Dyno Shocker - Lost Power!!

JSH · 10-13-2022, 01:38 PM

So, it made 965 at 7000 a month ago with a 103 and 3" upper. We put a 112 and 2.75 on it this week and are shocked that it now gets to 850 at 5800 and rolls over badly.

99% of the HPT data looks good (except for KPa 11 is not right). Gained 3 lbs. boost, MAT is fine, spark and advance look good, etc., etc.

Our first course of action is to replace the crimped exhaust pipe section today and redyno.

Has anyone here had this happen to them? I'd bet shops such as KaTech have.

Camaro1973 · 10-13-2022, 01:41 PM

Quote:

Originally Posted by JSH

So, it made 965 at 7000 a month ago with a 103 and 3" upper. We put a 112 and 2.75 on it this week and are shocked that it now gets to 850 at 5800 and rolls over badly.

99% of the HPT data looks good (except for KPa 11 is not right). Gained 3 lbs. boost, MAT is fine, spark and advance look good, etc., etc.

Our first course of action is to replace the crimped exhaust pipe section today and redyno.

Has anyone here had this happen to them? I'd bet shops such as KaTech have.

Your first step is to stop looking at corrected Data. You are not making 965rwhp at 7k feet. And for every 5mm you are going to gain roughly 1.5lbs of boost. And what is kpa 11?? Do you mean psi??? You should be close to 200kpa if your making 15lbs of boost.

Post the dyno log.

CW3SF · 10-13-2022, 02:07 PM

What does your fuel pressure and inj pw look like? Didn’t you do the LPE HPFP?

arpad_m · 10-13-2022, 02:53 PM

965 at 7k rpm isn't necessarily better than 850 at 5.8k rpm, was it much stronger at 5.8k rpm as well a month ago? The log or at least the entire dyno graph from both tests would be helpful. And yes, that wild correction was already discussed in another thread with you IIRC.

SATINSTEEL1LE · 10-13-2022, 03:48 PM

Lets see the log. Probably fuel pressure droping.

sr71bb · 10-13-2022, 03:55 PM

Quote:

Originally Posted by JSH

So, it made 965 at 7000 a month ago with a 103 and 3" upper. We put a 112 and 2.75 on it this week and are shocked that it now gets to 850 at 5800 and rolls over badly.

99% of the HPT data looks good (except for KPa 11 is not right). Gained 3 lbs. boost, MAT is fine, spark and advance look good, etc., etc.

Our first course of action is to replace the crimped exhaust pipe section today and redyno.

Has anyone here had this happen to them? I'd bet shops such as KaTech have.

My BET would be you are running out of fuel and that's why it is rolling over. Look at the logs to see what the duty cycle % is on the injectors.

Katech_Mike · 10-13-2022, 04:01 PM

The flat portion of the exhaust isn't your problem.

Could be a number of things. I would guess it's fuel delivery related without seeing a log or even dyno graph.

Shot in the dark guess is if you log the pid for high pressure fuel pump delivery angle you'll see its maxed at 130 degrees.

CW3SF · 10-13-2022, 04:05 PM

Quote:

Originally Posted by Camaro1973

Your first step is to stop looking at corrected Data. You are not making 965rwhp at 7k feet. And for every 5mm you are going to gain roughly 1.5lbs of boost. And what is kpa 11?? Do you mean psi??? You should be close to 200kpa if your making 15lbs of boost.

Post the dyno log.

Everyone uses SAE as the bellwether. If he’s using the same car on the same dyno and both in SAE, he’s doing what he should be doing in order to assess gains front his last round of mods. To try and read this current dyno run in anything other than SAE makes no sense. Not following your logic on that.

Trochoidal · 10-13-2022, 04:44 PM

Quote:

Originally Posted by CW3SF

Everyone uses SAE as the bellwether. If he’s using the same car on the same dyno and both in SAE, he’s doing what he should be doing in order to assess gains front his last round of mods. To try and read this current dyno run in anything other than SAE makes no sense. Not following your logic on that.

Maybe Camaro1973 was referring to this post.

https://www.camaro6.com/forums/showp...0&postcount=82

ZL1Atlanta · 10-13-2022, 05:17 PM

I promise you it isn’t the crimp. I ran 8.40’s at over 162 MPH with it still there. We got rid of it and didn’t see any measurable change. It was just annoying me. Is the power higher at any point of the pull up to where it falls off?

JSH · 10-13-2022, 05:24 PM

Quote:

Originally Posted by Trochoidal

Maybe Camaro1973 was referring to this post.

https://www.camaro6.com/forums/showp...0&postcount=82

Yes, it's SAE. I haven't a non-SAE dyno chart in years.

Z OH 6 · 10-13-2022, 05:56 PM

I think its fuel related too. The extra 3psi of boost is demanding more fuel.

JSH · 10-13-2022, 06:35 PM

Quote:

Originally Posted by ZL1Atlanta

I promise you it isn’t the crimp. I ran 8.40’s at over 162 MPH with it still there. We got rid of it and didn’t see any measurable change. It was just annoying me. Is the power higher at any point of the pull up to where it falls off?

You're probably right, but it is counterintuitive for a 5" column of intake air to pass unrestricted thru a 2.75" pipe crimped down to 1.5" or so.

Here's the log:

Fuel rail press 2812 psi
Low side 80 psi
Inj pulse width 4.8 ms

JSH · 10-13-2022, 06:43 PM

More data

10-13-2022, 01:38 PM	#1
JSH Drives: '20 ZLE Join Date: Jun 2020 Location: Mile High Posts: 3,547	Dyno Shocker - Lost Power!! So, it made 965 at 7000 a month ago with a 103 and 3" upper. We put a 112 and 2.75 on it this week and are shocked that it now gets to 850 at 5800 and rolls over badly. 99% of the HPT data looks good (except for KPa 11 is not right). Gained 3 lbs. boost, MAT is fine, spark and advance look good, etc., etc. Our first course of action is to replace the crimped exhaust pipe section today and redyno. Has anyone here had this happen to them? I'd bet shops such as KaTech have. __________________ '20 ZL1 1LE A10, OEM short block, LME heads/valve train, E2650. 100+ octanes, no eth, no meth, no N2O. 2/23 - 1031/1004 wheel. 4/23 - 1.41/9.61/145 at DA 7000 ft. (only made five passes). 2/24 - LME 390, E2650, FBO, 100 oct.; 1116hp/ 1063tq; 109 oct. dyno next.

10-13-2022, 02:07 PM	#3
CW3SF Drives: 2019 Chevy Camaro ZL1 M6 Join Date: Jul 2019 Location: Sea level Posts: 1,252 View My Garage	What does your fuel pressure and inj pw look like? Didn’t you do the LPE HPFP? __________________ Kong Stage X Port, NW103, LPE HPFP, XDI +30 Injectors, ARH Headers, Flex Fuel, JMS Booster, AWE Touring, Elite E2-X CC. Stock heads, stock cam, stock pulleys: Tuned by KingLT1. 740whp Uncorrected on e50

10-13-2022, 02:53 PM	#4
arpad_m Drives: 2018 Camaro 2SS A8 Join Date: Jul 2017 Location: East Tennessee Posts: 11,563 View My Garage	965 at 7k rpm isn't necessarily better than 850 at 5.8k rpm, was it much stronger at 5.8k rpm as well a month ago? The log or at least the entire dyno graph from both tests would be helpful. And yes, that wild correction was already discussed in another thread with you IIRC. __________________ 2018 Camaro 2SS — G7E MX0 NPP F55 IO6 735 rwhp \| 665 rwtq Magnuson TVS 2300 80mm pulley \| Kooks 1 7/8" LT headers \| JRE smooth idle terminator cam \| LT4 FS & injectors \| TSP forged pistons & rods JMS PowerMAX \| DSX flex fuel kit \| Roto-Fab CAI \| Soler 95mm LT5 TB \| 1LE wheels \| 1LE brakes \| BMR rear cradle lockout \| JRE custom tune 1100 - 1/30/18 \| 2000 - 1/31/18 3000 - 2/06/18 TPW 2/26/18 3400 - 2/19/18 \| 3800 - 2/26/18 4300 - 2/27/18 \| 4B00 - 3/01/18 4200 - 3/05/18 \| 4800 - 3/14/18 5000 - 3/16/18 \| 6000 - 3/19/18

10-13-2022, 05:17 PM	#10
ZL1Atlanta Drives: 2017 Chevrolet Camaro ZL1 Join Date: Jul 2018 Location: Canton, GA Posts: 405	I promise you it isn’t the crimp. I ran 8.40’s at over 162 MPH with it still there. We got rid of it and didn’t see any measurable change. It was just annoying me. Is the power higher at any point of the pull up to where it falls off? __________________ 2017 ZL1 - PB 8.05 @ 172 MPH @ 3730 lbs @ 70 DA (work in progress) Built by Vengeance Racing, tuned by Elite Tuned

10-13-2022, 06:43 PM	#14
JSH Drives: '20 ZLE Join Date: Jun 2020 Location: Mile High Posts: 3,547	More data Attached Images __________________ '20 ZL1 1LE A10, OEM short block, LME heads/valve train, E2650. 100+ octanes, no eth, no meth, no N2O. 2/23 - 1031/1004 wheel. 4/23 - 1.41/9.61/145 at DA 7000 ft. (only made five passes). 2/24 - LME 390, E2650, FBO, 100 oct.; 1116hp/ 1063tq; 109 oct. dyno next.

10-13-2022, 03:48 PM	#5
SATINSTEEL1LE Account Suspended Drives: 21 ZL1 Join Date: Feb 2022 Location: South East Posts: 662	Lets see the log. Probably fuel pressure droping.

10-13-2022, 04:01 PM	#7
Katech_Mike Drives: 2015 Camaro ZL1 Join Date: Oct 2020 Location: Clinton Twp, Michigan Posts: 243	The flat portion of the exhaust isn't your problem. Could be a number of things. I would guess it's fuel delivery related without seeing a log or even dyno graph. Shot in the dark guess is if you log the pid for high pressure fuel pump delivery angle you'll see its maxed at 130 degrees.

10-13-2022, 05:56 PM	#12
Z OH 6 Drives: 2021 Red Hot ZL1 Join Date: Sep 2020 Location: Gapplebees Posts: 3,065	I think its fuel related too. The extra 3psi of boost is demanding more fuel.

User Name		Remember Me?
Password