The lower (numerically higher) gear ratios are designed to make the engine turn more RPM at any particular throttle setting, keeping the engine within the torque curve where it produces more force. Horsepower sells cars, torque wins races. Horsepower is actually a function of torque and RPM. The formula is hp = torque x RPM / 5,252 (the 5,252 is a proportionality constant). Torque is the twisting force that actually turns the rear wheels and is the key element in accelerating out of a corner. Also, the more low-end torque an engine produces, the less downshifting you have to do when cornering.

The engine turns just 1,725 rpm at 71 mph and gets 29.2 MPG when the transmission is in 6th gear. This means fewer revolutions per mile which translates to less wear on the moving parts.

The dreaded CAGS on Corvette 6-speeds since 1989 is only possible because the Corvette engines have enough low-end torque to pull the car in 4th gear at low speed without lugging (and damaging) the engine. However, the LS6 engine does not produce as much low-end torque as the LT1 and LT4 engines. The LS6 does not pull 4th gear as well as the LT1 when the CAGS solenoid forces the skip-shift.

The horsepower and torque numbers are excellent but another big improvement in the Z06 is the weight reduction. It takes power to move weight (more correctly mass) and the less weight per horsepower, the quicker the car will accelerate. Below is a table listing the hosepower to weight ratios for some exotic cars. A lower ratio is better.

All 6-speed Corvettes come standard with a limited-slip differential that has a ring and pinion set with a 3.42:1 ratio as indicated by the green label on the rear of the differential housing. The RPO code for this rear-end ratio is GU6 and can be found on the Service Parts Identification label located on the glove box door.

Getting all the power to the road is the job of the wheels and tires. The Z06 has 17-inch by 9.5-inch front aluminum forged wheels, and 18-inch diameter 10.5-ich wide rear wheels. The front tires are P265/40/ZR17 Goodyear Eagle F1 Supercar tires. The rears are massive P295/35/ZR18 Goodyear Eagle F1 Supercar tires. The tires are asymetrical and directional meaning they can not be rotated. Recommended pressure is 30psi. These are not run-flat tires, and the low tire pressure warning system is unavailable with the Z06 so traveling without a spare will be an adventure. The car is delivered with a can of tire puncture sealant and an air pump that runs off the cigarette lighter plug. The theory is you fill the tire with sealant and then re-inflate it with the air pump. If it maintains pressure you can drive to a tire repair facility. If it does not maintain a minimum of 25psi, call AAA or the Chevy road-side assistance people. Make sure they send a flat-bed tow truck.

My Z06 corners much better than even my 1992 C4 Vette equipped with the RPO Z07 Adjustable Performance Handling Package and the ride is much better. Even though the Z06 is noisier inside than the base 2001 C5 coupe, it is much quieter than my 1992. An added plus is the delightful sound the exhaust makes, which you can plainly hear in the Z06 because it lacks any sound-deadening insulation (to save weight). The down-side to the absence of sound-deadening insulation is that at freeway speeds there is constant noise from the rear of the car. I believe this is tire noise because the intensity and character of the sound varies with the road surface. Rain-grooved California freeways are the noisiest, and at times it sounds as if the trunk is open (see below for tire update). Smooth asphalt produces almost no noise at all, allowing the exhaust sound to be heard (faintly in 6th gear). This is not a car for the gold-chain-crowd.

The excellent handling and cornering ability are a result of the sticky Goodyear Eagle F1 Supercar tires and the revised FE4 suspension. The car has SLA (Short Arm/Long Arm) control arms (A-arms) at each corner, eliminating the old 5-link rear suspension on the C4 Vette. The front anti-roll bar is 30mm in diameter and is tubular (to save weight). The rear anti-roll bar is 23.6mm in diameter. The shocks are 45mm in diameter. The base Corvette FE1 suspension features a 23mm front anti-roll bar, a 19mm rear anti-roll bar, and 36mm-wide shocks. The optional Z51 package, which can be ordered on coupes, features the FE3 suspension which includes a 28.6mm front anti-roll bar, and a 21.7mm rear anti-roll bar, but which retains the 36mm-wide stock shocks.

The front transverse composite leaf spring has a rate of 525 lb/in, the same as the Z51. The rear transverse composite leaf spring has a rate of 714 lb/in as opposed to the Z51 rate of 634 lb/in. Camber for the Z06, amazingly factory set, is -0.75 degrees front, and -0.25 degrees rear. Combined with the ultra sticky tires, this means potentially very rapid inside tire wear, but it also produces 1.00 G lateral acceleration. Caster is factory set at 7.5 degees.

As everyone knows the exhaust system is all titanium, including the mufflers and tailpipes. The tips are chrome plated and the owners manual warns that they will discolor from heat (they do).

I will provide additional information as I live with the car more and discover its idiosyncrasies (each Corvette model has its own). I can tell you that the C5 is easier to wash and wax. Since the body panels do not wrap under the car its easier to do both and the panels pick up less road dirt. Also, there are fewer places that trap water, meaning no annoying wet spots hours after you dry the car.

For now, happy motoring and Save The Wave!

Progress Update

With 5,880 miles on the car I can report that there have been no problems. Since this car was built in June 2001, it had the running-production-change pistons and rings installed which eliminated the cold start piston slap problem, and the high oil consumption problem found on some cars produced prior to mid-April 2001. The pistons are now a polymer coated type with a shorter skirt. The shorter skirt eliminates piston slap on cold starts and the polymer coating eliminates the chaffing which lead to improper ring seating and high (a quart in under 3,000 miles) oil consumption. My LS6 has not displayed any noticeable oil consumption at all.

The only issue with the car is the tire noise at freeway speeds. Long drives in the care can become fatiguing from the constant high-pitched noise from the tires. It is at its worst on rain-grooved freeways. It disappears on asphalt roads.

Automobile afficiandos (i.e. car nuts) recognize the car and slow measurably when passing you (or accelerating noticably if you pass them) to look at the car. The red brake calipers are what initially get their atttention I believe. You have to be careful when this occurs at freeway speeds because they invariably turn towards you while looking. Mustang drivers pretend they don't see you.

Tire wear at 5,880 miles was negligible and is apparently even across the tire contact patch. The negative camber of the front and wear wheels does not appear to produce uneven inner wear.

As with most Corvettes I have owned, the car seems better balanced with a full tank of gas, although that has a negative impact on straight line acceleration.

Fuel mileage is actually fairly good being over 28mpg on long stretches bewteen California and Arizona on interstate highways at around 80mph, and around 18.5 in normal California stop and go traffic. The fuel gage goes into panic mode when there are still about 5 gallons remaining in the tank, showing "low fuel" in the DIC display. My C4 cars would only do this when there was less than three gallons remaining. This is not a defect, it just seems to be the way the firmware in the onboard engine management systems is configured. Perhaps too many people ran out of fuel and complained, hence the more conservative configuration.

With 8,550 miles on the car tire wear is still negligible and no uneven wear is evident.

I had to add about 8 ounces of oil but that may be due to the fact that the engine was not filled completely by the dealer at the last oil change. Jay Harrison of Dallas, Texas sent me copies of two Chevrolet Service Bulletins which cover excessive oil consumption and also an engine noise that I heard but ignored (after my C4, with all the rattles and squeeks, I didn't pay any attention to it). The two service bulletins are reproduced below.

Service Bulletin #894549 Higher than expected oil consumption

Service Bulletin #1206539 Engine knock or lifter noise

There have been no issues with the vehicle after 18 months and 8,550 miles of mixed surface street/freeway/back-road-twisties driving.

At 8,705 miles I decided to change the engine oil and filter myself rather than have my local Chevrolet dealer perform the work. Here is a photo of the tools and materials you will need. I found two web sites that provide excellent information for the owner who wants to change the oil on a C5. Both sites offer good (albeit differing) advice on a safe method for lifting the car and proper techniques for the oil change. I used a combination of the two techniques, putting the front wheels on Rhino ramps and jack stands under the rear of the car. It is necessary to get the rear of the car higher than the front since the oil pan on the LS1/LS6 engines is completely flat with the drain plug at the front of the pan. It takes forever for the oil to drain. I let the car sit on the jack stands for 4 hours and there was still a good amount of oil dripping from the pan. Every source I found on the subject recommends waiting 7-10 minutes after refilling the crankcase with Mobil-1 before staring the engine. I waited a half hour. I also pre-filled the new AC-Delco PF46 (replaced by PF51) oil filter with 5W-30 Mobil-1 oil. Doing so eliminates the period of time it takes for the engine oil pump to fill the oil filter, preventing the engine from running with little or no lubrication while the filter fills.

With the engine oil filled to a known level I can now monitor the the level periodically to make certain I do not have the oil consumption problem mentioned in several magazine articles (see Automobile Magazine, July 2002, "Twelve Month Report: Big Red", page 110; Sports Car International, September 2001 issue, page 60) and in some Corvette forum posts. Based on the information I have seen from various sources, the problem is very hard to miss, so I doubt whether it's an issue I will have to deal with. I believe the small amount of oil I had to add was more likely due to the dealer's oil change mechanic simply not putting in the last half-quart of oil.

While you have the car up in the air, check the radiator for road debris which accumulates rather rapidly and can block cooling air to the radiator fins. Use a vacuum cleaner with a crevice tool to suck the debris out. If you drive over a plastic supermarket bag on the road and don't see it blowing around in your rear-view mirror, there's a good chance it wound up here. The plastic will block air rather effectively and should be removed as soon as possible.

An odd thing would occur when I would accelerate aggressively: Water would spray up onto the driver's side windshield. I was able to determine that it was windshield washer fluid being sucked out of the vent cap and forced back onto the windshield by the air flow. The fluid leaves a stain on the hood liner (along with a stain from debris kicked up by the alternator pulley) visible in this photo. One way to reduce the amount of splash is to not fill the windshield washer fluid reservoir completely. Another solution is to place a good size piece of foam material into the reservoir.

Added Michelin Tires

I spent the 2005 and 2006 ALMS racing seasons (including two trips to the 24 Hours of Le Mans) with the Corvette Racing Team (see the article I wrote in the April 2006 issue of Corvette Magazine detailing my experience with Corvette Racing).

                                                      (L-R) Neal Everhart, Rich Eldred, Ray Smith, and Steve Hartsell                                                       Ready for a pit stop. (L-R) Chuck Miller, Neal Everhart, Ray Smith, and Ray Gongla

During this period their Michelin tire engineer, Donnie Wilson, told me the Pilot Sport PS2 was a better tire for the Z06, so when the Goodyears were sufficiently worn I bought the Michelins. If Michelin tires are good enough for Corvette Racing, they are good enough for me. And man are these things sticky! Thank you Donnie!

With 23,800 miles on the car there is still no sign of any abnormal oil consumption.

Brake Upgrade

Upgrade to 2004 Z06 Rear Shock Absorbers

Upgrade to 2004 Z06 Front Shock Absorbers

After installing the Michelin Pilot Sport PS2 tires, the 2004 front and rear shocks, the 2004 end-links, and the polyurethane anti-roll bar bushings front and rear there has been a dramatic change in handling of the car for the better. The entire suspension is now identical to the 2004 Z06 and benefits from the polyurethane bushings that the 2004 Z06 does not have. My next project may be to replace the control arm bushings front and rear with the polyurethane bushings.

Braking performance is no different than it was with the OEM rotors, pads, and rubber brake hoses. Over time the stainless steel brake lines may prevent the pedal softness that results from the rubber hoses slowly deteriorating and bulging under pressure. The only way to actually increase the already world-class braking capability of any Corvette is to go to larger-than-OEM-size rotors and larger opposed-piston calipers. However, the slotted, cross-drilled, Zinc-washed rotors do look a lot better than the OEM rotors.

EBCM Replacement

Since this part is approximately $1,300 at retail from the Chevy dealer, and still costs $695 from GM Parts Direct, I searched the Internet for information. What I found was that 1) I'm not the only one to experience this issue, and 2) there is a fellow named Brandon Hite who runs a company called ABSFixer.com who can rebuild the EBCM for $150. All you have to do is remove it and send it to him. See the article for details.

Oil Change and C5 lifting links:

All of the following sites feature photos and detailed instructions

http://97vette.com/ Various tutorials on lifting, CAGS elimination, bleeding the clutch, oil change, etc.

http://97vette.com/howto/oil/index.html Specifically an oil change How-To

http://www.z06vette.com/diy_lift.php Safely lifting a C5 by Mark Vaquer

http://www.z06vette.com/diy_endlinks.php Upgrade plastic '01 Z06 rear anti-roll bar end-links to '02 aluminum by Mark Vaquer

http://www.c5forum.com/diy/oilchange.php C5 oil change

http://www.idavette.net/hib/02ls6/page5.htm Hib Halverson article on excessive oil consumption/piston slap issue (must read)

Save the wave.