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Old 09-14-2011, 06:51 AM   #41
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*on gasoline.

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Old 09-14-2011, 07:14 AM   #42
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Quote:
Originally Posted by MartinezA92 View Post
If I remember that conversation correctly, he was saying that 14.7 at WOT on an N/A car was safe. I also remember somebody posting their AFR target table and I believe that it showed 14.7 through the entire range up to redline. (N/A)

I don't know about you but that scares me a little.

Take some readings off of any car from the factory and I am willing to bet that none of them will read 14.7:1 at WOT.


I'm pretty sure that was someone else...
you maybe suprised at what the oems will read till a certain rpm and airflow is hit.

I didn't think he said anything about 14.7 is safe at wot

Here we go
http://forum.miata.net/vb/showpost.p...&postcount=108
he says transitioning into boost at 100kpa is 14.7 but notes only that, does not note if it is the same thoughout the rpm range.

Quote:
100kPa is 100kPa, regardless of whether the car is N/A or turbocharged, so one should aim for the good old 12.5:1 between 90 and 100kPa.
I'll disagree to a point, like say at top of the rev range than yeah I can agree
at low rpms no

Last edited by Techsalvager; 09-14-2011 at 08:02 AM.
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Old 09-14-2011, 10:23 AM   #43
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A lot of turbo cars stay at 14.7:1 in boost below peak torque...Think of the MSM or MS3 stock AFTR curves.

The N/A motor from that factory stays stoich below ~5.5K.

But if you are taking it to redline, you are crazy.
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Old 09-14-2011, 10:35 AM   #44
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around 4k rpm 100kpa I start adding more fuel.

its been a while but I iirc even at wot the factory computer in the 1.6 N\A wouldn't go open loop till after 4k rpms, but its been a while
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Old 09-14-2011, 10:40 AM   #45
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Quote:
Originally Posted by Braineack View Post
A lot of turbo cars stay at 14.7:1 in boost below peak torque...Think of the MSM or MS3 stock AFTR curves.
I noticed this same things with quite a few OEM turbo platforms. many stay 14.7 all the way up to 100kpa at low load and some even hit a few psi before dipping under 14.
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Old 09-14-2011, 10:42 AM   #46
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I stay in the high 13s in low boost at low rpm, and barely retard timing as well. Motor is running strong. Perfect compression and even leakdown.
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Old 09-14-2011, 07:12 PM   #47
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Quote:
Originally Posted by 18psi View Post
I noticed this same things with quite a few OEM turbo platforms. many stay 14.7 all the way up to 100kpa at low load and some even hit a few psi before dipping under 14.
emissions

If they could, I'd bet $20 that they would tune it just like we do - nice, fat, and safe.

(Just like the girls you date )
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Old 09-14-2011, 07:13 PM   #48
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I'd believe that. I just keep it lean under 5psi below 5K. I was getting something like 27mpg city.
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Old 09-14-2011, 07:14 PM   #49
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Quote:
Originally Posted by Braineack View Post
I stay in the high 13s in low boost at low rpm, and barely retard timing as well. Motor is running strong. Perfect compression and even leakdown.
Too lean. If you are in boost, it means that you're making as much/more torque than the car did naturally aspirated, which means that internal pressures/temperatures are just as high/higher than they were naturally aspirated.

N/A cars get tuned to ~12.5-12.8:1, which is where turbo cars should get tuned to at low boost. And by low boost I mean like 2psi. At 4psi it should be 11.6:1 because that's where it makes the most power.
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Old 09-14-2011, 07:20 PM   #50
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power is for suckers!
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Old 09-14-2011, 07:25 PM   #51
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Quote:
Originally Posted by Techsalvager View Post
I agree with him there as long it under certain rpm, my turbo likes to easily bring up to 100kpa under low rpm

shift, open throttle, to start going again and its back up to 100kpa easily

before tuning that area it would go to 13.x, why waste fuel, I haven't heard any det or noticed anything wrong yet, liked to see what EGT would show.
It's not the turbo, it's a function of mass flow rate through the motor at low RPM. Low RPM draws less vacuum than high RPM does, which means that you don't need to open the throttle as far to get the manifold back to ambient pressure. As the RPMs increase you have to open the throttle further so it's not a restriction.

The load on the motor itself is still fairly high, since it's ingesting all the air it wants to, but the EGTs probably aren't high enough to worry about at such low RPM/low exhaust restriction.

Fuel is cheaper than engines, so I tune conservatively.
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Old 09-14-2011, 07:37 PM   #52
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Quote:
Originally Posted by Braineack View Post
A lot of turbo cars stay at 14.7:1 in boost below peak torque...Think of the MSM or MS3 stock AFTR curves.
Yeah or the BMW 335 twin turbo.
All of these cars can make a lot more power when properly tuned. My suspicion is that the factory tune is set up based on EPA and fleet MPG targets.

Want to be jealous? Look what Vishnu does with a stock 335i with tuning tweaks (a lot of which is just adding fuel)...

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Old 09-14-2011, 10:50 PM   #53
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Good God!

I bet 390ft*lbs of torque at 2500rpm is pretty damn nice in a 3 series without a hood bulge.
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Old 09-15-2011, 02:19 PM   #54
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Good as it gets without going near the border. Lol
that is incorrect sir. corpus christi is good as it gets when it comes to "real" mexican food without going near the border. when we go san antonio or austin, mexican food is out of the question.
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Old 09-15-2011, 02:21 PM   #55
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now i want mexican. but im getting BBQ chicken pizza tonight.
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Old 09-15-2011, 02:37 PM   #56
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[QUOTE=Ben;771351]Yeah or the BMW 335 twin turbo.
All of these cars can make a lot more power when properly tuned. My suspicion is that the factory tune is set up based on EPA and fleet MPG targets.

Want to be jealous? Look what Vishnu does with a stock 335i with tuning tweaks (a lot of which is just adding fuel)...

that is crazy ^^^^ you sure that's stock filter/exhaust? amazing if so.
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Old 09-15-2011, 02:40 PM   #57
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Thats not bone stock. That plot is with downpipes/ehxaust at least. A friend of mine had that package.

Same thing happens when you do full exhaust and custom tune on most other turbocharged cars. Your typical Evo/STi see's a 40-70hp and 50-90tq gain.
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Old 09-15-2011, 05:51 PM   #58
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Quote:
Originally Posted by spoolin2bars View Post
that is incorrect sir. corpus christi is good as it gets when it comes to "real" mexican food without going near the border. when we go san antonio or austin, mexican food is out of the question.
I have grown to really like Corpus Christi. Good times and good food there.

Have you noticed that this thread is starting to look like the Amazon River in it's off topic turns?
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Old 09-15-2011, 10:07 PM   #59
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Quote:
Originally Posted by Savington View Post
Too lean. If you are in boost, it means that you're making as much/more torque than the car did naturally aspirated, which means that internal pressures/temperatures are just as high/higher than they were naturally aspirated.

N/A cars get tuned to ~12.5-12.8:1, which is where turbo cars should get tuned to at low boost. And by low boost I mean like 2psi. At 4psi it should be 11.6:1 because that's where it makes the most power.
Isn't the actual goal just EGT? You want EGT below a certain value even at part-throttle.

Also, I thought the most power was at 12-12.5:1 (when timing isn't not knock limited). I was a bit surprised while playing with mixtures at idle, the engine started dropping in revs below 12 or 12.5:1.
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Old 09-16-2011, 04:54 AM   #60
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Dyno testing shows that 11.6:1 makes more power than 12.0:1, even way down at 6psi. I was surprised too, I did not expect to pick up 5whp by going from 12.0:1 to 11.6:1 at ~6psi, but the dyno doesn't lie.
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