brewersprts

First off, please do not turn this into one of "those" threads dropped valve threads. This is exactly what I don't want. Those turn into arguments about nothing and have nothing to do with the original question by the time they get to 1000 posts or whatever they always do.

I was down in Wilmington, OH for work this weekend and they had a SCCA event running and there were a few c6z's running. They appeared to be mostly stock engines, I assume this is to keep it in a certain class.
So my question is for you c6z guys (or any ls7 powered car) that are regularly running autocross/ road racing/ hpde /whatever. Are you guys running completely stock engines and just feel the valve issues is corvetteforum hype? Those of you that believe it is a problem that's needs addressed, how did you address it? I assume that even just getting the heads redone with the common WCCH stage 2 package would not allow your car to be considered stock powered anymore.

I also assume that most people would rather not blow up an engine that could easily cost $15,000 to buy and have replaced. Maybe you guys are just all super rich. $10,000- $15,000 isn't going to cause me to live in a cardboard box under an overpass but it's more money than I like to just throw away.

I tried to look under the hoods of the c6z's and they all seemed to be stock. I would have liked to ask those running but they seemed busy and I don't want to be that guy who is asking dumb questions when you are trying to get focused and get ready for your next run.

Anyways, thanks for any and all input guys. I love my c6z and don't want to give up on her but want to make sure I can enjoy it for a long time. I would love to get into some autocross/ road racing without worrying about blowing up my car.

parsonsj

Nothing stock about mine: the car is on its third engine (warranty replacement at 2100 miles, forged rebuild at 6000 miles, odometer at approximately 8000 miles now). The most recent rebuild was due to a broken piston (#7), and all of my exhaust valve guides were out of spec. I went to bronze guides and Inconel exhaust valves. I plan on pulling the heads when I get to 10000 miles in a year or two.

My car still sees street duty, but not that much. I mostly run at Sebring and Miami Homestead.

braknl8

I don't track a c6z, just a lowly c5 cpe, but what you're asking doesn't have to be answered specifically by a c6z owner. Yes, there are issues with ls7 heads. No hype there. You CAN have the shop of your choice "fix" the issue and still run in "stock powered" classes if they are pw/wt based. That's your tuner's job. If there is an organization (I don't run with scca so am not familiar with the ruleset) that would add points (or however they may penalize) for addressing the guide issues, while you're still meeting the pw/wt limits..... I think I'd "fix" the heads and run with a different org. NASA ST1/2/3 are pw/wt, for example, so you could have the heads done correctly, tune for the pw/wt of the class and have a blast. I'm not pushing one organization over the other just highlighting a real-world example.

In our small group we've recently seen what happens to these heads and just how much play can develop. I'll post this in the group and maybe that owner can chime in.

Now, I've answered your question. Whether someone else chimes in to disagree and start "that thread".....outta my control, my friend.

moespeeds

In my relatively short time doing this (this is my 3rd season on track) I've personally witnessed 2 C6Z's blow engines. One was a kid bringing his street car to the track for the first time, the second was my buddy who bought his elderly neighbor's very pampered street car, and blew the motor on his 3rd track day. Both were dropped valves, and both were able to cut deals with GM on out of warranty engine replacement. I also have 3 friends who have been running C6Z's for years, and all are on their 2nd engine, one is on his 3rd. I'd say there is a problem there. There are lots of proposed fixes out there, my buddy put in the Lingenfelter sump and has been fine for the last dozen or more track days. Having said all that, I don't think any racing organization will ding you for a system that just increases oil flow. Can't speak for auto-x. And I'm not trying to say that increasing oil flow will solve the problem, just giving you my own personal experience. Good luck.

TorontoC6

I am running a forged stroker LS2/LS3 with ARE 3 stage dry sump, race cam...

Dead reliable, more power than stock LS-7 but not much more.

That's after 3 LS-7's. Two were defects, one was bonehead driver missed shift.

Happy with my choice. I don't need more than 550HP.

Mark2009

First, no, it is not hype. Just a few days browsing the C6 Z06 forum should tell you that (too many have blown up).

Second, to avoid disaster you need to take two straightforward steps:

1. Get your valve guide clearance checked.

2. If your valve guide clearance is excessive, get it fixed.

The method of checking and the type of 'fix' is up to you (any 'fix' is better than badly worn guides). If you don't want to check at all but proceed directly to a 'fix' then that is up to you as well (it's your money and your car).

It is unfortunately best if the details of how to check and how to fix are not discussed in this thread, for that is where the controversy always develops. But there is certainly plenty of discussion on it elsewhere

As long as the heads are not modified to produce more power I don't think any club rules would cause you any problem, assuming you go that route (personally I prefer the relatively unstructured nature of HPDE's -- run what ya brung, as long as it is safe -- as opposed a competition rule book, at least with a street car).
.

eric1855

I was one of the C6Z's in Wilmington. Engine has I/H/E and Tune, rest is stock, with 16k miles.

When I bought the car I bought an extended powertrain warranty that covers the engine itself for another 65,000 miles for peace of mind.

As far as hype, who knows who to believe. It seems pretty obvious that something is not right, but how bad, what %? Good question. Certainly not something that is specific to this car though, there are risks in lots of vehicles especially if you race it. I've seen STIs with 5k miles crack blocks, new Nissans and Toyotas spin rod bearings, and all other sorts of bad news.

Saying that, I do plan to take my car up to McCluskey this winter and get the heads checked, figure I'd rather have them fixed under warranty than the hassle of fixing something bigger under warranty.

Screamin Z

Ran on 2 bone stock LS7's one spun a main bearing at 96 hours and the other spun a rod bearing at 78 hours.

argonaut

I have personally have seen five stock C6Zs blow on track. About 30 - 40 hrs of hard track time is all they will take.

rocsvette

I have an 06 Z06, stock except for the larger sump. It has 100k, original equipment (except for sump) and I have tracked it heavily and shared it at the track with others. Most recently was VIR where my student shared my car; student is Assistant Plant Mgr at the BG assembly plant. I have no unusual oil usage and have just started to refresh the car with plugs, wires, rubber hoses, bushings, etc, all consumables. And for the first 10k miles the car was the Consumers Report test car, tires were totally gone in that time. YMMV

Bill Dearborn

It isn't hype. I personally know of 8 engines in addition to mine that expired at the track. Mine went in Aug of 11 after 40 track days and a bunch of autocrosses. The car had 24K miles on it then.

As far as I know all but one of the engines was completely stock. One of them had a cam and other mods. All but that one were replaced under the GM warranty.

As for worrying about blowing up your engine the adrenaline rush you get when you are driving around a track like the Glen is so high you usually never think about the car blowing up. The sport is very expensive once you are hooked and an addiction to crack might actually be cheaper. To reduce the expense you could make sure the heads are done properly but still use stock valves and keep the rest of the engine stock. In stock form the engine has more than enough power to keep the high dollar sports cars at bay. Driving a C6Z on a track at speed makes you feel like a God, especially when you are zinging past Ferrari's and Porsches.

Bill

McRat

Odd. The Z/28.R uses a factory sealed stock LS7 for the Continental Tire Series.

You'd think if there was a problem, they would let them upgrade the stock engine for racing.

Corvee

It does not use the factory dry-sump and frequent fresh engine swaps are likely.

phipp85

It's not hype. I have seen a couple LS7's blow on track. I even got the privilege to do a little dance in a pile of oil one left on track hahaha........... I also had issues with mine. Intake valve guides were horribly worn while the exhaust side was literally perfect. But before you get all caught up on what you are gonna do about it just check and see if you have a problem or not. As long as you have some mild mechanical skills and some basic tools you can do it in a couple hours.

Captain Buddha

I ran a '13 Z06 for a Summer of track days with zero issues...it was bone stock...if I blew the motor I didn't care...warranty...it's labeled as a track capable car...my take.

I did, however, worry about safety...and I also wanted to go w2w, so I bought a race car...cheaper consumables (brakes, tires, etc.), built to take a beating and built to be crashed and walk away (knocking on wood). Also cheaper than my '13 Z06! Just throwing that out there for your consideration...I had only had a few offs with my Z, just ended up with a few rock dings, just minor stuff...but I knew that if I had contact (or someone had contact with me - stuff happens) it was not going to be pretty (and cost a LOT of $$$$$).

Last C5

You don't need to be on the track to have a problem with the LS7s valves. I recently watched the tear down of a 16K, street driven, pampered LS7 that had 12 of the 16 valve guides out of spec.

Johns07Z

Looks like I have a new project for my 07 Z. It's got 10 track days at the Glen, 20k miles and while I've been worried more about upgrading my brakes, I personally know of a friend who replaced his LS7 last fall. He's had 20 plus events, so maybe 30 or 40 track days on his 08. Bill is right, the addiction is bad - nothing like leaving the Porsches behind you going up the Esses...

Mike.D

good info/advice

trj3

I just sold a 996 track car due to the Porsche 996 engines blowing for no reason. I've had about 10 track cars and love the C6Z06. In my opinion it's the best track car right out of the box that I've had yet. However 40 track days per engine does not sound appealing...... ):

rocsvette

As a side note, the problem with the Porsche engines has been somewhat linked to cars that were NOT driven hard, this from an article sent to me by a Porsche owner.

Of all the Zs with blown motors I am curious how many were on cars with R comp tires as opposed to street tires.