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| Tofuball's '94 XFi; It's all about city MPG | |
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| Tweet Topic Started: Mar 12 2011, 08:59 AM (39,440 Views) | |
| 100MPG | Apr 27 2011, 06:59 PM Post #136 |
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nice to see that we agree or at least close on most things. and bigger differences are probably mostly misunderstanding i can't always explain what i'm thinking exactly. putting the picture in your head into words is really tough sometimes i got you on the always flowing thing, definitely something that needs to be developed i think that even though you might not make any additional torque beyond a certain compression point, there might be a gain in burn speed and less lead time in the ignition and less pushing backwards on the crank. i can't agree with more air is more power, more rpm yes some ECUs can cover a small nitrous shot and thats huge compared to what i'm asking it to do i get the fine mist injectors and the hot valve hit just not sure how i feel about it for creating a homogeneous mixture Dana |
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| Tofuball | Apr 27 2011, 07:15 PM Post #137 |
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Strange Mechanic
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You don't want homogeneous - this isn't power, it's MPG, your ideal is a small rich pocket right at the spark plug and a sphere (or disc) of insane lean around it, then air without fuel. More air in the cyl is almost always more power, as you can then add more fuel, that's the idea behind most tuning ![]() I don't think you need to worry about burn speed to much in these engines, they have a decent stroke. Your burn speed is going to already be insane in the higher loads if you run the right mixture. You're making me very interested to see what comes of your work - especially since you're considering running in territory I previously thought unobtainable. |
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| 100MPG | Apr 27 2011, 07:26 PM Post #138 |
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more air in the cylinder, yep more power.. i was thinking volume of airflow come to think of it, at these low speeds you can trap a good sized load of air i only know homogeneous .. hmm, now your someplace that i don't have a clue about in building for power, your also building for efficiency , kinda the same thing, different application this is kinda hard to get your head around... lol Dana |
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| Tofuball | Apr 27 2011, 07:29 PM Post #139 |
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Strange Mechanic
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Yeah, that's why I want to do it!
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| 100MPG | Apr 27 2011, 08:01 PM Post #140 |
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well i'm going to have go with what i know and build my way, i'll leave all the new high tech stuff to the people that understand it.. for now... lol Dana |
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| Tofuball | Apr 27 2011, 08:10 PM Post #141 |
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Strange Mechanic
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Come over for a BBQ some time and I wont shut up till you understand the high tech stuff
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| Robertwb70 | Apr 27 2011, 10:08 PM Post #142 |
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Tofuball does your 94 have vacuum advance on the distributor? I was surprised when I took the distributor in my 91 apart and it had centrifugal advance, which means the ECU has absolutely no control over the timing in my car. What year did the computer gain control of the timing I wonder, maybe 95 with the redesign? Probably doesn't matter much since I'm pretty sure they didn't have knock sensors even then. |
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| 100MPG | Apr 28 2011, 12:50 AM Post #143 |
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Dude, your like 3,000 miles away and theres no way i can afford 30 gallons of fuel...lol Dana |
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| Woodie | Apr 28 2011, 06:41 AM Post #144 |
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Vacuum advance went away in 92. Cultus GTi and T3 turbos had knock sensors back in the late 80's. No Metros ever got one. |
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| Tofuball | Apr 28 2011, 06:44 AM Post #145 |
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Strange Mechanic
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Mine doesn't have a vac advance. BTW having the weights doesn't mean the ECU has no control of timing ![]() If the ECU didn't have control of timing, plugging the test connector would do nothing at all! Knock sensors aren't the only information the ECU would use to control timing. |
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| mcmancuso | Apr 28 2011, 10:53 AM Post #146 |
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You don't plug the wire connector in vacuum advance metros, just take off the vacuum lines for timing. |
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| Robertwb70 | Apr 28 2011, 04:03 PM Post #147 |
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Yeah, I was going to say, "what test connector?". With only a hot and ground wire going to the distributor I don't see any way the ECU could control anything, just another reason to find me a 92-94 3/5 when I get rid of this auto trans version. The knock sensor would be the one that matters, maybe an after market version is available that wouldn't cost too much, I seem to remember seeing one years ago in Hot Rod magazine (or one of the other Peterson publishing car mags) but haven't kept up on it. |
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| Bad Bent | Apr 28 2011, 10:40 PM Post #148 |
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Facetious Educated Donkey
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And plug them instead? |
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| Robertwb70 | Apr 29 2011, 01:49 AM Post #149 |
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Yep, really only need to plug one of them (the full time/ manifold vacuum line), I use a golf tee or sometimes just stick my finger over the end... |
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| Tofuball | Apr 29 2011, 07:41 AM Post #150 |
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Strange Mechanic
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MS2e Tuning guide on economy: http://www.msextra.com/doc/ms2extra/MS2-Extra_Tuning_Manual.html#economy It's not exactly the way I do it, but I think it should clear up a few things. Keep in mind it's explaining how to tune for 16.5:1, not 14.7:1 - and holding it there cleaner then the stock ECU would. Even with timing adjustments, it will likely produce slightly less power, so assume slightly less then a 11% gain in highway cruising FE from the change in AFR, though pumping losses will be very slightly reduced (you'll be slightly deeper into the throttle). If tuned very carefully, especially paired with other supporting mods, you could likely run even leaner, ESPECIALLY under less then cruising load - though as load increases you'll tend to want to run richer. |
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