Generation IV Internal Engine - Mast VVT HO or Comp XFI™, 267PHR14

I have a LY6 with a LS3 intake the VVT is intact and I will be running a 72mm turbonetics turbo. What cam is the better choice, the MAST VVT HO cam or the Comp XFI 267PHR14? I have read about both but I was hoping someone out there would have some real world info.

anyone? Does anyone have any feedback for the mast VVT HO with a turbo?

I'm running the same exact motor without the turbo...I have the mast vvt ho cam and love it! Car sounds great and runs even better. No Dyno runs yet but it's making some crazy power for the street. Don't know how to shoot you my thread... Try searching 67 cutlass ly6 if you want to check it out. Good luck!

I wonder how well this will work. I am curious to see if the valve springs can live with boost AND vvt

I am going to be using aftermarket dual springs just to avoid future problems.

Dual springs can cause the VVT to not operate exactly as commanded.

TSP sells dual valve springs with their VVT camshaft kits.

TSP sells dual valve springs with their VVT camshaft kits.

Yup....

Dual springs can cause the VVT to not operate exactly as commanded.

TSP sells dual valve springs with their VVT camshaft kits.

Yup....

Dual springs not designed as a package then. LOL:gruffy:

I talked to the guys at mast at I was told that because Im using a turbo I should be using dual springs. I asked them about the compatibility between the dual springs and the VVT the guy said it was no problem and the springs they have with the kit will work just fine.

This is an ongoing topic that will iron itself out in due time. I will be ordering my Mast camshaft hopefully this week, and it comes with springs, but I am unsure if they are duals. Should be, for the price. Yikes!

How much is the kit gonna run you? I priced the cam itself but never the whole kit.

SO I talked to 3 different manufacturers today and got 3 different answers.
Texas speed said no problem for VVT + Turbo and proper functioning with Double springs

Mast said some problems but no guarantees with VVT and a turbo only beehives

Fastlane said it could go either way but no double springs

Im gonna call comp cams tomorrow and see what they say, I wish I could get a def answer from someone that has experience. So far Mast has the best price (with military discount) across the board.

How much is the kit gonna run you? I priced the cam itself but never the whole kit.

Cam and springs....$899.00

Problems controlling vvt with dual valve spings and boost?

Thats what I figure is gonna be the problem. I talked to more people today and I was told that the springs will be to stiff for the VVt to function properly. Its not lookin good for the VVT at this point. I would rather peace of mind then an extra 1 or 2 MPG.

Thats what I figure is gonna be the problem. I talked to more people today and I was told that the springs will be to stiff for the VVt to function properly. Its not lookin good for the VVT at this point. I would rather peace of mind then an extra 1 or 2 MPG.

VVT is not about MPG, it's about spreading the power curve.. If you're looking at VVT for just mpg, it's not worth it..

VVT is not about MPG, it's about spreading the power curve.. If you're looking at VVT for just mpg, it's not worth it..

In the case of Gen IV v8s, it seems about MPG. Performance applications exclude vvt.

In the case of Gen IV v8s, it seems about MPG. Performance applications exclude vvt.

I'm sure a lot of L99 Camaro5 owners would disagree..

This has been discussed before. Just because the General won't make a Manual trans VVT performance car, doesn't make VVT all about fuel economy.

I'm sure a lot of L99 Camaro5 owners would disagree..

This has been discussed before. Just because the General won't make a Manual trans VVT performance car, doesn't make VVT all about fuel economy.

Yes, and I'm sure any corvette owner would disagree. I think in the next generation it will be more about performance, especially if they use a cam in cam system like the viper.

I have a LY6 with a LS3 intake the VVT is intact and I will be running a 72mm turbonetics turbo. What cam is the better choice, the MAST VVT HO cam or the Comp XFI 267PHR14? I have read about both but I was hoping someone out there would have some real world info.

After reading a couple of books about turbo charging, I would consider running the stock cam first. I might upgrade the valve springs. The world of vvt and boost(in gm vvt gen iv v8) is relatively unknown, and pioneering it could prove to be costly. The phaser will be working very hard with boost and high spring pressures. You can't compromise the springs.

My recommendation is, try the stock cam and if it meets your goals leave it alone. Then, if you want more power, upgrade to a 78mm turbo and upgrade the fuel system. You could consider a factory LS9 cam. I think putting the money into a good turbo system with proper wastegate placement and a good wastegate, and contolling IATs along with tuning, will pay far greater dividends than a cam swap with a cam not designed for boost.