Urgent: Will W-pistons fit a J-engine? - Camaro5 Chevy Camaro Forum / Camaro ZL1, SS and V6 Forums

aaberg · 06-04-2021, 05:57 AM

My car is a Camaro 2012 2SS automatic with original L99-engine. Vin 2G1FK3DJ7C9105243

I will remove the Auto Fuel Management (AFM), keep VVT and restore engine. I have ordered pistons from Summit and just got a call from my speed shop that the pistons I have ordered are plain at the top and don't have any place for the valves, that original old pistons have.

Looking at Summits website: https://www.summitracing.com/parts/S...%2byear%3a2012

The text says these pistons are for engine W but nothing to find out about engine J.
I will also add a cam stage 1 kit: https://www.summitracing.com/parts/cca-mk189-301-13

So, the bottomline and question is: Will these pistons fitt my L99-engine?

(Yes, I know they are over borred .020).

InFiD3ViL · 06-04-2021, 01:48 PM

You would likely need to get rid of the VVT to run with the flat top pistons (LS3 conversion). VVT needs pistons with valve reliefs for proper PTV. This is a very generalized answer, so hopefully someone else will comment.

Rock-It Man · 06-04-2021, 04:37 PM

You need the scooped out pistons to accommodate VVT.

Do not put in the flat topped pistons, the valves will crash into them.

And why get rid of VVT? It gives you a nice flat torque curve that is great for low end torque.

InFiD3ViL · 06-04-2021, 08:58 PM

Quote:

Originally Posted by Rock-It Man

You need the scooped out pistons to accommodate VVT.

Do not put in the flat topped pistons, the valves will crash into them.

And why get rid of VVT? It gives you a nice flat torque curve that is great for low end torque.

Right, I agree. I was only stating he would have to get rid of the VVT to run those pistons. The better solution would just be to get the correct valve relieved pistons.

Chris49066SS · 06-04-2021, 09:30 PM

Quote:

Originally Posted by InFiD3ViL

Right, I agree. I was only stating he would have to get rid of the VVT to run those pistons. The better solution would just be to get the correct valve relieved pistons.

If I were that deep I would just forge the bottom end, thats just me though, just my opinion.

Batmanntexas · 06-04-2021, 10:49 PM

You could possibly have those pistons fly cut for the PTV. Not sure how much material there is in the crown though, just a thought.

lemontwist · 06-05-2021, 12:39 AM

i had my dod/afm tuned out(makes it a different car) it seemed like like unnecessary work going into the motor unless you are going cam swap. imo with a gear change and a tune the l99 is a good set up. i have had a few friends say my l99 car is faster than my ls3 car was still the ls3 was more fun mainly because the tr6060 and 3.42's. i hate to say it but cam, converter and gears makes the l99 a STOUT performer....quite possibly better than most ls3 cars.

TheFlyingBananaSS · 06-05-2021, 05:12 AM

Quote:

Originally Posted by lemontwist

i had my dod/afm tuned out(makes it a different car) it seemed like like unnecessary work going into the motor unless you are going cam swap. imo with a gear change and a tune the l99 is a good set up. i have had a few friends say my l99 car is faster than my ls3 car was still the ls3 was more fun mainly because the tr6060 and 3.42's. i hate to say it but cam, converter and gears makes the l99 a STOUT performer....quite possibly better than most ls3 cars.

I agree.

aaberg · 06-05-2021, 05:53 AM

Thanks for your advice. Seems like I need to swap J-pistons since I want to keep VVT. Can't find any at Summit and Rockauto doesn't have them in stock. Any suggestion where to find them?

Rem0v3r · 06-05-2021, 11:16 PM

If the cam will work in an ls3 then it will work in an l99.. im also assuming you're getting the rotating assembly balanced..
If your planning on boost at all then I strongly recommend resleeving the block while you're in there.

06-04-2021, 05:57 AM	#1
aaberg 30th conv & 45th 2SS conv Drives: 1997 30th conv & 2012 45th conv Join Date: Jul 2017 Location: Sweden Posts: 127 View My Garage	Urgent: Will W-pistons fit a J-engine? My car is a Camaro 2012 2SS automatic with original L99-engine. Vin 2G1FK3DJ7C9105243 I will remove the Auto Fuel Management (AFM), keep VVT and restore engine. I have ordered pistons from Summit and just got a call from my speed shop that the pistons I have ordered are plain at the top and don't have any place for the valves, that original old pistons have. Looking at Summits website: https://www.summitracing.com/parts/S...%2byear%3a2012 The text says these pistons are for engine W but nothing to find out about engine J. I will also add a cam stage 1 kit: https://www.summitracing.com/parts/cca-mk189-301-13 So, the bottomline and question is: Will these pistons fitt my L99-engine? (Yes, I know they are over borred .020). Last edited by aaberg; 06-04-2021 at 11:38 AM.

06-04-2021, 01:48 PM	#2
InFiD3ViL Drives: 2010 CGM 2SS/RS LS3 Swapped A6 Join Date: Sep 2016 Location: Spring Hill, FL Posts: 4,735	You would likely need to get rid of the VVT to run with the flat top pistons (LS3 conversion). VVT needs pistons with valve reliefs for proper PTV. This is a very generalized answer, so hopefully someone else will comment. __________________ 2010 CGM Camaro 2SS LS3 Swapped A6 - GPI LS3 SS1 .647/.638, (224/237, 112 +4, 7º overlap) on CamMotion 8620 core, BTR Platinum .660" Dual Spring kit w/titanium retainers, CHE bronze trunnion upgrade, stock heads milled @ .015, Melling HV 10296 oil pump, TSP 1-7/8" long tube headers (W/Catless Off-road Pipes), Corsa Xtreme 3" Catback, GPI Ported/Rod Mod Intake, Stage 2 Ported Throttle Body, Vararam OTR CAI, Mike Norris Gen 2 catch can + GM 1LE clean side separator, 160º thermostat - Megan Racing adjustable coilovers (lowered 1.75"), MRR M017 10/11" wheels-Tuned by Ryan @ GPI

06-04-2021, 10:49 PM	#6
Batmanntexas Drives: 2012 Camaro SS (2SS) Join Date: Aug 2012 Location: Stafford, VA Posts: 1,394 View My Garage	You could possibly have those pistons fly cut for the PTV. Not sure how much material there is in the crown though, just a thought. __________________ 745RWHP/634RWTQ on 93 @ 10psi 806/676 on E85 @ 10psi Currently @15-16psi.... COTW 9/8/14

06-05-2021, 05:53 AM	#9
aaberg 30th conv & 45th 2SS conv Drives: 1997 30th conv & 2012 45th conv Join Date: Jul 2017 Location: Sweden Posts: 127 View My Garage	Where to find J-pistons? Thanks for your advice. Seems like I need to swap J-pistons since I want to keep VVT. Can't find any at Summit and Rockauto doesn't have them in stock. Any suggestion where to find them?

06-04-2021, 04:37 PM	#3
Rock-It Man 376 cubic inches of fun Drives: 2023 Camaro ZL1 A10 Join Date: Jul 2010 Location: MA Posts: 4,043 View My Garage	You need the scooped out pistons to accommodate VVT. Do not put in the flat topped pistons, the valves will crash into them. And why get rid of VVT? It gives you a nice flat torque curve that is great for low end torque.

06-05-2021, 12:39 AM	#7
lemontwist Drives: 12 2SS/RS L99,11 2SS/RS LS3totaled Join Date: Jun 2019 Location: mooresville nc Posts: 1,048	i had my dod/afm tuned out(makes it a different car) it seemed like like unnecessary work going into the motor unless you are going cam swap. imo with a gear change and a tune the l99 is a good set up. i have had a few friends say my l99 car is faster than my ls3 car was still the ls3 was more fun mainly because the tr6060 and 3.42's. i hate to say it but cam, converter and gears makes the l99 a STOUT performer....quite possibly better than most ls3 cars.

06-05-2021, 11:16 PM	#10
Rem0v3r Drives: 2013 ss2 vert l99 Join Date: Apr 2017 Location: South florida Posts: 151	If the cam will work in an ls3 then it will work in an l99.. im also assuming you're getting the rotating assembly balanced.. If your planning on boost at all then I strongly recommend resleeving the block while you're in there.