Nick996

I have an 09' Z06 with the LPE 660 kit with the GT21 cam. Cam surge is getting on my nerves and makes driving my car on the street less enjoyable. I drive around in 3rd to keep the revs above 2,500.

I was wanting to know if I put in 3.90 or 4.10 rear gear if it would help with the surging by keeping the revs higher and allow me to use 4th and 5th gear more? Also I would think that the shorter rear gear would make starting in 1st gear much easier right?

I've been reading up on this and would really like to hear from guys that have larger cams and possibly had the same issue(s) I have.

If you did swap form OE to 3.90 or 4.10 who did you buy the parts from?

Zeekaral

Nobody makes a different rear gear for Z06s. If you want a different rear gear you have to swap to a base C6 differential with a shorter/taller gear.

RedZ4me

Put a milder grind in it, you'll be happier and like the car again.

Michael_D

Get someone else to look at the tune. I've seen a couple files of LPE/ 660 tune cals, and they were shiit. No idea if they were canned calibrations or just a hack tuner, but they were woefully lacking talent. I would start there, prior to gears or cam swaps.

Nick996

Already did. Some of the issues I had have been fixed via the updated tune. Now it's just the low RPM surging that I have to deal with. Local tuner says it's a BIG cam and there will be surging below 2k RPM.

I thought about getting a new cam but don't want lose the HP. I guess I'll have to see what a few of the tuners say.

propain

This is why you don't put a big cam in a daily driver. Sure it sounds sick and the gains are amazing but the surge gets old fast when you drive it in traffic or on a daily basis.

Change out the cam or find another car to drive daily.

Michael_D

He's half correct. No, with that cam you will never dial out all the surge and coughing. It can be better though. Do you have a file you can email me?

MyLS1Hauls

Changing the gears isn't going to help. That cam shouldn't have surge above 2000 RPM under load w/ a good tune, but I will say this about the GT21...the lobes are WAY too aggressive for the LS7, IMO. Personally, I'd change it out to something with softer lobes and less overlap...kill 2 birds with one stone. I've seen too many valve train issues with the more aggressive lobes on this motor.

Nick996

You are correct. Under load it has no issue. My complaint is about part throttle in stop and go traffic. I am aware that this is NOT what the cam was meant to be driven in BUT I do enjoy driving it to and from work from time to time. The car (and cam) runs perfect when under load and being driven.

BTW - I bought this car as is. I didn't have it built this way.

Nick996

My tune was done by a shop here locally and I do not have the file. As I said above the car runs much better now that it's been tuned. I just think I am asking the car to do more than it's capable of doing with that cam.

Nick996

It's not my DD. I do enjoy driving it to and from work though on occasion.

The car runs perfect when not in city traffic and the revs are up.

propain

Ahhh... well suck it up then. It comes with the territory.

RedZ4me

Wonder why the previous owner sold it? Took the fun out of it maybe ? Go down on the cam, you'll be glad you did, forget the high rpm bragging rights on the hp.

Michael_D

Valid points. Those LSK lobes are brutal and make it hard to control the valve train. Plus, LPE likes to stick with the OE rockers, to keep the mass down, but they scrub too far and too much with those higher lifts. But they do make good power.....

Nick996

Right?!

Just means I drive around in 3rd and let everyone listen to my loud exhaust. So a yellow Z06 and loud exhaust..... yeah, that's not going to attract the wrong attention.

Nick996

I just might have to look into going down on the cam.

MyLS1Hauls

Yup. I still wouldn't use LSKs on a 1.7 rocker either. I feel like an old fart saying to tame things down a bit, but over the years, I've found that the ragged edge stuff just gets old quick. These days, I'm more about reliability and drivability. Getting to the office in your dress clothes, smelling like raw fuel, just ain't as fun as it used to be

stefuel

Ahhh just tell-em your car only gets 4 mpg and you had to stop for gas on the way to work AND you spilled gas on your pants because the pump didn't shut off automatically. You'll be excused AND you'll probably get laid.

sky1

I had a 3.91 rear gear on my 06 Z06 with a good size cam. It made drive ability alot better. It also turned the car into an animal.

REDZED2

RPM Trans. sells complete 3.73/3.90/and 4.10 C6Z (built) diff's. Stage 3 and 4. Pricey but......