I am currently doing research and in the process of selecting the right camshaft for my vehicle. (2007 Chevy Suburban 1500 5.3 Lc9/4l60e, weighing ~5600lbs) I am nearing an almost full bolt on status on my vehicle with intake, ignition, and exhaust upgrades and a 91/93 octane diablo tune and was looking to pick out the right cam for me once time comes for my afm parts to be swapped out (already has been tuned out). With all the modifications done i am estimating my vehicle to be at 410-430hp at the crank without a dyno but am planning on nearing 600-1000hp as my end goal. I am planning for and considering installing a centrifugal supercharger along with a progressive wet nitrous setup (up to potentially 200hp shot). I’ve been researching a few camshafts for my build such as a few btr cams, the ls7/ls9 cams as a budget build, potentially the chopacabra, but have had my sights set specifically on the summit racing pro ls stage 4 cam (sum-8709,8711). Dyno testing and charts show this cam has major gains in power above 3k rpm and a considerable hp gain (~50hp gain above the ls9 and truck norris cam alone). I am aware this large cam can potentially kill my low end power especially in a large suv like mine. The important question I am asking is if running this cam would be feasible on my build with other supporting mods to help my low end pick back up such as certain light weight reduction where i can, 3.73 to 4.10 rear end gear swap, a higher stall converter (2000-3000+), and the inclusion of forced induction in the future. I appreciate any advice and will take any answers into consideration.

 

You are probably making more like 340-350 hp at the crank wih the stock cam and heads. To get to 410-430 hp NA at the crank would require a larger cam than you would want to run in a 5.3L in that heavy brick. 800-1000 hp is pretty unrealistic for an aluminum block especially in something heavy. The cylinder liners are thin and the block is substantially weaker than the iron equivalent. Changing to an iron block and preferably a 6.0L stroked to a 408 to gain the added low speed torque would be a much better starting point.

 

I feel as though I should’ve fully elaborated all the modifications i’ve done so far. I have a cai with free flowing maf, high output ignition coils, spark plugs/wires, long tube headers with catless y pipe as well as the diablo tune. To my knowledge the 5.3 made about 310-330hp stock, do you really believe that these modifications only contributed that little to my hp gain? Would an overbore out to a 5.7L make a big difference as well? or is 6.0 the only way to go. I’m only leaning towards the 5.3 because it was a crate motor that was installed not too long ago and only has about 80-90k miles on it just would seem wasteful tossing a new motor that already seems to be keeping up with my abuse and torment lol

 

The headers/exhaust likely gained the most of actual mods, and the tune brought them all in synch.
The coils/wires/plugs gained nothing. Stock versions of all that are pretty good.
What a lot of guys don't realize is, the stock LS engines are VERY good. Intake manifold? Check, Heads? Check, Exhaust manifolds? Big improvements over those from 30-40 years ago.
The only thing that differentiates the truck engines from higher performance versions is the cam. That's it.
So different from the SBC that needed EVERYTHING to improve power and durability

 

I could not imagine enjoying that cam in that truck on the street... go with a smaller cam and just add boost to get to where you want

 

That aluminum block has thicker cylinders than pretty much any other ls block. People go way further on these blocks than 6.0 iron blocks overall, but I agree low speed torque is where it is at for a truck application.

 

Suburban with tallish gears, daily driven with stock-ish torque converter needs a SHORT duration cam.
Here's my best suggestion:
212 Intake, 218 Exhaust duration (.050") 110+3 degrees LSA .600" gross valve lift. Summit Racing sells one: K8728

 

The SUM-8728R1 is a good choice. If you go with a 3k stall and 4.10 gears (assuming stock tire diameter), then SUM-8720R1 218/227 112+2 is feasible too. Any bigger will be a complete dog off the line and suck driving around until you add the centrifugal supercharger.

 

you do not want that cam in an SUV, i run that cam (8711) in my 3400lb monte carlo with a 4.30 gear, 28" tire and 4400 stall converter and it still wants more converter than that lol

 

OP,

As others have mentioned, neither of those cams is the right fit for your application. Do we want to sell ya that "Big Cam"? Heck yeah. But we also want you to enjoy driving your Suburban every day, not just staring at a dyno sheet.

Neither of those cams is going to be much fun in a heavy Suburban with a 5.3. Our SUM-8728R1, which @Full Power and @68Formula mentioned, is a much better fit. Specs on it are .600/.585, 212/218, 110+3 with -5* of overlap.

With big heavy vehicles like a Suburban, you need an early IVC to get off the line and moving down the road. We typically like to see the IVC under 40* @.050" lift for trucks used as trucks. The 8709R1 has a 49* IVC, and the 8711R1 has a 47* IVC, whereas the 8728R1 has a 33* IVC. It's going to be much more enjoyable in the range you're going to be at, daily driving a Suburban. It makes great torque from 2,000 on up, and with our .600" lift beehives, it'll be happy out to 6,500+. Add in you're planned 3.73 gears and a 2,500+ stall converter, and it'll really come to life. Add in a good custom tune from a reputable tuner and you'll have smiles for miles.

Don’t fall for the “Big Cam” trap just to chase a peak number or some window-rattling chop. That might sound cool now, but in a 5.3 Suburban it gets old fast. You want something that works with the truck, not against it. The right cam now means better drivability, more fun on the street, and a solid foundation when you’re ready to throw boost or nitrous at it down the road.

And if you're after sound, too. The 8728R1 still has a nice, steady lope. It’ll turn some heads at a stoplight. Here’s an idle clip of it in a 5.3:

 

I’d like to start off by thanking everybody for their replies, has taken me a while to come back and read through the replies but I am viewing and researching the two summit cams that were mentioned (8720,8728) and the 8728 Torkinator does sound like a fairly solid option and was dynoed by the great richard holdener making gains above 2k rpms. My important question to you all is with the inclusion of my future nos and centrifugal/twin screw supercharger would this be a feasible option as well? Taking a look at both the cams the Torkinator (8728) did not mention use of forced induction however the stage 2 cam (8720) did include in the notes that it was both a nos and supercharger ready camshaft. The rpm range of the Torkinator does sound better to me 2k-6300k as opposed to the other being 2200k-6700k. I did not have any immediate plans to increase my 6k limiter just yet as I am a bit worried on how the stock bottom end will see more stress towards 7k rpm along with increasing boost pressures. Any advice from anyone? I also have not mentioned this yet but is anyone also aware if I would be able to retain my stock rocker arm ratio and only have to replace springs, lifters and potentially pushrods?

 

Forced induction can go with any cam really...it just kinda multiplies the power output for the most part.

 

The 8728R1 is a great power adder cam for a heavy truck. We just don’t label it specifically for superchargers or nitrous in the truck lineup since most customers use it N/A and never plan for boost or spray. If you went the centrifugal route, it would help in the low-end with a centrifugal's linear boost curve.

For an 8728R1 cam swap, we'd start with the SUM-8728-1-BHV. That gets you the cam, .600" lift beehives, valve seals, and valve locks.

You’ll want upgraded pushrods. A 7.400" length usually fits, but we recommend measuring before ordering. Go with at least a 5/16 Chromoly pushrod with a .080" wall.

We also recommend replacing the lifters and trays. The SUM-HTLSKIT2 gets you Delphi LS7 lifters and new trays.

Other parts to get:
- CMB-09-0029 LS2 timing chain with a cam change gasket kit
- SUM-150106 new cam retainer plate and gasket

Stock rocker arms are fine to reuse, but a trunnion upgrade is a nice bonus if your budget allows. That should cover a good bit to get you going with a 8728R1 cam swap.

 

Swap the cam out IFF and whenever you ever build whatever whenever. For NOW, buy a cam for the motor you're ACTUALLY building NOW.