This seems to make sense, if the only thing the PCM is looking at is rpm, while controling vvt. This may be over my head, but I don't think this is the case. A huge factor in controling vvt should be engine load, which should drastically alter valve timing, thereby increasing efficiency. So I think your comment may apply at full throttle, but would also suggest higher output at full throttle.

 

Well much to my chagrin as I have been bitching to the tuning companies for better VVT support it seems at this point the calculations are up to us. I am very decent at math but its been a LOOOOONG time since Ive had to try and formulate a process of determination for something such as this. In fact just the mere thought of it makes my brain ache as my day to day is very far from this thought process. I keep hoping a mech engineering student catches the bug and decides to look into this for fun and throw up some charts. It does seem daunting trying to imagine the valve timing vs lift/duration/RPM to maximize cyl pressures plus not go into some form of KR as a result of power greed. Blah...

Drink time

 

I think it is telling that when vvt came out in imports, it only varied intake valve timing. It would have been easier for them to vary both intake and exhaust at the same time like gm is forced to do with a single cam. So I assume that it is better to have vvt on the intake valves only compared to slaving exhaust valve timing like gm has to. One obvious benefit to vvt on the intake only is that overlap, lobe seperation angle can be varied. Of course, having independant vvt on the exhaust is even better.

 

Im not sure if you can say intake only would be superior to a slaved style like we have that does both simultaneously I just dont think theres enough R&D to know this. Its the cam grind/s that need perfecting to get the most out of this system.

Regardless independently variable systems are superior for sure. Look at Fords new 5.0L.... damn impressive

 

So, certain valve events have more effect than others. What you see if more OE's focus on Intake valve variable valve timing as the results are greater. Remember that intake closing (IVC) is the most important of your valve events. As a result of gas compressibility and inertia, closing the intake valve sooner produces more low end power and torque and less power at high RPM.

Closing the intake valve later produces more high end power at the expense of the low end.

This explains why an increase in the intake valve duration moves the power band to higher engine speeds.

When a cam is advanced, the intake valve closes sooner, so you get more power at the low end.

So, what you do with a VVT cam is plan around what you are going to do with regards to retarding the cam. You only have retard to play with. So, you design the cam with all the advance already in it. Then, you maximize the peak power by using the phaser to retard the camshaft. Its easy to say just retard the cam till you almost hit the piston, but just like spark advance, too much is not necessarily better.

On a stock cam you want to maximize the low end by retarding the low end tables to zero, and then you maximize the retard on the upper end of the curve to pick up power. You really need an iterative dyno process to determine where the advance and retard is maximized at.

I just haven't had time to play with mine enough to find where those spots are exactly. In my stock tune, the intake camshaft base angle low baro table does not have a lot of retard in it. But, the medium and high have a big "hole" the motor falls into where its retarded 25-30 degrees (another form of Tq mgmt).

You can wake up the motor by simply smoothing out that "hole" and copying in the low baro table to the medium and high tables.

When I have time I want to take the 13º at 5600 and ramp it towards 30º. But I just haven't had the time to get on the dyno to test it iteratively.

 

Sorry I havent been on here in a few, just been busy. Just a small follow up, I have been driving the car as much as I can, power is still great and very easy to drive MPG best is 28 on the highway at average speed of 75 mph. Point in posting this is that Im getting this kind of mileage with a 500+ fwhp 6 liter eng. I think that is where the VVT makes the real difference. I will be going to FI soon and I think the VVT will show even bigger gains there as well.

To answer one queastion in the thread: I set the rev limiter at 6k just for saftey sake, stock rod bolts and hell stock everything!!

 

I've been going back and forth over email with John Janz at TSP and they do offer mail order tuning service to complement their VVT cams. The cost quoted by email was a bit over $200 and included a year of retuning if things needed to be tweaked a little. This is an option to consider for those going the VVT route. It's currently at the top of my list for when the time comes.

 

Bandit, I don't recommend a mailorder tune, but maybe you'll have better luck than me and fatfree gto.

 

I just ran 11.89 at 113.97 with my cam/bolt on vvt delete LY6 shifting at 6300 rpm with 3.42 gears. I don't think I lost torque at any rpm. I can't hook my Nitto drag radials. But 28 mpg? I have trouble believing it, and I am certainly not getting that. Certainly an advantage for vvt if true. But torque advantage with vvt on the LS? It's a myth.

 

Thats ridiculous to say imo. Advancing and retarding cams for more power is faaaaaar from new. Heck we used to do it in the 80's with our BBC's using the Cloyes "hex adjust" system and thought we had all the angles covered. A whopping -4 degrees on our old ISKY solid cam whooooeeeee that was the shizzle.

But to have 20 degrees to play with and be able to adjust it on the fly? Shizzle me rizzle!!!

Besides as mentioned before its banned from Formula one and who knows what else because its a power adder

 

VVT in and of itself does not make better torque. It's the ability to tweak the VE's that allow you to make the same peak Hp you're making on your "LS3" combo, but also to make the awesome bottom end and mid-range torque of the baby cam combos. You get the best of both a large and small cam! That's no myth!

 

Okay so why doesn't gm use vvt in the performance car applications and why can't we use the big valve springs and why are the specs usually smaller? Also why are the grinds kept a secret? Can anyone post some LY6 results? I beat the Mast results with mine. And by more torque, are we talking about off idle-2000 rpm?

I'm not comparing this to other vvt apps like the ford, 5.0, but there is a shortcoming in using it in an LS motor and some folks aren't coming clean. If I'm wrong, don't just keep telling me I'm wrong, prove it. I've posted up my results and proof. Post yours.

 

We've posted a LOT of dyno results from stock to each of our VVT grinds, and they're linked on our website for all to see as well. You can't run a big duration cam on an LS2/L99 headed car because of the large intake valve, and that's a pretty well known fact. Specs are kept secret at TSP because we've put as much if not more time and effort into R&D on them than anybody else in this market. Surely you understand we want the reap the benefits of our work, rather than giving it out to folks working from their parent's basement drop-shipping parts from Comp and other suppliers, right? We've got 15 employees here, each with families and bills that we have to ensure get paid every week. Our R&D and testing comes at a price, and not all of the specs and results are shared. We keep very little secretive in our parts catalog/lineup. Can you imagine all the "secrets" that Comp and some others moving bigger volume keep for themselves?

 

GM does use LSx VVT in the L99 and the L92, but I suspect the main reason they don't use it in other performance vehicles is cost. They probably only implement it when mileage or emissions can be improved. For example, in the case of the L99 they are using it (along with AFM) for only the automatic variant of the Camaro, which is a higher volume car and probably reduces their corporate average fuel economy (CAFE). There are cheaper ways to make power than VVT, that's for sure.

I'm not completely sure we can't. TSP packages their cams with PRC double springs.

I am curious if this is to maintain compatability with AFM. I have heard valve clearance over the cam phasing range, but I'm not sure if that's real. The lift on the TSP cams is considerably more than the VVT cams from Mast and Comp (see below) and it is on par with a conventional, non-VVT cam for an LSx.

TSP did post some ballpark figures for their VVT cams on their website. For example:

That isn't incredibly specific, but it does give you an idea. It would be nice to have a ballpark on exhaust and LSA too.

Like you, I would really like to see some actual dyno results from an LY6 with TSP's cams. I had heard they were working on that, but I don't know if it ever happened.

Regarding the mail order tune, I am right with you. The quality of the tune can only be so good without actually driving the car or putting it on a dyno. I am more thinking for getting the thing close.

 

Thanks for the info. Do you think you could post a link to the dyno results? I couldn't find them on the website. I do appreciate the R&D that you are doing with vvt and supporting the hobby and community.

I did find this thread and compared it to my dyno results on the previous page.
https://ls1tech.com/forums/gen-5-cam...er-80rwhp.html

The L99 seems to have LS3 pistons which have a bigger bore and more compression than my LY6. Also the bolt ons with the two cars seem comparable and I assume that the 4L80e is less efficient than the 6L80. This is also the slightly larger vvt3 cam and I would think the vvt2 cam is more comparable to my Vengeance Stage 2 cam based on the approx specs.

That being said, my LY6 made 20ft/lb less peak torque with a flatter curve and 41 less peak horsepower. When I compare the graphs it looks like my power climbs and peaks right along with the vvt cam and I at some points I am making more low end torque. I think if my motor had the better pistons and throttle body and trans we would be very close and I might be making more torque. I also made more all around power based on the vvt dyno graphs by Mast.

So, for now, or until I see more graphs, I respectfully dissagree that vvt cams make more low and mid range torque. This is unless you are talking about from idle to 2500, and if this were the case, we wouldn't need to upgrade the converter. I hope the LY6 research is going well and I look forward to seeing results. What I will bet on, is that I gave up on some gas mileage, compared to vvt, but I am certain that the larger vvt cams do as well, especially when paired with a performance converter.

 

Bandit,
Thanks for taking the time to answer my questions. I just hope, whoever does your mailorder tune is very familiar with the vvt and swaps, along with all of the things that the PCM needs to run without the rest of the car, so that it starts for you the very first time.

I have to dissagree with you on one point: Cost. Considering that the Corvette, ZR1, ZO6, CTS-V, and Camaro ZL1 all do not have vvt, I would highly doubt gm didn't include vvt because of cost. These are the most expensive cars sold with Gen IV engines.

 

Comps VVT Cam made more torque down low, heres the dyno graph, and made 70hp up top.

If you know what your doing you wont loose torque! Most people just dont know what they are doing with VVT.

 

ZR1 CTS-V and ZL1 get their power from supercharging. VVT has little to add compared to a supercharger, so it doesn't make sense to add from a cost perspective. Since those are low volume vehicles, they do not necessarily have to squeeze every ounce of possible economy out of them to meet CAFE requirments, another reason not to use VVT. The Z06 uses the LS7 which has a different cylinder head design to acheive power, again achieving performance goals.

My opinion is the LSx cam phase VVT is a MARGINAL contributor to additional power / effective range. The cost/benefit ratio is low compared to other more traditional ways to get power. For the OEM I'd bet they put it in primarily for emissions and fuel economy.

 

The graphs are listed at the top of each of our VVT cams descriptions on the website. it has a little DynoJet icon. Click on it and the graphs pops up in a new window.

The L99 has valve reliefs which make it lower in compression as compared to the flat-top piston LS3.

 

More torque than the stock cam? This graph is not rear wheel horsepower.