Engine builders please help, need advice on valve springs

[flht99b]

I'm looking for some advice and guidance. Have a 9,600 mile 2010 SS LS3 6spd manual that I will be installing a GM LS9 cam in. I know the stock LS3 springs will work fine BUT I'm looking to make the valve train as bullet proof as possible. Car will not see drag strip use BUT will see a road course once or twice a year. At 54 I am no longer a die hard racer, just having occasional fun weekend with the car. Car is an occasional driver on the street as I work from home. I think it goes to the grocery store more than anywhere else . Here is what parts I have so far :

GM LS9 cam - to be installed
3 bolt cam gear and LS2 damper - to be installed
IWIS C5 R heavy duty timing chain - to be installed
Melling 10296 oil pump - to be installed
Comp Cams rocker trunion upgrade kit - to be installed

Springs - see paragraph below

CAI cold air kit - already installed
VMAX CNC ported throttle body - already installed
Elite oil catch can - already installed
ARH 1 7/8" LT's with HF cats - already installed
Stock cat back pipes - already installed
GMPP "touring mufflers" - already installed
AAM 3.70 gears - already installed

I have a set of the newer Comp Cams 26918 springs I had planned to use along with the stock retainers and locks but I am now wondering if they will be too much spring. Would I be better off with GM LS9 springs or something else ?? If the Comp Cam springs are OK, should I get the Comp Cam forged retainers and locks or will the stock retainers and locks be fine ??

I have 1 vote so far for the 26918 springs with stock retainers and locks. I thought I had this well planned out and was ready to go but now I have second thoughts about the springs. Any suggestions will be greatly appreciated.
Ed M.

[Ivan @ Southwest Speed]

Thats a heck of a lot of work for a LS9 Cam install......

The CC 918s would be much better than the CC 921s that we use in our G6X3 Cam kits. I think you'll be fine there.

Looks like you have a sweet plan, I'd just consider upping the Cam to something larger to get more power out of all the work and money you're putting into this project.

Good luck and subscribed!
Ivan

[Stingr69]

Ed,
Considering the specs: the LS9 cam has .011" more lift on the intake and .033" more lift on the exhaust. 6° more duration on the intake and 19° more duration on the exhaust. This profile has just a little more exhaust event to cope with the supercharger. In my opinion that just isn't enough of a difference to change the spring requirements .

I did the LS9 cam swap and it works fine with the stock valvetrain pieces. The cam drive gear swap was the only other 100% mandatory change. The LS2 damper is probably good insurance but I did not choose to change it. GM uses it in the LS9 tensioner and the loads on it come from the cam profile, RPM and spring rate so the stock tensioner was deemed good enough for me. If you were to go bigger on the cam then all those pieces would need to be considered.

Hope this helps,

-Mark.

[Jason 98 TA]

The comp springs will work great for you. Install & enjoy!!

[flht99b]

Ivan, Mark,
Thank you for the suggestions and your experience. Yes, the LS9 cam is very conservative. I am looking for as close to stock driveability as possible with just a mild boost in power over stock. Reliability is more important to me. I'd be thrilled with 430rwhp. Supercharging is not in my future, car will remain NA. I'm just trying to build what I feel a 5th gen Z28 would be, the handling and braking mods I've done would work well with the engine mods, one doesn't over power the other.
Ed M.

[BowlingSS]

Originally Posted by flht99b

Ivan, Mark,
Thank you for the suggestions and your experience. Yes, the LS9 cam is very conservative. I am looking for as close to stock driveability as possible with just a mild boost in power over stock. Reliability is more important to me. I'd be thrilled with 430rwhp. Supercharging is not in my future, car will remain NA. I'm just trying to build what I feel a 5th gen Z28 would be, the handling and braking mods I've done would work well with the engine mods, one doesn't over power the other.
Ed M.

I sure like the color- RJT. When I go with a cam I am going with a larger one for my DD. What I would do is install the comp springs in case you want to go bigger on the cam later.

Bill

[Louis @ LG Motorsports]

The LS9 lobe is similar to that of Comp Cams Xtreme energy lobes. You will need the equivalent of the LS9 spring, but remember the LS9 has to cope with the Ti intake valve, which is much lighter than the LS3s. The 918s will suit you just fine. I would not use the LS9 spring unless you change the intake valve.

[flht99b]

Looks like my initial plan to use the Comp Cam 26918 springs on the LS9 cam is the way to go. I just start to over think stuff at times. Thanks for all the replies, suggestions and information. Now I just have to put it all together.
Ed M.

[orange-prince]

if i were you ill get LPE gt9 cam but it's your own so do what you like

[flht99b]

Originally Posted by orange-prince

if i were you ill get LPE gt9 cam but it's your own so do what you like

I looked at several "mild" cams including the LPE GT9, GT2-3 and various other companies cams but still kept coming back to the LS9 cam for a mild mannered street cam. Check out these 2 graphs ( click on the graphs when they come up to enlarge ) :

http://reckartperformancetuning.blog...t-install.html
The above graph is a stock exhaust 2008 LS3 Corvette w/the LS9 cam which made 427rwhp and 401 ft lbs or torque with the addition of the LS9 cam.

Then look at graph :

http://reckartperformancetuning.blog...manifolds.html
This graph above is the same 2008 LS3 Corvette with the LS9 cam and the addition of the LS7/ZO6 log exhaust manifolds and made 444rwhp and 411 ft lbs of torque.

51 rwhp and 27 ft lbs of torque gain with a smooth idle and stock driveability works for me. I suspect those numbers are a bit high but in any event the LS9 cam does give a decent boost over the stock LS3 bumpstick. Since I already have the ARH LT's, HF cats and CAI, I suspect I MAY come close to those numbers which frankly is more than I was looking for. It's a bit of work to install this or any cam into the Camaro LS3 correctly with correctly matched parts and I've overbuilt the rest of the valve train so I suspect it will be durable and very easy to tune and live with. An added side benefit is the LS9 cam is around $120 ( I actually paid less ) which makes it a good value. To pay someone to install the LS9 cam may not be cost to benefit efficient but since I do all my own work except for paint, air conditioning and tuning, my labor is sort of "free".
Like I said earlier, I'd be thrilled with 430rwhp, anything over that is a plus. Durability and smooth, stock like driveability are higher priorities for me.
Ed M.

[flht99b]

After a weekend marathon car was back under it's own power Sunday evening. All looks and feels well after approximately 150 easy miles. Still no CEL even with LT's and LS9 cam but I'm sure over time a cat efficiency code would pop up without a tune. There is a definite, substantial SOP power increase from the LS9 cam, we'll see how much after next weeks MTI visit. Idle is smooth, drivability is smooth and stock like in traffic. Thanks to all that put my mind at rest concerning valve springs. Though changing 16 springs on the car AND adding rocker trunion upgrade kit to 16 rockers took 4 hours and may have been over kill, I like the peace of mind of having under stressed valve train parts for longevity.
Ed M.