Looking for constructive thoughts. I have a 2012 LS3 from a Camaro I got cheap ($700) because it had a bad lifter bore. It's being fixed right now and I'm debating on what cam to use in it because of the compression ratio they have. (I'm keeping the short block stock) I'm going to be using it in a 96 CCLB Silverado with a 4l80e. The truck already has an LQ9 in it, but that engine is tired (pulled from an LKQ pick-a-part unknown miles) and I happened upon the LS3, so swapped it shall be. The truck weighs around 6300lb, and the stock converter is flashing to around 2600rpm already. I want drivability and towing capability with it, so the typical LS3 cams are sort of out of the question. I know there was a truck version of the 6.2 (L92) with less compression, but I don't know if I'm over thinking this. Will a typical "stg 2 truck" cam yield good results in the larger LS3, or will it need more than I think it will? I could always get a cheap LS3 stock pull out cam.. IDK. Trying to keep my TQ, and everything for LS3 seems to be tailored for HP above 4500rpm driving. I plan on using the rec port truck intake with 50lb injectors for reference. Any thoughts helpful.

 

If it were my truck and I had that engine, I'd call CamMotion.....and have them grind me this cam with a 112* LSA.

6.2 Stage 1 LS Truck Camshaft (206/216-117+4) - Cam Motion

KW

 

kw b,
What would the difference be? Manners and all.

thanks,
jimbo

 

I'll call them tomorrow KW Baraka. I am also curious about the change in LSA. Wouldn't it just make more overlap and loose low end?

 

With a 112 + 4 degree LSA, this cam will have a -13 degree overlap. Almost no lope at all.

This is a baby cam that is ground for lower RPM torque (essential to get heavier vehicle moving) and can EASILY be driven as a daily driver in any traffic/weather conditions.

In the greater scheme of things, this is a 'baby cam'.

KW

 

I second that cam choice, but I would specify the higher lift lobes, as LS3 heads shine above .500 lift. It will help with cylinder filling at low RPM.

 

I think you could go a little bigger and not hurt any low end power. A stock LS3 cam is 204/211 117lsa with .550/524 lift. I'd run that before I paid $450 for virtually the same cam. Something like a 218/226 114+4 with whatever lift you're comfortable with would give up little or nothing on the bottom and still give you a nice bump in peak power. I have a 218/230 in an L33 (5.3L) and it tows the hell out of whatever I tie onto. A high compression (for a truck) 6.2L with a mild cam is torquey by definition...as long as you don't overcam it.

 

Doing some research for my truck today... Going to go with the BTR no spring required Truck Norris cam. Go look at Richard Holdener's dyno tests on this cam, and you'll see why. Picks up power everywhere in the RPM band. I've always been a proponent of significant overlap events on small duration cams, and it's nice to see companies finally embracing the idea.

 

At the rpm an engine built for grunt in a truck runs at I would suggest that the typical crutch the rec port heads weaker exhaust port with a huge duration split is neither needed nor desirable. I have an 11:1 383 SBC with heads that flow 68% I/E at 0.400" and 66% I/E @ 0.600. With thorley tri-ys and a decent flowing exhaust it performs extremely well with 6* of duration split @ 0.050. I had 10* and reduced it to 6* by changing from a 1.7 to a 1.5 rocker on the exhaust. 218/228 @ 0.050 to 218/224 @ 0.050 measured at the valves. Exhaust lift went from 0.578 to 0.503 too. At 2,000 rpm it gained nearly 20 ft/lbs of torque, smoothed out the idle a bit by decreasing the overlap and just runs stronger all around. No loss in peak power either. To an extent the earlier you open the exhaust valve and blow down the cylinder at low rpm the less work the still expanding gases exert on the piston resulting in less torque and less mpg as well as more exhaust noise. In my experience IVC closely followed by EVO are critical to making or breaking torque production.

 

I think you are pretty close to ideal. I am assuming he is deleting the VVT in it if it had it. Myself I would probably use the old Comp 51-414-11 the XR269HR that comes in at 269/273 @ 0.006, 216/220 @ 0.050, 114 LSA + 2* advanced, 0.525/0.532 lift. While I do not have the exact numbers from his engine I can get pretty close assuming GM was halfway accurate with their advertised compression ratio. I do not have the actual piston valve relief dimensions of the LS3 piston or the assembled piston depth down the bore. I was able to get close to the GM advertised 10.7:1 static using a 4.080" x 0.051" compressed head gasket, 68cc chamber, no piston dish and piston 0.002" down the bore. Going off that with an IVC of 66.5* the dynamic compression works out at a pump gas friendly 8.40:1 with a quench distance of 0.053". If the piston on the 6.2L sticks out of the deck slightly like my Gen3 6.0L that came from GM with a GenIV rotating assembly, it will be slightly higher with slightly better quench which works out as a wash IMO. I think that 216/220 would work very well doing truck things especially if the truck has long tube headers. I also feel he would barely be able to tell the engine had an aftermarket cam idling around 750 rpm. The overlap is only 43* @ 0.006 and -10* @ 0.050 which will have a very stable, smooth idle with good vacuum even in gear with the stock converter and the ac cranked up. He could increase the lift, however in my experience the valve train will be quieter and longer lasting with less lift. A cam like that is set it up once and forget it for the next 100K or so miles which I find ideal for a tow vehicle. Having to get a tow while towing is a hassle especially if it is something dumb that breaks like a spring or rocker bolt from the added stress of 0.600+ lift.

Running that setup through Engine Analyzer as a stock LS3 with truck intake runner dimensions, with that cam and 1 3/4" primary long tube that has ~30" long primary tubes and 3" collectors with free-flowing mufflers predicts about 480 hp @ 5,500 and more importantly over 450 ft/lbs from 2,500-5,500 rpm with 507 ft/lbs @ 4,000 rpm. At 2,000 rpm it is already at a healthy 425 ft/lbs. At 6,000 it is still holding on at 470 hp. Predicted idle vacuum about 16 in/hg which should work well with vacuum boosted breaks if the truck is not hydroboost equipped.

 

Given the torque increases that camshaft probably has a very early IVC to go along with that tighter LSA. At 10.7:1 towing I would want around 8.4:1 dynamic at most. I have a SBC that I tow with that runs 9:1 dynamic but it requires a very weak advance curve to prevent detonation on 91+ octane. For me it was not a real big problem given it spends 95% of its time on E85 but took some real effort getting it dialed in detonation free on 91 while towing in Texas heat with the a/c blasting.

 

Just for grins, I threw a rectangle port spec'd Comp 146-456-11 which is grind 269LRRHR13 into the theoretical 6.2L. That cam is 269/285 @ 0.006, 219/235 @ 0.050, 113 LSA and 109 ICL with 0.607/0.621 lift. Under 2,500 rpm it loses a decent chunk of torque compared to the XR269HR. At 1,500 rpm it is 20 ft/lbs down. At 2,000 rpm it is 10 ft/lbs down. From 2,500-5,000 it is pretty much single digits off the XR269HR. At 5,500 rpm the 219/235 pulls ahead 14 hp. At 6,000 rpm it is up 17 hp. The XR269HR has a 8.40:1 dcr and the 269LRRHR13 has an 8.60:1 dynamic compression ratio. The 269LRRHR13 has a bit more overlap at 51 @ 0.006 and 1 @ 0.050. it is down a solid 2" in/hg vacuum to 14 in/hg at idle. Part throttle torque is also 30 ft/lbs less at 1,500 rpm using a throttle opening equivalent to 230 cfm of airflow. Using that low airflow value, it is substantially weaker throughout the torque curve to 5,000 rpm. I like looking at those numbers as well as it gives a strong comparison between the camshafts as to how they will perform in normal driving at part throttle. Typically, the more torque it shows the better throttle response and fuel mileage it will get. To match the low-speed performance of the XR269HR would require part number 146-201-13, grind LSAE264 with 210/222 @ 0.050. That cam is on a 116 LSA with 0.541 lift. That cam shows a peak of 463 HP @ 5,500 and 446 HP @ 6,000 with 425 ft/lbs @ 2,000 rpm. Peak torque is up slightly to 512 ft/lbs @ 4,000 rpm. Dynamic compression ratio is 8.57:1 and overlap is 37 @ 0.006 and -16 @ 0.006. Comp claims 30 HP over the stock cam using the LSAE264. The torque at 230 cfm airflow is almost an exact overlay of the XR269HR.

I ran 6 different Rectangle port spec'd cams and 4 different Cathederal port spec'd cams in the same model. Using similar intake duration and advertised powerband numbers from the 3 different manufacturers the high lift, wider duration split cams lost torque under 2,500 each and every time both WOT and at 250 cfm simulating part-throttle with only moderate gains starting at 5,500+, Assuming this truck has 3.73 or 4.10 gears and a near stock size 30-31" tall tire it is going to reach 5,500-6,000 rpm one time and one time only at WOT 1-2 shift while towing at legal speed limits. The 1,500-5,000 rpm torque curve is much more important than the peak power at 5,500-6,000 rpm.

Just some info on how I arrived at the XR269HR being the cam I would choose if it were my tow vehicle.

 

@Fast355 Would you mind throwing in the SUM-8720R1 for comparison? That's the one I was going to suggest. DCR should be @ 8.5:1. OL is -1 @ 0.050".

 

The Truck Norris cam will run the DCR up almost to 9:1 in an LS3. Big load on a hot day....?

 

Same reason I didn't recommend the Summit Big Torkinator. IVC @ 0.006" of 57* would put the DCR too high for pump E10. Work great on E85 though.

 

Might as well kiss your pistons or head gaskets good bye.

 

I should have been more clear, I wasn't suggesting the OP use the Truck Norris cam. I was referring to what I was going to run in my 9.4:1 stock 6.0, which should have no issues with the added cylinder pressure, especially in Michigan weather.

 

Tomato to Tamoto so to speak against the XR269HR cam. In an actual vehicle, I do not believe one would be noticeably different than the other in anything except valvetrain life over the next 100K miles. The 0.600 lift on that cam will put more of a tax on the valve train components. If you ran the same springs, the Summit cam having higher open pressure due to increased lift.

The XR269HR shows about 5-8 numbers higher under 3,000 rpm with the highest being 8 ft/lbs @ 1,500 and drops from 1,500. From 3,000-4,000 the Summit cam edges out the XR269HR by 3-5 numbers in torque. The summit cam showing 512 ft/lbs @ 4,000 compared to the 507 @ 4,000 from the XR269HR. The largest difference is at 5,000-6,000. The Summit cam climbs ahead of the XR269HR by 4 hp @ 5,000, 10 @ 5,500 and 16 hp @ 6,000. At 250 cfm of airflow illustrating part throttle, the XR269 is up 2-3 until 3,000 and the Summit cam is 2-4 higher from 3,000-4,500. Not that you would really rev to 4,500+ with ~1/4 throttle, but it is possible, both are in the 300-315 hp range @ 4,000-4,500.

I feel this test just re-iterates the torque curve being extended at high rpm by longer exhaust duration while giving up some low-speed torque due to an earlier EVO. The LS3 heads flow so well even with their "weak" exhaust port that the added lift of the 0.600 camshaft just does not have much benefit at this rpm and horsepower level. With 297 cfm of port flow at 0.500" the 821 castings are not being taxed by a sub 500 hp engine that is only spinning 6,000 rpm. Even if you ran the engine out well past the peak power of a mild cam under a truck intake, the Summit cams longer exhaust duration and 0.600 lift only add about ~22 hp @ 6,500 rpm.

My 4L85E with 3.73s and 30.5" tall tires spends most of its life when I am towing heavy in the 2,500-3,000 rpm range in 3rd gear at highway speeds. If I am foot to the floor I am at ~4,000 rpm at 70 mph. If the roads are winding, narrow and I am at 50ish MPH foot to the floor in 2nd gear is just over 3,000 rpm. I do not see much need looking at power at 6,000-6,500 rpm with a 4spd Auto and towing unless you just want to destroy things. Sure, you could spin 6,000+ in 1st gear at 50 mph, but why would you want to if you have the grunt to pull 2nd or 3rd gear at the same speed? 2nd gear at 3,000 doubles fuel economy compared to 1st gear at 6,000 rpm. Just for the record, I am not saying either of these cam choices lack power at 3,000 rpm. That being said, I have seen some guys put some crazy long duration, wide split cams in their build. They then wonder why it will not make it up a decent hill without having to run the thing in the lowest gear they can at that speed to rev the engine 5,500-6,000 rpm.

 

`10-4, I read it as if you were suggesting that cam in the LS3.

That cam should work pretty well in a stock LQ4. Then again, a set of 862 or 706 heads and a cam with a later IVC would be just as torquey if not more and make more power across the whole rpm range while having a smoother idle. Either way will work but the 317 heads are pretty lazy in port velocity at lower rpm compared to a cleaned-up set of 5.3L heads. My LLoyd ported 862s flow nearly 300 cfm and still have intake ports that CC about the same size as the stock 317s. When you have 210-215cc of port area flowing ~250 cfm vs 215cc flowing 300 cfm, the slightly larger ported 5.3L ports are flowing air at a much higher velocity, aiding in cylinder filling at lower rpm. By virtue of a higher static compression ratio via smaller chambers as well as ramming more air/fuel into the cylinder the ported 5.3L heads do not need as early of an IVC to trap the same cylinder pressure as the 317s. This allows for as much torque, but a broader curve overall. The small 4.8/5.3L chambers are also very octane tolerant and do not require as much timing as the larger open chamber 317s. I have seen the 317 heads on a LQ4 want as much as 28-30* of timing to make peak power. The small, closed chamber 5.3L heads make their peak power at 24-26* of timing. It is a subtle difference but a substantial one in making torque on cheap pump gas.

 

Do you have the full specs on the Norris cam? I need the 0.006 specs and ICL if you have them. I want to compare a LQ4 stock head lower compression Norris cam setup to a LQ4 higher compression 5.3L head setup with a cam like the XR269HR or Summit 8720R1 to see what happens. I have a buddy trying to tell me that a Norris cam setup in a stock 317 head 6.0L will spank a LLoyd ported 5.3 862 head on a LQ4 with a SDPC cam motion cam similar to the XR269HR, has a little more duration and lift. Degreed about 276/280 @ 0.006, 226/228 @ 0.050, 0.585/0.588 lift, 114 LSA and 110 ICL. I only have that cam because another buddy gave it to me when he put a larger cam in the 5.3 in his car that went on to make 450 wheel. I think he is full of himself to be honest. He refuses to run my 6.0L with his Norris 6.0L but yet runs his mouth. I think he is scared of the peg leg 3.08 geared 87 G20 6.0/Th400 with his 6.0L powered NBS Burb. Then again he might be scared of tearing up his hopelessy overpriced level infinity 4L60E again. I have riden in that suburba tank its not that impressive considering that the 87 van is only 4,400 lbs with me sitting in it and a 1/2 tank (16 gallons in the 33 gallon tank) sitting directly behind the rear axle. I figure that the LQ4, ported 862s, 226/228 cam, TBSS intake and long tubes are kicking out atleast 470 hp/tq under 6,000 rpm and likely more.