Repair-It

Undercover Boss—A Look Inside Ford’s Prototype V10 Mustang

https://www.msn.com/en-us/autos/enthusi ... spartanntp


Wow! This would have really pushed competition had this happened. Pretty cool.

Yeah that is interesting. However, they did not do it, and I am going to assume cost was a big factor. I could be wrong but I would not be surprised if that was even more expensive to produce than the LS7 that GM would release only a year or so later in the 06 Z06. It still revved to 7,000 rpm (maybe 7,100 depending on where I look) but did have 100 fewer HP. But they did release it. You could argue the only reason Ford did not was because they did not have a premium vehicle that could absorb the cost of the engine. Maybe so. I also suspect that engine was huge and heavy. In fact the Cobra R 5.4L was so big that the Cobra R had a huge hood bulge whereas the LS7 fit cleanly under the low hood of a C6. I don't think the V10 would have been more compact. They said 60 lbs lighter than the Cobra R 5.4L but that was an iron block! That thing was probably a boat anchor itself.

So I will of course say I wish they made it, but I will also reiterate that only GM had that magical formula of low cost (relative to other 505 hp N/A engines), high reliability (LS in general, notwithstanding valve spring issues on the LS7), small external volume and weight combined with manufacturing in huge numbers (LS in general, not so much the hand built LS7). These high performance Ford engines are rare as hell, and NEVER swapped into anything by anyone other than a Ford guy. The Coyote is the best mainstream V8 Ford has had in decades. Like two decades.

I bet when the 06 Z06 dropped they were kicking themselves. Oh well.

Let me continue picking on Ford.

I mentioned the Cobra R. The Cobra R was a cool Mustang but a Corvette Z06 made it look downright silly. Apples and oranges? Well, a 2000 Cobra R, which is so rare you will have a very hard time finding one, cost like $55k in 2000. That is $80,527.12 today. The Z06 was actually like $5k cheaper.

https://www.caranddriver.com/reviews/ch ... rison-test

Sorry, the 01 Z06 was $48,920. And I don't mean $49k plus $10k of options. I mean $49k.

Oh look the Z06 placed first against the Mustang Cobra R and Viper GTS ACR. In 2001. Against two vehicles that are pretty much track vehicles. Before, I am told, GM made anything good...

Squeaks, rattles, and wind whistles were constant companions out on the road, where our Cobra R's front tires followed every rut and valley in the pavement like a chain-gang bloodhound.

The Cobra R fulfills its mission: to prove that the Mustang can still run with Detroit's best and provide a genuine race-car experience. But ultimately, it isn't that fulfilling.

No surprise that it turned in the fastest acceleration numbers and lap times, beating the Corvette and the Cobra to the quarter-mile by 0.4 second.

But you still need titanium nerves to fully exercise the Viper on public roads. The tires never found a wheel track or rut they wouldn't follow to oblivion. With so much of the car's distant flanks out of sight, placing the leering snout between the yellow line and the guardrail is stressful exercise on narrow ribbons. "The car seems so big I can't tell where it ends or starts," commented one tingly-headed driver.

Folding yourself into the Viper is like sinking into a cast iron bathtub. The monochromatic gray walls are cold and encircle in some places to nostril level. The manual pedal adjuster increases the likelihood of achieving real comfort, although the left knees of tall drivers still meet the dash panel near the light switch. Frills are few, but an ACR can be "loaded" with air conditioning and a CD player as ours was. Actually hearing the wireless over the constant moan of the four rolling pins underneath is another matter.

Despite its flaws and its ever-climbing price, the Viper is simply lovable. It will do pretty much anything you ask of it except haul the family to the ski lodge. Just ask nicely.

The Z06 doesn't win because it's the fastest (it isn't), it doesn't win because it's the prettiest (at least we don't think so), and it doesn't win because it's the most exciting (it's not bad).

Highs
Improved electronics are less nannylike, a Rolls-Royce inside compared with the others, fun-to-dollar ratio beats all.

Lows
Squirrelly rear end lengthens lap times, flabby seats lack support, reviled one-to-four skip shift" still with us.

Verdict
Fewer florins buy as much performance and more comfort.

The Corvette wins by a single point because it's almost as fast, just about as pretty, and certainly plenty exciting. It also costs almost eight grand less than the Cobra, a little more than half the price of the Viper, and has more amenities and space than either one.

The "competitive mode" is the system's best. It tolerates all the wheelspin and oversteer a Z06 needs to be fast, cutting in only at the point it becomes stupid. Turn it off, and the Z06 is free to be as squirrelly as it wants, and it does want.

The LS6 V-8 doesn't have the power of the Viper's V-10, but it provides more grunt down low than the Cobra's motor without gasping at the top end like its pushrod forbears. And each horse has just 8.1 pounds to pull vs. 9.3 in the Cobra. All the porting work to give air a straighter path to and from the cylinders pays off handsomely on mountain switchbacks, where third gear is all that is needed to lunge from one corner to the next. When it's time to shift, the stick falls easily to hand and the Tremec transaxle, although a bit noisy, changes cogs without a fuss but still operates under the hated one-to-four regime.

The Z06 is not perfect, but it asks less and gives as much or more. Mr. Yeager, your car is waiting.

My CTS-V has competitive mode. It's pretty good.

Z06 lap: 1:36.3
Viper GTS ACR: 1:34.9
Mustang Cobra R: 1:38.7

So 2.4 seconds faster than the Cobra R but only 1.4 seconds slower than the Viper.

70-0
Z06: 152 ft
Viper: 186 ft
Cobra R: 169 ft

Those are some damn decent brakes.

It is easy to look back and scoff at the C5 Z06 and be like "well that was really just an ordinary Corvette. The other two are truly special vehicles." Sure you could make that argument, and I'd challenge you on the Cobra R because, despite the IRS, that was an antiquated platform and the review indicated as much.

But GM built and shipped far more Z06s at a cheaper price point in an overall more compelling and usable package than the other two. And isn't that what a lot of car guys are asking for? No intentional limited production BS, just make as many as people want to buy. GM did that. In fact between 01 and 04, they made 28,388 Z06s which represented a startling 20% of C5 production in those years, which is also nearly 3x as many CTS-V1s that were made! And now I feel like people look back and say, yeah, but I'd rather own the Viper or Cobra R, you see, because they are more special. Are they damned if they do and damned if they don't? I kind of feel that way, yes.

Decided to follow up on the LS7 production.

Here is what I captured.

C6 Z06 production from model year 06-13: 27,996 (mind you, the great recession fell smack in the middle of this run!)
2013 Corvette 427 Convertible: 2,552
2014 Camaro Z/28: 515
2015 Camaro Z/28: 1,292

Total LS7 production: 32,355

That's actually really high imo.

This does not count crate engines obviously.

And now that I've turned this into an LS7 thread, I found some information about what exactly the issue is with the LS7. It is not the valve springs but the valve guides. And not the actual guides but the machining for them.

i have heard that the cylinder head supplier had improperly machined the guides on some heads.
This correct , its not the material the guides were made from but rather the machining process that was out of spec.

This entire time I did not realize that.

From a Canadian forum so pardon the imperfect English:

The original 09 motor dropped valve at 30k km. It got a replacement crate motor put in which built Sep 2013. After another 25k ish with 13 crate. I pull off the crate heads and intake guides were more loose than exhaust, had them re guide with bronze. Now valvetrain quieter after new guides and nearly 65k km and hope its fine now.

GM has traced the problem back to one of its cylinder head suppliers. By analyzing heads returned under warranty, it was discovered that some weren't machined properly. On these LS7s, the valve guides and valve seats weren't concentric, which led to severe wear of the valve guides.

https://www.thoughtco.com/ls7-engine-pr ... est-916184

That last one paints a pretty clear picture of the issue. So you have the valve seat which is a ring that is pressed into the head, and that is what the valve makes contact with, and seals against, when it closes. It contacts the perimeter of the valve. Then you have the valve guide which is the thing that the valve stem travels through and provides support (and a leaky/worn valve stem seal allows oil to drip from the upper head area, past the guide, and into the engine). So when the valve closes, it needs the guide and seat to be concentrically correct. Instead it sounds like the valve guide was slightly off center, which would either try to bend the valve, or put a tremendous amount of pressure on one side of the guide as it moves up and down. This all makes sense. At least the mystery is cleared up. It would just be a matter of ensuring your engine was either "fixed" or was manufactured properly in the first place. Then it would be just fine.