[W126 Coupe] tornado air twister

[eurotech1 at charter.net]

Didn't work that way on the BMW, we were in that area, it lost some throttle response, felt better at 14.1 and better, until you went 14.5 or more, then it started leaning itself out, it would stop around 17:1 or a little more, but it was getting plenty of fuel, we had a high volume pump, and big injectors. Nobody could explain it, but when the WOT map was set in the 14.3-14.4 range, it made more power, and it stopped leaning itself out. This was all done on the road, at 18lbs. of boost, the boss was driving, and I was plugging the figures into the ECU program on the laptop, and monitoring the a/f ratio display, and operating a stopwatch. It was kind of busy in the cockpit, but a week or so later, we put it on a dyno at another shop, turned up the boost, and made some changes on the fuel map, but don't remember what changes were made, because the boss was running the laptop that time. But that's where that one ended up while we were driving it.

                      Later,
                      Chris

============================================================  
> From: Jim Nowak <jjnowak_32503 at yahoo.com>
> Date: 2005/04/03 Sun PM 04:10:29 EDT
> To: Mercedes Coupes Mailing Lists <mbcoupes at mbcoupes.com>
> Subject: Re: RE: [W126 Coupe] tornado air twister
> 
> 14.7:1 is stoichiometric.  That's ideal for emmisions
> but not ideal for power.  For maximum power 13.5:1 is
> ideal.      
> 
> http://www.kennebell.net/faq/faq-answers11%286%29.htm
> http://www.carcraft.com/techarticles/116_0402_tune/
> 
> Jim
>      
> --- eurotech1 at charter.net wrote:
> > 
> > Hi Jim,
> > 
> >   In the case of a 318 BMW we turbo'd at the shop I
> > worked at, we had to remap the fuel map in the
> > ECU.We used a H-P laptop with a USB to diagnostic
> > connector cord. We connected the connector to a
> > piggyback computer on the BMW ECU. The piggyback
> > overwrote the original fuel map with a program from
> > Underdog Racing Development we used to remap.
> > We read the air/fuel ratio with a wideband sensor
> > display unit from Innovate Motorsports. As you know,
> > 14.7:1 is the ideal air/fuel ratio for a gasoline
> > engine. At higher RPM at the top end of the boost
> > (18 lbs.), we set the mixture at 14.3-14.5:1 (a hair
> > richer) to prevent a lean condition at WOT. Tuning
> > the fuel map made a world of difference, as a matter
> > of fact, the brand new BMW clutch and pressure plate
> > were starting to slip at about 3500 RPM , the motor
> > was producing so much torque. A Centerforce six-puck
> > racing clutch and pressure plate took care of that.
> > The 1.8 had a pair of cams from Web-cam, Rossi 8.5:1
> > pistons, rods were stress-relieved, the turbo came
> > from a 2.0 Buick Skyhawk, and used a Jackson Racing
> > dump valve. Used Innovate's electronic boost control
> > unit, with an indash control center. On a Dynojet
> > dyno, it did 307 hp at 6200 rpm at 20 lbs. of boost,
> > with a 50 shot of nitrous at 5800.
> > That was a fun car!
> > 
> >                        Later,
> >                        Chris
> > 
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