Wnts2Go10O

iTrader: (12)

are they wanting to have a double punch with some new DI heads with it or something? there has not been much on whats going on in GM engine development lately..

jeffreycastgsx

They did, its in the L99 and L92. Maybe it didnt need and instead they just used an "aggressive" cam to create decent power, and because the engine is big enuff it it create the necessary torque. Or there just waiting till later to add VVT and really spruce things up.

Wnts2Go10O

iTrader: (12)

thats the odd thing.. you know they know they could gain a nice pit of power everywhere while adding to efficiency which, for the LS3, seems like a given thing to do. just doesnt make sense to me.

rsz288

It may be something to do with misfire detection. They dont do AFM or VVT with M6 trans's due to difficulty in identifying misfire.

dimetweaker

iTrader: (1)

it the LS3 had vvt, it would also have the pistons with larger valve reliefs, so it would be a somewhat different motor, resulting the L92, L99, the smaller L76(?). They offered it in the heavier vehicles, with an automatic transmission, but thinking in terms of what it didnt come in, the vette? That car has more than enough power for the general consumer, if the general consumer wants more, they opt for the zed. And if neither are fast enough, well, thats where the gear heads and aftermarket come together. You put the average joe in a stock escalade with a L92 and have them put it to the wood, they say "hey this truck gets up and goes". You have them do it in a corvette with no traction control, they will say " wow, I cant believe how hard we just hit that other car parked on the side of the road without VVT" It is a good question to ask, but it just leads me to questions like why isnt the LS7 in everything, why didnt they put V8s in s-10s, why does ford have to make an engine half again the size of GM to get the same power, etc lots of reasons and answers, but not everyone agrees with them.

flintwrench69

iTrader: (11)

If they did put VVT in the LS3 then there would be a lot more that wondered why they did

dimetweaker

iTrader: (1)

youre probably right. Then the ford fan boys would be all over it saying how GM had to use VVT to make any power LOL

cam

iTrader: (9)

I have searched to the end of the internets on VVT in the 6.2's and found no good info anywhere on this very question. What I did uncover was a few interesting things about VVT on gen 4 GM engines in particular however. The biggest of which was spring load and phaser failures. It seems that the design of the phaser itself is not really ideal for hi-performance use as it cannot handle high pressure valve springs required for bigger cams. The reason being is the phaser uses engine oil pressure to change the cam timing and has to work against the valve springs. For all the factory applications its a LOT easier to control engine RPM with an auto than it is with a manual and my guess its for these kinds of reasons VVT was passed over on factory stick cars. Also auto cars are driven easier than sticks for the most part. Guys who buy the manual bang gears loud and proud typically while the older guy who just wants a fast cruiser opts for the auto and seldom abuses it. Besides GM has never been the kind of company that puts all of its eggs in one basket they slowly phase ( pun intended ) things in over various models and years.

Second there is big time development going on with GM V8 engine design right at this very moment. From the rumors buzzing around VVT is a HUGE part of this program and I've even read that the new V8's will run independently variable intake and exhaust valve timing as well as direct injection. There is chatter that they are already boasting about the efficiency and power output of these new engines and these are due to appear around 2013 iirc. Interesting times indeed for us power junkies...

Anyways the fact of the matter is providing the specs are the same ( engine size, heads cam etc ) and basically the only difference was a VVT set up or a static cam set up; The VVT engine will make more power at low RPM and high RPM than a static cam will. Somewhere in the middle of the curve they will be identical in power out put but above and below that VVT will produce more horse power and torque period.

So theres no real problem with running VVT and a manual trans ( im about to hehehe ) but my best guess is related to the comments above as to why GM doesnt put it on the manual cars now.

Plus think of the cost? Why install something extra if you dont need to? The new Camaros are stellar performers without VVT and they passed EPA regulations so why would they waste the dough?

68Problemchild

iTrader: (1)

Just started tuning the L92/Ls3 intake with VVT motor last week. Stay tuned.

Yes the springs were replaced with dual and the phase limiter should protect any on the fly extreme variations in timing.

Pat G cam.

Video in the link.

http://www.flickr.com/photos/41575483@N07/

Jason 98 TA

iTrader: (4)

We have a harness to give LS3 engines VVT. With the PRC LS3 heads better p/v there will be good room for VVT!

cam

iTrader: (9)

What springs did you run? cam specs/duration?

68Problemchild

iTrader: (1)

Cam is custom for street, not race but:

Comp cam grind # L92 13115R/13117R HR 114+5
According to the comp cam card gross valve lift=

Intake .595
Exhaust .598


I have the card but don't know much about cams, hence why I had help from Pat G.

If you need more info off the card, let me know.

cam

iTrader: (9)

I have one grind larger than yours also EPS lobes but im running the beehives Im afraid of blowing the phaser up with the duals. Ive read some spooky things that during testing COMP and MAST grenaded some phasers with duals. This is why MAST only offers their "premium" singles which are likely comp 918 or PAC 1518's

Im running the PAC's fwiw

3pedals

iTrader: (3)

I bet we see "cam in cam" independant intake/exhaust phasing in a chevy near you soooon. not sure how they'll controll it, but I'm thinking something mechanical that is more reliable and predictable than oil pressure.

Wnts2Go10O

iTrader: (12)

i hope they didnt revive that dual in block cam idea

Whiteside Customs

We are big fans of VVT, and have done some work on new Camaro's with the technology.

Here is a project we recently did on a 2010 Camaro, installing a 2300 Maggy on a VVT and AFM L99. The results the VVT gave us in terms of the torque curve was very impressive - TSP provided the cam for us -

https://ls1tech.com/forums/gen-5-cam...t-results.html

We also have VVT Cam install specials for the new Camaro going on right now.

We're looking forward to convert a non-vvt motor over to the dark side. This is very cool technology. Nice manners at low RPM, lots of torque AND lots of HP. Best of all worlds.

Wnts2Go10O

iTrader: (12)

sounds like a great basis for an aftermarket phaser

luigiandme

iTrader: (2)

VVT front cover sticks out too far for a corvette balance to mount up front. The balancer would hit the connector. So either they just removed VVT or they changed the geometry of ALL the accesory brackets and different water pump to accomodate for the 'further' balancer. Which would then have clearance issues with fan shroud, accessories are in the way by an RHC, etc. My $0.02 !

68Problemchild

iTrader: (1)

You can keep the truck water pump and just put the PS and Alt on some spacers. 1/2" spacers plus a couple washers.

Now in my initial testing with dual springs, I am getting some pretty serious spark advance. This is just with a rev in place, not driving yet. Not sure if these springs will be an issue yet.

ringram

I agree its likely because of emissions and managing the manual trans and vvt. Auto you have control over the whole drivetrain. Manual you dont.