6.2 ls3 GM performance crate engine

[Charlie207]

What are you even talking about? Did you read what I said at all? Who wants to have the engine screaming all the time and sounding like you’re driving a Mustang in a parking lot at WOT in 1st gear to get into the power? Not me.

Well, I quoted you, so.... start there.

 

[j91z28d1]

Tacking on a few more thoughts about VVT (this subject is like the oil brand and filter debates from the bobistheoilguy forum, on the LS1tech forum pages), but the facts are these: VVT is worth 10 lb-ft more at 400 fewer rpm with the cam advanced and 18 additional horsepower at 300 rpm higher in the powerband with the cam retarded. For a stock cam.

In my cam research for my 2012, I could find zero examples of any back-to-back power comparison run between aftermarket VVT and non-VVT cams with similar specs. And most aftermarket VVT cams require a phaser limiter anyway to keep the valves from starting territorial disputes with the pistons.

But I do know this: I own a '07 Yukon XL Denali with the stock cam and VVT enabled. I also own a 2012 Yukon XL Denali with a Cam Motion Stage 2 Truck Cam without VVT (3-bolt), and I get to drive them both back to back. Both are Blackbear tuned and there is no comparison. The 2012 with the 3-bolt cam is a beast. The throttle response and punch in the back when tapping the throttle at lower RPM, like when leaving my street, make me smile every time.

But my reasons for not keeping VVT in the 2012 were about ease of install, simplicity and durability. In my case, the trade-off was the right one for me. But that's the great thing about this country - we get to choose based on what matters most to us.

so what I believe is happening there, something to do with lobe angle. so gm made an interesting cam for the ls7. this is a 7L that needs to idle dead smooth and here's the kicker. run to 7k redline with no veritable anything and pass emissions. a buddy had one for a while, got to drive it and it runs cleanly all the way to 7k and idles like any stock ls.

if I'm remembering right they did this with a super wide LSA. you get no chop, but also give up mid range tq but able to have enough duration to make it rev to 7k. that's what vvt is trying to work around, wide lsa. so once you go cam that's OK with some chop and doesn't need to pass oem emissions. tighten up the lsa, get a cleaner air supply in the piston and you end up with more mid/low end tq.

my buddy with the ls7 before he got rid of it put a stage 2 cam in it and it picked up a good amount of tq under 3k, didn't really do as much as he had expected up top, and since you have more tq then you need in a manual tranny 7L 3200lb car. the cam honestly was more annoying then anything, especially because he went thru 3 different tuners and it never really idled right form open exhaust to closed exhaust. living in a hoa he really needed it to run well closed up. in the end the cam was the down fall of the car and he got a c7 z06 instead and is enjoying boosted life.

but yeah, long story to say I'm not surprised at all that a aftermarket cam that doesn't have to follow the same emissions standards as the oem does still makes more low end than a stock wide lsa does. even with the crutch of vvt.


now vvt on a dual over head cam engine with aftermarket cams being a whole new can of worms. that can be solid gains because you can get one set of valves out of the way of the pistons and take advantage of it. if you add turbo to that combo. it becomes magical in the hands of a good tuners.
I believe the camaro guys have to fly cut pistons to get much use out of vvt cars. where vvt cam in the automatic cars but not the manual.

 

[Geotrash]

Great perspective. Thank you for sharing!

now vvt on a dual over head cam engine with aftermarket cams being a whole new can of worms. that can be solid gains because you can get one set of valves out of the way of the pistons and take advantage of it. if you add turbo to that combo. it becomes magical in the hands of a good tuners.

Yes, DOHC with dual cam phasers (4 total), is whole different animal altogether.

I believe the camaro guys have to fly cut pistons to get much use out of vvt cars. where vvt cam in the automatic cars but not the manual.

Yessir, I think we're on the same page.