Generation IV Internal Engine - To vvt or not to vvt

I think I'm going to get a different cam soon. Instead of dealing with a hydroboost conversion and getting a bigger stall so my truck actually gets its bottom end grunt/ vacuum back I think I may just change the cam and get something a bit smaller. Current specs are 219/228 .550/.550 114. Been talking to Comp cams and they recommend a VVT cam sized at 210/224 .556/.568 114 for my application. The new cam is listed from 1300-6500 in their catalog and the closest one they have to my current one is 219/235 with 113 LSA which they list RPM range of 1500-6700. I just don't want to go through all the work again and still have similar characteristics. I have also thinking about ditching the VVT since I could almost do it for the same price and get a custom single bolt grind like the 212/216 in a single bolt ? Name of the game on this one is as much useable street friendly torque possible.

My trucks set up is 2010 Silverado 4.8 Ext Cab 4x4
K&N cold air***Magnaflowmuffler***Pacesetter Headers***ls3 hot cam***2800 stall***Nelson Performance tune***Vette servo**3.42 gears

Keep the VVT! When tuned properly, you get to keep all the low end grunt you are looking for, but can have the peak power of a bigger cam too! Ditch the VVT and you basically have to pick which one of those you want.

I have also thinking about ditching the VVT

My trucks set up *ls3 hot cam

Are you running a VVT tune&system on a LS3 hot cam? What are you ditching?

The cam was sold to me as a ls3 "hot cam" and has very similar specs to previous Hot cams. The cam is definitely a VVT cam since it has the oiling journals and set up for the Oil actuator. Its been in the truck for about 3 months now. I had a PCM for less tune on the truck and had tons of lights and when trying to contact them to get a reflash I got a bit of the run around. I ended up getting a Nelson performance tune where I did state I was installing a VVT cam and wanted to keep the system. Truck does run good but I have NO bottom end. I got the cam from a another sites forum member as a single bolt cam, with him not knowing it was VVT, I wonder if I got a cam with the earlier style core and not the newer style my truck has?

VVT rocks, I'd keep it. Trying to maintain bottom end in a 4.8 is hard enough, VVT helps that. They will custom grind you one as well, in our 5.3 here they ground us a 218/222 VVT cam. I just wouldn't talk to the average tech guy there about custom grinding a VVT cam.

The one I was looking at is based on the 189 core (newer style) its 189-400-13 but still think it may be a bit big for what I am wanting. Do you know the agent you spoke with there ? I was thinking of specs around the 206/218 mark with around 114-116 Lsa and .560/.560 lift. I want it to be well into the power when my converter flashes at 2800

BTW currently installed cam 219/228 .550/.550 114 is not really making power until 3500 if that gives you any more clues or ideas.

I would keep VVT. Texas Speed has been doing really cool stuff with it.

If you decide to go that way, I also have that 210/224 VVT Comp Cam never installed sitting in my garage. My truck was totalled so I'm trying to get rid of it.

Spoke with comp cams and they mentioned putting the 212/218 high lift cam 54-424-11 on a 189 vvt core.. Think this would be a good fit with my stall and gear.

Patrick G

Custom Patrick G VVT cam.
http://ls1tech.com/forums/generation-iv-internal-engine/1239688-lets-find-tr224-version-vvt-cam.html

Nuf said.

For your application, I think keeping the vvt is a good thing, with a good install and tune. There are advantages to removing the vvt system for race/high performance applications.

The disadvantage of the Gen IV 4.8L is the compression ratio is really low since GM went with the 243/799 heads its 8.8:1 stock. I would look at milling the heads or switching back to the smaller chamber 5.3 heads to bump CR.

The more articles I read I think I got the first VVT core cam installed so it is severely retarded at low RPM. The stock cam pulled way harder with a stock stall then this one does. Stock cam only was slightly less at the top end. Just to explain how bad it is today after a fresh bit of rain I couldnt get the truck to spin if my life depended on it. Stock with a tune and headers No problem... I have really looking at the 189 core version of the xfi 210/224 vvt cam comp offers or getting the LSR 215/223 cam ground on the correct vvt core. Really dont think I need the lift of the LSR version but the intake centerline is 107 vs the xfi's 105 intake centerline. I think that extra 2 degrees would really help with my trucks size and towing and with the VVT being able to retard the cam a at the higher RPMs I shouldnt lose much up top. I'm going to call comp monday and ask them if they can put that 107 centerline on a xfi lobe. Anyone think I should ask about having them move the 114 lsa down to 112 or 113 to give it that sound and increase the midrange also? Truck is shifting at 6000 now and since I am looking for more of a flat curve instead of all out power this would be a good combo for custom grind?

Sitting here thinking I may call Allen at nelson performance Monday also, See if he can look at the VVT tune for my truck and see if he can advance my cam more on the low end and possibly retard it less on the upper RPM.... If there is enough range in the VVT maybe he can "tune out" the core differences....... Just a thought after a couple beers....

Sorry for all the posts but the beer is full effect and it looks like there isnt enough range to make it happen on the advance side to see if my theory is correct.

Article from Hotrod MagThe Gen IV's VVT system is very flexible and allows advancing the cam 7 degrees and retarding it 45 degrees for a total of 52 degrees of latitude.

Tech note from Comp cams VVT tech bulletin. The difference in the pin between 156 and 189 cores equates to 13 degrees cam retard (if a 156 is used
where a 189 is required). {thinking i have a 156 "type" core installed and with only 7 degrees of advance available in the phaser I am not going to be able to make up the 13 degree difference... Looks like I won't need to call Allen..

Gus,
Good find. It very well could explain your problem.

Keep the VVT! When tuned properly, you get to keep all the low end grunt you are looking for, but can have the peak power of a bigger cam too! Ditch the VVT and you basically have to pick which one of those you want.

In our testing we did NOT find that to be true. Marketing yes, actual power no. We adjusted the cam timing up down and sideways trying to find a few #'s on the dyno....(stock SB TVS'd LS3). The VVT cam from MAST made no more than like 4 hp difference, nor was a large increase in TQ witnessed. I don't have the exact numbers (been a while), but it was so paultry (when you also figure in the potential for something in the VVT setup vs conventional to screw up) I elected to pay another $400 and go back to a regular cam setup. Car ended up picking up power without the VVT.

Top graph was the VVT cam.
http://i139.photobucket.com/albums/q316/05pharmd/102_5743.jpg

This graph the non VVT cam (note this graph also had the advantage of 2 extra PSI from the TVS 1900).
http://i139.photobucket.com/albums/q316/05pharmd/547Dynoresult.jpg

Couple of thoughts.

1. You are comparing a supercharged application to a NA application.
2. Do you think GM and other manufacturos would go to all the trouble of installing a VVT system in their motors if there was not something to it?

Just thought of something else that may let me run the current cam. Pick up the early style phaser 12585994 if anyone has one of these pleas let me know actually have a damaged late style I can compare it to before I pull the engine apart.

I run a mast 230/244 that I just installed. VVT grind. I picked up 70 rwhp with it.
Crazy rpm range.

http://i49.photobucket.com/albums/f278/rhino79/IMAG0328.jpg

Good numbers with an unreal torque curve. I take it with stock L99 heads and a 6L80E. I just hope my numbers are as good when I am done. I will also be using the Yank SS3200. How does it drive?

Yea that looks pretty promising, Guys on some of the other forums say yank it out and go with standard cam but with so many OEM's putting it in the engines there has to be something there. Hoping I can sort this out. I think the older style phaser fixes my problem and I dont need to buy a new cam I can get HP tuners and try and tune it or put the extra cash to a nitrous kit.....

Other oems can vary exhaust and intake valve timing independently. There is a huge advantage to doing this. The first vvt systems on imports would only vary intake valve timing, not both at the same time. Even these earliest systems on imports are superior to what's on the "LS" system. LS3, LS7, LSA, LS9 all exclude vvt. The "LS" vvt system is to help gm meet cafe fuel economy standards.

Couple of thoughts.

1. You are comparing a supercharged application to a NA application.
2. Do you think GM and other manufacturos would go to all the trouble of installing a VVT system in their motors if there was not something to it?

1) just giving my experiences with the topic...it was on a SC application the point is still valid, VVT didn't do jack.
2) How many things have manufacturers done throughout the years that turned out to be just a fad? Its like saying everyone's doing it so it must work. I got rid of DOD and VVT and the car made more power, back to back apples to apples...period, in my experience its all marketing.

Also, we need good data. I realize most folks aren't going to take the time or money to compare cams, but its really the only way to get a clear picture of what parts "actually" do and don't make power in each application. Posting up a graph saying I made xx power more vs my stock cam isn't helpful...you could have made the same (OR MORE) power increase by using a non-VVT cam. I am just trying to provide honest real world experiences on the topic.

1) just giving my experiences with the topic...it was on a SC application the point is still valid, VVT didn't do jack.
2) How many things have manufacturers done throughout the years that turned out to be just a fad? Its like saying everyone's doing it so it must work. I got rid of DOD and VVT and the car made more power, back to back apples to apples...period, in my experience its all marketing.

Also, we need good data. I realize most folks aren't going to take the time or money to compare cams, but its really the only way to get a clear picture of what parts "actually" do and don't make power in each application. Posting up a graph saying I made xx power more vs my stock cam isn't helpful...you could have made the same (OR MORE) power increase by using a non-VVT cam. I am just trying to provide honest real world experiences on the topic.

Advancing and/or retarding a cam isn't a fad or marketing scheme, it's been used effectively for as long as anyone in performance can remember to move the powerband around. The benefit can not be argued. Peak gains in HP an TQ will vary, some will see quite a bit and some will not see as much if any. To me that's irrelevant as IMO that's just a bonus to the most useful advantage of VVT which is broadening the power range.

So I'm going to order a custom cam today. After doing a ton of article reading I am going to stay with the VVT. I will post my current cam for sale after the swap which would be good for a Reg cab or lighter car... Just not a 4x4 ext cab 4.8 trying to pull a 5500 boat trailer......I agree with scoggin, in any v8 app advance it in the Low RPM or retard for Upper RPM has been around forever. Even though most guys dont degree a cam doesnt mean you are getting the full potential. I like the idea of being able to do this without changing keys and not being locked into having to choose where I want my power. The Specs of the cam I am going with are 189 core vvt, 210/224 @.050, .556/568 and a 112 + 5 intake advance.. With or without vvt I think these specs should give my little 4.8 a good low RPM boost.

Any thoughts on the new cam specs think it should give me more bottom end? 210/224 @.050, .556/568 and a 112 + 5 vs currently installed 219/228 .550/.550 114

I think in your situation with a 4.8L motor and a extended cab truck that cam will be fine. I also think you made the right decision in keeping the VVT.

I know its not the most powerful engine out there but the currently installed cam was actually slower I think then stock..... Once I get this in I will be looking for a 4l80 and a t70....

Advancing and/or retarding a cam isn't a fad or marketing scheme, it's been used effectively for as long as anyone in performance can remember to move the powerband around. The benefit can not be argued. Peak gains in HP an TQ will vary, some will see quite a bit and some will not see as much if any. To me that's irrelevant as IMO that's just a bonus to the most useful advantage of VVT which is broadening the power range.

^^THIS^^

I think the real question is if the gains are worth the additional costs and whether or not the LSx VVT system will prove reliable in performance applications. My biggest concern with the VVT setup I'm pursuing (TSP VVT-2) is how stable the cam valve timing will be and whether or not that will cause problems with valvetrain control. As long as the timing control is good, you could theoreticaly grind any cam profile onto a VVT core and see the benefits of on-the-fly timing adjustment.

Futureuser, you should have Vengence grind your cam profile on a VVT core, do a swap and let us know what the gains are after cam timing optimization ;) I bet you could do it for less money than I'm spending to fix my rust pile lol.

^^THIS^^

I think the real question is if the gains are worth the additional costs and whether or not the LSx VVT system will prove reliable in performance applications. My biggest concern with the VVT setup I'm pursuing (TSP VVT-2) is how stable the cam valve timing will be and whether or not that will cause problems with valvetrain control. As long as the timing control is good, you could theoreticaly grind any cam profile onto a VVT core and see the benefits of on-the-fly timing adjustment.

Futureuser, you should have Vengence grind your cam profile on a VVT core, do a swap and let us know what the gains are after cam timing optimization ;) I bet you could do it for less money than I'm spending to fix my rust pile lol.

As a side note, I spoke with my tuner. He has tuned thousands of cars, several with VVT. In his experience he had not seen any "SIGNIFICANT" power or torque increases with VVT cams vs regular cams. Like The Bandit is saying, put a conventional cam in a car, tune it for max power, then swap to a VVT cam, tune it for max power...same dyno, heads, compression, exhaust etc this is the only way to see "IF" their is significant power to be had. picking up 3-5 HP here or there isn't SIGNIFICANT, IMHO doesn't justify the expense or risk. I realize VVT failure leading motor damage is largely a myth at this point, but more moving parts = less reliability...I think most would agree with that. Im not bashing VVT, I just know for me, on my car, in my application, it did NOTHING, and cost me more money. And I would have to imagine I am one of the few non-shop, average consumer type people that have done back to back testing of VVT vs conventional cams, especially that are on a board posting unbiased results. Just trying to share information and help folks be more informed.

"several with VVT"

Did these cars have the VVT software tables installed from companies such as TSP who have spent countless hours and hundreds of dyno pulls refining the VVT software for their cams? Were they just using the factory tables?

I know its not true for every application but I am not trying to get every last bit of HP from my cam install. It actually cost me the same money to do the VVT cam a new solonoid bolt and timing gasket set as it would of to buy all the conversion parts brand new. With the cam being able to advance a bit in the low end I think that should really help MY 4.8 on the bottom end when getting my 22ft Hurricane deck boat up to highway speeds.