L76 to LS9 Cam - Results If Interested.

[BigDaddyCool]

I thought I'd come back with some results on my stock L76 CAM to LS9 N/A cam swap results. This is comparing the BEST runs of each over 6 months based on the engine torque feedback (yes might be out for the LS9 cam but will still provide an idea).

- Long story short, dont fit it. Go a LS3 or even a LS7 if your fitting a stock GM cam to replace yours.

2009 Holden Commodore VE SS (RAMJet, Overdrive Balancer, Upgraded Alternator, FlexFuel, HSV Headers, 200Cell HiFlow Cats, X Pipe - Stock Rear Mufflers)
L76 CAM Stock: 260KW @ 5700RPM / 517NM @ 4400RPM
L76 CAM Tuned: 285KW @ 6400RPM / 550NM @ 3800-4000RPM (all mods)
LS9 CAM - Initial Base Tune: (table copying) before tuning : 295KW @ 6200RPM / 500NM @ 4600RPM (KR)
LS9 CAM Final Result: 310KW @ 6300RPM / 510NM @ 4600-4800RPM (No KR)

LS9 has a massive loss of torque over the stock cam under 4500RPM:

Estimate Loss:
500 -20nm
1000 -40nm
1500 -50nm
2000 -90nm
2500 -90nm
3000 -100 to 130nm
3500 -100 to 130nm
4000 -85nm
4500 0nm
5000 0nm
5500 +10nm
6000 +45nm
6250 +50nm

Once I get the car dynoed I'll post before and after dyno sheets. The car is an noticably worse when towing now. I'm going to upgrade the diff from the 2.92 to 3.27 to help deal with the lack of torque down low and to help get it off the line.

0-100KM/H - No time difference (5.6 - 6.3 sec - tune timed from initial throttle response). 0-60KM/H no time difference (3.4 to 3.6 sec approx). I suspect above these speeds the LS9 cam may come into play. It does seem to breathe alot better flat out the faster you go so a dyno wont really show it's full power output.

The good news.... uses roughly the same amount of fuel, little more if your trying to reach it's power @ 4500RPM. It's better to drive in the wet due to missing some torque and it's better on your tyres.

You can tell by the manifold pressure etc that it's designed for a supercharger. Basically it cant get the air out of the manifold because the LSA is so wide, it needs a superchargers pressure to force it's hand so to speak with that cam.

What you commonly see on this cam is the air stuck in the manifold so the MAF will have reversion on a WOT run .... because it cant get the air out. It's only a small amount so I'm hoping changing the diff will aid in getting the air moving and the cam rotating.

For me it will be more interesting to see if the diff improves airflow by removing the constipation side of things.

It generally idles fairly nicely but cold start did need a fair bit of work. And for general everyday driving it's pretty much the same..... bit slower off the line marginally.... the diff should fix that. Overall I'm happy with it, I wanted top end..... so I have the option of using it rather then just running out of power.

With the diff I should be able to live with it.

If you do decide to do the LS9. My advice is.... do the lighter valves (I didnt do). Upgrade to 1.85 rockers and upgrade the diff by one or two ratio's. But ultimately you could do the same with the LS7 cam which would be better suited and truth be told the LS3 cam could probably match the LS7 cam at the top with enough work on the tune.

-----
L76 Camshaft 200/208 0.472 0.479 116.75 LSA
LS9 Camshaft 211/230 0.558/0.552 122.5 LSA

[ddtech]

Interesting results - thanks for sharing.

[GHuggins]

Do you know your original cam specs vs the ls9 cam specs - I haven't seen any from a cam reader to know the specs for sure... I'm actually surprised with the higher lsa that your gaining the power up top that you are, so it must have a decent amount of duration and a touch more lift... Guess I could go do some digging and get the cam specs...

[cyrus_the_great]

L76/L98 cam is 200/208 0.472 0.479

[Earwax]

Did you degree the cam when it was installed?
GM retards the cam timing on almost all the factory cams.This is done for emissions.
The LS-9 cam is made with a 1* retard (pin location),the LS-7 cam is retarded 3 *.
Except for a 1.5* of LSA difference and lift the LS-9 and LS-7 cams are almost identical.
If you add the slop in the timing chain and the location of the crank key,timing gear pin location.
You could be over 4* retarded.This is why most A/M cams are ground 4* advanced.
I think that this is the reason you had a loss of torque with your install. And gained upper rpm power only.
Retardng the cam moves the power band higher in the rpm range at the expense of low rpm tq.
There are plenty of magazine tests of the LS-9 cam vs a stock cam that gain 50 lb ft of torque (low rpm) with an increase in(high rpm) hp.

[BigDaddyCool]

Notch to notch as you install most cams? The LS9 was listed as not retarded or advanced. My stock cam came out notch to notch, new one when in notch to notch (cam marking to gear marking).

http://www.lingenfelter.com/PDFdownloads/12638427.pdf so it is retarded -1.0 but again fitted correctly.

Did you degree the cam when it was installed?
GM retards the cam timing on almost all the factory cams.This is done for emissions.
The LS-9 cam is made with a 1* retard (pin location),the LS-7 cam is retarded 3 *.
Except for a 1.5* of LSA difference and lift the LS-9 and LS-7 cams are almost identical.
If you add the slop in the timing chain and the location of the crank key,timing gear pin location.
You could be over 4* retarded.This is why most A/M cams are ground 4* advanced.
I think that this is the reason you had a loss of torque with your install. And gained upper rpm power only.
Retardng the cam moves the power band higher in the rpm range at the expense of low rpm tq.
There are plenty of magazine tests of the LS-9 cam vs a stock cam that gain 50 lb ft of torque (low rpm) with an increase in(high rpm) hp.

[Earwax]

The reason you degree a cam is due to the possibility of the of the actual cam lobes position being wrong ,even with the timing marks aligned on the gears.
As stated, the timing gears, chain, cam,crank can all affect the cam to crank position. With out checking , you will never know if the cam is installed correctly.
If it is degreed and is only 1* out of spec, no change is needed. Remember, as the chain wears and stretches the cam timing retards.
Here is one of many links on degreeing a cam.
Link:http://www.cranecams.com/bulletins_listview.php?s_id=5