Why does Stage 1+ ping... Re: [s-cars] Octane and Unleaded Race Gas Article

[Robert Pastore]

<snip>
........Perhaps the MTM Stage 1+ should carry a minimum octane requirement
of 93 octane.  I think this would probably also apply to the similar
power-output level IA Stage 3+. <snip>


Keith/rob/etc:

MTM 1+ is pings IMO for 2 reasons:  1) it was designed for German 98 octane,
at a price of $4/ gallon.    With high quality gas, the lean part throttle
characteristics serve two important purposes:  (a) Lean mixture burns hotter
and spools turbo quicker when you get into it.  (b) Lean mixture delivers
excellent fuel economy!

The setup Ned calls his III+ uses MTM's 1+ boost chip, and Lehmann's rs2
timing chip.   It is a coincidence ( that I assume Ned discovered) that its
mapping works well with a k24.  This is the same timing chip Hoppen uses in
all of their rs2 setups.    This chip, in an otherwise stock k24 environment
( w/ 3 bar 1+ boost chip) runs smoother and richer than mtm1+.    I've
solved drivability issues for several 1+ setups by just swapping the timing
chip.

I prefer the hard hitting feel of the 1+, but in reality I don't think it is
any faster than Ned's III+.    This is a good solution for 1+ cars that
ping, but the downside is that fuel economy will suffer.

I plan on writing/testing a 1+ based chip that will have injector duration
increased below 40-50% load (i.e throttle opening).  It'll be a month or so
before I get the time to do this and test it.

Bob