Mark,
The ignition curve is changed and re-shaped, advance starts sooner.
But the fuel map is untouched. This is true for all computers from 96
through current.
> -----Original Message-----
> From: Mark Kuzia [SMTP:flyboy01@worldnet.att.net]
> Sent: Thursday, May 20, 1999 7:28 PM
> To: dakota-truck@buffnet.net
> Subject: DML: Re: MP PCM - How do they do it?
>
> Jon,
>
> From what I understand by talking to programmers, they actually change the
> shape of the curve and fuel flow. The stock computer limits timing advance
> under 3000 rpm, over that they throw the timing back in, but only for the
> next 2000, then they pull a little out again at 5000. The fuel curve is
> overly rich which limits heat and detonation problem as well as reducing
> horsepower. These problems seem to be worse in the 97+ engines.
>
> Aftermarket computer lean the fuel curve for more power and give plenty of
> advance under 2400 rpms. They also give the sensors a wider set of
> parameters for operation with higher lift cams. the 15 to 30 horsepower
> gains depend on the level of modification, the more modified, the less
> power
> gained. !5 to 20 hp seems more accurate for modified trucks.
>
> Mark
>
>
> -----Original Message-----
> From: Jon Steiger <stei0302@cs.fredonia.edu>
> To: dakota-truck@buffnet.net <dakota-truck@buffnet.net>
> Date: Thursday, May 20, 1999 6:08 PM
> Subject: DML: MP PCM - How do they do it?
>
>
>
> I believe this has been discussed to some extent in past (I have even
> answered variations of this question), but I'm wondering if anyone out
> there knows exactly what MP does to put the "performance" in their
> "performance computers"?
>
> Here's the stuff I do know:
>
> The WOT fuel maps are richer.
> The timing is advanced. (I think I have heard 4 degrees?)
>
> Of course, the rev limiter and speed governer are altered as well, but
> they don't have any direct effect on the power output of the engine like
> timing would.
>
>
> Is the (supposed) 30hp gain from the computer merely from advancing
> the
> timing and a richer mixture at WOT, or is there more? As far as the
> timing
> goes, is it advanced X degress across the board, or did they actually
> alter
> the shape of the timing curve?
>
> Here is the reason I ask... I have been doing a lot of aftermarket
> ignition research lately (trying to hash out a plan for a nitrous system),
> and in my travels, I came across the Holley Pro Strip Annihilator. This
> ignition actually lets you program your own timing curve. Here is a
> snippet from their web site:
>
> >>>>>>>>>>>>>>>>
> Fully Programmable Timing Computer - Program a 32 point
> timing curve from zero to 50° (in 1° increments) from 500 RPM
> to 16,000 RPM (in 500 RPM increments). Max. timing span is 34°.
> Timing is accurate to within ±1/4° from idle to 16,000 RPM.
> <<<<<<<<<<<<<<<<
>
> You can probably figure out where I'm going with this... If most of the
> performance is merely from the timing, could you just slap this ignition
> on
> there and program in a similar curve? (With this method, you could even
> program in a custom curve to meet your unique requirements; you wouldn't
> be
> stuck with the MP one.) Get a set of high flow injectors and now you've
> got a richer WOT, just like the MP PCM...
>
> What do you think? Is it that simple, or is there more? I was thinking
> that if this would work, it might be an option for you '97+ folks that are
> waiting for computers.
>
> The one big drawback to this method is that, even *if* it does work,
> this
> particular ignition is in the $500 neighborhood. (Jegs has it listed for
> $559.99) Figure another $200 or so for the high flow injectors (for the
> WOT fuel increase), and you're looking at almost $800 to simulate a $250
> computer, but I guess if you're desperate enough... :-)
>
> Any thoughts on this? Feasable, or is my brain running a few volts shy
> of stoch? :-)
>
>
> -Jon-
>
> .--- stei0302@cs.fredonia.edu ------------------------------------.
> | Affiliations: DoD, EAA, MP Race Team, NMA, SPA, USUA. RP-SEL |
> | '96 Dodge Dakota v8 SLT CC (14.58@93.55), '96 Kolb FireFly 447 |
> `----------------------- http://www.cs.fredonia.edu/~stei0302/ ---'
>
>
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