Timing, Fuel or more boost?
02-11-2010, 01:19 PM
#1
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Timing, Fuel or more boost?
I've been pondering this since my dyno run and want to be prepared next time I go.
Say I do my first couple pulls and everythign looks good. 8psi and 12psi pulls go great with 11.3 AFRs, timing around 12/0 up top. For my third pull I want to sqeeze more power out of it.
Which would you do? Lean it out to 11.8, give it 4-5 degrees more timing or just leave it alone and turn it up to 15-16psi? which do you think is safer and why?
Once I finish fine tuning I'd like to have several variations already programmed into my cobb and ready to flash once its strapped to the dyno.
Thanks in advance for any advice
Say I do my first couple pulls and everythign looks good. 8psi and 12psi pulls go great with 11.3 AFRs, timing around 12/0 up top. For my third pull I want to sqeeze more power out of it.
Which would you do? Lean it out to 11.8, give it 4-5 degrees more timing or just leave it alone and turn it up to 15-16psi? which do you think is safer and why?
Once I finish fine tuning I'd like to have several variations already programmed into my cobb and ready to flash once its strapped to the dyno.
Thanks in advance for any advice
02-11-2010, 01:53 PM
#2
I like to get the tuning done before i get to the dyno and just do pulls based on what I already know works on the road by analysing MAF logs .
That way the dyno runs are pretty drama free and I can analyse what happened in my own time afterwards .
That way the dyno runs are pretty drama free and I can analyse what happened in my own time afterwards .
Last edited by Brettus; 02-11-2010 at 01:56 PM.
02-11-2010, 03:14 PM
#5
Fill it with race gas, leave the AFRs alone and move the timing around to see which delivers more power. If adding 2° timing makes no more power, up the boost and them play with timing again.
I'd actually do all this at 10.5:1 if your ignition can handle it.
You also might be surprised what happens when you pull timing.
Until you have moved the timing 2° - 3° in both directions, you don't really know where you are in relationship to detonation, and you can find out waaaay before it breaks something by the way it affects power and EGTs with high octane fuel.
That said, unless you have a ton of money, do it on the street first and then bring the results to the dyno for verification.
I'd actually do all this at 10.5:1 if your ignition can handle it.
You also might be surprised what happens when you pull timing.
Until you have moved the timing 2° - 3° in both directions, you don't really know where you are in relationship to detonation, and you can find out waaaay before it breaks something by the way it affects power and EGTs with high octane fuel.
That said, unless you have a ton of money, do it on the street first and then bring the results to the dyno for verification.
02-11-2010, 03:29 PM
#6
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Fill it with race gas, leave the AFRs alone and move the timing around to see which delivers more power. If adding 2° timing makes no more power, up the boost and them play with timing again.
I'd actually do all this at 10.5:1 if your ignition can handle it.
You also might be surprised what happens when you pull timing.
Until you have moved the timing 2° - 3° in both directions, you don't really know where you are in relationship to detonation, and you can find out waaaay before it breaks something by the way it affects power and EGTs with high octane fuel.
That said, unless you have a ton of money, do it on the street first and then bring the results to the dyno for verification.
I'd actually do all this at 10.5:1 if your ignition can handle it.
You also might be surprised what happens when you pull timing.
Until you have moved the timing 2° - 3° in both directions, you don't really know where you are in relationship to detonation, and you can find out waaaay before it breaks something by the way it affects power and EGTs with high octane fuel.
That said, unless you have a ton of money, do it on the street first and then bring the results to the dyno for verification.
I really wasnt sure which direction to approach it to try squeeze more out of it.I intend to do all I can on the street. But the more 3rd(and 4th) gear pulls I do the greater my risk of a ticket :P
02-11-2010, 04:12 PM
#7
I would also add that it is best to have two boosted profiles set up and tested going in.
Since the AP and flashing all that jazz can take a while - try to get one good map with say a 10 and a 12 PSI boost setting. THen you can do both those pulls back to back and see what your power curves look like.
One last note - make a map with no knock retard in case that jumps into the mix. When CW was dynoing his, while troubleshooting we noticed he was running like 8 degrees of advance at 5000 RPM, we zeroed out his knock maps and get got back to his normal timing - EVEN though the Knock was reading zero... I don't know why - I wasn't there I was on the phone. But something to consider. And our Knock sensor is junk anyway.
Since the AP and flashing all that jazz can take a while - try to get one good map with say a 10 and a 12 PSI boost setting. THen you can do both those pulls back to back and see what your power curves look like.
One last note - make a map with no knock retard in case that jumps into the mix. When CW was dynoing his, while troubleshooting we noticed he was running like 8 degrees of advance at 5000 RPM, we zeroed out his knock maps and get got back to his normal timing - EVEN though the Knock was reading zero... I don't know why - I wasn't there I was on the phone. But something to consider. And our Knock sensor is junk anyway.
02-11-2010, 04:19 PM
#8
Just for fun...since I dynoing my car next week.
I'll post my dyno plan so far - I still need to finish it.
1) MAF and VE% done - scale the maf in those high areas that you can't hit normally on the road for very long.
2) Just WG
3) BC Low @ 10 PSI
4) BC High @ 12 PSI
Those are my first four pulls...
I'll post my dyno plan so far - I still need to finish it.
1) MAF and VE% done - scale the maf in those high areas that you can't hit normally on the road for very long.
2) Just WG
3) BC Low @ 10 PSI
4) BC High @ 12 PSI
Those are my first four pulls...
02-11-2010, 05:03 PM
#11
Well, get on it, because that is where are your timing calculations are done.
The base ignition maps are just that - a base.
Did you actually see him do it? (Understand what I am asking you?
)
There is a lot of interaction, BTW. If the KS tables have base values that affect "0" range, you can get some weird stuff.
I actually never touch the KS tables. My knock sensor is removed from the block, wrapped in foam and wire-tied to the oil filter stand-off.
The base ignition maps are just that - a base.
Did you actually see him do it? (Understand what I am asking you?
)There is a lot of interaction, BTW. If the KS tables have base values that affect "0" range, you can get some weird stuff.
I actually never touch the KS tables. My knock sensor is removed from the block, wrapped in foam and wire-tied to the oil filter stand-off.
02-11-2010, 05:07 PM
#12
Well, get on it, because that is where are your timing calculations are done.
The base ignition maps are just that - a base.
Did you actually see him do it? Understand what I am asking you?
There is a lot of interaction, BTW. If the KS tables have base values that affect "0" range, you can get some weird stuff.
I actually never touch the KS tables. My knock sensor is removed from the block, wrapped in foam and wire-tied to the oil filter stand-off.
The base ignition maps are just that - a base.
Did you actually see him do it? Understand what I am asking you?
There is a lot of interaction, BTW. If the KS tables have base values that affect "0" range, you can get some weird stuff.
I actually never touch the KS tables. My knock sensor is removed from the block, wrapped in foam and wire-tied to the oil filter stand-off.
I agree removing the KS is not a bad idea....
With my base timing tables only - and leaving the RPM Delta ones alone, I am getting timing where I want it to date (within 2 degrees).... then again - I had to go on a small break until I get my Cobb Tuner software link emailed to me, so now I'll have to see what is up.
02-11-2010, 05:08 PM
#13
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Thanks for all the input guys
That is exactly where my train of thought was. If I switch to my other spring and valve seat(8PSI) Then use my 3 BC settings off, A and B for the other runs. Or I could even use A, B and "Scramble boost"
something like:
1. WG 8PSI
2. BC "A" 12PSI
3 omgwtf BC "B" 15PSI(but ramping up from 10 or 12 spring setting)
Um, I wouldnt be the guy boosting his engine with a homemade turbo kit if I was the squeamish type. I would look at it as a good excuse to try some porting and upgraded seals 
Now I"m not trying to blow it up, but I"m not afraid to push it a bit either.
Just for fun...since I dynoing my car next week.
I'll post my dyno plan so far - I still need to finish it.
1) MAF and VE% done - scale the maf in those high areas that you can't hit normally on the road for very long.
2) Just WG
3) BC Low @ 10 PSI
4) BC High @ 12 PSI
Those are my first four pulls...
I'll post my dyno plan so far - I still need to finish it.
1) MAF and VE% done - scale the maf in those high areas that you can't hit normally on the road for very long.
2) Just WG
3) BC Low @ 10 PSI
4) BC High @ 12 PSI
Those are my first four pulls...
something like:
1. WG 8PSI
2. BC "A" 12PSI
3 omgwtf BC "B" 15PSI(but ramping up from 10 or 12 spring setting)
Now I"m not trying to blow it up, but I"m not afraid to push it a bit either.
Last edited by Mawnee; 02-11-2010 at 05:15 PM.
02-11-2010, 05:10 PM
#14
That is exactly where my train of thought was. If I switch to my other spring and valve seat(8PSI) Then use my 3 BC settings off, A and B for the other runs. Or I could even use A, B and "Scramble boost"
something like:
1. WG 8PSI
2. BC "A" 12PSI
3 omgwtf BC "B" 15PSI(but ramping up from 10 or 12 spring setting)
something like:
1. WG 8PSI
2. BC "A" 12PSI
3 omgwtf BC "B" 15PSI(but ramping up from 10 or 12 spring setting)
I thought about doing a 16PSI OMGWTFBBQQQQQ pull, but technically I really should have charge cooling to do something like that.... ego is a bitch sometimes.
02-11-2010, 05:19 PM
#16
Based on my 12 PSI flow... I figured 16 would be the max this 3071 can run on this engine.
I pull 400 on factory WG, and I am looking for 430 at 12 psi. I was hoping for 450 at 16.... but then again, I have never run it higher than 12 so.....
I pull 400 on factory WG, and I am looking for 430 at 12 psi. I was hoping for 450 at 16.... but then again, I have never run it higher than 12 so.....
02-11-2010, 05:21 PM
#17
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02-11-2010, 05:50 PM
#19
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02-11-2010, 07:26 PM
#23
At 14 PSI, I'm already moving over 55 pounds of air.
Remember, this turbo is designed for about 54 pounds of air at most (which is a f*ck-load of air and about what the BNR is capable of as well). You do the math.
As far as the hot side, the wastegate is open at the HP peak so the total flow area after the ports is already bigger than the exhaust ports themselves.
Once again, you do the math.
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