Running a huge blower cam with twin turbos.

Umbriel · 04-07-2022, 09:19 AM

Hey guys, I have 2016 SS with a Thompson Motorsports forged 416 and Huron Speed twin kit running Comp 68/71s.

I originally was going to go with an F1 Procharger but Huron made me a great deal on the twin kit and I couldn't pass it up. I talked with my tuner about the cam since we were halfway through the build and he said just leave and he'll make it work. The car doesn't make as much power as I feel it should and won't make anymore power past 20 pounds so I am thinking there is a backpressure issue and I think it is being caused by the mismatched cam that is in it and was wondering if people familiar with these motors and set ups could give me an idea what you think? I want to replace the cam with a cam specifically for twin turbos but don't want to waste the money if it isn't causing an issue.

Umbriel · 04-07-2022, 09:21 AM

Here are the cam specs. If you would like any other information about the build just let me know.

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Umbriel · 04-07-2022, 09:22 AM

That pic is terrible, not sure why it is loading like that but the specs are:

238/262 .648/.630 114 LSA 4 ICL

KingLT1 · 04-07-2022, 09:28 AM

The "make it work" mindset is fine for most modest builds but when you start pushing the envelope and going over 20psi, cam selection definitely becomes more important. I would change the cam for sure. 22 degrees of overlap is likely the problem. I wouldn't even want that on a big Centri setup. Overlap is kryptonite for making boost. Those cam specs look like something for a Big cube NA high compression build.

Umbriel · 04-07-2022, 10:14 AM

Quote:

Originally Posted by KingLT1

The "make it work" mindset is fine for most modest builds but when you start pushing the envelope and going over 20psi, cam selection definitely becomes more important. I would change the cam for sure. 22 degrees of overlap is likely the problem. I wouldn't even want that on a big Centri setup. Overlap is kryptonite for making boost. Those cam specs look like something for a Big cube NA high compression build.

I figured it was costing me power but not sure how much power. This cam was done by GPI for an F1 Procharger and I changed builds in the middle to twin turbo. So you are pretty certain my cam is definitely causing a big issue? Who does good boost cams for these cars? I used John Bewley on my LS platform for a turbo cam and GPI for this cam.

Umbriel · 04-07-2022, 10:35 AM

I'm basically trying to figure if it is worth changing the cam or keeping it like it is and selling the turbo kit and going to an F1x Procharger.

ZO6Ted · 04-07-2022, 11:13 AM

I'd definitely change the cam and keep the twins.

Umbriel · 04-07-2022, 11:30 AM

Quote:

Originally Posted by ZO6Ted

I'd definitely change the cam and keep the twins.

Do you recommend a certain company to spec the cam for me?

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KingLT1 · 04-07-2022, 03:41 PM

I would call cam motion and give them details on the setup. My guess is they spec something around 5 degrees of overlap. You need less overlap to keep from blowing boost right out the exhaust.

Umbriel · 04-07-2022, 04:17 PM

Quote:

Originally Posted by KingLT1

I would call cam motion and give them details on the setup. My guess is they spec something around 5 degrees of overlap. You need less overlap to keep from blowing boost right out the exhaust.

That is what I was looking for, who to get in touch with. Thanks.

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LT1ornothing · 04-07-2022, 04:34 PM

Agreed with King and Ted, a properly spec'd cam for your twin turbo set up will drastically improve the curve and the limits at higher boost levels. Also believe that your Big Centri cam specs are more common in NA Big cube builds and/or nitrous. Get the right cam in there and it will be night and day difference, keep the twins for sure.

cad78 · 04-07-2022, 07:37 PM

How much backpressure? I would guess you may be limited by your turbine size more than the cam.

Joshinator99 · 04-07-2022, 07:54 PM

Quote:

Originally Posted by KingLT1

I would call cam motion and give them details on the setup. My guess is they spec something around 5 degrees of overlap. You need less overlap to keep from blowing boost right out the exhaust.

Cam selection needs to be for your twin setup, specifically. No doubt about it, as you’re seeing.

95 imp · 04-07-2022, 10:31 PM

Blower cam timing and turbo cam timing are very different animals.

Do yourself a favor and change the cam.

04-07-2022, 09:19 AM	#1
Umbriel Drives: 2016 Camaro SS Join Date: Sep 2018 Location: Bartlett, TN Posts: 1,121	Running a huge blower cam with twin turbos. Hey guys, I have 2016 SS with a Thompson Motorsports forged 416 and Huron Speed twin kit running Comp 68/71s. I originally was going to go with an F1 Procharger but Huron made me a great deal on the twin kit and I couldn't pass it up. I talked with my tuner about the cam since we were halfway through the build and he said just leave and he'll make it work. The car doesn't make as much power as I feel it should and won't make anymore power past 20 pounds so I am thinking there is a backpressure issue and I think it is being caused by the mismatched cam that is in it and was wondering if people familiar with these motors and set ups could give me an idea what you think? I want to replace the cam with a cam specifically for twin turbos but don't want to waste the money if it isn't causing an issue.

04-07-2022, 09:28 AM	#4
KingLT1 Drives: 2016 1SS NFG A8 Join Date: Aug 2017 Location: 46804 Posts: 6,796	The "make it work" mindset is fine for most modest builds but when you start pushing the envelope and going over 20psi, cam selection definitely becomes more important. I would change the cam for sure. 22 degrees of overlap is likely the problem. I wouldn't even want that on a big Centri setup. Overlap is kryptonite for making boost. Those cam specs look like something for a Big cube NA high compression build. __________________ 2016 NFG 1SS A8 Options-2SS Leather/NPP Perf. mods-Whipple 2.9/Fuel System/Flex Fuel/103mm TB/Rotofab Big Gulp/Cat Deletes/Corsa NPP Per. times- 10.5 @ 137 w/ 1.8 60ft Full weight on 20's 1200DA

04-07-2022, 11:13 AM	#7
ZO6Ted Old badass Drives: 14GMC 2.9 16GMC Turbos 2020Silv.6.2 Join Date: Mar 2020 Location: Arlington Tx Posts: 238	I'd definitely change the cam and keep the twins. __________________ I've had 7 Camaro's. All gone...for now. Current build in progress 2016 GMC4x4 RCSB twin hair dryers ~1k whp fbe port inj 1/8 mi & stealth street terror

04-07-2022, 03:41 PM	#9
KingLT1 Drives: 2016 1SS NFG A8 Join Date: Aug 2017 Location: 46804 Posts: 6,796	I would call cam motion and give them details on the setup. My guess is they spec something around 5 degrees of overlap. You need less overlap to keep from blowing boost right out the exhaust. __________________ 2016 NFG 1SS A8 Options-2SS Leather/NPP Perf. mods-Whipple 2.9/Fuel System/Flex Fuel/103mm TB/Rotofab Big Gulp/Cat Deletes/Corsa NPP Per. times- 10.5 @ 137 w/ 1.8 60ft Full weight on 20's 1200DA

04-07-2022, 10:31 PM	#14
95 imp Dumb Ass Deluxe Drives: A Tricked Out Mountain Bike Join Date: Jun 2019 Location: Arizona Posts: 1,959	Blower cam timing and turbo cam timing are very different animals. Do yourself a favor and change the cam. __________________

04-07-2022, 09:21 AM	#2
Umbriel Drives: 2016 Camaro SS Join Date: Sep 2018 Location: Bartlett, TN Posts: 1,121	Here are the cam specs. If you would like any other information about the build just let me know. Sent from my SM-N986U using Tapatalk

04-07-2022, 09:22 AM	#3
Umbriel Drives: 2016 Camaro SS Join Date: Sep 2018 Location: Bartlett, TN Posts: 1,121	That pic is terrible, not sure why it is loading like that but the specs are: 238/262 .648/.630 114 LSA 4 ICL

04-07-2022, 10:35 AM	#6
Umbriel Drives: 2016 Camaro SS Join Date: Sep 2018 Location: Bartlett, TN Posts: 1,121	I'm basically trying to figure if it is worth changing the cam or keeping it like it is and selling the turbo kit and going to an F1x Procharger.

04-07-2022, 04:34 PM	#11
LT1ornothing Drives: 2020 LT1 M6 Join Date: Jan 2016 Location: South, the DEEP south Posts: 1,114	Agreed with King and Ted, a properly spec'd cam for your twin turbo set up will drastically improve the curve and the limits at higher boost levels. Also believe that your Big Centri cam specs are more common in NA Big cube builds and/or nitrous. Get the right cam in there and it will be night and day difference, keep the twins for sure.

04-07-2022, 07:37 PM	#12
cad78 Drives: 2022 ZL1 Join Date: Mar 2022 Location: Winter Haven Posts: 12	How much backpressure? I would guess you may be limited by your turbine size more than the cam.

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