AFR difference Z06 bi-mode valves open / closed
01-02-2012, 03:11 AM
#1
Pro
Thread Starter
AFR difference Z06 bi-mode valves open / closed
On my C6 I have Z06 bi-mode mufflers and the NPP in a box.
What is the difference in AFR between valves closed or open for the Z06 bi-mode mufflers.
With my limited knowledge I know the AFR is important, and the wrong AFR (what is the ideal one) can potentially harm your engine.
When you tune your car to run perfect with the valves closed, and you go for a high speed run with the valves open, can this damage the engine.
Is there a significant difference in HP between valves open / closed.
I recently installed Kooks 1 ¾ headers and catted x-pipe, those coupled with the bi-mode Z06 mufflers make a real nice sound. For long highway journeys they are a bit too loud for my taste, so my plan is to have the valves closed most of the time, and open them occasionally.
Would the Trinity AFR gauge be a good way to keep track of the AFR readings while doing a high-speed German Autobahn run with the valves open.
Fred
What is the difference in AFR between valves closed or open for the Z06 bi-mode mufflers.
With my limited knowledge I know the AFR is important, and the wrong AFR (what is the ideal one) can potentially harm your engine.
When you tune your car to run perfect with the valves closed, and you go for a high speed run with the valves open, can this damage the engine.
Is there a significant difference in HP between valves open / closed.
I recently installed Kooks 1 ¾ headers and catted x-pipe, those coupled with the bi-mode Z06 mufflers make a real nice sound. For long highway journeys they are a bit too loud for my taste, so my plan is to have the valves closed most of the time, and open them occasionally.
Would the Trinity AFR gauge be a good way to keep track of the AFR readings while doing a high-speed German Autobahn run with the valves open.
Fred
01-02-2012, 08:30 AM
#2
Drifting
On my C6 I have Z06 bi-mode mufflers and the NPP in a box.
What is the difference in AFR between valves closed or open for the Z06 bi-mode mufflers.
With my limited knowledge I know the AFR is important, and the wrong AFR (what is the ideal one) can potentially harm your engine.
When you tune your car to run perfect with the valves closed, and you go for a high speed run with the valves open, can this damage the engine.
Is there a significant difference in HP between valves open / closed.
I recently installed Kooks 1 ¾ headers and catted x-pipe, those coupled with the bi-mode Z06 mufflers make a real nice sound. For long highway journeys they are a bit too loud for my taste, so my plan is to have the valves closed most of the time, and open them occasionally.
Would the Trinity AFR gauge be a good way to keep track of the AFR readings while doing a high-speed German Autobahn run with the valves open.
Fred
What is the difference in AFR between valves closed or open for the Z06 bi-mode mufflers.
With my limited knowledge I know the AFR is important, and the wrong AFR (what is the ideal one) can potentially harm your engine.
When you tune your car to run perfect with the valves closed, and you go for a high speed run with the valves open, can this damage the engine.
Is there a significant difference in HP between valves open / closed.
I recently installed Kooks 1 ¾ headers and catted x-pipe, those coupled with the bi-mode Z06 mufflers make a real nice sound. For long highway journeys they are a bit too loud for my taste, so my plan is to have the valves closed most of the time, and open them occasionally.
Would the Trinity AFR gauge be a good way to keep track of the AFR readings while doing a high-speed German Autobahn run with the valves open.
Fred
01-02-2012, 08:47 AM
#3
Pro
Thread Starter
@REVAK,
Does that mean that when you adjust the tune to be perfect with the valves closed, there is no chance of it being to lean (bad for your engine) with the valves open.
We spend our holidays in Italy, loads of tunnels and high speeds, in those situations I would like the valves open.
Does that mean that when you adjust the tune to be perfect with the valves closed, there is no chance of it being to lean (bad for your engine) with the valves open.
We spend our holidays in Italy, loads of tunnels and high speeds, in those situations I would like the valves open.
01-02-2012, 10:06 AM
#4
Drifting
Member Since: Jan 2005
Location: Tucson Arizona
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165 Posts
St. Jude Donor '08
short answer
The valve position on your mufflers will not affect the AFR in ANY meaningful way under ANY driving conditions.
The long answer has to do with how the ECM manages AFR under the various driving conditions using internal ECM settings and various sensors all located forward of the mufflers thereby unaffected by the muffler valve position.
The long answer has to do with how the ECM manages AFR under the various driving conditions using internal ECM settings and various sensors all located forward of the mufflers thereby unaffected by the muffler valve position.
01-03-2012, 05:37 PM
#5
Drifting
@REVAK,
Does that mean that when you adjust the tune to be perfect with the valves closed, there is no chance of it being to lean (bad for your engine) with the valves open.
We spend our holidays in Italy, loads of tunnels and high speeds, in those situations I would like the valves open.
Does that mean that when you adjust the tune to be perfect with the valves closed, there is no chance of it being to lean (bad for your engine) with the valves open.
We spend our holidays in Italy, loads of tunnels and high speeds, in those situations I would like the valves open.
01-03-2012, 05:38 PM
#6
Drifting
The valve position on your mufflers will not affect the AFR in ANY meaningful way under ANY driving conditions.
The long answer has to do with how the ECM manages AFR under the various driving conditions using internal ECM settings and various sensors all located forward of the mufflers thereby unaffected by the muffler valve position.
The long answer has to do with how the ECM manages AFR under the various driving conditions using internal ECM settings and various sensors all located forward of the mufflers thereby unaffected by the muffler valve position.
What he said , 
01-03-2012, 08:27 PM
#7
Team Owner
Anywhere about 3500rpm and WOT your valves are open so no worries about WOT fueling.
01-04-2012, 09:51 PM
#8
Racer
Just a little info from on hands experience.............
I owned an 06 A6 std cpe prior to my GS. Back in May of '11 I bought a set of NPP Mufflers from a forum member. After installation of the mufflers and the Bi Mode kit you mentioned, I had terrible KR in the closed position. So bad that you'd swear somone was under the hood with a coffee can with marbles in it. Well I went crazy tying to figure it out. Recalibrated the MAF, pulled timing, no luck. Finally I contacted a friend with a dyno and started picking away at the possibilities. Turns out when the baffles were in the open position the KR disappeared. In the closed position it was back to the KR. Needless to say I put the stock mufflers back on and was back to normal. For the life of me I cannot understand what the affect of the closed baffles had to cause the issue, but just wanted to let ya know its not always a guaranteed problem free swap. Yes I know mine as an LS2 not an LS7, but it's food for thought.
I owned an 06 A6 std cpe prior to my GS. Back in May of '11 I bought a set of NPP Mufflers from a forum member. After installation of the mufflers and the Bi Mode kit you mentioned, I had terrible KR in the closed position. So bad that you'd swear somone was under the hood with a coffee can with marbles in it. Well I went crazy tying to figure it out. Recalibrated the MAF, pulled timing, no luck. Finally I contacted a friend with a dyno and started picking away at the possibilities. Turns out when the baffles were in the open position the KR disappeared. In the closed position it was back to the KR. Needless to say I put the stock mufflers back on and was back to normal. For the life of me I cannot understand what the affect of the closed baffles had to cause the issue, but just wanted to let ya know its not always a guaranteed problem free swap. Yes I know mine as an LS2 not an LS7, but it's food for thought.
01-05-2012, 12:27 PM
#9
Pro
Thread Starter
Just a little info from on hands experience.............
I owned an 06 A6 std cpe prior to my GS. Back in May of '11 I bought a set of NPP Mufflers from a forum member. After installation of the mufflers and the Bi Mode kit you mentioned, I had terrible KR in the closed position. So bad that you'd swear somone was under the hood with a coffee can with marbles in it. Well I went crazy tying to figure it out. Recalibrated the MAF, pulled timing, no luck. Finally I contacted a friend with a dyno and started picking away at the possibilities. Turns out when the baffles were in the open position the KR disappeared. In the closed position it was back to the KR. Needless to say I put the stock mufflers back on and was back to normal. For the life of me I cannot understand what the affect of the closed baffles had to cause the issue, but just wanted to let ya know its not always a guaranteed problem free swap. Yes I know mine as an LS2 not an LS7, but it's food for thought.
I owned an 06 A6 std cpe prior to my GS. Back in May of '11 I bought a set of NPP Mufflers from a forum member. After installation of the mufflers and the Bi Mode kit you mentioned, I had terrible KR in the closed position. So bad that you'd swear somone was under the hood with a coffee can with marbles in it. Well I went crazy tying to figure it out. Recalibrated the MAF, pulled timing, no luck. Finally I contacted a friend with a dyno and started picking away at the possibilities. Turns out when the baffles were in the open position the KR disappeared. In the closed position it was back to the KR. Needless to say I put the stock mufflers back on and was back to normal. For the life of me I cannot understand what the affect of the closed baffles had to cause the issue, but just wanted to let ya know its not always a guaranteed problem free swap. Yes I know mine as an LS2 not an LS7, but it's food for thought.
Any idea how much difference there is in power between valves closed / open ?
01-05-2012, 12:43 PM
#10
Safety Car
Logical Conclusions or Not?
On a ls3 GM saids 6 hp more with npp over the standard mufflers. 
so z06 should be the same or more. and between open and closed on the same muffler maybe even more than that! 
Think about it; 
i.e. post #8. PS: thats why the second valve/pipe opens at 3500 rpms because you need more flow at that point per GM. 
AH hell, keep life less complicated and stick with "standard set-ups" that are less likely to fail/quit working from bad vacuum valves (2), sticking or frozen baffles (2), leaking vacuum hoses (?) and maybe a bad electronic controller (1); LIKE I DO. 
so z06 should be the same or more. and between open and closed on the same muffler maybe even more than that! Think about it; i.e. post #8. PS: thats why the second valve/pipe opens at 3500 rpms because you need more flow at that point per GM. AH hell, keep life less complicated and stick with "standard set-ups" that are less likely to fail/quit working from bad vacuum valves (2), sticking or frozen baffles (2), leaking vacuum hoses (?) and maybe a bad electronic controller (1); LIKE I DO.
Last edited by C7/Z06 Man; 01-05-2012 at 02:14 PM.
01-05-2012, 02:38 PM
#12
Pro
Thread Starter
Thanks everyone for the info, made things a lot clearer.
1. No need to tune specifically for open / closed valves
2. Dynorun with the valves open just to make sure we make max power
GF happy when we go cruising with the valves closed, me happy I don't run the engine to lean when I go for a spirited drive with the valves open.
Fred
1. No need to tune specifically for open / closed valves
2. Dynorun with the valves open just to make sure we make max power
GF happy when we go cruising with the valves closed, me happy I don't run the engine to lean when I go for a spirited drive with the valves open.
Fred
01-09-2012, 09:44 PM
#13
Racer
