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Old 02-26-2009, 02:41 PM   #141
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Quote:
Originally Posted by The_Pipefather View Post
Simple terms, richer mixture needs more time to burn hence needs more advance to reach the optimum PPP, which is between 12-20 ATDC depending on the engine. For a bore size of 80 to 90 mm, 14-16 ATDC seems reasonable.

Thats why MBT (max. brake torque) timing advances with a richer AFR.



You're hitting pcp for THAT combination of AFR & timing. That doesn't mean that's the best pcp you can achieve for your engine. All I'm saying is, a safer way to make equal or higher torque is to run richer and more advanced. Try it, you might be surprised at the result.
well, I tried it initially, and found that 11.5 made more power than fatter or leaner, and that at MBT, it made no more torque. How else do I determine the reasonable limit on AFR?
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Old 02-26-2009, 02:42 PM   #142
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ugh, tuning is complicated :(
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Old 02-26-2009, 02:51 PM   #143
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well, I tried it initially, and found that 11.5 made more power than fatter or leaner, and that at MBT, it made no more torque. How else do I determine the reasonable limit on AFR?
so if I understand correctly, you richened the cell in question to below 11.5, and THEN did a spark sweep on that cell. You found it made less power than your present map?
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Old 02-26-2009, 02:53 PM   #144
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so if I understand correctly, you richened the cell in question to below 11.5, and THEN did a spark sweep on that cell. You found it made less power than your present map?
more like "no improvement" than less. I tried everything under the sun to get torque to flatten out on top. It made no improvement. This is how I arbitrarily determined that 11.5 was the magic #. It was actually stronger leaner, but that didn't sound safe to me.
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Old 02-26-2009, 03:10 PM   #145
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then you probably didnt reach MBT in the rich condition at all. I would suggest a re-try using the EGT number instead of the torque number once you've attained said peak torque number for that cell. The reason is, you might be in the dyno "deadband" and might not see the torque change produced by 1 or 2 degrees of advance.

I wish someone with more knowledge than I would chime in on this too.
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Old 02-26-2009, 06:32 PM   #146
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when should I put the cops and new plugs in? A week before going to the dyno, right before I go on, or half way through? Tips on gap for "big boost?"
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Old 02-26-2009, 06:44 PM   #147
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MBT minus 2-3* = the correct timing you should tune for in every cell. Most cars can't find MBT in boost without getting detonation. Adding fuel helps to combat detonation and allows more advance to further approach MBT.

If you're can get to MBT at 12:1, then 11.5:1 won't make any more power. But if you were at 12:1 and could not get to MBT without detonation, you would find that dropping the AFR and dialing in more advance will yield more power. And lower EGT's too.

Here's what you should do IMO. Put the COPs on now. Put new BKR7E plugs in there and gap them at .020 or .025 inches. Make a new AFR table that mimics mine in boost. Much like I smoothed your timing table and you noticed an improvement, the same will be true with your AFR table. This will help spool, response, and smoothness rather significantly.
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Old 02-26-2009, 07:03 PM   #148
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Originally Posted by patsmx5 View Post
Adding fuel helps to combat detonation and allows more advance to further approach MBT.

If you're can get to MBT at 12:1, then 11.5:1 won't make any more power. But if you were at 12:1 and could not get to MBT without detonation, you would find that dropping the AFR and dialing in more advance will yield more power.
MBT timing is NOT a single constant number for a given cell.

A definition of MBT timing so there is no further confusion:

"The minimum amount of spark advance required to output Max Brake Torque at a given operation condition (aka "cell")"

In other words, for every parameter like AFR, atmospheric temp and pressure, fuel octane, spark energy, compressor efficiency, intercooler efficiency etc, the MBT timing can change at a given operation condition (aka "cell")

Efficiencies, fuel octane, spark energy and to some extent atmospheric temp and pressure are things he cannot change for his setup (forget COPs for a moment). The only parameter that's under his control is AFR, and therefore, that has to be taken care of first before an MBT timing FOR THAT AFR MAP can be determined.

Get it?
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Old 02-26-2009, 07:14 PM   #149
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Quote:
Originally Posted by The_Pipefather View Post
MBT timing is NOT a single constant number for a given cell.

A definition of MBT timing so there is no further confusion:

"The minimum amount of spark advance required to output Max Brake Torque at a given operation condition (aka "cell")"

In other words, for every parameter like AFR, atmospheric temp and pressure, fuel octane, spark energy, compressor efficiency, intercooler efficiency etc, the MBT timing can change at a given operation condition (aka "cell")

Efficiencies, fuel octane, spark energy and to some extent atmospheric temp and pressure are things he cannot change for his setup (forget COPs for a moment). The only parameter that's under his control is AFR, and therefore, that has to be taken care of first before an MBT timing FOR THAT AFR MAP can be determined.

Get it?
I get it. Did you read what I wrote? Perhaps you misinterpreted what I said? MBT is minimum best timing in my book. You tune for LPP of ~14*ATDC. For a given set of conditions, he'll adjust spark timing and watch the torque output measured by the dyno. If he can advance till he finds max torque and any further advance makes less power, he's crossed MBT and moved LPP too early, inducing more negative torque. He'll then retard to find MBT which will put LPP ~14*ATDC. Then if he's smart he'll pull 2-3* from that value to allow for small changes in the tune and to reduce PPP some without affecting total output substantially.
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Old 02-26-2009, 07:47 PM   #150
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Originally Posted by hustler View Post
more like "no improvement" than less. I tried everything under the sun to get torque to flatten out on top.

This is the issue we had on Newbsauce's motor, and why he ultimately purchased a new IM from BEGI.


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I realize he's down 1-2 pounds of boost past 6.5K, but thats a 55rwtq drop from peak...fooling with spark or fuel would not alter the curve.
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Old 02-26-2009, 09:56 PM   #151
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Quote:
Originally Posted by patsmx5 View Post
Here's what you should do IMO. Put the COPs on now. Put new BKR7E plugs in there and gap them at .020 or .025 inches. Make a new AFR table that mimics mine in boost. Much like I smoothed your timing table and you noticed an improvement, the same will be true with your AFR table. This will help spool, response, and smoothness rather significantly.

pat that's awfully tiny gap for COPs. part of the idea behind running the COP setup is to increase the gap in boost so you dont have to worry about spark blowout.

(sidenote: show on tv just mentioned pascagoula, ms and the northrop grumman plant)

anyway, I'd encourage hustler to run as much gap as possible. for up to 15 psi, even .040 isn't out of the realm of possibility. above that, drop a few thou. maybe .035 for 20 psi?

it should be pretty solid.
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Old 02-27-2009, 01:15 AM   #152
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patsmx5, my response was in regards to this statement of yours, which is not true:

Quote:
Originally Posted by patsmx5 View Post
If you can get to MBT at 12:1, then 11.5:1 won't make any more power.
MBT timing at 12:1 is separate from that at 11.5:1, is my point.

On a different note, "minimum best timing" is a term I havent heard before.

MBT = Max. brake torque. is a term frequently used to denote engine load, at least in engineering circles.
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Old 02-27-2009, 01:25 AM   #153
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minimum best timing for maximum torque
or minimum timing for best torque
or whatever.

the thing is, timing and air/fuel ratio are interactive quantities. you have to iterate to get both right to be ideal. the easiest way is usually "make it really rich and find MBT" and then retune your fuel map after that. then if you want to check for MBT again, you will be able to zero in on it better because the fuel delivery will be closer to optimized.

but it's probably very close to the same within a small range of AFRs. between 11.5 and 12:1, it's doubtful you'll be off by more than a degree from MBT either way.
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Old 02-27-2009, 08:56 AM   #154
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I put in a new manual boost controller and now my ca drives like a whipple again. :(

My gauge is so innacurate that its more of an idiot light. I'm going to now pre-load the actuator, maybe that will help.
I think this is a case of "real world" vs. dyno.

oh, and apparently I've been driving around at 12.5psi...not 16 like I did on the dyno. No wonder it feels slow. 250whp is for bitches. Seriously, turn the boost up, like a man.
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Old 02-27-2009, 10:05 AM   #155
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so, I emailed omori to see if they'd make a "KPA" unit mechanical boost gauge. lol

Apparently all these ricer companies think KPA and BAR are synonymous. ******* retards.
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Old 02-27-2009, 10:07 AM   #156
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I missed something.
What caused the boost level to drop off between the dyno and now? What changed?
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Old 02-27-2009, 10:13 AM   #157
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I missed something.
What caused the boost level to drop off between the dyno and now? What changed?
I had to change the boost controller because the one I borrowed came apart on the drive home and overboost protection / backfiring saved my life.

I thought I had it dialed in, but apparently not. I was a dumbass and checked boost target with a gauge, not the computer or a log. Its hard to read the westach gauge from that angle, and its inaccurate to begin with.
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Old 02-27-2009, 10:29 AM   #158
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You could use a BAR gauge and add two zeros. 1 BAR = 100 kPa, 2 BAR = 200 kPa

This one is in kPa x 100 and looks just like the BAR gauge.
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Old 02-27-2009, 10:37 AM   #159
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I had to change the boost controller because the one I borrowed came apart on the drive home and overboost protection / backfiring saved my life.

Spend $30 and get a boost solenoid and use the EBC function of your MS.
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Old 02-27-2009, 10:41 AM   #160
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only 1.0 bar is actually 200kpa, lol.
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