttle pull to 140, then do some mountain climbs at those speeds, pulling some G's in those 65 mph corners. Its really a lot of fun.

I forgot to mention I do have a modded low temp thermostat already on my car one of the 1st things I did for longevity had too many bad valve steam seal episodes and plastic parts failing. Before the last race I replaced my spark plugs and coil packs, oil change, brake fluid change (new rear breaks and rotors), all new PCV system, filtered air ducts, oil pan leak fixed, front diff leak fixed (no leaks allowed during tech inspection), new pneumatic pressure converters both turbos, new air filters and etc.

[Thecastle]

P.S. I'll mention on race day every unlimited car blew their engine, and 2 caught on fire. A lot of tuned cars, and even stock DNF'd due to mechanical failures. The X5 in front of me disqualified for going to slow, so only my 550i and a 128 BMW finished of the BMWs.

I'm not trying to be difficult, I'm just trying to win. Not having the car go into limp mode or blow, or blow some part is part of the battle, but so is going fast. I've had a lot of tuned cars over the years and its very easy to go from functional race car to garage queen (its always broken). But some people find that fun, mod, break, fix, repeat. Thats not what I'm after anymore. I maybe beyond what the forums can offer, I realize but I like their wisdom!

[Unspec]

I think this is only a question you can answer, at this point. You're basically asking us to do for you what normally a race engineer decides, which none of us are really qualified for.