C6 vs Z06 questions

[ian_uk1975]

I currently own a C6 Coupe (manual trans) and am tempted by Z06 ownership. However, thinking about the difference in used prices between my C6 (prob worth around £25k) and a used Z06 (£40k+), I'm finding it hard to imagine the £15k price differential is worth it?

I'm most interested in the difference in straight-line performance between the C6 and Z06. Has anyone on here driven/owned both? If so, I'd love to know how the Z06 compares in terms of midrange acceleration and all-round in-gear urgency. Of course, I realise I'll learn all this by test-driving one, but I'm not at that stage just yet.

Is the LS7 anymore rev-happy than the LS2? I'm aware of the higher rev limit (amazing for a pushrod engine), but is the engine more responsive with it and smoother/happier at high revs than the LS2?

How is the Z06 ride comfort compared to the C6?

FYI, I'll be using the car for road use only.

Cheers,
Ian.

Edited by ian_uk1975 on Tuesday 28th April 21:21

[roughrider]

They are rather scarce now!!

From the forums in the States, the consensus is that the C6 has better mid-range, and yes, the LS7 is more peaky.

My Z06 rides like a V8 Vantage, firm, but soaks up the bumps. For a production car, it handles on circuit impeccably [2008 model].

[G4HKS]

I'll second that - I've come from a C6 into a new Z06 only last last month and whilst the performance of the former is probably all you'll ever need, it's just the way the Z is built, all alloy chassis, carbon fibre wings etc etc, handles and sheer grunt that makes it even more special. Wish the roof came off though - that I really do miss!

[vetteheadracer]

G4HKS said:

Wish the roof came off though - that I really do miss!

I'd would only upset your hair!

Not driven a standard C6 so not qualified to make comparisons but I drive my C6 Z06 every day and it is does everything extremely well. It is comfortable, fuel efficient (averages 23 MPG), ride is excellent, my only complaint is the steering could do with being a bit sharper.

[ian_uk1975]

G4HKS said:

I'll second that - I've come from a C6 into a new Z06 only last last month and whilst the performance of the former is probably all you'll ever need, it's just the way the Z is built, all alloy chassis, carbon fibre wings etc etc, handles and sheer grunt that makes it even more special. Wish the roof came off though - that I really do miss!

Interesting. Could you expand a little on the performance difference between the two please? Is there a slight perceived difference in acceleration, or is it quite a dramatic and obvious difference? Thanks.

[G4HKS]

I'd would only upset your hair!" I take it you meant “IT”

Nige, you're such a b1tch! Still at least my hair doesn't clash with the colour of my car.

Anyway, where were we? Yes there is an appreciable difference between the two from the very start but my C6 employed the older LS2 engine -it would be interesting to see how the LS3/LS7 engines compare. I’m sure Bill and Ben from Manchester would comment haven driven the two on a regular basis but they seem to have deserted PH at present. Come back Mitch all is forgiven.

[300bhp/ton]

ian_uk1975 said:

I currently own a C6 Coupe (manual trans) and am tempted by Z06 ownership. However, thinking about the difference in used prices between my C6 (prob worth around £25k) and a used Z06 (£40k+), I'm finding it hard to imagine the £15k price differential is worth it?

I'm most interested in the difference in straight-line performance between the C6 and Z06. Has anyone on here driven/owned both? If so, I'd love to know how the Z06 compares in terms of midrange acceleration and all-round in-gear urgency. Of course, I realise I'll learn all this by test-driving one, but I'm not at that stage just yet.

Is the LS7 anymore rev-happy than the LS2? I'm aware of the higher rev limit (amazing for a pushrod engine), but is the engine more responsive with it and smoother/happier at high revs than the LS2?

How is the Z06 ride comfort compared to the C6?

FYI, I'll be using the car for road use only.

Cheers,
Ian.

Edited by ian_uk1975 on Tuesday 28th April 21:21

Seriously speaking there is am American tradition call modified. This may be a more cost affective route to go.

If you want out of the box performance then the Z06 wins and of course uses more exotic materials and has a dry sump engine. But in the big picture it all counts very little.

The LS7 engine is not really any different to any other LS engine.

They can all be made to produce similar specific outputs. A 6.0 litre C6 can easily be tuned to around 90bhp/litre with the correct parts (that's 540bhp) in n/a trim. Or there are a host of forced induction offering which can offer even more.

If you want more info let me know and I'll point you at some places that'll be able to help you out.

But for around half the cost to upgrade to a Z06 you could get your C6 being a lot quicker in every respect.

[roughrider]

Or,,,buy a brand new crated LS7 for less than 10 grand, bargain!!
Shaving the weight off the car may be a slightly more difficult project though...

[300bhp/ton]

roughrider said:

Or,,,buy a brand new crated LS7 for less than 10 grand, bargain!!
Shaving the weight off the car may be a slightly more difficult project though...

Losing the weight will be the biggest hurdle. But IMO the weight difference is not so great and unless you a re building a dedicated track car I can't really see it being much of an issue.

In short - I'd simply not bother with too much weight reduction.

New bigger brakes.
Uprated shocks/springs.

A decent catback
Tubular headers (of some description)

4.10 final drive gears (depending on final setup, maybe 3.90's)

short shifter if manual

Shift kit if auto with a decent stall

If n/a better heads/cam

Bigger/ported TB and FAST intake manifold

Tune

However, if its in budget I'd be leaning more to a forced induction setup. ProCharger or Vortech offer some nice bolt on centrifugal blowers.

Magnason offer an Eaton (not my chioce)

Or Kenne Bell offer a twin screw blower.

STS offer a single or twin remote mount turbo setup. And there are a few companies offering other turbo kits.

On the stock internal long block you'll be able to run 5-8psi on the correct tune and fuel. You'll easily top the HP a Z06 makes stock.

If you want to go all out (which is still easily in budget) you could up the engine internals with better heads and a more suitable cam and see over 750hp on pump fuel with good reliability!!

[JimexPL]

You'll never get any of that money back from modifying the car though, unless all of the items are reversable and you have the free time to do so and sell on separately.

[ian_uk1975]

300bhp/ton said:

Seriously speaking there is am American tradition call modified. This may be a more cost affective route to go.

If you want out of the box performance then the Z06 wins and of course uses more exotic materials and has a dry sump engine. But in the big picture it all counts very little.

The LS7 engine is not really any different to any other LS engine.

They can all be made to produce similar specific outputs. A 6.0 litre C6 can easily be tuned to around 90bhp/litre with the correct parts (that's 540bhp) in n/a trim. Or there are a host of forced induction offering which can offer even more.

If you want more info let me know and I'll point you at some places that'll be able to help you out.

But for around half the cost to upgrade to a Z06 you could get your C6 being a lot quicker in every respect.

I had considered going FI, but the lousy GBP/USD exchange rate makes that a very expensive option at the moment. Also, there are some question marks over how long the stock LSX bottom end can survive with FI (only cast pistons, remember). Although an FI LS2 would be more powerful than a stock LS7, it may come at the expense of reliability and it wouldn't make the C6 quicker (probably about the same, but not quicker), due to the Z06 weighing 50kg less and having different gear ratios. On top of all that, a blower is quite noisy (ie. whine)... some like the noise, some don't. I think I'm in the latter category, to be honest. HOWEVER, a C6 with a blower does mean you can have Z06 power and retain a removable roof.

Heads and cam aren't really worth doing due to the fact that UK MOT emissions will not allow any kind of lairy cam to pass the sniff test. About the wildest cam that would still stand an excellent chance of passing MOT emissions would only add about 15-20BHP at most. If you've been reading the US forums and reading about the LG cams, forget it! They wouldn't stand a hope in hell of passing UK MOT emissions. There are also big compromises to be made with big cams... 'lope' (ie. very rough idle), surging, bogging, etc, etc. A wilder cam would also need a custom map (expensive and time-consuming). Regarding heads, stock LSX heads are known to be excellent anyway... I think you'd need a big cam to warrant changing the heads.

It's not just mechanical though... the Z06 does look meaner and converting a C6 to look like a Z06 is very, very expensive.

I've already got some of the other mods you mentioned... short-shift, cat-back, intake, etc.

Cheers,
Ian.

Edited by ian_uk1975 on Wednesday 29th April 11:05

[ian_uk1975]

JimexPL said:

You'll never get any of that money back from modifying the car though, unless all of the items are reversable and you have the free time to do so and sell on separately.

Agreed... a highly-modded C6 may also be a white elephant in terms of resale. Certainly, a stock Z06 would be far easier to sell and lose less in depreciation than a highly-modded C6.

Realistically, my decision is limited to sticking with my stock-ish C6, or trade-up to a Z06. Just not sure if the extra performance in the Z06 is worth the extra £15k and not sure if I'd miss the removable roof of the C6 (can't take if off very often, but it's nice to do when the sun's shining).

[300bhp/ton]

JimexPL said:

You'll never get any of that money back from modifying the car though, unless all of the items are reversable and you have the free time to do so and sell on separately.

Most of it could easily be removed. But you don't modify a car to make money.

Buying a new BMW M6 will lose you plenty. And if you plan to keep the car a while it's not such a bother.

[anonymous-user]

Own neither but driven both,

C6 = seriously powerful and very competent sportscar.

Z06 = rocket ship!

Which would I buy? Probably the base car.
Why? Just how much quicker would you drive in the Z06! (and the roof doesn't come out...)
IMO base C6 looks astounding value for money.

[300bhp/ton]

ian_uk1975 said:

I had considered going FI, but the lousy GBP/USD exchange rate makes that a very expensive option at the moment. Also, there are some question marks over how long the stock LSX bottom end can survive with FI (only cast pistons, remember).

I admit the exchange rate is not in our favour at the mo, but it’s still not out of the question. As for the stock bottom end. There will always be a debate, but in all honesty people have been adding blowers and turbos to LS motors since 1997 with little issues. Just get a good tune, run the right fuel and don’t get greedy on the boost.

I think it’s more the fact that adding a turbo sounds scary, so too many people post horror stories about what they think might happen, rather than those that have actually done it. Most of the ones that have trouble are often due to other reasons and not directly the result of adding FI.

All IMO of course

ian_uk1975 said:

Although an FI LS2 would be more powerful than a stock LS7, it may come at the expense of reliability and it wouldn't make the C6 quicker (probably about the same, but not quicker), due to the Z06 weighing 50kg less and having different gear ratios.

50kg is nothing IMO, it’s not even a passenger. I don’t think for sensible road use (or even mild track use) 50kg is much of a deal. I’d even question 100kg being an issue on a car of this weight, ok if it was a 400kg superlight, but the Vette isn’t such a car.

As for gearing, well doesn’t the Z06 use different internal ratios? I’m sure they help, but I’m not sold on them making the biggest difference. Changing the final drive diff ratio is quite easy, if it was me I’d match this up with the tuning option. Some setups suit taller final drives better than shorter ones.

ian_uk1975 said:

On top of all that, a blower is quite noisy (ie. whine)... some like the noise, some don't. I think I'm in the latter category, to be honest. HOWEVER, a C6 with a blower does mean you can have Z06 power and retain a removable roof.

Yes the blower will make a noise. But depending on the blower type it’ll make a different noise. Centrifugals don’t sound like PD blowers and turbo’s are different again.

ian_uk1975 said:

Heads and cam aren't really worth doing due to the fact that UK MOT emissions will not allow any kind of lairy cam to pass the sniff test. About the wildest cam that would still stand an excellent chance of passing MOT emissions would only add about 15-20BHP at most. If you've been reading the US forums and reading about the LG cams, forget it! They wouldn't stand a hope in hell of passing UK MOT emissions.

Not really a fan of LG – a bit too pricey and don’t go for all the secrecy on their classified specs, lol

As for the emissions. I’ve never been able to find a fully satisfactory answer for it. In the US they test for different emissions than we do in the UK, so asking on the American forums/or sellers always turns up no answers. I do know other cars manage to run wild cams and still pass, so if its possible for them I can’t see why it can’t be possible for a Corvette.

Example of emissions testing. EGR reduces Nox emissions, but the UK MOT doesn’t test for it, on any car in the UK you could remove the EGR system and still fly thru the MOT emissions testing. I think we only test for Co2 emissions (was ages back when I was reading up on it), but in the US they test other emissions which is what the guys over there fail on.

If you have any other info on the matter I’d be interested though

ian_uk1975 said:

There are also big compromises to be made with big cams... 'lope' (ie. very rough idle), surging, bogging, etc, etc.

But isn’t that part of the fun

I’d love a big lopping idle

ian_uk1975 said:

A wilder cam would also need a custom map (expensive and time-consuming).

I admit its more difficult and expensive here in the UK, but you could buy a starting map from the US and then spend an hour or maybe 2 on a dyno. Can’t see it being a real issue. All the turbo Jap cars are tuned the same way and they seem to manage.

ian_uk1975 said:

Regarding heads, stock LSX heads are known to be excellent anyway... I think you'd need a big cam to warrant changing the heads.

Have you got a LS2 or LS3?

I don’t know so much about the LS3 heads (are they different?) but I know there are some decent improvements to be made, but yes they often suit a cam swap more than just doing the heads on their own.

ian_uk1975 said:

It's not just mechanical though... the Z06 does look meaner and converting a C6 to look like a Z06 is very, very expensive.

I agree the Z06 does look better and that there’s no cheap way to make a C6 appear the same.

But I guess thats the trade off in terms of cost/outlay and performance.

ian_uk1975 said:

I've already got some of the other mods you mentioned... short-shift, cat-back, intake, etc.

Cheers,
Ian.

Edited by ian_uk1975 on Wednesday 29th April 11:05

What catback do you have?

BTW – I’m not against the Z06 at all. In many ways (and in the UK probably to more people) it makes perfect sense.

I just thought I throw out an alternative option.

[300bhp/ton]

ian_uk1975 said:

JimexPL said:

You'll never get any of that money back from modifying the car though, unless all of the items are reversable and you have the free time to do so and sell on separately.

Agreed... a highly-modded C6 may also be a white elephant in terms of resale. Certainly, a stock Z06 would be far easier to sell and lose less in depreciation than a highly-modded C6.

Realistically, my decision is limited to sticking with my stock-ish C6, or trade-up to a Z06. Just not sure if the extra performance in the Z06 is worth the extra £15k and not sure if I'd miss the removable roof of the C6 (can't take if off very often, but it's nice to do when the sun's shining).

If you just want extra grunt now and again maybe have a look at nitrous oxide?

Google Wizards of Nos.

They are very good (and have a forum). You could get a very decent setup for around £1000-1500 with the potential of 125-150hp shot when you want it. Ok its not a Z06 but in terms of acceleration it'd make a big difference. Also the nitrous kit can be removed in under an hour and either sold on (for at least 50-70% of what you paid for it) or fitted to your next vehicle.

This way you are not highly modifying and only spending 10% of the cost to get similar acceleration.

[Tom74]

Test drove a C6, albeit an LS2, and thought it was great, walked into the showroom after and saw the Z06 and that was the car I bought.

Its faster and more techy/racecar linked which sold it for me, I don't really care about wind in my hair so the removeable roof is not an issue for me. I guess it just depends on how you drive smile

Oh and to the suggestion of remote turbos....you know they mount these at the rear of the car? Lag anyone?

[ian_uk1975]

Tom74 said:

Test drove a C6, albeit an LS2, and thought it was great, walked into the showroom after and saw the Z06 and that was the car I bought.

Its faster and more techy/racecar linked which sold it for me, I don't really care about wind in my hair so the removeable roof is not an issue for me. I guess it just depends on how you drive smile

Oh and to the suggestion of remote turbos....you know they mount these at the rear of the car? Lag anyone?

How would you say the LS2 C6 (same as mine) compared in a straight line to the Z06?

[Rob LM]

I think having the extra bhp would just be more frustrating sitting in the long streams of bumper to bumper traffic

[G4HKS]

It isn't, believe me.....