LS6 cam in a 03 5.3L questions

[HotRodV6]

Here you go, 229 for the cam

12565308, GM Factory Replacement Parts CAMSHAFT

And heres the LS6 ZO6 springs for 52 bucks

12499224, GM Performance Parts SPR PKG

[Slimsilverado]

Do you also need longer pushrods for this application 7.450" ????????

[HotRodV6]

well, i asked the guy i got the cam from and he said they run 7.400 pushrods with this cam all the time and dont have any problems, but SD's website says it has a .050 smaller base circle, and that the LS6 engines had longer valves to compensate, so im wondering if i have the 243 heads milled to raise CR on my 5.3 i may need to buy some adjustable pushrods to figure out what length i need.

Probably a good idea to check them to make sure your geometry is correct.

[HotRodV6]

Ok, heres some more info i found on the LS6 cam in a 5.3L truck engine.

I found this in a book i bought, "How to build High Performance LS1/LS6 V8s.

It has a dyno chart of a bone stock 5.3L engine, with stock manifolds, stock air intake and tube, and it dynoed at

Baseline 293HP at 5100, 5200 and 5300 RPM and 324TQ at 4000 RPM

In test two they added the stock 2002 (405HP) LS6 cam only and dynoed it again and made 332HP at 5800 and 6100 and 335TQ at 4700 and 4800 RPM

In test 3 they added a catback exhaust system but still had the stock manifolds and dynoed 344HP at 5900 and 6000 and 343TQ 4700 and 4800 RPM

In test 4 they added 4 degrees of Ignition advance and dynoed 352HP at 6000 and346TQ at 4800 RPM

So my guesstimate would be atleast another 10 HP with the pacesetter LT headers and ORY, and with a full Nelson performance dyno tune you could probably find another 25-30 horse pretty easy, which puts total crank HP right around the 390 mark.

The article said they also did a test with the LS6 243 heads, but since the 5.3 lost CR it also lost power, but that if you milled the heads to keep the stock 5.3L CR there is probably another 15-20 horse in the 243 heads, which is enough to put an otherwise stock 5.3 well over 400 Horses.

This is my plan, i have the heads and cam, just need to get the pushrod thing worked out and figure out how much i need to mill off the heads and then its install time.

[RedHeartbeat]

Yeah I read those, too. They say the numbers are "corrected". I dont quite understand the process of correcting but the numbers you normally see on a wheel dyno are uncorrected. A lot of the numbers you see in dyno tests in books and magazines are engine dyno numbers, too. Drivetrain eats a lot of power. Its a hungry beast.

[ff_jeff]

at 400hp youd be right at 322whp. the same as if you had a stock 5.3. Added a cam, LT's, muffler, intake and a tune. easier IMO

[Defunct SO]

we usually just use the 7.4's with the LS6 cam and it works fine. There is typically too much pre-load on stock engines.

[HotRodV6]

well i found out the regrind cam didnt start out as a stock 405 horse Ls6 cam, so its not the smaller base circle one, so 7.400 pushrods will work fine.

But since i already have the 243 heads here, im gonna have them milled down to atleast get back to my stock 9.5:1 CR, maybe bump it up alittle to 10:1 or 10.5:1 for alittle more power, and even at 10.5 it should run fine on the mid grade 89 octane gas with a good tune.

[lsxs10]

Here you go, 229 for the cam

12565308, GM Factory Replacement Parts CAMSHAFT

And heres the LS6 ZO6 springs for 52 bucks

12499224, GM Performance Parts SPR PKG

so will this cam work with the stock 5.3 pushrods?