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Author Topic: e85, timing, mpg?  (Read 7558 times)
ktm733
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« on: March 19, 2015, 09:40:52 AM »

So we can advance timing in higher load and we have a course we run to see when adding timing makes no difference. how would I do this for say 50% load cruising around? I'm tired of horrible gas mileage with e85 so why not make it more efficient. I could just advance timing but how would I know I've advanced to far?
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prj
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« Reply #1 on: March 19, 2015, 10:14:36 AM »

The only way is on a dyno with a real time emulator monitoring torque in real time, and stop to add timing once torque does not increase anymore.
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ktm733
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« Reply #2 on: March 19, 2015, 10:45:27 AM »

Ouch only a dyno Sad sounds expensive.
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prj
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« Reply #3 on: March 19, 2015, 12:05:33 PM »

Is everything that costs more than "free" expensive to you?

Yes you need a dyno to make for example a timing map from scratch, that's why those things actually exist, not to do dyno runs for who has the bigger d..k Wink
And essentially what you need is to make a map from scratch for your car.

Also you need a realtime emulator. The RoadRunner will work, but that is around 500$ - probably also too "expensive".
Commercial stuff before the RoadRunner came used to cost thousands.
There is an alternative way - you could use something like lemmiwinks to adjust your timing in each cell on the dyno and write down the result.

At some point you have to pay to play, especially if you take on more ambitious stuff.
« Last Edit: March 19, 2015, 12:07:35 PM by prj » Logged

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turdburglar44
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« Reply #4 on: March 20, 2015, 07:52:11 AM »

Timing at low loads on ethanol isn't much different than gas. The limiting facotr with gas is knock control and you don't run into that at low loads. One thing you can do is find a long stretch of empty flat road. Set cruise control and average your injector on times. Saw a cool write up somewhere on the internets. The guy found it was better to be slightly over-advanced than under advanced.
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prj
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« Reply #5 on: March 20, 2015, 08:05:23 AM »

Timing at low loads on ethanol isn't much different than gas. The limiting facotr with gas is knock control and you don't run into that at low loads. One thing you can do is find a long stretch of empty flat road. Set cruise control and average your injector on times. Saw a cool write up somewhere on the internets. The guy found it was better to be slightly over-advanced than under advanced.

If even a little wind comes your measurements will be off.
Plus, you of course can not visit all the cells in the map. You can only visit the ones that will be used in cruise, but you can't tune the mid-range loads where a lot of fuel economy is realized (like going uphill on cruise).

There are no two ways about this, you need a load bearing dyno. It's the only right way to do this, everything else you might as well use the stock map and forget about it.
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overspeed
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« Reply #6 on: March 20, 2015, 12:39:15 PM »

Timing at low loads on ethanol isn't much different than gas. The limiting facotr with gas is knock control and you don't run into that at low loads. One thing you can do is find a long stretch of empty flat road. Set cruise control and average your injector on times. Saw a cool write up somewhere on the internets. The guy found it was better to be slightly over-advanced than under advanced.

I disagree, you can raise 6° all over the curve withou any issue,

Here in brasil we have E100 and I ussually raise between 9 and 13° in these cases... more than 10° didn´t make much diference in torque/power, but help a little with consuption
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prj
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« Reply #7 on: March 20, 2015, 12:44:04 PM »

I have dyno tuned MBT timing maps for some engines on E85, but I am not sure how I feel about posting them...

Maybe if you told us what engine you have...
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turdburglar44
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« Reply #8 on: March 20, 2015, 03:20:48 PM »

If even a little wind comes your measurements will be off.
Plus, you of course can not visit all the cells in the map. You can only visit the ones that will be used in cruise, but you can't tune the mid-range loads where a lot of fuel economy is realized (like going uphill on cruise).

There are no two ways about this, you need a load bearing dyno. It's the only right way to do this, everything else you might as well use the stock map and forget about it.
Yea I agree but the write up was very interesting. Wish I could find it. He got pretty conclusive  results. That one timing cell was tuned perfectly! Ha
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ktm733
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« Reply #9 on: March 20, 2015, 06:16:19 PM »

You would be a god!! Haha i have amb 1.8t same with the other guy. His car is my twin, well very close. So i advance 3 degrees and i love how smooth it is. It's like glass.
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prj
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« Reply #10 on: March 21, 2015, 03:21:02 AM »

1.8T I have only dyno tuned on gasoline, and there are so many different variants (port configurations, compression ratio), that most likely even if I had something it would not be a good match.

You can try asking Nick, he might have something for you.
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ktm733
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« Reply #11 on: March 21, 2015, 04:38:13 PM »

Who is Nick?  Can you point me in his location?
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