RE: New 'vette V8

[David87]

Oh yes! This, a GT-R or an F-Type? Hmm...

[RichardD]

E38Ross said:

Stuff

In fairness this is a road engine for a car that has emissions and economy considerations (like the Germanic saloon car) and as previously posted could add another 100+ bhp easily if you aren't bothered by these things.

Another way to compare - how much is a new 420bhp BMW engine by the way?

[Gizmoish]

E38Ross said:

Strange isn't it though. Sticking to high revving engines in Bmws just quickly

High revving engine - ph say it's too stressed, needs revving to get the best etc

BMW put a high torque turbo engine in M5 - ph say the high revving engine is better as it's more enjoyable when you want to hoon etc which is how it should be in a sports car

Corvette make a low down torque engine - ph say low down torque in a sports car is just what I want

Hourses fer corses, innit.

I think my dream garage would feature both an Exige S (buzzy and revvy) and a C6 ZR1 (all torque).

[CTE]

I was lucky enough to spend a week driving a C6 430HP recently in the states. Was not expecting too much, and a few details reagrding trim were a bit lightweight etc, but overall the cars were superb to drive, excellent handling, very comfortable, loads of grunt, and not too bad on fuel if driven reasonably. I`d be driving one now if they were available in right hand drive...I know you can get a conversion. Not razor sharp like a Lotus, but in the real world, excellent.

[P4ROT]

Call me a car snob, but in 2012 the words 'direct injection and variable valve timing' should not be in the same sentence as 'New tech'.

[Gixer]

chris116 said:

N63 is the comparison surely?

N63B44
4,395 cc (268 cu in)
408 PS (300 kW; 402 hp)@5500-6400
600 N·m (440 lb·ft)@1750-4500
7000 max rpm

Would prefer na over turbos myself.

I thought these BMW V8's were high revving? My 1990 vette V8 hits the limiter at 7650.

See all the usual comments have appeared. Fact is my average on the trip computer on the Z06 is higher than my mates focus ST. Who's gone back to using his Mustang cause the ST is so bad.

[RocketRabbit]

DonkeyApple said:

Interesting.
Re the 2v versus 4v arguement. These engines are built for torque and not power at high rpm as such, 2v is fundamentally superior to 4v.

Hahahahahahahahahahahahahahahahahahahahahahahahahahahahahahahahahahahahahahahaha!!!!!!!!!!!

There is no point in me quoting maths/physics here because that would wasted on you.

4 valves are better than 2 valves.

The higher the engine can rev, the lower the gearing on the gearbox you can have, the more ACTUAL torque you can have.

Engine torque is only meaningful to work out the combustion rate per cycle.

And 40mpg out of a Corvette?!

I have never managed to get 40mpg out of my Westfield which weighs 1/3 the amount and has an engine 1/3 the size!

[Gixer]

It must have a st engine or gearing then. Odd as you obviously know so much about it;)

[DonkeyApple]

RocketRabbit said:

Hahahahahahahahahahahahahahahahahahahahahahahahahahahahahahahahahahahahahahahaha!!!!!!!!!!!

There is no point in me quoting maths/physics here because that would wasted on you.

4 valves are better than 2 valves.

Silly boy.

[ViperDave]

RocketRabbit said:

Hahahahahahahahahahahahahahahahahahahahahahahahahahahahahahahahahahahahahahahaha!!!!!!!!!!!

There is no point in me quoting maths/physics here because that would wasted on you.

Mainly because it would be wrong judging by the rest of your post, please don't tell me your a teacher

RocketRabbit said:

4 valves are better than 2 valves.

Throw away statement, no better than the one you were complaining about, horses for different courses.

RocketRabbit said:

The higher the engine can rev, the lower the gearing on the gearbox you can have, the more ACTUAL torque you can have.

or you could just start with more torque in the first place and not have to rely on high revs and gearing

RocketRabbit said:

Engine torque is only meaningful to work out the combustion rate per cycle.

quite a bit of gibberish in this one and maybe my A level Physics and B.Eng were not in your universe but one would have thought engine torque to be fairly fundamental to the whole ability of it to perform work, ie the less you have of it the faster you have do do things to get anything done.

RocketRabbit said:

And 40mpg out of a Corvette?!

Well i have personally seen 34mpg out of my C5 corvette with an engine two generations older than this one.

RocketRabbit said:

I have never managed to get 40mpg out of my Westfield which weighs 1/3 the amount and has an engine 1/3 the size!

Different car, different engine, effectively different application, where is the relevance, if anything just goes to prove the big LS/LT engines to be way better than a tiny 4 banger. Don't forget the USA is very hot on emissions, so there is no chance Chevy are lying. if anything they will be conservative with both BHP, TQ and MPG so they don't get fined or hit with customer law suits.

Edited by ViperDave on Friday 26th October 17:58

[kambites]

Now put the steering wheel on the right side and sell the thing here.

[Pesty]

kambites said:

Now put the steering wheel on the right side and sell the thing here.

^^^^^^^^^^^^^^^^^x100000000

[Gixer]

Pesty said:

kambites said:

Now put the steering wheel on the right side and sell the thing here.

^^^^^^^^^^^^^^^^^x100000000

/\ no thx x - 10000000000

It's fine just how it is at the moment.

[E38Ross]

DonkeyApple said:

Interesting.

VVT has been used since 07 in the L92 in Escalades, Suburbans etc.

DoD/AFM in the L99 in Camarros with auto boxes.

Both deliver a little less output than the LS3.

I suspect that most of the gains in the Gen V will be coming from the new direct injection.

Re the 2v versus 4v arguement. These engines are built for torque and not power at high rpm as such, 2v is fundamentally superior to 4v.

2V engines don't give more torque than 4V engines generally.

Edited by E38Ross on Friday 26th October 17:50

[IdiotH]

A nice engine which if it went bang (which it wont), won't cost much more than £5k to replace.

So, how much was that M3 engine again?

[Pesty]

Gixer said:

/\ no thx x - 10000000000

It's fine just how it is at the moment.

Nobody says you had to buy one;)

Only thing stopping me is LHD. If these came over I imagine they would sell well which means plenty around second hand cheap

[mackie1]

Comparing it to the engine in the M3 is silly. Comparing it to the engine in the C63 makes more sense as they are much closer in ethos, and compared to that it stacks up quite well, especially since it's only 2 valves per cylinder. These engines in production cars are in a very mild state of tune too. Let it breath properly and I reckon you'd see 500bhp easy.

[DonkeyApple]

E38Ross said:

2V engines don't give more torque than 4V engines generally.

At low rpm they do. 2v is more efficient as there is less cross flow in the chamber and better dispersion.

4v comes into its own at higher rpm. It's why it works so well with a dohc set up than ohv.

VVT is used to replace the missing low down torque.

But these are Chevy engines and probably 90% of them are in trucks. When moving a fridge you want to sacrifice some bhp potential in exchange for superior low down torque. This is why a pushrod 2v is perfectly good and in some regards better. It has a lighter, simpler and very much cheaper top end.

In a sports car I'd prefer the European approach as I feel it gives a sportier driving feel using a dohc 4v. And even Ford have gone this way and are getting LS matching figures with a litre less of cc as a result.

[mackie1]

E38Ross said:

Now do torque per litre and see any difference.

M3 as 6.2/4=457lb ft and over 640bhp

If you made it rev to over 8000rpm it would make that power. But with more torque you need fewer revs. Making big engines rev high is expensive.

[Futuramic]

Quite looking forward to this as I've always liked Corvettes; hopefully they'll consider a 7 litre variant as well. Given current trends in America this will probably come coupled to a proper manual gearbox and won't need a noise generator!

For whoever mentioned new technology; as far as I know this application of VVT is unique in a pushrod engine owing to the complex engineering involved.

Would anyone else be able to clarify how it works? From my inexpert perusal of the diagram it looks as if the cam isn't solidly mounted to the timing wheel and there is a control unit on the other side. Preumably this will allow alteration of the cam timing in relation to the crank offering different duration profiles.

That is quite exciting as it differs from DOHC designs were the phasings are adjusted individually. In fact it's rather reminiscent of a certain Bavarian maker's system; rhymes with HANOS? Oh well Americans never got irony!

The really good bit, if I'm right, is that intake and exhaust timing will be altered in concert owing to the fact that they are controlled by the same cam.

Add to this that it appears to have funny tappets. It's possible that they could be used to alter the pushrod length dynamically thus increasong valve lift? Agaon this is quite exciting as it would offer a number of profiles rather than a two stage system like VTEC. Perhaps it could give a smooth idle and low emmissions for town driving?

Well that's my reading of the diagram. Does anyone know any better?

I like the fact that Chevy have kept the essence of the US V8 alive. Others would probably have gone down the quad OHC route, and eventually turbocharging and lopping cylinders off.