Variable Valve Timing - to keep or not???

[scherp69]

I've searched this topic on the forums, internet and read in magazines, but still can't make up my mind. Everytime I think I have my mind made up about whether or not I should keep the VVT on my L92, I find something else that changes it. I was going to go VVT, then I found out that it would be quite a bit cheaper to get rid of the VVT, or so I thought. I went on to the Pace Performance site and found the performance package from Mast Motorsports has gone down in price to 2300 for computer, cam, springs, harness and a few other parts including dbw pedal. Frank had a good point with the fact that any local performance shop should be able to tune non-vvt, and harder to find someone to tune vvt. Then I read the latest Hot Rod article and it seems the VVT is pretty easy to tune with the Mast software ($399).

So I need your guys' input as to whether you think it's worth it to keep the VVT or just drop it and go to a regular LS3 cam setup. I don't completely understand the VVT set up, but keep reading it has so much potential. One thing I'm wondering is whether where I live would impact my decision. Where I am, it is mostly mountain therefore lots of hills. I used to have a Dodge Ram with the MDS but never noticed a difference since I'm in the mountains. Would this be the same with VVT? I know a lot of guys are dropping the VVT, but why if it's supposed to have so much more potential.

Here's what I've come up with so far:

Pros:
- better performance at higher rpms
- 5 - 10 % better fuel mileage
- potential is more than non VVT motor

Cons:
- Not very well known set up. Mast Motorsports is the only place that sells a plug n play set up, although it is supposed to be very easy to install and tune
- May be harder to find someone to tune it. Any performance shop should be able to tune a non VVT computer.
- Cost is a bit more. A LS3 cam set up would be around 1k for the computer and about 1k for the cam, springs, water pump, etc. The Mast set up is about 2300 for computer, cam, springs, harness and a few other parts. Another 300 to get some spacers to run a LS3 serpentine set up.

If anyone has any suggestions/advice, etc. on this topic, please feel free to jump in. Any advice is greatly appreciated. I'm sure I'm not the only that is trying to make this decision and hopefully this thread will help others as well. Thanks in advance.

[dhutton]

Your pros don't justify the risk of all the cons in my mind. I like to keep things relatively simple and with a large base of information and experience to draw on. If this is your first LS based swap you will have enough learning to do without messing with the VVT.

Just my two cents,
Don

[LSx_88_Ciera]

I say keep it, it is the wave of the future and it's potential has not been fully realized yet. Why wait to be a passenger on the band wagon when you can be a conductor.
Besides what you listed you also get a cleaner running engine which equates to longevity and maybe most important lower emissions.
Remember our children don't inherit the world from us we borrow it from them.

[daytonayellaz]

Im thinking keep it also.... Mike Norris (Norris Motorsports, sponsor here on the site) for tuning/computers and John Spears ( Speartech) Harness mods and custom built harnesses are 2 phone calls I would make when you get a minute.

My understanding is VVT gives you the best torque and HP at low and high rpm ranges. I dont have the ability give all the deatails here, but make a couple phone call to the above.....worth it in my opinion.

[RodDawg]

Mike,

You know I'm a little biased, but I agree with the two posts above. From what I have researched, they've just started to uncover the potential of VVT. Like you said, Mast is about the only choice for a complete system. I ordered the L92SS (cam, spring, cpu package) and also their Black Label heads. Everything is installed, but you and I look to be finished with our builds about the same time so I can't tell you how it works yet. I plan on having Mike Norris tune it. I talked to Horace Mast and Damon yesterday (about torque converter selection) and they are thinking I should be right at 600fwhp with my package. They said that DSE is installing VVT engines for several clients now. I thought they even said that the DSE '70 Camaro had a stroked VVT in it.

After looking at several options, I'm confident that I'll be happy with the VVT.

[The WidowMaker]

maybe im expecting too much, but with mast having a few combos using the ls3 and vvt, along with you using their entire package minus the cnc'd heads, why wont the supplied tune be perfect?

[scottyd2506]

I've searched this topic on the forums, internet and read in magazines, but still can't make up my mind. Everytime I think I have my mind made up about whether or not I should keep the VVT on my L92, I find something else that changes it. I was going to go VVT, then I found out that it would be quite a bit cheaper to get rid of the VVT, or so I thought. I went on to the Pace Performance site and found the performance package from Mast Motorsports has gone down in price to 2300 for computer, cam, springs, harness and a few other parts including dbw pedal. Frank had a good point with the fact that any local performance shop should be able to tune non-vvt, and harder to find someone to tune vvt. Then I read the latest Hot Rod article and it seems the VVT is pretty easy to tune with the Mast software ($399).

So I need your guys' input as to whether you think it's worth it to keep the VVT or just drop it and go to a regular LS3 cam setup. I don't completely understand the VVT set up, but keep reading it has so much potential. One thing I'm wondering is whether where I live would impact my decision. Where I am, it is mostly mountain therefore lots of hills. I used to have a Dodge Ram with the MDS but never noticed a difference since I'm in the mountains. Would this be the same with VVT? I know a lot of guys are dropping the VVT, but why if it's supposed to have so much more potential.

Here's what I've come up with so far:

Pros:
- better performance at higher rpms
- 5 - 10 % better fuel mileage
- potential is more than non VVT motor

Cons:
- Not very well known set up. Mast Motorsports is the only place that sells a plug n play set up, although it is supposed to be very easy to install and tune
- May be harder to find someone to tune it. Any performance shop should be able to tune a non VVT computer.
- Cost is a bit more. A LS3 cam set up would be around 1k for the computer and about 1k for the cam, springs, water pump, etc. The Mast set up is about 2300 for computer, cam, springs, harness and a few other parts. Another 300 to get some spacers to run a LS3 serpentine set up.

If anyone has any suggestions/advice, etc. on this topic, please feel free to jump in. Any advice is greatly appreciated. I'm sure I'm not the only that is trying to make this decision and hopefully this thread will help others as well. Thanks in advance.

The VVT thing is just advancing the cam or retarding it slightly...

Advancing the cam gives more cylinder pressure, and more low end.. Retarding the cam kills off some cylinder pressure, but has more top end power..

The intake closes after bottom dead center ABDC is what calculates dynamic compression or cylinder pressure..

Retarding the cam will push a little more air back through the intake just slight on the power up stroke.. This will also not only kill off some dynamic compression, but increase gas mileage..

That's why the Toyota Tundra's 5.7 Iforce engine can get 381 Crank HP and still get 22 mpg. With 4 valve racing heads, this isn't a ton of power, but the concept would be great to use on a superior engine like the LSX Gen3-4 GM engines... imagine

if your building a high performance engine.. don't care about torque... then you do not need VVT.. my Ls1 powered Camaro has 411 RWHP and gets around 30 mpg hyway driving easy..
big cams kill off cyl pressure... 3600 stall converter... no need for ultra low end for heavy weights truck or towing.
I'm sure that with VVT I'd have a little more top end power, and more low end too.. maybe 10-15 low end rwtq and 10-15 top end rwhp

in a 4500-5500 lb truck, the VVT would be better...if you want performance, and still have good low end, plus MPG..

in the long run, who knows how long the VVT will hold up...
if something breaks at 80k or 150k, you have bent valves or broken pistons...maybe trashed heads..

I got to say I have mixed feelings.. 10-15 years from now when we know they last or start to break, then we'll know.

[gkring]

Keep the VVT. The MAST computer is easier to tune as it has wideband capability and is a standalone system anyone familiar with an Accel DFI, Big Stuff, Fel-Pro, Haltech, etc will be able to tune, not just guys with HP tuners. The Mast computer will also have a dyno tune matched exactly to their cam so there will be no reason to mess with the tune until you start changing things. The benefit of the GM computer is control of a 4L60E, 4L80E automatic, but it will most definitely need to be tuned.

[subtlez28]

I say keep it, it is the wave of the future and it's potential has not been fully realized yet. Why wait to be a passenger on the band wagon when you can be a conductor.
Besides what you listed you also get a cleaner running engine which equates to longevity and maybe most important lower emissions.
Remember our children don't inherit the world from us we borrow it from them.

I agree. I picked up my L92 a couple years ago now. Although I have not got to that project yet, I assumed the aftermarket would continue to embrace VVT and costs would come down. So far, so good!

The reason I like the VVT so much is it makes the strong low end torque. It was originally implemented in Escalades. If it can pull along a 2.5 ton plus SUV, my Buick should be child's play, right... The better torque made it easy to go LS motor rather than big block Buick. Add a magna charger (some-day) and it should really shine!

[holschen]

how about 6l80e or 6l90e at the same time as wideband I only want to know if it´s possible and if i get all the features as without the 6l80e
someone told me wideband and 6l80e didn´t work or i missunderstood???
i´m all for vvt

[scherp69]

Thanks for all the responses guys. Unfortunately I'm still undecided. Was just trying to find some info on running a manual trans with the VVT. Anyone have any experience with that yet and how did it work out?

[srh3trinity]

I have had the same debate regarding VVT vs. no VVT. I scored a Comp Cams cam and phaser for pretty cheap, so I guess I will go with a VVT setup when the time comes.

[buddyholly]

The VVT is nothing to be scared of. In stock form it basically takes the cam from a base of 0 which starts a few degrees advanced and retards it to give you the top end. Where GM pushes it is at low rpm and low airflow where it advances it up to 25 degrees for emissions and fuel economy. Aftermarket cams like mast block the degrees to a much smaller range. There is no real tuning of the VVT necessary, it just works progressively as RPM changes. There may be more power to be found with tweaking just how the cam moves as rpm changes.

[T_Raven]

in the long run, who knows how long the VVT will hold up...
if something breaks at 80k or 150k, you have bent valves or broken pistons...maybe trashed heads..

I got to say I have mixed feelings.. 10-15 years from now when we know they last or start to break, then we'll know.

I've only recently been reading up on VVT but say you lose pressure to your cam phaser at the worst it would go to the full retard position, I wouldn't think that's not enough for the valves to hit the pistons, and the reliefs are bigger in the pistons.

[T_Raven]

I've only recently been reading up on VVT but say you lose pressure to your cam phaser at the worst it would go to the full retard position, I wouldn't think that's not enough for the valves to hit the pistons, and the reliefs are bigger in the pistons.

Just read a little more, I was thinking backwards, the phaser allows for a lot of retard so I guess valve to piston contact would be an issue and that's why Mast puts in limiters so this doesn't happen
https://static1.pt-content.com/images/pt/2010/07/Never_go_full_retard-1.jpg

[Blown353]

I've only recently been reading up on VVT but say you lose pressure to your cam phaser at the worst it would go to the full retard position, I wouldn't think that's not enough for the valves to hit the pistons, and the reliefs are bigger in the pistons.

That's why you limit the travel of the cam phaser when using larger aftermarket cams. You put stops in the phaser assembly to limit the travel so there is no physical possibility of piston to valve contact even if the oil control solenoid fails. You also need to check piston to valve clearance at both extremes of the phaser travel when building the engine to ensure adequate clearance.

I have a custom VVT cam for my twin turbo LS2 build being controlled by a Pantera EFI ECU... unfortunately because the VVT cam cover is thicker it pushes all the accessories forward and I don't have the necessary clearance to the radiator fans. I found that little problem during mockup of the engine in the car. Back to a standard cam setup for me which is unfortunate because the simulation numbers for the VVT setup showed VERY impressive torque gains below 3K rpm (we're talking almost 90 ft/lb more torque under 3K for the VVT cam in the advanced position compared to an LS6 cam which I'm now going to be using.)

The biggest concern about the VVT setup right now is longevity when subjected to aftermarket use involving higher cylinder pressures, more aggressive cam profiles, and heavier valvesprings than GM had in mind when they designed the cam phaser assembly. So far the VVT setups have been holding up very well even in boosted engines but I don't know any of them that have enough miles on them yet to be a good data point for long term reliability.

If you have the room for it, I'd keep it. With a properly ground cam and some dyno time to find the best cam timing curve the VVT can show significant gains in all areas over a conventional fixed-timing cam. However, you need to keep in mind that there will always be the potential of a failure down the road using the phaser assembly beyond what GM had in mind for it. The safety margin is probably rather high but until that limit is found, tested, and documented consider yourself a guinea pig.

[srh3trinity]

What accessory drive are you guys planning on running? I have most of the pieces for an F-body style setups, but I know with the timing cover you have to run spacers to use that setup.

[Blown353]

What accessory drive are you guys planning on running? I have most of the pieces for an F-body style setups, but I know with the timing cover you have to run spacers to use that setup.

I'm using a Vintage Air Frontrunner; they offer a spacer kit to make it compatible with the VVT front cover.

[LS1MonteSS]

how about 6l80e or 6l90e at the same time as wideband I only want to know if it´s possible and if i get all the features as without the 6l80e
someone told me wideband and 6l80e didn´t work or i missunderstood???
i´m all for vvt

I'm not sure about the wideband.. but the OEM computer will

The L92 was used in the following applications:



2007+ Cadillac Escalade**
2007+ GMC Yukon Denali / Denali XL
2007+ GMC Sierra Denali
2008+ Hummer H2


The 6L80E/6L90E was used in the following applications:

2009 Chevrolet Camaro (http://en.wikipedia.org/wiki/Chevrolet_Camaro)
2006 Cadillac XLR-V (http://en.wikipedia.org/wiki/Cadillac_XLR)
2006 Chevrolet Corvette (http://en.wikipedia.org/wiki/Chevrolet_Corvette)
2006 Holden VE Commodore (http://en.wikipedia.org/wiki/Holden_VE_Commodore)
2006 Holden WM Statesman (http://en.wikipedia.org/wiki/Holden_WM_Statesman)
2006 Holden WM Caprice (http://en.wikipedia.org/wiki/Holden_WM_Caprice)
2007 Cadillac STS (http://en.wikipedia.org/wiki/Cadillac_STS)
2007 Cadillac Escalade** (http://en.wikipedia.org/wiki/Cadillac_Escalade)
2007 GMC Yukon Denali (http://en.wikipedia.org/wiki/GMC_Yukon_Denali)
2008 Hummer H2 (http://en.wikipedia.org/wiki/Hummer_H2)
2008 Pontiac G8 (http://en.wikipedia.org/wiki/Pontiac_G8)
2009 Cadillac CTS-V (http://en.wikipedia.org/wiki/Cadillac_CTS-V) (6L90)
2009 Chevrolet Silverado 1500 Series (http://en.wikipedia.org/w/index.php?title=Chevrolet_Silverado_1500_Series&action=edit&redlink=1)

So to answer the question of "if" the VVT will work in a L92/6L80E application is yes..
My question is... Will the MAST control the 6L80E in the same way the OEM computer?

[kball]

Good thread. I bought my complete L92 about 8 months ago and there's already a lot more development and progress being made using VVT since then. Mine's just been sitting in a corner until I have time to dedicate to it and I was also waiting to see what became of the VVT in the aftermarket. I was always leaning toward keeping it.

I'll be keeping my tko600 behind it and Speartech thought it would not be an issue since the tko has a vss for a reference signal to the ecm.

I'm just sitting on the sidelines for now until I find a buyer for the BBC in the car and then it's full on for the LS.

[srh3trinity]

I finally found an F-body oil pan. So, I am a little closer. Next, I am going to decide about a subframe and them I will be buying an LY6. I have my cam/phaser/springs and a rectangle port intake. I still need a fuel rail and I am going to have to figure out the accessory drive. I have most of the parts for an F-body setup and I know there are some companies that sell spacers.

[MastMotorsports]

My question is... Will the MAST control the 6L80E in the same way the OEM computer?

Yes! :twothumbs