View Poll Results: Do you have problems (spike over 23=over 22). All votes are disclosed
Voters: 79. You may not vote on this poll
Boost Poll
07-04-2010, 03:33 PM
#1
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Boost Poll
It would very informative to find out how many here have any problems which MAY BE RELATED with modified boost and at what levels. I have drawn the *line in the sand* at 22 Lbs. Since I would like to see a % in each range, I have provided two choices within each. Spikes are going to be counted. Use this *spike* rule: If spikes over 23, then it counts as *over 22*.
POLL IS FOR TC CARS ONLY
Ok folks here's a recap and some explantions.
First off,TWO of the *YES* votes in the *Under 22/spike under 23* were cast in error. This was confirmed by both voters (they were over the 22/23 spike threshold) and they gave me permission to move them over to the YES vote in *over 22/spike over 23* column.ONE additional *YES* vote in the *Under 22/spike23* was an error and moved to the *NO* column for *Under 22*.
*** 1 ADDITIONAL car IN THIS CATEGORY is SC car and not counted. It was also a *no problem car* as well
The results are very compelling:
NOTE: THE 2 VOTES IN ERROR ARE CHANGED IN THESE CALCULATIONS
76 Votes Total as of July 16
*40% of all those boosting [OVER 22lbs/spike over 23] had problems (20/50)
*60% of all those boosting [Over 22lbs/spike over 23] had no problems (30/50)
*4% of all those boosting [UNDER 22lbs/spike under 23] had problems (1/25 TC cars) ***
*96% (TC cars only) of those boosting [UNDER 22lbs/spike under 23] had no problems (24/25 TC cars only)
*34% of all votes cast were under 22lbs/spike under 23 (26/76)
*66% of all votes cast were over 22lbs/spike over 23 (50/76)
So, the majority of those voing were in the higher boost category.
I guess the #s speak for themselves. Thanks to all of you who participated. Hopefully, others will benefit from this poll.
POLL IS FOR TC CARS ONLY
Ok folks here's a recap and some explantions.
First off,TWO of the *YES* votes in the *Under 22/spike under 23* were cast in error. This was confirmed by both voters (they were over the 22/23 spike threshold) and they gave me permission to move them over to the YES vote in *over 22/spike over 23* column.ONE additional *YES* vote in the *Under 22/spike23* was an error and moved to the *NO* column for *Under 22*.
*** 1 ADDITIONAL car IN THIS CATEGORY is SC car and not counted. It was also a *no problem car* as well
The results are very compelling:
NOTE: THE 2 VOTES IN ERROR ARE CHANGED IN THESE CALCULATIONS
76 Votes Total as of July 16
*40% of all those boosting [OVER 22lbs/spike over 23] had problems (20/50)
*60% of all those boosting [Over 22lbs/spike over 23] had no problems (30/50)
*4% of all those boosting [UNDER 22lbs/spike under 23] had problems (1/25 TC cars) ***
*96% (TC cars only) of those boosting [UNDER 22lbs/spike under 23] had no problems (24/25 TC cars only)
*34% of all votes cast were under 22lbs/spike under 23 (26/76)
*66% of all votes cast were over 22lbs/spike over 23 (50/76)
So, the majority of those voing were in the higher boost category.
I guess the #s speak for themselves. Thanks to all of you who participated. Hopefully, others will benefit from this poll.
Last edited by ronn; 07-17-2010 at 01:48 AM. Reason: Results added at this time
07-04-2010, 04:10 PM
#3
Hi ronn, I boost 24 psi up to 4500 rpm, tapering to ~17 at 7k.
The excessive boost issue happens if you hold 24 psi for long hard pulls in 4th & 5th. The piston rings expand greater than the ring end gaps allow due to the high combustion temps causing the rings to gouge into the cyl walls and popping the ring lands off of the piston.
The stock & GMPP tunes also run the F/A ratio pig rich (.74 lambda) when the ECU calculates cat temps over ~1800*f, don't know if this helps or hurts the ring lands though. I know it loses all kinds of power in COT protection.
Happens in the same 4th & 5th pulls. I used to hit cat OT protection all the time before I disabled it and went catless.
No issues for 41k miles now.
The excessive boost issue happens if you hold 24 psi for long hard pulls in 4th & 5th. The piston rings expand greater than the ring end gaps allow due to the high combustion temps causing the rings to gouge into the cyl walls and popping the ring lands off of the piston.
The stock & GMPP tunes also run the F/A ratio pig rich (.74 lambda) when the ECU calculates cat temps over ~1800*f, don't know if this helps or hurts the ring lands though. I know it loses all kinds of power in COT protection.
Happens in the same 4th & 5th pulls. I used to hit cat OT protection all the time before I disabled it and went catless.
No issues for 41k miles now.
07-04-2010, 04:59 PM
#4
Hi ronn, I boost 24 psi up to 4500 rpm, tapering to ~17 at 7k.
The excessive boost issue happens if you hold 24 psi for long hard pulls in 4th & 5th. The piston rings expand greater than the ring end gaps allow due to the high combustion temps causing the rings to gouge into the cyl walls and popping the ring lands off of the piston.
The stock & GMPP tunes also run the F/A ratio pig rich (.74 lambda) when the ECU calculates cat temps over ~1800*f, don't know if this helps or hurts the ring lands though. I know it loses all kinds of power in COT protection.
Happens in the same 4th & 5th pulls. I used to hit cat OT protection all the time before I disabled it and went catless.
No issues for 41k miles now.
The excessive boost issue happens if you hold 24 psi for long hard pulls in 4th & 5th. The piston rings expand greater than the ring end gaps allow due to the high combustion temps causing the rings to gouge into the cyl walls and popping the ring lands off of the piston.
The stock & GMPP tunes also run the F/A ratio pig rich (.74 lambda) when the ECU calculates cat temps over ~1800*f, don't know if this helps or hurts the ring lands though. I know it loses all kinds of power in COT protection.
Happens in the same 4th & 5th pulls. I used to hit cat OT protection all the time before I disabled it and went catless.
No issues for 41k miles now.
I think it takes more than 24 PSI to do that because many people are boosting that much with no issues, more like 26+ to do all that damage.
07-04-2010, 05:11 PM
#5
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Well, that's why I'm doing this poll. No more *speculation*...we already have people over 22 ( or spiking 23) with problems. I assume you've had none so far?
07-04-2010, 07:24 PM
#11
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Silly question but how exactly is a couple more psi pushing the ring limits? Once all of the air gets into the cylinder and the piston compresses it and the plug ignites the mixture, there's a whole lot more pressure in the chamber pushing the piston down than the 26psi that filled it.
Isn't boost simply the amount of pressure in the intake manifold that's not getting into the engine due to a restriction ie. valve lift/duration, valve size, intake runner size?
Isn't boost simply the amount of pressure in the intake manifold that's not getting into the engine due to a restriction ie. valve lift/duration, valve size, intake runner size?
07-04-2010, 07:44 PM
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Silly question but how exactly is a couple more psi pushing the ring limits? Once all of the air gets into the cylinder and the piston compresses it and the plug ignites the mixture, there's a whole lot more pressure in the chamber pushing the piston down than the 26psi that filled it.
Isn't boost simply the amount of pressure in the intake manifold that's not getting into the engine due to a restriction ie. valve lift/duration, valve size, intake runner size?
Isn't boost simply the amount of pressure in the intake manifold that's not getting into the engine due to a restriction ie. valve lift/duration, valve size, intake runner size?
07-04-2010, 08:42 PM
#13
I'm unsure about my vote. "22Lbs or less (spike under 23) YES"
I sit right around 22 lbs. It's hard to tell because I just glance really and pay attention to the road. It HAS spiked upwards of 25lbs but it's inconsistent. Sometimes it goes straight to 22.
I think the spiking has a lot to do with what RPMS/Gear you're in since flow would have a direct effect on this.
I sit right around 22 lbs. It's hard to tell because I just glance really and pay attention to the road. It HAS spiked upwards of 25lbs but it's inconsistent. Sometimes it goes straight to 22.
I think the spiking has a lot to do with what RPMS/Gear you're in since flow would have a direct effect on this.
07-04-2010, 08:50 PM
#14
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07-04-2010, 09:05 PM
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I'm unsure about my vote. "22Lbs or less (spike under 23) YES"
I sit right around 22 lbs. It's hard to tell because I just glance really and pay attention to the road. It HAS spiked upwards of 25lbs but it's inconsistent. Sometimes it goes straight to 22.
I think the spiking has a lot to do with what RPMS/Gear you're in since flow would have a direct effect on this.
I sit right around 22 lbs. It's hard to tell because I just glance really and pay attention to the road. It HAS spiked upwards of 25lbs but it's inconsistent. Sometimes it goes straight to 22.
I think the spiking has a lot to do with what RPMS/Gear you're in since flow would have a direct effect on this.
Thanks for the added info.
07-05-2010, 03:34 PM
#18
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Think even higher. At 22 psi guage pressure the inlet pressure is 22.0+14.7 psi = 36.7 psi absolute. Take that and a static CR of 10.0:1 (easy calculation) and you have 367 psi peak cylinder pressure. A NA car with the same 10.0:1 CR would have 14.7 psi inlet pressure (atmospheric pressure) would see 147 psi peak cylinder pressure. So in this case you have make your effective CR to 25 : 1 running 22 psig.
07-05-2010, 04:00 PM
#19
Thanks for posting that..so far you're the only one posting a problem with 22lbs & spike under 23. Looks like you should have posted that in the OVER 22lbs camp, since the 25LB spike puts you there. When I do a summary analysis, I'm going to move your vote over...if you don't mind. If you do, please PM me.
Thanks for the added info.
Thanks for the added info.
07-08-2010, 01:59 PM
#21
sub'd for an interesting discussion.
Currently I'm 22psi. No spike.
On old boost tables I went over 26psi on an extended run with an SL55 AMG and I think that was the beginning of the end for my number 1 piston/ring. I agree that the boost level and ring gap issues are related. On a buddy's Wiseco install, we noticed that the gaps are much more liberal on them vs the stockers, so I'd imagine you could run more boost or even nitrous without issue. On that note, there's nothing that says you couldn't just increase the gap a bit on the stockers though... just that if you did all the work to get in there to do that, you might as well have put better stuff in there.
On the first gen dual tune, I also had a little bit of "bleed over" of tuned boost levels to my stock tune. Sometimes on stock, it would run harder than stock but less than tuned, with boost levels up to say 20psi on the high end sometimes. There's a new tune revision out that fixes that as a part of the boost table tweaks.
Currently I'm 22psi. No spike.
On old boost tables I went over 26psi on an extended run with an SL55 AMG and I think that was the beginning of the end for my number 1 piston/ring. I agree that the boost level and ring gap issues are related. On a buddy's Wiseco install, we noticed that the gaps are much more liberal on them vs the stockers, so I'd imagine you could run more boost or even nitrous without issue. On that note, there's nothing that says you couldn't just increase the gap a bit on the stockers though... just that if you did all the work to get in there to do that, you might as well have put better stuff in there.
On the first gen dual tune, I also had a little bit of "bleed over" of tuned boost levels to my stock tune. Sometimes on stock, it would run harder than stock but less than tuned, with boost levels up to say 20psi on the high end sometimes. There's a new tune revision out that fixes that as a part of the boost table tweaks.
07-08-2010, 02:17 PM
#23
Well it's like 22.5psi usually, so I voted "above", since it technically is. I took it as "I'm boosting just above 22psi, but don't spike above 23psi", so I picked that one.
Yeah, I didn't know which I should do at first since I've had 22.5psi days and just below 22psi days. I felt if I was ever over 22psi I should note it that way for the purposes of this thread.
Yeah, I didn't know which I should do at first since I've had 22.5psi days and just below 22psi days. I felt if I was ever over 22psi I should note it that way for the purposes of this thread.
