Regarding Upgrading My L99 Camaro SS

[CC BOY]

Hello everyone, and greetings to all the veterans here! I’m a Camaro enthusiast from China. Please excuse my English—it’s not the best. I picked up my car in 2021, a 2013 fifth-gen Chevrolet Camaro 2SS with the L99 engine and 6L80 transmission. I absolutely love this car and enjoy every moment driving it on the track. Over the years, I’ve experimented with modifications and upgrades, but I’ve gradually reached its limits. That’s why I’ve decided to take the transformation further. In China, there aren’t many people who are into American muscle cars (most prefer JDM or German vehicles), and expertise in modifying them is scarce.

My current setup includes: KW V3 ClubSport suspension, 20-inch forged wheels, AP9570 front calipers with Chinese ADTORY racing brake pads and rotors, a Flowmaster long-tube exhaust, KOOKS headers and manifold, Injen intake system, TROFEO R tires, an APR GTC-300 rear wing, a custom front splitter, Recaro bucket seats, and more. As mentioned, I’ve been exploring its limits step by step, and now I want to focus on enhancing the engine performance.

First, I plan to convert my L99 engine to an LS3. Below is the parts list I’ve put together through my own research. However, I don’t have any friends or experts around me familiar with American car modifications, so I’m turning to you all for guidance:

ARP Head Stud Kit ARP-234-4317

Johnson Lifters 2110R

Chevrolet Performance Lifter Trays 12595365

KAT-A2390 High Capacity Gen3/4 Oil Pump

BTR LS.660 Dual Spring Kit

BTR Premium LS & LT Rocker Arm Trunnion Kit - TK002

BTR LS3 Stage 4 V2 Camshaft

BTR VVT Conversion Kit Delete Kit

Genuine GM LSA/LS9 Head Gasket

Rollmaster Timing Chain - 06+ LS2 & Wet Sump LS3 - Single Roller - 4 Pole - 58X - CS1190

Circle D HPseries 278mm 6L80LS Torque Converter; 3000-3200 rpm - w/Billet Cover #CDS-07N-09-07-2A

Camshaft Shim

Timing Chain Damper

Camshaft Bolts

Valve Cover Plate

Transmission Seal

Water Pump Gasket

Crankshaft Bolts
........

My goal is to achieve at least 480 wheel horsepower (ideally more) on a DynoJet dynamometer, so I can fully leverage the car’s potential on the track.

I’d appreciate your advice on the following:

Is this parts list sufficient, or are there adjustments needed?

Have I overlooked anything important?

How well do these components work together? (Specifically, is the BTR Stage 4 camshaft compatible with the Circle D HPseries 278mm 6L80LS torque converter rated for 3000-3200 rpm?)

PS: This is just the first phase of my build. Eventually, I plan to upgrade the cylinder heads, intake manifold, pistons, connecting rods, etc., staying true to a high-power naturally aspirated path. So, I want to choose parts that leave room for future improvements.

Thank you all in advance for your help!

[1JEWLDSSRS]

One of the items I didn't see listed that is a MUST, you will need an aftermarket transmission oil cooler for the stall converter. Also a stage 4 cam is a pretty big cam for a 3200 stall, I am running TSP Stage 3 cam, specs in my sig, and originally had a
3200 and it wasn't enough for my power band, so I went with a 4200-4500 Circle D which made a huge difference in the cars performance. Also you really don't need to use the Johnson lifters as they are pretty much "overkill", and you would have to measure/calculate for your pushrod lengths, whereas you can use the GM Performance lifters which is what I and some of the other guys are running, or you can go a step up and run the "Caddy lifters" pt# 88958689, they are used in the CTSV Cadillac's, and COPO Camaro's. I also didn't see the locks and retainers listed for the valve springs.

[1JEWLDSSRS]

Also didn't see the LS2 chain tensioner listed either..

[CamaroDreams76]

Originally Posted by 1JEWLDSSRS

One of the items I didn't see listed that is a MUST, you will need an aftermarket transmission oil cooler for the stall converter. Also a stage 4 cam is a pretty big cam for a 3200 stall, I am running TSP Stage 3 cam, specs in my sig, and originally had a
3200 and it wasn't enough for my power band, so I went with a 4200-4500 Circle D which made a huge difference in the cars performance. Also you really don't need to use the Johnson lifters as they are pretty much "overkill", and you would have to measure/calculate for your pushrod lengths, whereas you can use the GM Performance lifters which is what I and some of the other guys are running, or you can go a step up and run the "Caddy lifters" pt# 88958689, they are used in the CTSV Cadillac's, and COPO Camaro's. I also didn't see the locks and retainers listed for the valve springs.

Great suggestion. Was thinking the exact same thing with the stall as well.


I have no experience with KAT oil pumps. Meiling is the tried and true pump here in the states.

What are you doing as far as tuning goes?

Also I dont see any toe links or trailing arms or rear subframe bushings listed in your mods. May want to look into those. Adding power to these cars with IRS is a recipe for wheel hop..... which breaks axles.

[1JEWLDSSRS]

Originally Posted by CamaroDreams76

Great suggestion. Was thinking the exact same thing with the stall as well.


I have no experience with KAT oil pumps. Meiling is the tried and true pump here in the states.

What are you doing as far as tuning goes?

Also I dont see any toe links or trailing arms or rear subframe bushings listed in your mods. May want to look into those. Adding power to these cars with IRS is a recipe for wheel hop..... which breaks axles.

Thank you sir! One of my friends back before I did my cam swap did the exact same cam and all the supporting goodies as I did, except he went with the Circle D 3600 stall and did the 3.91 gear swap too and ran a 10.97 at Bradenton on DR's and skinnies up front! He showed me the time slip. AND, his Camaro wa the same color as yours!! lol. Lashway did his build back then as did mine. He also owns a 2014 COPO Camaro, him and his dad went up and brought it back to Florida. I was at the dealership when he pulled in to "brag" about and show us. It was pretty cool!!

[CC BOY]

Originally Posted by 1JEWLDSSRS

One of the items I didn't see listed that is a MUST, you will need an aftermarket transmission oil cooler for the stall converter. Also a stage 4 cam is a pretty big cam for a 3200 stall, I am running TSP Stage 3 cam, specs in my sig, and originally had a
3200 and it wasn't enough for my power band, so I went with a 4200-4500 Circle D which made a huge difference in the cars performance. Also you really don't need to use the Johnson lifters as they are pretty much "overkill", and you would have to measure/calculate for your pushrod lengths, whereas you can use the GM Performance lifters which is what I and some of the other guys are running, or you can go a step up and run the "Caddy lifters" pt# 88958689, they are used in the CTSV Cadillac's, and COPO Camaro's. I also didn't see the locks and retainers listed for the valve springs.

Thanks for the advice!
1. Regarding the upgraded transmission oil cooler, I’m already working on getting it prepared—thank you!
2. As for the valve spring locks and retainers, as well as the LS2 chain tensioner, I’ll continue looking around. If possible, could you share some suggestions? It’s really hard to get reliable information here in China…
3. About the torque converter—if the one I chose (rated for 3,000–3,200 RPM) isn’t sufficient, would switching to a converter closer to yours (around 4,500 RPM, right?) be necessary to match the Stage 4 cam?
4. Regarding the Johnson lifters, part of the reason for choosing them was to leave room for more power down the road. Another factor is that the price difference between Johnson lifters and GM Performance lifters (including shipping, tariffs, and dealer markups to China) is only about $100. So I originally thought it would be better to go with the more capable option from the start.

Thanks again for taking the time to reply and share your suggestions—I really appreciate it! It’s been great talking with you!

[CamaroDreams76]

Originally Posted by CC BOY

Thanks for the advice!
1. Regarding the upgraded transmission oil cooler, I’m already working on getting it prepared—thank you!
2. As for the valve spring locks and retainers, as well as the LS2 chain tensioner, I’ll continue looking around. If possible, could you share some suggestions? It’s really hard to get reliable information here in China…
3. About the torque converter—if the one I chose (rated for 3,000–3,200 RPM) isn’t sufficient, would switching to a converter closer to yours (around 4,500 RPM, right?) be necessary to match the Stage 4 cam?
4. Regarding the Johnson lifters, part of the reason for choosing them was to leave room for more power down the road. Another factor is that the price difference between Johnson lifters and GM Performance lifters (including shipping, tariffs, and dealer markups to China) is only about $100. So I originally thought it would be better to go with the more capable option from the start.

Thanks again for taking the time to reply and share your suggestions—I really appreciate it! It’s been great talking with you!

2. Check out Brain tooley Racing or Texas Speed an performance. They sell kits for all that. One stop shopping.
3. You are going to want at least 3600 or 3800 stall for that big of cam.
4. Nothing wrong with over building. I dont know how Johnson is today but they were on back order for a long time.

You should give Ted Jannetty a call or GPI. Or at least email them. Those people have been in the game a LONG time and do this stuff for a living. Will have great suggestions

[1JEWLDSSRS]

Originally Posted by CamaroDreams76

2. Check out Brain tooley Racing or Texas Speed an performance. They sell kits for all that. One stop shopping.
3. You are going to want at least 3600 or 3800 stall for that big of cam.
4. Nothing wrong with over building. I dont know how Johnson is today but they were on back order for a long time.

You should give Ted Jannetty a call or GPI. Or at least email them. Those people have been in the game a LONG time and do this stuff for a living. Will have great suggestions

Great advice here! All the items I used in my build came from BTR,( Brian Tooley Racing) and TSP, (Texas Speed and Performance). The cam was a TSP piece, the pushrods, retainers and locks, valve springs were all BTR pieces, they came as a kit from them. We went with the steel retainers and locks due to strength and longevity, titanium were lighter and could be used for their lightness for higher revs, but not necessary. As mentioned on the stall converter, you will want a higher than 3200 for that big cam, like mentioned at least a 3600-3800, or even higher if you want. Like one of our great members on here that really knew his stuff on these cars, "don't fear the stall"! I trust him and his builds, and his knowledge, so I went with the 4200-4500, all good! Love it. BO WHITE was his member name, great guy!!Thanks BO!! And as for the Johnson lifters, you WILL have to make sure to measure for the needed pushrod length as they are shorter than the normal size lifters we use. And as Dreams mentioned, those two shops really know their stuff, you can't go wrong with either one!!

[CC BOY]

Originally Posted by 1JEWLDSSRS

Great advice here! All the items I used in my build came from BTR,( Brian Tooley Racing) and TSP, (Texas Speed and Performance). The cam was a TSP piece, the pushrods, retainers and locks, valve springs were all BTR pieces, they came as a kit from them. We went with the steel retainers and locks due to strength and longevity, titanium were lighter and could be used for their lightness for higher revs, but not necessary. As mentioned on the stall converter, you will want a higher than 3200 for that big cam, like mentioned at least a 3600-3800, or even higher if you want. Like one of our great members on here that really knew his stuff on these cars, "don't fear the stall"! I trust him and his builds, and his knowledge, so I went with the 4200-4500, all good! Love it. BO WHITE was his member name, great guy!!Thanks BO!! And as for the Johnson lifters, you WILL have to make sure to measure for the needed pushrod length as they are shorter than the normal size lifters we use. And as Dreams mentioned, those two shops really know their stuff, you can't go wrong with either one!!

Thanks man! I definitely need to re-check my lifters. If my mod shop can’t measure lifter length, I might have to go your route…

I also wanted to ask about the fuel system. My tuner told me that without cutting pistons, it would be pushing the limits, and he recommended upgrading and optimizing my fuel system (injectors, ignition coils, and fuel rail). Do I really need to upgrade? I recall the stock L99 injectors are 42 lb/hr. Based on my target of 480–490 hp and the requirements for E85, that’s already very close to their limit. So if upgrading is really necessary, are there any recommended brands or part numbers? It’s been tough finding reliable info around here.

Also, my use case is track-focused, especially stop-and-go style circuits. I don’t run endurance races, but I do frequently hit high RPM. With zero tolerance for knock, is it still possible to reach my target power?

I looked into the 4500-stall torque converter you mentioned earlier, but I found a potential issue: paired with a BTR stage 4 camshaft, it seems like it won’t lock in 1st or 2nd gear because temps would spike too quickly? Not being able to lock 2nd on track might be pretty annoying… Would a 4300-stall converter be better? At least on a ~1:50 per lap circuit, I could use locked 2nd occasionally. I already have an independent oil cooler, transmission cooler, and an oversized aluminum radiator. Any suggestions? Thanks!

[acutron42]

I reached out to Andrew Cammer @ GPI for you. You can email him at andrew@gwatneyperformance.com He can guide you through everything you need & steer you in the right direction.

[CamaroDreams76]

Originally Posted by CC BOY

Thanks man! I definitely need to re-check my lifters. If my mod shop can’t measure lifter length, I might have to go your route…

I also wanted to ask about the fuel system. My tuner told me that without cutting pistons, it would be pushing the limits, and he recommended upgrading and optimizing my fuel system (injectors, ignition coils, and fuel rail). Do I really need to upgrade? I recall the stock L99 injectors are 42 lb/hr. Based on my target of 480–490 hp and the requirements for E85, that’s already very close to their limit. So if upgrading is really necessary, are there any recommended brands or part numbers? It’s been tough finding reliable info around here.

Also, my use case is track-focused, especially stop-and-go style circuits. I don’t run endurance races, but I do frequently hit high RPM. With zero tolerance for knock, is it still possible to reach my target power?

I looked into the 4500-stall torque converter you mentioned earlier, but I found a potential issue: paired with a BTR stage 4 camshaft, it seems like it won’t lock in 1st or 2nd gear because temps would spike too quickly? Not being able to lock 2nd on track might be pretty annoying… Would a 4300-stall converter be better? At least on a ~1:50 per lap circuit, I could use locked 2nd occasionally. I already have an independent oil cooler, transmission cooler, and an oversized aluminum radiator. Any suggestions? Thanks!

I had to upgrade to 660cc injectors when I did heads/cam and E. Ignition coils are fine and so are fuel rails. Im at 800whp on E with triple in tank pumps on factory fuel rails and factory coils.

[1JEWLDSSRS]

Originally Posted by CC BOY

Thanks man! I definitely need to re-check my lifters. If my mod shop can’t measure lifter length, I might have to go your route…

I also wanted to ask about the fuel system. My tuner told me that without cutting pistons, it would be pushing the limits, and he recommended upgrading and optimizing my fuel system (injectors, ignition coils, and fuel rail). Do I really need to upgrade? I recall the stock L99 injectors are 42 lb/hr. Based on my target of 480–490 hp and the requirements for E85, that’s already very close to their limit. So if upgrading is really necessary, are there any recommended brands or part numbers? It’s been tough finding reliable info around here.

Also, my use case is track-focused, especially stop-and-go style circuits. I don’t run endurance races, but I do frequently hit high RPM. With zero tolerance for knock, is it still possible to reach my target power?

I looked into the 4500-stall torque converter you mentioned earlier, but I found a potential issue: paired with a BTR stage 4 camshaft, it seems like it won’t lock in 1st or 2nd gear because temps would spike too quickly? Not being able to lock 2nd on track might be pretty annoying… Would a 4300-stall converter be better? At least on a ~1:50 per lap circuit, I could use locked 2nd occasionally. I already have an independent oil cooler, transmission cooler, and an oversized aluminum radiator. Any suggestions? Thanks!

On your stall converter I have my tune for the trans to lock up anytime I am in manual mode in whatever gear I am in, and in sport mode it doesn't lock until 6th gear at 55 mph. I would call Chris @ Circle D and ask him what he suggests, he helped me with mine. Your converter operation would be all in how it's tuned. I don't race, so I couldn't answer all that about it. As far as your fuel system, I'm at 486rwhp,475rwtq and am running stock injectors just fine with a ZL1 fuel pump, no issues, still have plenty of injector left, but if you are going to run E85, you will need to upgrade your pump and injectors to handle the different characteristics of E85, and a flex fuel kit. I don't run E85 as all I have read about in on here, and other performance websites says there isn't much to be gained from it unless you are boosted, then there are really good gains to be had. On your coils and fuel rails, you will be fine with the stock items. And as you mentioning being at the limits on having to flycut your pistons, with some stage 4 cams with very high lifts, you would need to do that and fly cut the valve reliefs deeper that are already in the L99 pistons so the valves don't accidentally "kiss" the pistons when you do any high rpm's. As far as compression goes, that wouldn't have to be done, our L99's are at 10.5, and the LS3's are at 10.7. So you see that is why your pushrod length is curcial for engine/valve train safety. If any of this is incorrect, someone will surely chime in, or they will add to what I wrote. And as acutron said, contact Andrew at GPI, and he can get you going in the correct direction.