14.5+ psi boost on the track - should I try and limit with the set screw?

wakespeak · 05-08-2023, 08:02 PM

Am I losing power with pulled timing at this level (per the PDR)? Advertised limit per Chevy is 9.4 psi. I did try adjusting the set screw limiter at one point but should be back at the stock setting. At this track this weekend I was about even with an SS 1LE in the long straights.

Should I adjust the set screw on the SC flap?

BROCKgoFAST · 05-09-2023, 07:08 AM

Any time you crank up the boost you will get heat soak. At stock levels you shouldn't have heat issues. I just did a track weekend at Sebring with 95 degree temps and the car ran amazing for 6 30 min sessions.

hawk02 · 05-09-2023, 07:29 AM

If your car is stock except for an expansion tank, why are you making so much boost? With a perfectly closed bypass valve, you gain maybe a pound of boost max.

Katech_Zach · 05-09-2023, 08:29 AM

Do not mess with the bypass valve, if you start to recirculate hot air into the blower, you are going to lose even more power, and potentially overheat.

This is the nature of a supercharged car, overtime you will almost always get slower. My advice to you would be getting a race heat exchanger (CRR 42mm), and potentially their supercharger bricks as well. You could add even more water with a fender expansion tank as well.

The way my car is setup (modified, maggy 2650, etc), I tackled cooling first, and I pull near 0 timing on track after a hot session. On the street, I get a degree of timing advance.

wakespeak · 05-09-2023, 03:35 PM

The set screw looks to be at the original stock setting based on the matching of the loctite. I don't know why the PDR data is indicating 14+psi.

Car runs well though I am about even in a drag race on the straights with regular SS's.

wakespeak · 05-09-2023, 03:39 PM

Quote:

Originally Posted by BROCKgoFAST

Any time you crank up the boost you will get heat soak. At stock levels you shouldn't have heat issues. I just did a track weekend at Sebring with 95 degree temps and the car ran amazing for 6 30 min sessions.

Did you use the PDR? Can you post your Vehicle Health from one of your sessions (as I did above)? Would be interesting to compare.

clg82 · 05-09-2023, 04:27 PM

Quote:

Originally Posted by Katech_Zach

Do not mess with the bypass valve, if you start to recirculate hot air into the blower, you are going to lose even more power, and potentially overheat.

This is the nature of a supercharged car, overtime you will almost always get slower. My advice to you would be getting a race heat exchanger (CRR 42mm), and potentially their supercharger bricks as well. You could add even more water with a fender expansion tank as well.

The way my car is setup (modified, maggy 2650, etc), I tackled cooling first, and I pull near 0 timing on track after a hot session. On the street, I get a degree of timing advance.

Don't mean to hijack his thread, but what cooling mods did you do to include the magnuson? Been looking into this as well, as I have some warm track days in the future.

Stephen12ZL1 · 05-10-2023, 01:00 PM

Mine is usually 10.7-11.2

ZLRob · 05-10-2023, 05:53 PM

Quote:

Originally Posted by Stephen12ZL1

Mine is usually 10.7-11.2

You run 10.7-11.2 STOCK?

wakespeak · 05-10-2023, 07:18 PM

Quote:

Originally Posted by Stephen12ZL1

Mine is usually 10.7-11.2

Thanks. Is that from the PDR data? Trying to get a sense of how accurate it is.

wakespeak · 05-10-2023, 07:43 PM

OK, I reviewed the data with the Pi Toolbox and the boost pressure looks much more expected. I see a level max of ~10.4psi. A few spikes in the 12psi range during up shifts. Max accelerator is 99.61%.

So the Cosworth Toolbox looks to be overstating the boost psi.

To Katach_Zach, great comment on the heat factor. The intake air temp is about even with the outside air temp at this stock tune per this data. I do have an added SC expansion tank.

05-08-2023, 08:02 PM	#1
wakespeak Drives: 2020 ZL1 1LE Join Date: Sep 2012 Location: Austin, Texas Posts: 1,420	14.5+ psi boost on the track - should I try and limit with the set screw? Am I losing power with pulled timing at this level (per the PDR)? Advertised limit per Chevy is 9.4 psi. I did try adjusting the set screw limiter at one point but should be back at the stock setting. At this track this weekend I was about even with an SS 1LE in the long straights. Should I adjust the set screw on the SC flap? __________________ 2020 ZL1 1LE [Moroso SC Expansion Tank, otherwise stock]

05-09-2023, 07:29 AM	#3
hawk02 Coupe Newbie Drives: '23 CT5-V BW, '21 Corvette HTC Join Date: Jul 2011 Location: Columbus, Ohio Posts: 3,469 View My Garage	If your car is stock except for an expansion tank, why are you making so much boost? With a perfectly closed bypass valve, you gain maybe a pound of boost max. __________________

05-09-2023, 03:35 PM	#5
wakespeak Drives: 2020 ZL1 1LE Join Date: Sep 2012 Location: Austin, Texas Posts: 1,420	The set screw looks to be at the original stock setting based on the matching of the loctite. I don't know why the PDR data is indicating 14+psi. Car runs well though I am about even in a drag race on the straights with regular SS's. Attached Images __________________ 2020 ZL1 1LE [Moroso SC Expansion Tank, otherwise stock]

05-10-2023, 01:00 PM	#8
Stephen12ZL1 Drives: '21 ZLE A10 Join Date: May 2012 Location: Mechanicsville, VA Posts: 6,824	Mine is usually 10.7-11.2 __________________ '21 ZLE A10 Wild Cherry PDR 2:00.78 VIR Full 10.68@131.69 1.68 60' '17 ZL1 A10 Mosaic Black PDR/Nav 2:03.08 VIR Full 11.003@129.2 1.75 (sold) '15 Z/28 #325 Black a/c & stereo. 2:10.1 VIR Full (sold) '12 ZL1 A6 Black 10.52@131 1.55 60' 2:13 VIR Full (sold)

05-10-2023, 07:43 PM	#11
wakespeak Drives: 2020 ZL1 1LE Join Date: Sep 2012 Location: Austin, Texas Posts: 1,420	OK, I reviewed the data with the Pi Toolbox and the boost pressure looks much more expected. I see a level max of ~10.4psi. A few spikes in the 12psi range during up shifts. Max accelerator is 99.61%. So the Cosworth Toolbox looks to be overstating the boost psi. To Katach_Zach, great comment on the heat factor. The intake air temp is about even with the outside air temp at this stock tune per this data. I do have an added SC expansion tank. __________________ 2020 ZL1 1LE [Moroso SC Expansion Tank, otherwise stock] Last edited by wakespeak; 05-10-2023 at 07:57 PM.

05-09-2023, 07:08 AM	#2
BROCKgoFAST Drives: 2019 Camaro ZL1 1LE Join Date: Nov 2021 Location: Tampa, FL Posts: 134	Any time you crank up the boost you will get heat soak. At stock levels you shouldn't have heat issues. I just did a track weekend at Sebring with 95 degree temps and the car ran amazing for 6 30 min sessions.

05-09-2023, 08:29 AM	#4
Katech_Zach Drives: 14 Camaro SS 1LE Join Date: Feb 2019 Location: Clinton Twp, MI Posts: 483	Do not mess with the bypass valve, if you start to recirculate hot air into the blower, you are going to lose even more power, and potentially overheat. This is the nature of a supercharged car, overtime you will almost always get slower. My advice to you would be getting a race heat exchanger (CRR 42mm), and potentially their supercharger bricks as well. You could add even more water with a fender expansion tank as well. The way my car is setup (modified, maggy 2650, etc), I tackled cooling first, and I pull near 0 timing on track after a hot session. On the street, I get a degree of timing advance.

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