VVT or no 6.2 Yukon XL

[BigMike42]

Hey all, been away from the forum a while.

I have a 5.3 Yukon XL, it is anemic as you can imagine. I did a DOD delete with a 206/212 112 cam, eliminated VVT, and added headers. It picked up huge gains at 3500 and up but still very anemic down low and it's not very fun to drive because you have to rev it so much.

I just picked up a stock L94 6.2 I am going to drop in. I am planning on eliminating the DOD, but I am torn on whether to do the VVT or not. I want the throttle response 1500-2500 to be much snappier than current, so I was thinking of going the VVT route, getting a cam with like 6-8 degrees advance ground in, then tweaking the tune. The only thing I am worried about is the fueling for VVT looks very involved, like it would be impossible without hours on a dyno.

I have no issue going plain 3 bolt non vvt setup if I can still have a snappy throttle response down low with the 6.2, but if its like a 40 ft/lb difference, I'd prefer vvt.

[10_SS]

keep VVT! The 6.2 is a beast. Had a 2019 Yukon with it and the 10 speed... I couldn't believe the low end torque, insane. Thought about adding VVT to my LS3 Camaro with a Whipple

[BigMike42]

keep VVT! The 6.2 is a beast. Had a 2019 Yukon with it and the 10 speed... I couldn't believe the low end torque, insane. Thought about adding VVT to my LS3 Camaro with a Whipple

That's great to hear. That's exactly what I want.

Guess I got some reading to do.

[IARLLC]

Yep. For a mild build, the benefits really outweigh the... oh wait! There isn't anything negative about VVT unless your cam is big enough to cause valve clearance issues.

[BigMike42]

Thanks.

Any recommendations on specs? I am a big fan of Cam Motion. They were amazing to me when I had issues with "whining" camshafts from another vendor and sent me a free cam to fix it. I try to stick with them whenever possible.

The TSP stage 5.3 cam looks like it would fit what I want, which is subtle to no lope and no chance of exhaust smell. It's a 212/218 112. I can order a cam motion custom grind, just not sure how much advance to grind in. Is 0 degrees on the VVT table straight up, as in defaults to the advance inside of the camshaft? Or is is 8.5 degrees added to the advance ground in?

[IARLLC]

That is a great question. Is the 8.5 advance that they park at ground into the factory cam? or? The answer to that could easily account for strange/illogical results people sometimes see trying to retard a larger cam at higher rpm (if it is already ground with more retard than the stock stick).

[BigMike42]

https://www.underhoodservice.com/gm-...flow-pressure/

Looks like parked is 7 crank degrees advanced. It makes sense that these huge numbers in the tune are in crank degrees, not cam. So I am thinking of speccing a cam with about 6-8 degrees ground in.

[IARLLC]

The guy kicks off the article with an inaccurate statement, "The CMP actuator system controls the amount of intake and exhaust valve overlap". The article is supposed to be about LS V8 VVT which of course have the overlap ground into the cam... He probably got the quote (or idea) from an article about DOHC motors with VVT. At any rate, it is clear that he lacks understanding...

Years ago I read that they park at 8.5 advanced. I have also seen 7 here or there so I cannot remember why I came to the conclusion that they are actually at 8.5. Maybe some years are 7 and some are 8.5. I'd just be careful where you get your info

I still am not too clear. Is the cam ground straight up and the actuator parks it at 8.5? Or is the cam ground 8.5 advanced and the actuator parks it? Not sure but probably important in your case. Either way, if you are ordering an LS VVT cam it should be ground with this in mind.

Enjoy your 6.2. They rock!

[BigMike42]

The guy kicks off the article with an inaccurate statement, "The CMP actuator system controls the amount of intake and exhaust valve overlap". The article is supposed to be about LS V8 VVT which of course have the overlap ground into the cam... He probably got the quote (or idea) from an article about DOHC motors with VVT. At any rate, it is clear that he lacks understanding...

Years ago I read that they park at 8.5 advanced. I have also seen 7 here or there so I cannot remember why I came to the conclusion that they are actually at 8.5. Maybe some years are 7 and some are 8.5. I'd just be careful where you get your info

I still am not too clear. Is the cam ground straight up and the actuator parks it at 8.5? Or is the cam ground 8.5 advanced and the actuator parks it? Not sure but probably important in your case. Either way, if you are ordering an LS VVT cam it should be ground with this in mind.

Enjoy your 6.2. They rock!

Thank you, I was about to drop a tvs2300 on top of the 5.3 but decided on the 6.2 instead. I like simplicity... It has 50k on it, so it's fairly fresh.

As for the cam degrees, from the illustrations it seems dot to dot is 0 degrees and it parks it advanced at 7 or 8.5 like you said. This is irrespective of whatever is ground in the cam.

The only question is whether it is cam degrees or crank degrees. I think it makes more sense that the numbers are crank degrees because all the aftermarket VVT cams advance 6-8 degrees into the cam. If the "parked" advance is really 7 or 8.5 at the camshaft, you'd then have ~16 degrees of cam advance which to me seems excessive. The numbers add up better if it's in crank degrees, meaning the cam advance is around 3.5 (half of 7 crank degrees) making the aftermarket cams advance around 10 or so which makes more sense to me. Furthermore, there are some large numbers in the tune which also seem excessive if it is in cam degrees.

TSP sends out their tunes with 0 across the board until mid range RPM, and has 6 degrees of advance built into the cam, so that would be 9.5 degrees of advance.

[BigMike42]

Per this older thread from 2012 on tech, it suggests the phaser and limiter is measured in crank degrees. So that "7" parked is 3.5 at the cam.

But they seem pretty certain the values in the tune are in cam degrees

https://ls1tech.com/forums/generatio...vvt-cam-4.html