GM plans to transform small-block V8

[irlewy86]

Pity GM put all their eggs in the Volt basket and the next line of V8's will be developed on using money psyphoned out of other business units.

Take a look at what Lutz is saying, either the small blocks getting a new block or its getting new heads. But he cant develop a whole engine at once.

[4Vman]

"Grandads axe" was a very apt description...

[Bad Bird]

Sorry, wrong thread...

[Wally]

Originally Posted by Scotty85

........ I wont speculate how OHC is better than Pushrods, since I really don't have any factual information, but there is obviously a very good reason since nearly all engine manufacturers are moving onto OHC.

The generally accepted notions by design engineers are:

pushrods have a heavy valve train, which limits reliable rpm;
pushrod valve trains flex, limiting aggressive grinds;
the tradeoff is to increase capacity, resulting in fuel economy loss when on power;
pushrod engines are cheaper to make than complex DOHC castings.

[sleekism]

I thought GM had already developed VVT pushrod engines as well as ones with 3 valve heads. I remember the LS7 was originally supposed to have a 3 valve head.

Also doesn't BMW and Moto Guzzi already succesfully run motorcycle engines with 4 valves per head?

[Road_Warrior]

Originally Posted by outback_ute

Surely the Gen III was new block and heads at the same time?

Third generation small block was a clean sheet design, yeah.

Also, I would take whatever Bob kLutz says with a pinch of crap.

[boris]

Also doesn't BMW and Moto Guzzi already succesfully run motorcycle engines with 4 valves per head?[/QUOTE]


As do most other motorcycle companies, for a long time!

[mcnews]

And Yamaha ran five valve head for nigh on 20 years. And then of course there was Honda with an eight valve per cylinder design...

[burnz]

Originally Posted by outback_ute

Are you sure? Not aware of any engines pre-1900 that didn't use pushrods.

otto engine 1876 i think, OHC
1912 for a 4V DOHC.

1949 oldsmobile OHV
not shure what year with the ford flathead tho.

[Bud Bud]

Originally Posted by burnz

otto engine 1876 i think, OHC
1912 for a 4V DOHC.

1949 oldsmobile OHV
not shure what year with the ford flathead tho.

Why do people think that overhead cams are recently new???

[xbgs351]

Originally Posted by chevypower

Well Ford is moving back to 2v on the 6.2. It takes more energy to drive 2 cams than one, so having 2 large valves on that engine sounds good to me. Maybe this is why Ford says the 5.0 will get similar fuel Econ to the 5.4. But when talking about the 6.2, Ford says it will get better fuel econ than the 5.4.
I think the most reliable way to drive a cam is with a chain. For efficiency? Maybe pushrod. I kind of go with chain for reliability cos I bet I'm one of very few people in the world that has thrown a rod and broken a timing belt on the same night in two different cars obviously. They were both Holdens too!

Don't you mean 4 camshafts?

Besides it will still take less energy to turn 4 camshafts in a OHC engine than one in a pushrod engine. The reasons for this are:
-A OHC Bucket system has no lateral movement, unlike a rockers on a valve tip of a pushrod motor.
-A pushrod motor has friction at the lifter, both ends of the push rod and at the rocker bearings.
-A pushrod motor requires far higher valve spring rates to control the heavier valves, and greater lifts.

[olds]

The future doesn't involve 8 cyls

[Wally]

Originally Posted by burnz

otto engine 1876 i think, OHC
1912 for a 4V DOHC.

1949 oldsmobile OHV
not shure what year with the ford flathead tho.

Wasn't the first production OHV by Buick in 1902? Before that, side valve engines were the go.

[Jeddak]

Over head cams? multi valve?
try 1929 with Deusenberg's 420cubic inch straight eight
twin-cam,4 valves per cylinder,and twin spark,
and if that's not enough ,this engine was available with supercharging as well

as King Solomon said "there is nothing new under the sun"( sorry Toyota ....not!)

[xbgs351]

Originally Posted by olds

The future doesn't involve 8 cyls

12 or 16?

[Chilliman]

At this late stage in the game I can't see GM going in a totally different direction to the current push-rod small block architecture - they don't have the cash anyway. Isn't the new V8 that this article is alluding to the GEN V 5.5Litre OHV V8 with direct injection? I think the variable timing statement maybe a bit of a furphy or something that won't be available until much later. GEN V is supposed to be production ready by 2012?

[olds]

Originally Posted by xbgs351

12 or 16?

Electric

[ebxr8240]

Isn't the block they use in V8 series a twin cam engine as well ???
They will make a new V8 when Daewoo make one ???

[Ryan]

Originally Posted by Bud Bud

Why do people think that overhead cams are recently new???

I guess, because alot of manufacturers didn't adopt it until later on.

[mickyyyy]

Pushrod engines sound better and are so easy to work on and last forever. throw on a Direct injection system to make them more eco friendly and away u go again. Only OHC engines i like are ford inline 6, Barra & toyota 1JZ & 2JZ.

[CobraJet351]

The future doesn't involve 8 cyls

My future involves lots of them

[outback_ute]

Originally Posted by burnz

otto engine 1876 i think, OHC
1912 for a 4V DOHC.

1949 oldsmobile OHV
not shure what year with the ford flathead tho.

Looking at the video of the Otto engines on http://en.wikipedia.org/wiki/Otto_engine the cams are on the shaft running beside the cylinder.

From what I can find with a quick search on OHV - a 1886 Daimler patent for an engine included an ohv exhaust valve. 1902 David Dunbar Buick developed and engine with both valves ohv. 1904 Lanchester cars with ohv sold commercially. Even in the US there were plenty of ohv used prior to the Olds V8 - but in manufacturers no longer in existence hence lack of info on Wikipedia. From a practical point of view the ohv had to be invented before you could have an ohc!

More relevant to the topic, when looking at that I came across the CamInCam system used on the Viper V10 which could be further developed to give TiVCT, and refers to GM having it already - http://www.sae.org/automag/technewsl...ertrain/04.htm

[Saraco]

Originally Posted by Wally

The generally accepted notions by design engineers are:

pushrods have a heavy valve train, which limits reliable rpm;
pushrod valve trains flex, limiting aggressive grinds;
the tradeoff is to increase capacity, resulting in fuel economy loss when on power;
pushrod engines are cheaper to make than complex DOHC castings.

Pushrods are limited for reliability at high rpm eh?! Please explain to me why NASCAR engines pull constant 9500 rpm for 500 mile races? That is also with restrictor plates on. Who knows what these engines will be capable of without restrictions.P.S. Take the time to look at these new PUSHROD NASCAR engines. They really are state of the art! I keep on saying, because an engine has pushrods,it does NOT make it redundant.

[4Vman]

Originally Posted by svov88

Pushrods are limited for reliability at high rpm eh?! Please explain to me why NASCAR engines pull constant 9500 rpm for 500 mile races? That is also with restrictor plates on. Who knows what these engines will be capable of without restrictions.P.S. Take the time to look at these new PUSHROD NASCAR engines. They really are state of the art! I keep on saying, because an engine has pushrods,it does NOT make it redundant.

When was the last time you saw a nascar spec engine in a brand new regular production car?

[Saraco]

I'm Talking About High Rpm Reliability, Not About Prodution Cars.

[4Vman]

Originally Posted by svov88

I'm Talking About High Rpm Reliability, Not About Prodution Cars.

He was talking about production cars, not race engines....

[Saraco]

Do modified production engines count? Are you a GT ENTHUSIAST 4V MAN!

[Wally]

Originally Posted by svov88

Pushrods are limited for reliability at high rpm eh?! Please explain to me why NASCAR engines pull constant 9500 rpm for 500 mile races? That is also with restrictor plates on. Who knows what these engines will be capable of without restrictions.P.S. Take the time to look at these new PUSHROD NASCAR engines. They really are state of the art! I keep on saying, because an engine has pushrods,it does NOT make it redundant.

Why are you on your high horse? I don't have a problem with pushrods, you are just assuming I do. They have their place, but if you really want to crank an engine up them DOHC makes it easier in so many ways... it;s not black magic and it's not a conspiracy.

[smoo]

Originally Posted by Mr X

How many pushrod engines are currently in production around the world today I wonder?Not to sully in any way the legend of the small block Chev but its time it joined the 21st century.

You might wanna find out just how (in)efficient the internal combustion engine really is, then you might realise been on the dohc high horse/band wagon is a waste of time.

[burnz]

Originally Posted by outback_ute

Looking at the video of the Otto engines on http://en.wikipedia.org/wiki/Otto_engine the cams are on the shaft running beside the cylinder.

From what I can find with a quick search on OHV - a 1886 Daimler patent for an engine included an ohv exhaust valve. 1902 David Dunbar Buick developed and engine with both valves ohv. 1904 Lanchester cars with ohv sold commercially. Even in the US there were plenty of ohv used prior to the Olds V8 - but in manufacturers no longer in existence hence lack of info on Wikipedia. From a practical point of view the ohv had to be invented before you could have an ohc!

More relevant to the topic, when looking at that I came across the CamInCam system used on the Viper V10 which could be further developed to give TiVCT, and refers to GM having it already - http://www.sae.org/automag/technewsl...ertrain/04.htm

interesting little tidbit
http://www.motorera.com/history/hist03.htm
The T-head engine gave way to the L-head (also called the flat-head or side-valve) engine in which valves were placed on one side of the engine. The L-head dominated the scene for years. Ford used it on V8s until 1953. But waiting in the wings was another design, introduced in 1898 by Wilkinson Motor Car Co. -- an engine that had the camshaft and valves in the cylinder heads. You know it as the overhead-cam (OHC) or overhead-valve (OHV).