Pulleys - Camaro5 Chevy Camaro Forum / Camaro ZL1, SS and V6 Forums

cornfield camaro · 03-02-2019, 04:50 PM

I have a 2011 SS that was a L99, converted to a LS3 when we installed a BTR stage cam. Before this work, it would boost up to 11-12 psi. I'm running a Kennebell 2.8. Now I'm down to about 3 psi. I understand why I'm down but what would be a good choice for a pulley size to get me back to 10 or so psi? I'm thinking stock is a 4" pulley.

Nighthawk89 · 03-02-2019, 05:06 PM

Stock bottom end? I would suggest against 12psi long term..

DSMer1 · 03-02-2019, 08:19 PM

What caused the drop in boost? The cam didn't cause that much of a drop (11 to 3psi)...

cornfield camaro · 03-03-2019, 10:26 AM

Quote:

Originally Posted by DSMer1

What caused the drop in boost? The cam didn't cause that much of a drop (11 to 3psi)...

Oh yeah it did. The L99 cam is a weiner of a cam. The cam in there now is flowing big time. Beed to spin the blower (positive displacement) a little harder! Maybe not 10 psi, maybe 6-7?

DSMer1 · 03-03-2019, 03:41 PM

Well with a btr stage 3pd torque cam, a real ls3, stock 7.5" balancer and a 4" pulley I was seeing about 6.5psi out of a Whipple 2.9. I saw 8-9 on a 3.75 and 10.5 on a 3.5". All also with longtube headers, no cats and full exhaust.
If you are legitimately only seeing 3psi now I think something else is wrong.

cornfield camaro · 03-03-2019, 04:23 PM

Well a little bit smaller supercharger and maybe i'm wrong on total boost. Things are happening fast in my car so maybe it's above 3 psi. Maybe i need to talk to KB.

DSMer1 · 03-04-2019, 12:14 AM

Maybe you need some facts. Talking to KB isn't a bad idea but some facts will be needed for them or anyone to help you.
First you say the car was previously making 11psi. Then 6-7
Next you claim it is only making 3 psi, now it might be more but you don't know.
Do you have anyway to monitor what is happening? Do you have anyway to log l
What do you want? Buy a smaller pulley, make some more boost.
I recommend a 2.75" upper and get a 8+" harmonic balancer ��

cornfield camaro · 03-04-2019, 05:31 PM

Easy there big dog! You do alot of boosted runs in the winter? I havent driven this thing since last October. And then not a whole lot. Just day dreaming about a winter from hell project.

Batmanntexas · 03-04-2019, 07:28 PM

Cornfield, I have a Whipple, and Whipple says that for every 1/8" of pulley change is worth about 1 psi of boost (+/-).

For what it's worth, with ported heads, mild blower cam, stock damper, and a 3.625" pulley, I made ~10psi.

03-02-2019, 04:50 PM	#1
cornfield camaro Drives: 2011 l99 Join Date: Aug 2012 Location: Ames, Iowa Posts: 305	Pulleys I have a 2011 SS that was a L99, converted to a LS3 when we installed a BTR stage cam. Before this work, it would boost up to 11-12 psi. I'm running a Kennebell 2.8. Now I'm down to about 3 psi. I understand why I'm down but what would be a good choice for a pulley size to get me back to 10 or so psi? I'm thinking stock is a 4" pulley.

03-02-2019, 08:19 PM	#3
DSMer1 Drives: 14 and 15 SS's Join Date: Feb 2018 Location: Minneapolis, Minnesota Posts: 387	What caused the drop in boost? The cam didn't cause that much of a drop (11 to 3psi)... __________________ Bolt-ons!

03-03-2019, 03:41 PM	#5
DSMer1 Drives: 14 and 15 SS's Join Date: Feb 2018 Location: Minneapolis, Minnesota Posts: 387	Well with a btr stage 3pd torque cam, a real ls3, stock 7.5" balancer and a 4" pulley I was seeing about 6.5psi out of a Whipple 2.9. I saw 8-9 on a 3.75 and 10.5 on a 3.5". All also with longtube headers, no cats and full exhaust. If you are legitimately only seeing 3psi now I think something else is wrong. __________________ Bolt-ons!

03-04-2019, 12:14 AM	#7
DSMer1 Drives: 14 and 15 SS's Join Date: Feb 2018 Location: Minneapolis, Minnesota Posts: 387	Maybe you need some facts. Talking to KB isn't a bad idea but some facts will be needed for them or anyone to help you. First you say the car was previously making 11psi. Then 6-7 Next you claim it is only making 3 psi, now it might be more but you don't know. Do you have anyway to monitor what is happening? Do you have anyway to log l What do you want? Buy a smaller pulley, make some more boost. I recommend a 2.75" upper and get a 8+" harmonic balancer �� __________________ Bolt-ons!

03-04-2019, 07:28 PM	#9
Batmanntexas Drives: 2012 Camaro SS (2SS) Join Date: Aug 2012 Location: Stafford, VA Posts: 1,374 View My Garage	Cornfield, I have a Whipple, and Whipple says that for every 1/8" of pulley change is worth about 1 psi of boost (+/-). For what it's worth, with ported heads, mild blower cam, stock damper, and a 3.625" pulley, I made ~10psi. __________________ 745RWHP/634RWTQ on 93 @ 10psi 806/676 on E85 @ 10psi COTW 9/8/14

03-02-2019, 05:06 PM	#2
Nighthawk89 Drives: 2011 Camaro 2Ss M6 Join Date: Dec 2011 Location: Southern California Posts: 4,013	Stock bottom end? I would suggest against 12psi long term..

03-03-2019, 04:23 PM	#6
cornfield camaro Drives: 2011 l99 Join Date: Aug 2012 Location: Ames, Iowa Posts: 305	Well a little bit smaller supercharger and maybe i'm wrong on total boost. Things are happening fast in my car so maybe it's above 3 psi. Maybe i need to talk to KB.

03-04-2019, 05:31 PM	#8
cornfield camaro Drives: 2011 l99 Join Date: Aug 2012 Location: Ames, Iowa Posts: 305	Easy there big dog! You do alot of boosted runs in the winter? I havent driven this thing since last October. And then not a whole lot. Just day dreaming about a winter from hell project.