S/C Boost Question

cfabrizio · 06-06-2018, 06:32 AM

So this is my first car with a supercharger (2018 A10) and trying to see if what I notice is normal or if something needs to be adjusted.

I have noticed under acceleration that my boost pressure is not consistent. Some days when I accelerate, I seem to have decent boost and I can here the SC whining, other days when accelerating about the same the boost seems to only be at the neutral level (O on the gauge) and I don't here any whine. Also, some days when I rev the engine from idle I don't here any whine and other days I do. Now, under full throttle, the car pulls and whines like a champ, its the normal conservative driving that the boost isn't consistent.

Being inexperienced with forced induction, I thought that the boost would be a steady and consistent. If this is normal, is there a way to adjust things so the boost is more fluid and steady?

Thanks again and excuse the ignorance....cf

TDS · 06-06-2018, 07:27 AM

My understanding is boost is controlled by a vacuum valve on the front of the SC. It closes to let the boost build. However the vacuum valve is overridden by the computer for a number of different reason ( Throttle position vs speed, traction control, IAT's, Ect…). As long as the car is accelerating smooth thru the gears and not cutting out, then I would say all is normal.

EDFHOBBIES · 06-06-2018, 10:22 AM

You forgot Timing to.. mainly from air filter restriction and high IATs.

Chevy71 · 06-06-2018, 05:09 PM

Quote:

Originally Posted by cfabrizio

So this is my first car with a supercharger (2018 A10) and trying to see if what I notice is normal or if something needs to be adjusted.

I have noticed under acceleration that my boost pressure is not consistent. Some days when I accelerate, I seem to have decent boost and I can here the SC whining, other days when accelerating about the same the boost seems to only be at the neutral level (O on the gauge) and I don't here any whine. Also, some days when I rev the engine from idle I don't here any whine and other days I do. Now, under full throttle, the car pulls and whines like a champ, its the normal conservative driving that the boost isn't consistent.

Being inexperienced with forced induction, I thought that the boost would be a steady and consistent. If this is normal, is there a way to adjust things so the boost is more fluid and steady?

Thanks again and excuse the ignorance....cf

If you want steady boost put your foot in it more. The valve on your screws opens and closes to allow boost to the engine. When you are getting inconsistent boost it's because you are teetering on that fine line of open and closing the valve.

cfabrizio · 06-07-2018, 06:58 AM

Cool, thanks for the info!!

tx915zl · 07-24-2018, 10:00 AM

I noticed that when my M6 is at idle, the boost reads negative and if fluctuates up and down and it never stays at zero. Is this normal? on my 2012 cts v, when the car sat at idle it would read zero.

17CamaroZL1 · 07-24-2018, 11:34 AM

Quote:

Originally Posted by tx915zl

I noticed that when my M6 is at idle, the boost reads negative and if fluctuates up and down and it never stays at zero. Is this normal? on my 2012 cts v, when the car sat at idle it would read zero.

When it reads negative, that's vacuum. Perfectly normal.
Maybe your CTS V didn't show vacuum?

tx915zl · 07-24-2018, 11:45 AM

I was a bit worried about it not being normal.

Rlhay2 · 07-24-2018, 04:19 PM

Turbo cars are more sensitive but s/c cars are also affected by environmental conditions too.

I could discern the air quality in my old TT car by how quickly it would build boost!

nicktechla · 07-24-2018, 05:09 PM

Quote:

Originally Posted by 17CamaroZL1

When it reads negative, that's vacuum. Perfectly normal.
Maybe your CTS V didn't show vacuum?

++ Guarantee it just didn't show vacuum.

06-06-2018, 06:32 AM	#1
cfabrizio Drives: 2018 Silver ZL1 Join Date: May 2017 Location: Maryland Posts: 42	S/C Boost Question So this is my first car with a supercharger (2018 A10) and trying to see if what I notice is normal or if something needs to be adjusted. I have noticed under acceleration that my boost pressure is not consistent. Some days when I accelerate, I seem to have decent boost and I can here the SC whining, other days when accelerating about the same the boost seems to only be at the neutral level (O on the gauge) and I don't here any whine. Also, some days when I rev the engine from idle I don't here any whine and other days I do. Now, under full throttle, the car pulls and whines like a champ, its the normal conservative driving that the boost isn't consistent. Being inexperienced with forced induction, I thought that the boost would be a steady and consistent. If this is normal, is there a way to adjust things so the boost is more fluid and steady? Thanks again and excuse the ignorance....cf

06-06-2018, 07:27 AM	#2
TDS Drives: 2019 Jeep Rubicon Sold:2017 ZL1 A10 Join Date: Feb 2017 Location: Scappoose, OR Posts: 560	My understanding is boost is controlled by a vacuum valve on the front of the SC. It closes to let the boost build. However the vacuum valve is overridden by the computer for a number of different reason ( Throttle position vs speed, traction control, IAT's, Ect…). As long as the car is accelerating smooth thru the gears and not cutting out, then I would say all is normal. __________________ Travis SOLD ZL1 Summit White, A10, Black Strip, PDR, ZL1 floor mats Ordered 2/11, 2000 2/14, 3000 2/20, 3100 2/24, 3300 3/7, 3400 3/8, 4300 3/16, 4B00 3/21 Bayed at train yard in Ohio, 4200 3/26 All Abroad for the West Coast, 4800 4/4 Deliverd to portland train yard, 5000 4/7 3:00AM Deliverd to Dealer, 6000 4/7 6:45PM Delivered to Customer

06-06-2018, 10:22 AM	#3
EDFHOBBIES Dyno Show Queen LOL Drives: 16 SS & 17 ZL1 Both Yellow Join Date: Jan 2014 Location: Houston Posts: 4,345 View My Garage	You forgot Timing to.. mainly from air filter restriction and high IATs. __________________ Kong Ported 2650, Crawford Racing Port Injection, Weapon X 112mm Adapter, NW112mm TB, Livernois Ported LT4 Heads, Lingenfelter GT32 stealth cam, Haltech Elite, and Carbon by Trufiber

06-07-2018, 06:58 AM	#5
cfabrizio Drives: 2018 Silver ZL1 Join Date: May 2017 Location: Maryland Posts: 42	Cool, thanks for the info!!

07-24-2018, 10:00 AM	#6
tx915zl Drives: 2017 Camaro zl1 Join Date: Jul 2018 Location: El Paso, Tx Posts: 19	I noticed that when my M6 is at idle, the boost reads negative and if fluctuates up and down and it never stays at zero. Is this normal? on my 2012 cts v, when the car sat at idle it would read zero.

07-24-2018, 11:45 AM	#8
tx915zl Drives: 2017 Camaro zl1 Join Date: Jul 2018 Location: El Paso, Tx Posts: 19	I was a bit worried about it not being normal.

07-24-2018, 04:19 PM	#9
Rlhay2 Drives: 2017 ZL1 Join Date: Mar 2014 Location: DFW, TX Posts: 302	Turbo cars are more sensitive but s/c cars are also affected by environmental conditions too. I could discern the air quality in my old TT car by how quickly it would build boost!

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