Negative effects of SEL scaling to decrease boost?

[bigdo26]

Headed to the track next week and will be running 25 minute sessions. I have used stock programming in the past at the track, and will again next week for part of the day. But I'd like to run a couple sessions in "chipped" mode, although I don't want to run 25 minutes with the standard GIAC boost levels. Since I don't yet have a MBC, I'm planning to use Lemmiwinks to turn down my boost levels by ~20% (peak of ~18 down to ~14.5). This is for turbo preservation since I run original K03's. Couple questions regarding this:

1. Any negative effects of using SEL scaling to decrease boost? Fueling concerns? Other?
2. In past tweaking experiments with Lemmi, it as seemed that SEL scaling decreases peak boost by the requested amount at lower RPMs, however as RPMs climb, the boost levels return to the level they would be without scaling down. This may be an incorrect observation since the boost delta is greater at mid range RPMs than high RPMs and is therefore more noticable. But I want to be sure...

Thanks

[Pete_S4]

I've considered doing what you are talking about, but I'm not sure anyone has ever seriously looked into the effects on other parameters aside from boost. Track connditions probably not the place to find out the other effects if they exist. :) I like your restraint on power when at the track, you are the type us intructors really appreciate. 25 minute run sessions are a little long, but you do have an external oil cooler which should help keep the turbos' oil cool enough. I'd probably just back off sometime mid session for a few laps to let things cool down a little if you are concerned. I've run my stage 2, 2+, and 3 cars for 10 years this way.

Also, you might want to look into getting the GIAC integrated boost controller option for your ECU. It's like $100 and lets you both raise and lower the boost target in the ECU itself. All you need is an OBDII cable (or VAGCOM) and the free chip switcher utility GIAC provides. I like this over a MBC because the ECU remains fully in control of the boost and can still cut boost to protect itself.

[bigdo26]

Thanks for the feedback - I might do as you suggest and just back off for a couple laps as temps climb. The car runs strong and turbos appear to be in great shape so with the large oil cooler I have I think I can keep temps down enough to be safe.

I didn't actually know about the GIAC 'boost control' option - I'll look into this, as I have VAGCOM as well as the GIAC flash loader / program switcher. Might be a handy thing to have the option of controlling boost through that - would be great actually!

[Pete_S4]

I actually find that, with my external oil cooler, I don't see temps past about 240-250 on even 25-30 min. run sessions with my AWE K04 kit. I really do like that boost controler option, hopefully it's available for your ECU. I recently had my K04s rebuilt with RS6 compressors, so I've been playing with setting the boost controller at ~22 PSI vs the standard ~20 PSI. I would have to take a good look at the EGTs, injector duty cycles, and so on before I'd feel comfortable running it at the track. One thing you should know is that the boost setting is not in PSI or BAR. It is a number between 1-255 with some number (210 in my case) being the "chipped" boost setting. I think 1 corresponds the WG spring pressure and 255 is the limit of the boost sensor, ~22 PSI on the 2.7T.

[bigdo26]

Good to know that your oil temps stay 240-250. I rarely go above 210 in regular driving with the external oil cooler, and as it sits now it only sees recirculating air (it's behind the bumper, not receiving airflow). I'm relocating it down behind the lower bumper openings for the track, figure that will significantly increase it's effectiveness.

I also run w/m - usually 50/50, but I'm dialing back my timing advance as well for the track, and I'm considering runing 100% water for cooling purposes only. Any experience with w/m injection at the track? It worked great for me over the summer - I had no heat soak at all in 90+ degree temps. I had chilled 5 gallons to about 10F the night before as well - I think that helped a lot. But that was a 50/50 mix as I was hoping for some knock resistance due to the high heat and only running 93 octane. This time with cooler temps, would just like to keep exhaust temps down some.

I realize I'm probably being overly cautious, but I'm an aerospace engineer and it's in my blood ;)

[Pete_S4]

I realize I'm probably being overly cautious, but I'm an aerospace engineer and it's in my blood ;)

Don't worry I understand your type just fine, I'm a EE myself. I've pobably way over thought more than a few things on my car!

My oil cooler is in front of the the lower passenger side corner of the radiator/condenser, basically where you are intending to move yours.

I have never used W/M, partially because I have upgraded ICs. I decided against it for power purposes because didn't want a custom tune that could blow up the engine should the W/M ever system fail. I honestly don't know anyone who has ever run W/M for cooling purposes at the track. Most people I know have just run a chip with a full exhaust or did a K04 upgrade in addition.

My prefered way to gain knock protection is to add a few gallons of 100 octane. I've also run 100 octane with my race fuel file on occasion. Pure 100 is not just higher octane, its produced in smaller batches and tends to have high quality control so your chance of getting tank of gas is pretty low.

The other thing you might consider is installing downpipes/piggie pipes. Getting rid of the flow restriction/heat mass that is the pre-cat should keep your EGTs down and help turbo life. It really helps spool up and has the added benefit of 20-30 HP. I really liked that configuration on my car and probably wouldn't have upgraded to K04s if it weren't for the K03's reputation and the smoking deal I got on a mildly used K04 kit.

[AudiSportB5S4]

OP - What do you use for the W/M? Are you running VP M1 50% to Distilled H20?

[bigdo26]

Agreed on the DPs - I have a set (test pipes too) just haven't put them on yet. They're the SSAC ones that came with my cat-back, so I'm a little hesitant to put them on. We'll see.

They sell unleaded 104 at the track, and I've considered filling up with that and running my 100 octane program too... Or just putting in a couple gallons of 100 and using my regular program. Did that once and it seemed that the car ran stronger.

I have the vast W/M kit, #4 nozzles, pump set to 150psi. Been running it since April with good results (and lots of logs). I get my methanol from J&M Motorsports in Manchester, CT and I don't recall the brand. I always mix it with distilled water as well. I've only experimented with 50/50 mix so far (give or take a couple %)

[NefMoto]

ME7 does all calculations based on actual load and specified target load. SEL (Specified Engine Load Scaling) is used to scale the specified target load. Setting this value to 80% does the exact same thing as only pressing the accelerator pedal down 80% of the way. Assuming a linear mapping of pedal position to driver specified load of course.

GIAC stage 1 doesn't do anything crazy like underscale load, so you shouldn't have to worry about any side effects to fueling or timing either.

[jibberjive]

I ran my GIAC stage 2+ car through 20 min sessions at the roadcourse a good amount of days. After each session I'd take cool down laps around the parking lot for like 5 mins at like 4th or 5th gear idle. The turbos held up fine, and actually looked really good when I pulled the engine afterwards. I'd personally fill up with racegas and not worry too much about it. The W/M scares the crap out of me though.

[bigdo26]

Appreciate the feedback - so SEL scaling simply tells the ECU the gas pedal is depressed a certain % less than it really is - kind of makes sense... Probably will just end up running the program as is and backing off the throttle on my own as needed.

I never rely on W/M at the track - too much potential to damage things if I tweaked my tune to rely on spraying w/m. I figure having it spraying on a standard tune may not help power wise, but it will at least keep IAT temps down while it works, and if it goes, it goes and everything just runs a little warmer.