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Old 02-18-2011, 03:01 PM   #177 (permalink)
abell75
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Join Date: Nov 2010
Location: St. Louis
Posts: 38

Grand Prix - '02 Pontiac Grand Prix GP
90 day: 24.01 mpg (US)
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Quote:
Originally Posted by MetroMPG View Post
If that line does show torque at WOT, that may make it incredibly useful: could you not essentially use it to extrapolate what throttle/pedal position to use to get the engine closest to the sweet spot at a given RPM?

EG. in the Saturn chart, 7/9 throttle @ 2000 RPM looks like it would put you squarely in the 250 g/kWh island.

Of course it doesn't work quite that simply, because the engine doesn't "idle" at 2000 RPM ("0/9ths"), so you'd likely have to factor in the amount of pedal required to get there with no load on the engine.


I think our group is close to nailing this down, but since I just got an Ultra-Gauge I thought I'd ask for some clarification. (I get to apply the science, yay!)

1. Have we concluded that torque on the chart correlates to load and/or throttle position on the SGII or the UG?
2. If we have, which is the preferred gauge to monitor (load or TP)?

It would seem to me that load correlates to torque, and the %load we should target during the Pulse part of P&G is defined as that which puts us in the middle of the most efficient island. Others have mentioned TP though; is there a reason it would correlate better?

It's difficult for my brain to believe that accelerating at 80% load/throttle is the most efficient use of the fuel - I've always been told that slow/steady acceleration is better. I have faith in science though (oxymoron alert!), and will certainly give the high load rapid acceleration approach a shot.

If we do reach this conclusion, perhaps it should be added to the BSFC wiki page.
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