Expert: Dan Liddy - 5/12/2009

Question
Hello Dan,
On my track prepared '94 Mazda Miata 1.8L (OBD-I), I run a Eaton MP45 supercharger (7psi), non-intercooled.  My fuel management is a Jackson Racing unit that intercepts the injector drive lines and extends the duty-cycles to dump in tons of extra fuel under boost conditions.  Timing control (an MSD unit) intercepts the crank angle sensor signal and spoofs the ECU into pulling timing when boost is detected.  I was told that if I add water/methanol injection (very affordable) that my effective octane rating would be high enough, and my intake charge cool enough that I can start running a much leaner mixture and run more aggressive timing, all for significantly more power.  My questions center on the use of a wide-band AFR meter as a primary tuning tool, and if this all seems a worthwile effort that should indeed yield more power (in my hot New Orleans climate). I was told that this whole thing was as simple as investing in the wide-band, installing the injection system, then start leaning my mixture (through adjustments to my fuel management) to run less "rich" under boost as indicated by the wide-band.  I believe I can get some good guidance on what would be a prefered AFR to shoot for.  As for timnig retard under boost, use my ears, listening for ping.  Can it really be this simple or do I need to find a dyno and professional tuner?  Mainly I don't want to hurt my engine, but as you are very well aware, we all need more power and will do almost anything to get it!  Is water/methanol injection a good means to get some?  Your advice welcome.  Thank you!
Leon

Answer
Hi Leon:

Water/Methanol injection has been around since my teen years
(the 50's)  But all that electronic wizardry baffles this old goat.  I use an MSD 6A for my racer and an electronic distributor, it stops there with dual carbs.  

So my answers are :  Yes, the water/methanol injection will help. and yes you should do your tuning on a dyno with all the good instrumentation you can get. trying to time an engine by ear these days will most likely get you a basket full of piston pieces. Trying to adjust a supercharged engine by ear is just crazy. One thing you should do is get an Exhaust temperature guage attached to each header down pipe,  Read the guages at max effort and max revs.  Any temps beyond about 1250Deg. F are chancy. I run my Datsun with forged pistons at 1325 F and if it starts to creep, I lift just a tiny bit.  This is head to head road racing in SCCA, I take no prisoners, but I also watch my guages well enough that I don't spend the season building engines.

I guess for the real answers regarding all the electronic gizmos, you'll need to find someone a bit younger. Try the Tech line at Summit Racing 1-330-630-3030.

Good Luck

Dan Liddy
Sarastoa, Florida