02-25-2024, 10:51 AM | #1 |
Drives: '20 ZLE Join Date: Jun 2020
Location: Mile High
Posts: 3,565
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Manifold Pressure Drop
We're in the tuning process, the car runs well, and the most surprising data we've seen so far is a drop in absolute manifold and boost pressure from 31# in the previous build to 25# in this build.
The previous build was OEM shortblock with LME heads designed for the Hennessey 850. The new build has LME's short block and race heads. Kong has always said that 31# was too high and that I needed a more efficient motor. Has anyone else here seen such a drop?
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'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. Last edited by JSH; 02-25-2024 at 04:12 PM. |
02-25-2024, 01:31 PM | #2 | |
Drives: 2017 Camaro 2SS A8 Join Date: Aug 2018
Location: Petersham MA
Posts: 4,761
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Quote:
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2017 Chevy Camaro 2SS A8 Whipple 3.0, Mast Black Label heads, Fore triple in-tank pumps, 112mm TB, LPE +52% injectors, LPE BB HPFP, 15” conversion 1059 WHP/944 WTQ, 9.48@150
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02-25-2024, 02:12 PM | #3 |
Drives: '20 ZLE Join Date: Jun 2020
Location: Mile High
Posts: 3,565
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I was using a 2.625 upper previously but put a 3" on it to start with. Sounds like I should go back to 2.625
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'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. |
02-25-2024, 03:00 PM | #4 |
Drives: 2017 Camaro 2SS A8 Join Date: Aug 2018
Location: Petersham MA
Posts: 4,761
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For sure, that still might not be enough but it’s a logical next-step.
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2017 Chevy Camaro 2SS A8 Whipple 3.0, Mast Black Label heads, Fore triple in-tank pumps, 112mm TB, LPE +52% injectors, LPE BB HPFP, 15” conversion 1059 WHP/944 WTQ, 9.48@150
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02-25-2024, 04:10 PM | #5 |
Drives: '20 ZLE Join Date: Jun 2020
Location: Mile High
Posts: 3,565
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Shouldn't I expect the boost to go down a little bit as my tune gets better and more efficient? This has changed my thinking about boost.
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'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. Last edited by JSH; 02-25-2024 at 05:08 PM. |
02-25-2024, 07:51 PM | #6 | |
Drives: 2017 Camaro 2SS A8 Join Date: Aug 2018
Location: Petersham MA
Posts: 4,761
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Quote:
Boost is a measure of restriction. Letting the engine move air more easily means the blower puts the air into the motor with less “boost”. This lets the blower operate at a different point in its compressor map…so less boost doesn’t mean less airflow…it just gets into AND out of the engine more easily. You can tell by your MAF values how much air you’re moving so just adjust your blower speed accordingly. If you’re trying to max out a PD blower, you can’t be trying to run 30-35 pounds of boost (unless the blower is specifically designed for that like some turbos are)… you needed more airflow but lower boost…say 22-24 pounds max.
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2017 Chevy Camaro 2SS A8 Whipple 3.0, Mast Black Label heads, Fore triple in-tank pumps, 112mm TB, LPE +52% injectors, LPE BB HPFP, 15” conversion 1059 WHP/944 WTQ, 9.48@150
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02-25-2024, 10:07 PM | #7 |
Drives: '20 ZLE Join Date: Jun 2020
Location: Mile High
Posts: 3,565
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When you say boost, you mean total manifold pressure (ambient + boost)?
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'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. |
02-26-2024, 07:06 AM | #8 |
Drives: 2017 Camaro 2SS A8 Join Date: Aug 2018
Location: Petersham MA
Posts: 4,761
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Yes. Boost is just the differential between manifold and atmospheric pressures.
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2017 Chevy Camaro 2SS A8 Whipple 3.0, Mast Black Label heads, Fore triple in-tank pumps, 112mm TB, LPE +52% injectors, LPE BB HPFP, 15” conversion 1059 WHP/944 WTQ, 9.48@150
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02-26-2024, 10:20 AM | #9 |
Drives: 2017 Chevrolet Camaro ZL1 Join Date: Jul 2018
Location: Canton, GA
Posts: 405
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My last engine was a 416 ci with LME's max effort CID heads and made 29.5 psi. On the new engine (427 ci) using the same pulley combo it made 21.5 psi. The lower the better with a 2650.
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2017 ZL1 - PB 8.05 @ 172 MPH @ 3730 lbs @ 70 DA (work in progress)
Built by Vengeance Racing, tuned by Elite Tuned |
02-26-2024, 10:57 AM | #10 |
Drives: '20 ZLE Join Date: Jun 2020
Location: Mile High
Posts: 3,565
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This has changed how I think of boost. Kong had told me all along that I needed an engine that would flow more air to take full advantage of the 2650. I was thinking that more spark advance would consume more air.
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'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. |
02-26-2024, 01:12 PM | #11 |
Drives: 2017 Chevrolet Camaro ZL1 Join Date: Jul 2018
Location: Canton, GA
Posts: 405
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Yep, keeping boost down has been a major focus on this build. TooHighPSI explained the importance early on with the 2650 and it definitely seems to have paid off.
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2017 ZL1 - PB 8.05 @ 172 MPH @ 3730 lbs @ 70 DA (work in progress)
Built by Vengeance Racing, tuned by Elite Tuned |
02-26-2024, 02:49 PM | #12 |
My stock LT4 engine made 21lbs of boost and when we installed the new bullet it made 15lbs! Pully'd up to get to 17lbs.
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2018 ZL1-NFG-A10
New Iron L8T 9.32 147MPH |
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02-26-2024, 03:34 PM | #13 |
Drives: Chevy Camaro Join Date: Sep 2022
Location: IN
Posts: 193
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Like others have stated, boost a measurement of resistance. A bigger engine, moving more air is going to have less resistance. Look at airflow or hp numbers if you want to compare apples to apples. It could also make a little less boost as the tune is dialed in and the engine is running more efficient.
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'20 Camaro LT1
Twin 67/62 turbo 401(L8t) Texas speed forged piston & rod, BTR stg1 turbo cam, holley ultra lo, port injection, circle d 3600 stall, hoosier bias ply quick time pro's on racestar recluse wheels 1.45 4.01 6.07@120.74 9.28@153.43 '94 Camaro Z28 6mt cc306 cam, 4:10's, longtubes with x pipe, getting an engine rebuild |
02-26-2024, 05:56 PM | #14 | ||||
Drives: 2017 Camaro 2SS A8 Join Date: Aug 2018
Location: Petersham MA
Posts: 4,761
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2017 Chevy Camaro 2SS A8 Whipple 3.0, Mast Black Label heads, Fore triple in-tank pumps, 112mm TB, LPE +52% injectors, LPE BB HPFP, 15” conversion 1059 WHP/944 WTQ, 9.48@150
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