Yes, after a little searching it appears that the L99 has 10.4:1 compression. Closer to the LS3's 10.7 than the LY6's 9.6:1.

I see the graphs now and thanks for pointing them out. You may want to add a little text on your website that says click here for dyno graph, because being mentally challenged, I never thought to click on that symbol.

 

I agree with you as to why gm uses vvt on gen IV engines. What I'm not sure of is why they don't use vvt in the top performance engines. You maybe right about this, but wouldn't it be cheaper just to use all L99s intead of L99s and LS3's?

Matt touched on to something that caught my attention. The L99 has .3:1 less compression than the LS3 apparently due to valve reliefs. So it may be that piston to valve clearance becomes a problem on GM's top performance GenIV engines with vvt and that is why it's not used.

 

LOL, they had to show me where it was too! I'll see if the web guys can make that more clear! Thanks for the feedback.

 

Another wrench in the theory, that valve relief is on the exhaust side, which even on the LS3's typically have plenty of room and can run much more duration than the intake side.

 

I don't know man. This is one of those things that only a handful of people at GM could probably answer. All I can do is conjecture. The merits of LSx VVT in performance applications will likely be debated forever. I have mulled over the GM High Tech articles on the Mast and Comp VVT cams and while they make claims in the text that the VVT setups are better, I honestly don't see much difference in the data. The big problem with that data is they're comparing nonVVT cams with significantly higher lift than the VVT cams, or VVT aftermarket vs stock, and sometimes LS3 vs L99 vs L92 engines. There's never a good apples to apples comparison. Not to mention the poor LY6 hsa gotten no love.

I am personally still willing to try, just have a lot of other things on my plate to take care of before the cam swap.

 

It looks to me like the Texas Speed vvt3 cam is closest to the Vengeance Stage 2. So why not run it and we'll do our own apples to apples comparison? One thing's for sure, I don't think you're going to be dissapointed in the neglected LY6.

I don't think the argument will last much longer, because I think the genV will have overhead cams with independant vvt and for that, there is no debate. There is plenty of hood clearance in the new Camaros and for the Corvette, they'll just move the engine to the back. Or worse still, they'll phase out V8s in cars and give us turbo V6's. 'Hope I'm wrong.

 

So, the plot thickens. Could this support my theory that sometimes when you vary the intake valve timing you don't want the exhaust valve to follow, as is the case with genIVs? To support my theory, early vvt systems only varied intake valves, to save cost, and left exhaust valves alone which is easier to do on engines that already have DOHC. Is this unwanted exhaust valve movement the reason for the larger exhaust valve reliefs in the L99 pistons?

 

On paper, you might be right....it's above my pay grade though for sure I'm sure someone at GM could tell you for sure yes or no, but I don't know what they would.

 

I don't want that much cam. The LY6 doesn't have enough compression and I don't plan on running a 4billion rpm stall like somebody I know Besides, you can't compare a houndstooth seated Camaro to a pink framed Nova. LOL just poking fun.

 

Ha Ha! They're called hounds tooth in my car 'cause it looks like a dog gnawed on them! Are you using your turbo 400 stall? 3000, right?

Edit: I just looked at your build thread and see you have a 2500 stall. I could have easily gotten away with a 2500, but the new converters are more efficient and since I was getting lock up I wasn't as worried about stall. I think your motor would love it. The cam in my LY6 was designed for LS3 and is about the same size as vvt2-3, makes gobs of torque, I don't need to bother revving past 6300 and it idles at 850rpm. Plus you have better gear and you will stall a little more since you will be making more low end torque. Don't be afraid of it!

 

Ive measured PTV on an L92 with VVT. I locked the phaser full advance, and then locked it full retard. Even with the valve reliefs I got .080" on both the intake and the exhaust valves. Pretty tight for an OEM 100k mile engine.

I also mess with some DOHC VVT (Ford 5.0L Coyote), and moving the exhaust around does much less than moving the intake around.

I have to assume GM figured out the range they wanted to move the intake lobe around and found they had to make reliefs to make the exhaust valves fit in the same package.

 

Stall is an interesting subject. When I bought my converter, it was built specifically for me by BTE based on what I told them about my car and engine combination. It's a 10" converter and with the internals they used, they said it would stall at about 2,800rpm with the combo I had then. I expect the LY6 with a decent sized cam will make a bit more torque and will result in a higher stall speed. I noticed as my small block got tired, it felt less and less like I had a looser stall converter in the car because stall speed reduces as less torque is transmitted. In the end, the number is not exact. Why I'm ranting about this, I don't know - I can't help myself sometimes.

VVT2 vs VVT3, well that's a question I might be able to answer with more specs on the cams. Perhaps TSP could recommend one for an LY6 or post results of using them in the LY6. I have so far only seen two people on here using TSP VVT cams and both were LY6s with VVT2 cams. One posted his dyno peak numbers here in this thread and the other, tiresmokinV8 has not posted dyno results, but has plenty of videos.

Matt/TSP, my car is a full weight Chevy Nova (3800lb about) with a TH400, 2,800rpm stall, 3.73s and 275/60R15s. I have an LY6 with long tube headers and an LS3 intake manifold, otherwise stock including the LY6 85mm throttle body. I like to autocross my car and periodically drag race, but mostly I drive around town. I don't care about gas mileage. I want crisp, instant throttle response and like everyone, plenty of power. Which of your VVT cams would you recommend?

 

Ok I have a 2008 VMaxx truck. Has a 3700 stall and built FLT Stage 5 4L80e. I was thinking about putting a blower on my L76, but I'm thinking I might be better off with just a cam. She put down 272hp/282tq wheel with the stall and trans. I just put on a cat back and intake, and I'm planning on long tubes and possibly a fast.

My question is what type of numbers can I seriously expect from a VVT cam? I know how VVT works and I'd love to use it. This is my wife's daily but we aren't wimps and I don't want a small cam lol. I'd like to see 425whp outta the truck with some decent torque, who offers the best VVT cam for my set up? Currently the truck shifts out at about 6050-6100 RPMS. I'd like to keep the redline in that rang but could always change it if needed.

Also what supporting parts would I need? Just better springs or pr's too? Is the factory timing chain up to the task?

 

ultradriver, I am fairly sure the L76 uses AFM. From what I understand this can limit the cam significantly, so you're options are to either run AFM friendly lobes which are less aggressive or swap the lifters and disable AFM. I would not do an aggressive cam swap without matching springs and good pushrods. That is money well spent for valvetrain stability & reliability. Do you know the compression ratio on your L76?

 

It deff has AFM. I have the AFM and DOD turned off via HPT. I'm not sure on the compression ratio its totally stock. I'm guessing it has the 9.6:1 compression ratio. I could do the caddy ctsv lifters, double springs, hardened push rods, and the cam maybe even a boost friendly cam. 9.6:1 should allow some friendly boost right?? lol

 

Talk to yout local experienced tuners. If you come up with a combonation like boost and vvt and noone in your area has tried it, then you are the guinea pig. It is one thing if you are going to ship your vehicle to texas, but if you are not, listen to who is local to you, experienced and reputable. The R&D cost is very expensive and you don't want the bill. Hell, even the guys in Texas may not recommend that combo. Either way, it looks like you're fixin, to pull the heads to change the lifters. You definately are not the first to boost a truck with stock pistons or boost a truck engine with stock pistons. I haven't done it yet, though, so don't trust me.

 

Don't know if this has been mentioned but Darin Morgan knows his stuff and this was a good read. I think that this vvt stuff is a holy grail somehow. Read this...Post 116

http://www.camaro5.com/forums/showth...05#post3818805

 

I'm not new to this game I have a 418 LS3 in a C5 and a 408 in my WS6 lol.

My only question (mainly to venders on this site) is that is there a cam I can directly swap into my engine to see good results with? (Keeping DOD and stock lifters in.) If not I'll pull the heads toss the lifters put in a thicker head gasket and boost her. She'll be fine as long as I don't run too much boost.

 

I spoke with Mike a few times when i was building mine at first and he was LESS than helpful to say the least. In fact he went so far as to try and convince me to ditch VVT and run a static cam. I was clear in my direction and told him that this was the way I was going for the reasons Ive been ranting about above and he then calmed and said in a nutshell that he would like to share information but this is his livelihood and the second one of us independents gets the info we plaster it all over the internet and then theres no business for him etc. I can understand this position but "trade secrets" are simply a fools thinking IMO. He should be ALL over these boards bragging up what he has developed and why. In this day and age you win customers trust by showing off how smart you are. For instance Tony Mamo's approach to cyl head porting and whatnot. VERY helpful and open with the info cuz he/they are so damn good they are always a few steps ahead of most and their QC is TOP notch so they sell well as a result. Its a shame more of the experienced people dont open up about it I think they would sell more stuff. Its the mass confusion most have about VVT that messes up support for it in terms of $$$.

As far as controlling VVT advance retard like post 116 mentioned in Craparo5 this is simple BUT.... You have to trust your tuning suite completely as with no limiter you can go +-20 degrees iirc and with a big cam you will certainly be putting pistons into valves if this isnt 1000% perfected. Plus I have HPtuners and so far only a beta will support VVT so.... Dicey. Considering this for my first VVT set up I run the limiter and -4 degrees cam advance but Im sure there will be more cams coming down the road as the tuning suites catch up ( maybe EfiLive is already there I dont know ) I'll practice with this in the meantime as Im not an experienced tuner so this is safe.

As for VVT = holy grail? Its good stuff theres no doubt and when someone from Reher Morrison chimes in about its advantages the case against is getting thinner by the second

 

Keep in mind porting is a different game than ordering a cam. You can stare at a port for years, and not be able to replicate it correctly without some very expensive machines.

A camshaft on the other hand, everybody AND their brother has a Comp Cams account, and can buy at WD. All you need to know is the cam core part number, lobe numbers, LSA and ICL and bam you've copied someone else's R&D.

Sadly, this happens a lot in this industry and some "shops" working out of their garage with no overhead will drop-ship cams all day and take business away from those of us doing the R&D all because they can make a quick $50-75 by having that Comp Cams account (helluva run-on sentence there).