I've been without a vette for a year or so and am preparing to buy my next one. I'm either getting a c5 base or a c5z (which I've always loved). The price difference is around 6,000 dollars or so from base to z, and I plan to eventually put an A&A v2 si kit on the car. It seems a waste of money to buy the z06 for the small weight advantage and 55 extra hp from the get go, but I find myself drawn to it anyway.

Is there a good reason I should nag my wife into letting me get the Z instead of the base coupe?

 

All things being equal, there shouldn't be a $6K difference between a coupe and a Z06 at this point unless one has a lot of miles and the other is very low mileage or there is a lot of difference in the years of the cars. Yes, you can make the coupe very competitive with the Z06, but if the Z06 body style is what you really like, not sure I would settle for something else.

 

can be with ultra low mile cars. people still pay 25k for a very low mile mint z06. hard to get a coupe over 20 unless it's the 03 old man edition. those still bring cash

 

the main selling point will be the body style, whether you want a coupe with a removable top or the fixed roof z06... all things equal on the blower kit the z will make slightly more power due to the heads and cam but those can easily be swapped out on either car and upgraded, you can't swap body styles

 

Blown C5 Vert is my vote

I would go with base model and do some upgrades

500 RWHP on any street driven C5 is more than plenty

 

I liked the hard top myself, and was able to find a FRC to start my build with and saved some money, that's another option to consider.

 

The advantages to getting the C5 Z06 over a base coupe for a Supercharged application are a few things:

(1) The block of the Z06 has stronger metallurgy (stronger material) over the C5 LS1 (with the exception of a '04 model, GM went with the LS6 block in all C5's)

(2) The cam is excellent for a blower application - many people use these for their set-ups (most however go more aggressive in the cam later)

(3) More compression - meaning it will take less Boost to make more power (nice thing is that it is not too much compression for a supercharged set-up)

(4) One of the best things is that the 243 casting head of the Z06 is really really good for the Supercharged application (many choose these heads and make excellent power)

(5) The LS6 Heads' Springs are good and much better for a Boosted application (LS1 heads will need to have the springs upgraded to hold the Boost)

(6) LS6 manifold is also better and flows much better than the stock LS1 manifold (however from '02 up all C5's came with a LS6 manifold)

(7) Z06 has a racing tranny, stronger and better (M12 model) over the stock C5 Coupe

(8) The rear of the Z06 is equipped with 3.42 gears the same as a base model manual coupe (M6 Tranny) "BUT" the Z06 rear has Shot Pined gears where the base coupe does not!

Quite frankly the LS6 (Z06) will make more power easily and with less effort and Boost and is better for a Boosted application to 'BEGIN' with!

Don't get me wrong you can Boost a stock LS1 and make good power but the Z06 with the LS6 is a better start ESPECIALLY since you like the model of the Z06 to begin with!

Thanks,Matt

 

Can you point me to evidence of the block and transmission being stronger? I know the transmission is closer geared and has a lower top speed in the Z, but never heard the block and trans were physically tougher before.

Also, I cant see how a valve soring can't "hold the boost." We arent talking a hot cam here, were talking increased cylinder pressure, which would actually push the valves closed. I mean, i could see stronger retainers I guess, but springs shouldnt matter.


Thanks for all the info guys. In the okc area right now a ~70k mile m6 runs low teens, and a 405hp Z runs high teens or 20.

 

First: SPRING

You say pushing it closed, well that's not the case, unfortunately that assumption is wrong because:

Boost causes cylinder pressure as you stated, however "IF" a spring is not strong enough the Boost will escape around the valve "SINCE" the spring cannot hold it up or closed - it's that easy - Spring pressure is essential or Boost will escape!

Second: Block

The LS6 shares its basic block architecture with the GM LS1 engine, but other changes were made to the design such as windows cast into the block between cylinders, improved main web strength and bay to bay breathing, an intake manifold and MAF-sensor with higher flow, a camshaft with higher lift and more duration, a higher compression ratio of 10.5:1, sodium filled valves, and a revised oiling system better suited to high lateral acceleration.[8] LS6 intake manifolds were also used on all 2001+ LS1/6 engines. The casting number, located on the top rear edge of the block, is 12561168.

Both LS1 and LS6 blocks are semi-permanent mold castings of 319-T5 aluminum, however, the LS6 case is different from LS1 unit in the design and strength of the main bearing bulkheads.

Pistons: LS1/LS6

The LS1 pistons are made of a good, standard aluminum alloy that was more than adequate for a regular motor, but the pistons for the LS6 pistons were made of a premium alloy that had more copper and nickel in it so they were stronger and they didn’t expand quite as much when they were hot. The additional strength was important in a performance motor, but the lower expansion rate was more important because it allowed

LS6 Engine:

The Z06 uses a high-output version of the LS1 small-block engine. The name was changed to LS6 after substantial modifications. The new engine powerplant produces about 12% more power than the LS1 and looks identical in external appearance save for the red engine covers. The LS6 produces 405 horsepower (302 kW) at 6000 rpm, and 400 lb·ft (542 N·m) at 4800 rpm. The engine redlines at 6500 rpm (versus the LS1's 6000 rpm redline).

The LS6 utilizes an aluminum block which has been modified to allow greater bay-to-bay breathing. Typically the LS1 engine allows too much air in its crankcase developing into parasitic loss of power. The LS6 relieves this unwanted pressure translating into a removal of parasitic loss thus gaining more power.

New Pistons
The LS6 utilizes modified versions of the LS1 pistons. The new pistons are made from M142 aluminum alloy which has proved to be stronger and more durable than the material used in the LS1. The pistons have been reshaped to have a slight barrel shape difficult to see for the normal onlooker. The new design also reduces internal mechanical noise because of its increased efficiency.

Increased Compression
The LS6 cylinder heads have been cast with pent-roof combustion chambers. This modification of the LS1 has decreased the cylinder size thus promoting a greater Compression ratio; from 10.1:1 to 10.5:1. The LS6 ports have been cast using tighter tolerances which has resulted in increased power, thermal efficiency, and increased volumetric efficiency.

High-Profile Camshaft
The LS6 utilizes a camshaft constructed from steel billet materials. The timing of the camshaft has been altered by increasing the lift from those of the LS1 to provide quicker opening times. To accommodate higher lift and longer duration of the camshaft the valve springs have been manufactured to become stiffer. The springs are wound tighter than those in the LS1 which results in stronger springs able to handle the increased strain from the camshaft. These modifications result in more efficient air-flow into the combustion chambers and thus an increase in power.

Fuel Injectors
The LS6 utilizes new and larger fuel injectors. The new injectors deliver 3.6 grams of fuel per second, an increase of 10% above the LS1. The injectors were designed to deliver more fuel as a result of the increase in air flow from the increased compression and camshaft opening duration modifications. The fuel to air mixture ratio needs to remain proportional to achieve operational status.

Internal PCV System
The LS6 utilizes a newly designed Positive Crankcase Ventilation valve. The new PCV valve now rests in the "V" of the engine. The "V" aluminum cover contains composite oil separating baffles with unique tubing. This results in less overall oil tubing thus reducing the probability of multiple oil leak sources. The presence of the oil baffles also reduces oil consumption and increases the performance capabilities of the ventilation system during high-performance maneuvers (greater than 0.55 lateral G) which the Z06 is capable of.

Exhaust Manifolds
The LS6 utilizes newly designed exhaust manifolds. These manifolds are constructed of cast-iron material and have been designed to reduce weight by utilizing thin walls.

Excellent links here:
https://www.corvetteforum.com/forums...tions-faq.html
http://www.c5registry.com/documents/ls6/page3.htm
http://en.wikipedia.org/wiki/Chevrolet_Corvette_C5_Z06http://www.enginebuildermag.com/2005...m-small-block/
I apologize I cannot seem to find the info (I remember reading it somewhere, and if not then egg on my face about the block material)

M12 Tranny:

The Z06 utilizes the specially built M12 6-speed manual transmission. While outwardly similar to the base-model MM6 manual transmission, the M12 transmission is unique to the Z06, and not available on other Corvettes, i.e., coupés and convertibles. The M12 has more aggressive gearing to increase torque multiplication in most forward gears, allowing for more rapid acceleration and more usable torque at higher speeds. A transmission temperature sensor was added to protect the M12 from higher thermal stresses. The sensor warns the driver, via the Driver Information Center, with a "TRANS OVER TEMP" message if transmission temperatures approach their operating limits, and which could lead to damage if the transmission were not allowed to cool down. As with all C5 Corvettes, the transmission is located toward the rear of the vehicle, as a rear-mounted transaxle assembly. This allows a better overall weight distribution for the vehicle, as the weight of the transmission offsets some of the weight of the forward-sitting engine.

Synchronizers
Carbon blocker rings have been installed on all manual transmission forward gears to provide for smoother shifts and additional robustness.

I hope this helps some and again I might be mistaken about the metallurgy of the LS6 block over the LS1 - However the LS6 block was indeed designed stronger than the LS1 as shown in the links and the info above!

Thanks,Matt

 

My Heads and Cam coupe is testament to why the Z06 is not much better than the base model. I wouldn't spend the money when you sound like the kind that's going to change it all out anyway.

For a very small amount of mods, the Z06 is left in the dust. It also depends on what you want to do with the car. My experience on the drag strip is that the z cars are flat out worthless. That might rub a lot of owners the wrong way. But even before the heads and cam. I was beating supercharged z's.

There's nothing that you can do to the z that cant be done to the coupe. And as for as the engine block being better. I don't quite believe it. It's just different. My coupes stock block handles 430whp n/a and a 100 nitrous shot. I acknowledge there are some engineering differences that make the ls6 a more technologically advanced engine, but the differences are very subtle and in no way make an ls1 "weaker" than an ls6. People make 1000 horse out of ls1's now.

Let's look at few simple reasons why you pay more for a z.. Number one, it has better heads, larger cam, (and a better intake than early models). All easily changed out. Even the z owners change them out. So when you take a coupe and a z and put the same aftermarket cam in and a set of those heads on the coupe. You're making basically the same numbers.

Different suspension on the z, again coupe and z owners alike change out the suspension with aftermarket. You then have the same thing here too.

Weight, ever so slight the difference and any number of things can be done to remedy that. A lot of the weight difference is in the rear glass, which in the case of a drag car has the effect of making the z light over the rear end.

Gearing, this is solely based on what you want to do with the car that makes the gearing good or not. A simple ring and pion swap does more than what the transmission differences are.

I say get the car that looks best to you. But if you are aimed at modifications and performance. The coupe will be the best bet as everything that makes the z better will be changed out anyway. This is all just my opinion. I'm sharing it because I went through the same decision too. I'm glad I chose the coupe because the car is modified far beyond what a z ever was now. So it just saved some money.

 

Falcon Punch is correct about what he wrote. In addition, on the Z06 you have to look at the suspension, camber mods, etc. It is not just the engine that is different, the suspension and handling characteristics are as well.

If all you intend to do is use your new Vette for straight line acceleration, it doesn't make too much difference in terms of power. If you plan to track it, you are going to be spending quite a few dollars to match the overall differences between the Z06 and a base coupe. Not that either are bad, but you wanted to know the differences.

I have owned both, and the Z06 is well, like a better Corvette.

BTW, Here is a link comparing the LS1 and the LS6. This was a 2001 comparison (and of course valve train differences in the 01 and 02-04s), but will provide you with the basics.

http://www.cadillacfaq.com/faq/answe...s6-article.pdf

 

You are slow by these standards with today's cars.

 

on street tires it's moot, there's no traction

unless you have an evo or GTR with AWD you aren't hooking street tires past 500, in fact it's challenging to hook 400whp on street tires in 1st gear if you jump on it

 

That is also part of the problem...

 

Can you be more specific as to what FalconPunch is correct as you stated?

His question or statement?

Thanks,Matt

 

Totally agree!

Thanks,Matt

 

Here is some additional information to look over as to why it is necessary to increase your valve spring strength in a Supercharged application: (It needs to be able to close, due to increased cylinder pressure)

http://magnumpowers.com/valve%20springs.htm

Thanks,Matt

 

stock for stock the Z06 is faster in both the 1/4 and around the track..add a supercharger to each a base and a Z06 and the Z06 will still come on top...

 

Exactly what the thread was about and the OP was asking!

Thanks,Matt

 

And even after you build your dream car you better make sure you have a guy that can tune your ride, lots of power left on the table if its not tuned correctly