02 tahoe cam questions.
 

I want to cam the 02. I'm pretty dumb when it comes to this so help me. I have a 1000 budget with 400 going to instal. I want a 0-3500ish power range as I do lots of city driving. It must sound like a cam. If I'm dumping the cash I want to hear it. My current mods are lts, intake, live tune, 4.11 gears and basic magnaflow muffler. Truck has 140k and I know the trans will likely go shortly after. Ill address that later.

Sounds like you need a 6.0L LQ4 to me. Nothing cam wise is going to gain you much off-idle through 3,000 rpm.

There are cams that will build power below 3500, but all of them will sound and idle almost stock. A cam that produces a noticeable lumpy idle will move the powerband upwards at least 1000 RPM, from 1500 RPM to 2500 RPM with a significant reduction in low-end torque below 2000 RPM.

Now with your 4.11 gears you can get above 2000 RPM easier, but it will still be soft until the engine gets "on the cam". You can offset the low-end torque loss with a big cam by increasing compression ratio, but the idle will smooth out again as the compression bump makes the cam appear "smaller" at low engine speeds. The advantage is even more power at upper RPM with cam AND compression increase. That's what I did, I used a small cam and bumped compression to 10.25. Idles stock but low rpm power is great.

One solution for this is to have some lope tuned into the idle. Typically this can be done by messing with the spark tables at idle. It will give a sound and lopey idle very similar to a cam, but will smooth out above idle to produce useable torque.

I would suggest a 212/218 high lift LSA112 you should be happy with the right time you will hear it and not lose any bottom end.

Something like that should work. The Lobe Separation on the stock cam is 114 degrees. The 112 LSA should have a slightly noticeable idle and still have good torque starting about 1800-2000 RPM. It also depends on how much advance is ground into the cam.

Typically as you reduce the LSA, the peak HP increases and comes in a bit earlier (for a given duration). The downside is a rougher idle and the power falls off faster above peak HP. Basically you squeeze the bottom and top of the power curve for a higher peak. But for what you're doing a small duration cam with tighter LSA should work pretty good. If you had 3.42 gears I'd be concerned it'd be soft off-idle but with 4.11s you'll be fine.

There's a misconception that an engine isnt making power unless it sounds choppy at idle. The choppy idle is actually a reduction in low RPM power, an undesirable side-effect of moving the powerband upward in RPM. Deep gears, stall converters, etc are really a crutch to a certain extent (on a street machine) to get the engine into its powerband at lower road speeds. You don't necessarily need the chop to make big power, it just depends on the sound you want and what tradeoffs you're willing to make.

Idle chop is the sound of fuel going straight from your injectors to your exhaust. Seriously.