big engine and nothing else

[Guibo]

I'm not sure of the marketshare of V8's, but it is probably much more prevalent here than anywhere else. As a general trend, trucks and SUV's probably sell more than anything else.

Yes, the Northstar 32-valve is still available. That is the workhorse of Cadillac's upper level cars (Seville, DeVille). The CTS-V, though, will have a version of the LS6.

[Nildo]

To answer Mkielbasa's question:
1. 1880's single 'automatic' valve operated by spring/vacuum forces (effective for 1 cylinder and 300 or so rpm). Seperate cam shaft was included to mechanically close the exhaust valve on every second revolution.
2. 1890's-1900's 2 valve design dropped pressure too much with vacuum operated valves, side valve designed with cam using followers to control valves directly. Valves opened upwards, because they were beside, not above the engine, hence 'side valve'.
3. More efficient and more powerful OHV configuration was then designed. Creating a different combustion chamber shape increased compression by removed need for compression reducing valve chambers. These motors began volume selling in 1930's.
In many 'modern' V8's the cam is still mounted in the centre of the V so that the pushrods can transfer motion to both the rockers and the valves of both heads (one on each side of the engine).
4. DOHC was first used in a 1912 Peugeot GP race car, which was victorious in the French Grand Prix.

These days it is possible to disguise many of the disadvantages of OHV design engines (mainly by using large capacity-their problems would be very obvious in a 2 litre motor, which is why we never see that-hence the HP/L argument on this page) but OHC design is fundamentally more efficient, provided it is correctly designed. It is, as also stated on this page, heavier than the equivalent OHV arrangement, but the actual difference is not as great as has been suggested here.

Lastly, can anyone explain how 'Vette/16 is going to use VVT? I dont get how it would work, since their can be no cam 'overlap' and using one cam would not be very effective. Anybody?

[BPx]

Originally posted by henk4
If you compare the output of these two engines you will notice that the LS6 has 36% more displacement.
The LS06 (2002 spec) pumps out 405 BHP at 6000 revs, the Audi does 340 at 6500 revs.
Torque of the LS6 is 400 lb/ft at 4800 revs, the Audi has 317 at a comfortable 3500 revs.
If for sake of the argument we increase the Audi figures by 36% to make up for the displacement difference it would produce about 460 BHP and 430 lb/ft of torque. May be people will differ in opinion here but it looks like there is something to be gained in applying modern technology.
I have not checked the weight of the engine. Motorhead knows all about Audi's so he might come up with the correct figure.

The thing is though, the LS6 can easily produce more power. It's not like they are only limited at that amount. If GM wanted to, they could probably put a smaller V8 into the Corvette, but they probably want to keep with tradition and leave a 5.7L / 350ci (even though it's more like 346ci now) engine in there.
The LS6 was designed to make it's power higher up than the LT1, that's why it has to rev so high (which isn't really TOO high) to make it's peak. Although peaks don't mean as much as the powerband itself... Should check some dynos between the two engines and see how they look.

[crisis]

If the Corvette is going to have the GenIV motor then it is because that motor will run two cams with pushrods. The cams will be housed in the V and run collapsible lifters that will enable the car to operate on 4 cylinders in cruise for economy and operate on all 8 under acceleration. So much for "low tech" pushrod motors. Thats real innovation.

[henk4]

This is getting interesting. First, Nildo thanks for the historic update, which, if correct, shows that (D)OHC engines came slightly later than OHV engines. I new about the Peugeot, so I was wondering what OHC engine came prior to that. Wasn't it also the first 4 valve head?
Last night I found some specs about the BMW 745I engine, which has slightly more displacement than the Audi, but has about the same output. It does operate with variable valve timing so probably the Audi also. They both have a 4 valve head.
I am really curious to see how this twin cam arrangement in the new Vette is going to work. Any design pictures available of the Caddy V16?
As far as the possibility of shutting off 4 cylinders is concerned, I thought that the Northstar engine already offered that option, and I have a hunch that some Mercedes engines can do the same.
As far as OHV for small engines is concerned, it was common on most engines produced during the sixties and the seventies and only when the cam chain was replaced by a cam belt (invention of German manufacturer Glas, later to be absorbed by BMW) it became more feasible to apply OHC. Still there were some very high revving (over 9000 rpm) OHV engines used in racing touring cars, such as the FiatAbarth, the Ford Kent engine and the BMC Cooper engine.
The cam belt of my own car will have to be routinely replaced every 160,000 km, (15,000 km from now) which is going to be arelatively costly affair ($600 or thereabouts) so I sympathise with the argument that OHV engines are more simple to maintain.
Finally to add another element to the discussion, I think the recent success of the Ducati 4 cylinder desmo engine in the MotoGP class, already beating the Honda 5 cylinder in shear power, might trigger some engine designers in applying the same principle for cars. (after the aborted Mercedes experiments from the fifties).

[PyroManiac]

http://www.gminsidenews.com/xv82.htm
http://www.gminsidenews.com/PV__007753__.jpg
http://www.gminsidenews.com/PV__007754__.jpg

A DFI 24 valve 4.3L Pushrod (OHV) V8 with 300hp, dual oil pumps, cam-phasing, and DoD thats the length of a 4 cylinder?

You better believe it.

[henk4]

Originally posted by PyroManiac
http://www.gminsidenews.com/xv82.htm
http://www.gminsidenews.com/PV__007753__.jpg
http://www.gminsidenews.com/PV__007754__.jpg

A DFI 24 valve 4.3L Pushrod (OHV) V8 with 300hp, dual oil pumps, cam-phasing, and DoD thats the length of a 4 cylinder?

You better believe it.

Thank you for providing this informative link. It really looks an impressive piece of new technology. Interestingly this engine is very comparable in size to the Audi V8, (still with slightly more displacement) but is still down on both BHP and torque levels.
Somehow I have a feeling that GM wants to maintain with OHV engines at all costs, suiting the demand of the american market.

Its main advantage is obviously its compact size, I don't think an audi V8 could be squeezed into the Signum. On the other hand, given the average size of US build cars, what is the real need of a small size, (apart from the lower weight). Maybe GM is targeting the European market after all?

[PyroManiac]

Originally posted by henk4
Maybe GM is targeting the European market after all?

Ding ding ding. Correct.
GM is not keeping the pushrod engine alive for the sake of marketing. The average car buyer couldn't give two shits whether or not it has OHC or Pushrods, then again, the average car buyer doesn't know what OHC is. Definitely not marketing.
If you were to compare the size of the Audi V8 to the XV8, the Audi V8 will make the XV8 look like a little 6 cylinder, yet the XV8 has the weight advantage. Also, may I add, power isn't everything, especially in passenger cars, and that hp/l is still irrelevent. But if you would like to continue with the power argument, I'll just argue that the Audi V8 isn't effectively using its size and that the XV8 is larger in displacement, yet significantly smaller in dimension.

[guyt_x]

but what does it all mean basil?

[henk4]

Originally posted by PyroManiac
Ding ding ding. Correct.
GM is not keeping the pushrod engine alive for the sake of marketing. The average car buyer couldn't give two shits whether or not it has OHC or Pushrods, then again, the average car buyer doesn't know what OHC is. Definitely not marketing.
If you were to compare the size of the Audi V8 to the XV8, the Audi V8 will make the XV8 look like a little 6 cylinder, yet the XV8 has the weight advantage. Also, may I add, power isn't everything, especially in passenger cars, and that hp/l is still irrelevent. But if you would like to continue with the power argument, I'll just argue that the Audi V8 isn't effectively using its size and that the XV8 is larger in displacement, yet significantly smaller in dimension.

I think you have to realise that selling a V8 in Europe is definitely something else as selling one in the USA. In Europe this is a premium market, only served by top brands, and in this market people know very well about the prestige of DOHC. It would be a hard nut to crack to convince the up-market customer. GM branches such as opel and vauxhall have always played a minor role in this market segments. Opel tried to introduce a Chevy V8 in the Opel Diplomat in the sixties, but this model did not live long and the Omega and Carlton are about to be replaced by the Signum, a stretched version of the Vectra. GM is just considered to be bread and butter.

Is there somebody out there who knows the exact dimensions of the Audi engine? I know the A8 is very light, but that is mainly due to its generous aluminium content.

You may have misunderstood me in your reference to BHP/litre. I am not so keen on absolute power, torque is what I am interested in because that makes a car driveable. This is why diesel technology is currently dominating the European market, combining high fuel efficiency with very driveable cars, certainly in densely populated areas where traffic jams are the order of the day. You may want to check out the Audi A8Tdi on this site to get some more info on the current status of diesel technology. I feel that also because of the predominance of diesel engined car sales in Europe (also in the topmarket sector) even this new GM gem will play a very minor role in sales over here.

May I finally kindly ask you to refrain from childish things like "ding etc" as if I have heard the ringing of the bell. I consider this to be a thread for grown-ups which should be reflected in the level of the contributions.

[henk4]

Originally posted by guyt_x
but what does it all mean basil?

this thread is not about Fawlty Towers.

[guyt_x]

please relax

this is a forum where people disuss cars...

all we do is argue about cars, it is juvinile but its fun.

so have a beer and relax henk4

[henk4]

Originally posted by guyt_x
please relax

this is a forum where people disuss cars...

all we do is argue about cars, it is juvinile but its fun.

so have a beer and relax henk4

As it just past nine in the morning I am having a very relaxed cup of tea. Are you actually old enough to know what juvenile means?
I hope you have noticed that it is possible to talk about American cars without having to mention that they suck of for that matter that anything american sucks.

[PyroManiac]

Originally posted by henk4

May I finally kindly ask you to refrain from childish things like "ding etc" as if I have heard the ringing of the bell. I consider this to be a thread for grown-ups which should be reflected in the level of the contributions.

Sure. But if you consider this a thread for grown-ups, what would be considered childish? The creator of the thread is certainly not "grown-up" especially with his mentality.

Originally posted by henk4

You may have misunderstood me in your reference to BHP/litre. I am not so keen on absolute power, torque is what I am interested in because that makes a car driveable. This is why diesel technology is currently dominating the European market, combining high fuel efficiency with very driveable cars, certainly in densely populated areas where traffic jams are the order of the day. You may want to check out the Audi A8Tdi on this site to get some more info on the current status of diesel technology. I feel that also because of the predominance of diesel engined car sales in Europe (also in the topmarket sector) even this new GM gem will play a very minor role in sales over here.

I am totally aware of diesel technology. GM, Ford, and Dodge/Cummins HD diesel truck engines have monstrous amounts of low-end torque, which is needed in HD trucks. The reason why diesels are not dominating sales in America as they are in Europe is because of the high sulfur content in American diesel fuel, and the "loud and dirty" stereotype leftover from the 80s. But I have read that we will soon be importing European diesel in the coming years.

[PyroManiac]

Originally posted by henk4
I think you have to realise that selling a V8 in Europe is definitely something else as selling one in the USA. In Europe this is a premium market, only served by top brands, and in this market people know very well about the prestige of DOHC. It would be a hard nut to crack to convince the up-market customer. GM branches such as opel and vauxhall have always played a minor role in this market segments. Opel tried to introduce a Chevy V8 in the Opel Diplomat in the sixties, but this model did not live long and the Omega and Carlton are about to be replaced by the Signum, a stretched version of the Vectra. GM is just considered to be bread and butter.

I see what you're saying, but I question the "prestige of DOHC," sure, it may be used in Formula 1, but then again its also used in "dime-a-dozen" econo cars. Thats not to say Pushrods are better though, they've been used in "dime-a-dozen" econo cars too.

Electromagnetic valves are where its at (or where it will be).