Camaro5 Chevy Camaro Forum / Camaro ZL1, SS and V6 Forums - Camaro5.com
 
Phastek Performance
Go Back   Camaro5 Chevy Camaro Forum / Camaro ZL1, SS and V6 Forums - Camaro5.com > Engine | Drivetrain | Powertrain Technical Discussions > Forced Induction - V8

Forced Induction - V8 V8 Supercharger, turbo, nitrous discussions

Reply
 
Thread Tools
Old 05-27-2013, 11:30 PM   #1
PMJ
Seeking 9s on M6...
 
PMJ's Avatar
 
Drives: 2012 2SS/RS LS3 aka "BlackWidow"
Join Date: May 2012
Location: Houston, TX
Posts: 371
Question Boost Spike

For a while I've been working on "reducing" the lean spike after a gear shift. Occasionally it will cause knocking so avoiding is ideal to avoid timing to get pulled (or something worse). After much review, I had an ah ha moment today...the lean spike isn't the issue...it’s a "boost spike".

I never noticed this before, but on a gear shift, i will occasionally see a "boost spike" like pictured below. The boost spike is significantly higher than my "normal" max boost (i'm running 15-16psi, and the boost maxes out my MAP sensor at 22.3psi). As a result I get a lean spike and ultimately detonation.

Any others with a super charger seeing this boost spike on gear shift? Has anyone solved it?
Attached Images
 
__________________
PMJ is offline   Reply With Quote
Old 05-27-2013, 11:36 PM   #2
Whipped416

 
Whipped416's Avatar
 
Drives: 2010 CAMARO SS
Join Date: Mar 2011
Location: Texas
Posts: 1,526
I have logged mine and I see nothing higher then 17-18 all the way through .
Whipped416 is offline   Reply With Quote
Old 05-28-2013, 08:37 AM   #3
old motorhead

 
Drives: Maggie blown LS3 vette
Join Date: Aug 2009
Location: SE TX
Posts: 1,321
Centrifugal blower with A6?
old motorhead is offline   Reply With Quote
Old 05-28-2013, 09:06 AM   #4
PMJ
Seeking 9s on M6...
 
PMJ's Avatar
 
Drives: 2012 2SS/RS LS3 aka "BlackWidow"
Join Date: May 2012
Location: Houston, TX
Posts: 371
No, PD blower w/M6.
__________________
PMJ is offline   Reply With Quote
Old 05-28-2013, 11:23 AM   #5
realcanuk
 
realcanuk's Avatar
 
Drives: 2007 Corvette C6 615 rwhp
Join Date: Dec 2011
Location: Montreal, Canada
Posts: 573
What kind of blower ? Some PD blowers do a spike like that right at the top of a run, but mine is .5 to 1 lb.... yours seems excessive.
__________________
2007 C6 vert, auto, F55, LT3
LME LS402 , WCCH 245 Heads, Pat G. Custom cam
E Force SC, ARH 1 7/8 headers, NPP with M2W
160 degree stat, Dual fans, Casper fan switch,
3.42 polished gears, hardened shafts, Alky control meth, Cartech line lock, ECS axle loops, Trans brace
ID 850 injectors, 2.75 pulley, comp rockers, Morel lifters, BT springs, Trend 3/8 pushrods, ATI 10% OD Damper
Circle D Triple Disc 2600 stall
780 RWHP @ 6250, 770 Lbs Torque @ 4300, Tuned by FEDERAL
New YSI build underway !!!
realcanuk is offline   Reply With Quote
Old 05-28-2013, 11:50 AM   #6
PMJ
Seeking 9s on M6...
 
PMJ's Avatar
 
Drives: 2012 2SS/RS LS3 aka "BlackWidow"
Join Date: May 2012
Location: Houston, TX
Posts: 371
Quote:
Originally Posted by realcanuk View Post
What kind of blower ? Some PD blowers do a spike like that right at the top of a run, but mine is .5 to 1 lb.... yours seems excessive.
I have a whipple 2.9l.
__________________
PMJ is offline   Reply With Quote
Old 05-28-2013, 12:46 PM   #7
carlos@redline-motorsport
 
Drives: 98 Z28
Join Date: Mar 2013
Location: Deerfield Beach, FL
Posts: 80
Looks like a little clutch slip at engagement.
carlos@redline-motorsport is offline   Reply With Quote
Old 05-28-2013, 03:26 PM   #8
PMJ
Seeking 9s on M6...
 
PMJ's Avatar
 
Drives: 2012 2SS/RS LS3 aka "BlackWidow"
Join Date: May 2012
Location: Houston, TX
Posts: 371
Quote:
Originally Posted by carlos@redline-motorsport View Post
Looks like a little clutch slip at engagement.
Are you saying I got on the gas before letting off the clutch? Or the clutch slipped after I engaged it and hit the gas? It is a mcleod RXT, so I wouldn't expect slip. I think I see a little tire spin as well.

I'm going to post another example prior to my engine mods and new clutch when I get home tonight.
__________________
PMJ is offline   Reply With Quote
Old 05-28-2013, 11:34 PM   #9
PMJ
Seeking 9s on M6...
 
PMJ's Avatar
 
Drives: 2012 2SS/RS LS3 aka "BlackWidow"
Join Date: May 2012
Location: Houston, TX
Posts: 371
So looking back at old logs, i've had this "problem" since day 1. The first shot shows a tuning log right after the whipple install on a stock motor (4" pulley). No AFR gauge at the time.

The second snap is from a texas mile run and shows a double spike! Only one of those i found. This was while running race gas. I had a 3.75" pulley getting a little over 11psi. Street tires.

The 3rd is at the track w/drag radials. Also getting 11psi. This should have been my best run ever, but no doubt the knock made me lose a few hundredths (was a better launch than my all time best that same day).

Last was another run at the texas mile. This was going into fifth gear...as you can see i had trouble getting there , i'm hoping this was resolved with my upgraded clutch, but i could never shift cleanly to 5th at 145 mph... anyway, this one surprises me the most because the blower had spooled down prior to getting in gear, but still see the spike.

Am I the only one experiencing this w/a Whipple or PD blower? Or am i the only one that keeps all his logs.

These snaps are all before Meth and engine mods.

.
Attached Images
    
__________________
PMJ is offline   Reply With Quote
Old 05-28-2013, 11:37 PM   #10
Supercharged SS
Account Suspended
 
Drives: 2010 Camaro
Join Date: Feb 2010
Location: Sandy Hook, CT
Posts: 12,003
I don't have any boost spike. I've never had it in 3.5 yrs of pd blower.


And I have no idea what's causing yours. Maybe the belt just grabs better at that moment. I have boost dips do to some slipping though.
Supercharged SS is offline   Reply With Quote
Old 05-28-2013, 11:56 PM   #11
PMJ
Seeking 9s on M6...
 
PMJ's Avatar
 
Drives: 2012 2SS/RS LS3 aka "BlackWidow"
Join Date: May 2012
Location: Houston, TX
Posts: 371
BTW, my defined "Boost" value is off in all of these by .2 For some reason my defined value had MAP.PSI - 14.7 instead of -14.5. So add .2 to the boost to = the MAP.
__________________
PMJ is offline   Reply With Quote
Old 05-28-2013, 11:58 PM   #12
Supercharged SS
Account Suspended
 
Drives: 2010 Camaro
Join Date: Feb 2010
Location: Sandy Hook, CT
Posts: 12,003
Quote:
Originally Posted by PMJ View Post
BTW, my defined "Boost" value is off in all of these by .2 For some reason my defined value had MAP.PSI - 14.7 instead of -14.5. So add .2 to the boost to = the MAP.
I know. I posted about that last night but deleted because I didn't want to crap up the thread with a moot point.
Supercharged SS is offline   Reply With Quote
Old 05-29-2013, 12:16 AM   #13
PMJ
Seeking 9s on M6...
 
PMJ's Avatar
 
Drives: 2012 2SS/RS LS3 aka "BlackWidow"
Join Date: May 2012
Location: Houston, TX
Posts: 371
Quote:
Originally Posted by Supercharged SS View Post
I know. I posted about that last night but deleted because I didn't want to crap up the thread with a moot point.
I'm guessing a manual transmition has something to do with it. I'm also assuming it may be something i'm doing...but talking to Mike at Whipple, I'm the first to report this...doesn't sound like i'm going to have a solutions any time soon...or maybe ever. Was hoping someone else has seen and solved this, but not looking good.
__________________
PMJ is offline   Reply With Quote
Old 05-29-2013, 12:19 AM   #14
Supercharged SS
Account Suspended
 
Drives: 2010 Camaro
Join Date: Feb 2010
Location: Sandy Hook, CT
Posts: 12,003
Quote:
Originally Posted by PMJ View Post
I'm guessing a manual transmition has something to do with it. I'm also assuming it may be something i'm doing...but talking to Mike at Whipple, I'm the first to report this...doesn't sound like i'm going to have a solutions any time soon...or maybe ever. Was hoping someone else has seen and solved this, but not looking good.
Try pm'in Ayousef. That guy knows quite a bit of stuff. He may have an idea.
Supercharged SS is offline   Reply With Quote
Old 05-29-2013, 01:33 AM   #15
PMJ
Seeking 9s on M6...
 
PMJ's Avatar
 
Drives: 2012 2SS/RS LS3 aka "BlackWidow"
Join Date: May 2012
Location: Houston, TX
Posts: 371
Quote:
Originally Posted by Supercharged SS View Post
Try pm'in Ayousef. That guy knows quite a bit of stuff. He may have an idea.
Thanks. I pm'd him.
__________________
PMJ is offline   Reply With Quote
Old 05-29-2013, 09:44 AM   #16
ayousef

 
ayousef's Avatar
 
Drives: 2013 ZL1
Join Date: Oct 2012
Location: Dubai
Posts: 759
Quote:
Originally Posted by Supercharged SS View Post
Try pm'in Ayousef. That guy knows quite a bit of stuff. He may have an idea.
Thanks!

Quote:
Originally Posted by PMJ View Post
Thanks. I pm'd him.
Well I have an idea in mind already based on the print screens but cant be too sure, can you send me the log and the file by email? I want the log from where you got the initial printscreen from.

Also, to get correct boost readings always make sure you subtract the Barometric pressure in PSI from MAP PSI, this is the only correct way to do it.

Using a static number such as 14.7 or 14.5 to estimate barometric pressure may only be accurate 10% of the time.

But thats not the problem. Ill send you my email address as a PM
__________________

1150bhp Whipple 4.0 Supercharged 427ci Camaro ZL1
ayousef is offline   Reply With Quote
Old 05-29-2013, 01:07 PM   #17
carlos@redline-motorsport
 
Drives: 98 Z28
Join Date: Mar 2013
Location: Deerfield Beach, FL
Posts: 80
Quote:
Originally Posted by PMJ View Post
Are you saying I got on the gas before letting off the clutch? Or the clutch slipped after I engaged it and hit the gas? It is a mcleod RXT, so I wouldn't expect slip. I think I see a little tire spin as well.

I'm going to post another example prior to my engine mods and new clutch when I get home tonight.
Yeah, looking at it again looks like tire spin.

Would be nice to see throttle blade position and pedal position to see what you are actually telling it to do vs what it's doing.

What happens if you go WOT in say 3rd or 4th gear, let off completely around the top of the gear and stab it again without shifting really quick? Also, what happens if you stab it from a high 3rd or 4th (somewhere that you get traction) gear roll? Also, rescale the speed and rpm in order to show more drastic changes in the graph.

Also, does this car have cats or cutouts?

Last edited by carlos@redline-motorsport; 05-29-2013 at 01:22 PM.
carlos@redline-motorsport is offline   Reply With Quote
Old 05-29-2013, 01:50 PM   #18
ayousef

 
ayousef's Avatar
 
Drives: 2013 ZL1
Join Date: Oct 2012
Location: Dubai
Posts: 759
Quote:
Originally Posted by carlos@redline-motorsport View Post
Yeah, looking at it again looks like tire spin.

Would be nice to see throttle blade position and pedal position to see what you are actually telling it to do vs what it's doing.

What happens if you go WOT in say 3rd or 4th gear, let off completely around the top of the gear and stab it again without shifting really quick? Also, what happens if you stab it from a high 3rd or 4th (somewhere that you get traction) gear roll? Also, rescale the speed and rpm in order to show more drastic changes in the graph.

Also, does this car have cats or cutouts?
Carlos, clutch slip or tire spin could not possibly cause a boost spike at all on a blower car, there is absolutely nothing that should cause boost to go up unless you're spinning the blower much quicker at a given RPM and even thats not possible unless the blower's carrying momentum from being spun at a high speed and over boosting at a lower rpm, even this doesnt make sense.

I do have some weird ideas however especially since MAF frequency isnt as high as it should be when the spike occurs.
__________________

1150bhp Whipple 4.0 Supercharged 427ci Camaro ZL1
ayousef is offline   Reply With Quote
Old 05-29-2013, 02:29 PM   #19
PMJ
Seeking 9s on M6...
 
PMJ's Avatar
 
Drives: 2012 2SS/RS LS3 aka "BlackWidow"
Join Date: May 2012
Location: Houston, TX
Posts: 371
Quote:
Originally Posted by ayousef View Post
Well I have an idea in mind already based on the print screens but cant be too sure, can you send me the log and the file by email? I want the log from where you got the initial printscreen from.

Also, to get correct boost readings always make sure you subtract the Barometric pressure in PSI from MAP PSI, this is the only correct way to do it.

Using a static number such as 14.7 or 14.5 to estimate barometric pressure may only be accurate 10% of the time.

But thats not the problem. Ill send you my email address as a PM
Fantastic! I'll get that e-mail sent out ASAP.


Quote:
Originally Posted by carlos@redline-motorsport View Post
Yeah, looking at it again looks like tire spin.

Would be nice to see throttle blade position and pedal position to see what you are actually telling it to do vs what it's doing.

What happens if you go WOT in say 3rd or 4th gear, let off completely around the top of the gear and stab it again without shifting really quick? Also, what happens if you stab it from a high 3rd or 4th (somewhere that you get traction) gear roll? Also, rescale the speed and rpm in order to show more drastic changes in the graph.

Also, does this car have cats or cutouts?
The car has OBX Hi-Flow Cats...I have considered that as one possibility, but i would think it would occur all the time, not just some of the time.

I am hopefully Ayousef finds something, but i like some of your suggestions...I'll see if getting off the throttle and punching it will reproduce it. I'll also see if i can add logging for throttle and pedal positions.

Thanks,
Pat
__________________
PMJ is offline   Reply With Quote
Old 05-29-2013, 02:30 PM   #20
yonson
 
yonson's Avatar
 
Drives: where to begin...
Join Date: May 2010
Location: MiSSiSSiPPi
Posts: 27
Has this calibration been scaled? You might have missed something during scaling...
yonson is offline   Reply With Quote
Old 05-29-2013, 04:19 PM   #21
carlos@redline-motorsport
 
Drives: 98 Z28
Join Date: Mar 2013
Location: Deerfield Beach, FL
Posts: 80
Quote:
Originally Posted by ayousef View Post
Carlos, clutch slip or tire spin could not possibly cause a boost spike at all on a blower car, there is absolutely nothing that should cause boost to go up unless you're spinning the blower much quicker at a given RPM and even thats not possible unless the blower's carrying momentum from being spun at a high speed and over boosting at a lower rpm, even this doesnt make sense.

I do have some weird ideas however especially since MAF frequency isnt as high as it should be when the spike occurs.
I wasn't implying that was the cause, just pointing it out.

Like I said, hard to figure out what's going on without seeing what position the throttle blade is at. This is why I was asking him about quickly interrupting a pull pre-gear shift. Also, because the PD blowers make instant boost and it's not really dependent on RPM, the only thing that would cause boost to legitimately go up would be a restriction down stream. That is, if it's not the MAP showing pressure backed up behind the throttle blade and the bypass isn't reacting fast enough, as the MAF doesn't seem to be on the same page, like you just mentioned.
carlos@redline-motorsport is offline   Reply With Quote
Old 05-29-2013, 04:44 PM   #22
Mike TexaSS
 
Drives: 454 LS7 Camaro SS
Join Date: Jun 2009
Location: Houston
Posts: 380
Ive seen boost spike on CTS-V's when you hit a lean spot.

Id bet your tune is off. If you look at your logs the 02 voltage is extremely lean when the boost spike occurs!
Mike TexaSS is offline   Reply With Quote
Old 05-29-2013, 04:47 PM   #23
Mike TexaSS
 
Drives: 454 LS7 Camaro SS
Join Date: Jun 2009
Location: Houston
Posts: 380
Also are you 2.5 bar SD? Or OL MAF? CLMAF.. Details buddy details!
Mike TexaSS is offline   Reply With Quote
Old 05-29-2013, 05:49 PM   #24
ayousef

 
ayousef's Avatar
 
Drives: 2013 ZL1
Join Date: Oct 2012
Location: Dubai
Posts: 759
Quote:
Originally Posted by Mike TexaSS View Post
Ive seen boost spike on CTS-V's when you hit a lean spot.

Id bet your tune is off. If you look at your logs the 02 voltage is extremely lean when the boost spike occurs!
You're saying the lean spike is causing the boost spike, hes saying the boost spike is causing the lean spike

hes running a MAF closed loop tune
__________________

1150bhp Whipple 4.0 Supercharged 427ci Camaro ZL1
ayousef is offline   Reply With Quote
Old 05-29-2013, 06:30 PM   #25
PMJ
Seeking 9s on M6...
 
PMJ's Avatar
 
Drives: 2012 2SS/RS LS3 aka "BlackWidow"
Join Date: May 2012
Location: Houston, TX
Posts: 371
Quote:
Originally Posted by Mike TexaSS View Post
Also are you 2.5 bar SD? Or OL MAF? CLMAF.. Details buddy details!
3 bar ZR1 MAP. Stock MAF.
__________________
PMJ is offline   Reply With Quote
 
Reply

Tags
whipple

Thread Tools

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump


All times are GMT -5. The time now is 04:56 PM.


Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2014, vBulletin Solutions, Inc.