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dwightlooi

A case for the Pushrod Engine:

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I already have the idea for the commercials in my head....

I was saying it sarcastically. Given how marketing operations are performed in the world

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buy the name "Simplicity"

That used to be a lawn mower brand, I think

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Yes it was.

Good thing we do not have many people who remember that. No need to confuse poor lemming buyers. :P

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I still prefer 'InBlockCam' (as the alternative denominator to 'DoubleOverHeadCam'), but I don't believe either has any resonance with the mass market consumer.

Edited by balthazar

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I still prefer 'InBlockCam' (as the alternative denominator to 'DoubleOverHeadCam'), but I don't believe either has any resonance with the mass market consumer.

IBC like the root beer..:) Problem is, the mass market consumer has no idea what a 'block' or 'cam' is.

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I know; we agree here. I don't think marketing a IBC motor on that principal is the way to go, even if it is the catalyst to a list of improved characteristics.

It should be marketed on the advantages, not on the cam location.

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I know; we agree here. I don't think marketing a IBC motor on that principal is the way to go, even if it is the catalyst to a list of improved characteristics.

It should be marketed on the advantages, not on the cam location.

Yes..something nebulous like Mazda's 'Skyactiv' could work...tout the efficiency and power of the engines without getting into technical specifics. 'Greenpower'.

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How about "Shared Unified Cam" -- SUCK? LOL

Really, I don;t the the moniker matters. At the end of the day, if the Horspower, Torque and MPG numbers are superior that is good enough for gear heads. For non-gear heads probably just the MPG numbers and the test drive experience.

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"Integrated cam" - "Unlike our competitors, our engines feature an integrated cam system, this allows us to give you more engine with lower weight, better fuel economy, and better reliability without sacrificing (cue video of Camaro, CTS-V, or Corvette pealing out and driving off).... any performance."

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"Integrated cam" - "Unlike our competitors, our engines feature an integrated cam system, this allows us to give you more engine with lower weight, better fuel economy, and better reliability without sacrificing (cue video of Camaro, CTS-V, or Corvette pealing out and driving off).... any performance."

Sounds good....i-Cam Technology FTW!

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Use clips from this video:

"Some auto makers like to use all sorts of complicated tricks to try and squeeze extra power out of their little engines. With our integrated cam system, you get more engine, better fuel economy, and better reliability with out all of the (cue clip of some V6 blowing a timing belt) .... fuss. Integrated Cam, just part of the Simplicity System by General Motors."

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"Some of our competitors try to hide their small engines by adding extra complexity like DOHC and turbo chargers.... Our integrated cam system gives you more fuel economy, better performance, with lower weight all in a bigger engine... because of course... (cue a Silverado ripping out a stump or something).... size matters. Integrated Cam, just part of the Simplicity System by General Motors"

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"Integrated Cam engines--Bigger on the inside, smaller on the outside and lighter than our competitors V8s.."

Edited by Cubical-aka-Moltar

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Guest Dewey Vicknair
QUOTE(91z4me @ Feb 16 2007, 01:25 PM) 252289[/snapback]
You do know that there are 4 valve OHV engines in produciton, right? The Duramax is probably the best example.

The Duramax head is not particularly good for airflow (the intake and exhaust ports run into one valve first then the other since the valves are tandem not side by side). Also, it is also possible only in a diesel because the Diesel engine uses a a completely flat combustion chamber roof and all four valves are parallel. The approach -- using one rocker to push down on two parallel valves connected by a bridge is not feasible for a gasoline engine.

The Honda CX500 engine used 4 valves per cylinder and a pushrod-and-rocker valvetrain. It also revved safely to 13,000 rpm.

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Well, it is "easier" to make a OHC engine rev to stratospheric RPMs compared to a pushrod engine. The elimination of the rod mass and the individually smaller valves which are lighter run into valve float at greater opening and closing speeds given the same spring tension. The CX500 also has 250cc cylinders (roughly comaprable to what you'll find in a 1.0 liter 4-cylinder engine. Smaller cylinders mean smaller valves and also generally lower piston speeds (they tend to have shorter strokes as well as smaller bores).

Still, the point is that the kind of engine speeds above which DOHC 4-valve heads really shine are not really employed in many, if not most, of today's DOHC powerplants. You really need to get to about 6000 rpm before you see any tangible benefits, 7000 rpm before it is significant and 8000 rpm before it is really worth it. With a few exceptions -- Such as Honda's B-series or F-series, Toyota's 2ZZ-GE, GM's LF1/LFX, BMW's S65, etc. -- most of today's DOHC 4-valve engines are DOHC 4-valve for no good reason!

For example, Toyota's 2.5L DOHC I-4 used in anything from Camrys to Scions makes 178 bhp @ 6000 rpm and 170 lb-ft @ 4100 rpm. That's 71.2 bhp/L. Their mainstream 3.5 V6 makes 268 bhp @ 6200 rpm and 248 lb-ft @ 4700 rpm. That's 76.6 hp/L. You can achieve that kind of numbers with Pushrod or SOHC heads, along with 2-valve per cylinder. The LT1 V8 is at 460 bhp @ 6000 rpm with 465 lb-ft @ 4,600 rpm. That's 74.2 bhp/L. Even the Ecotec3 6.2L pushrod V8 used in Silverado trucks makes 420 bhp @ 5600 rpm with 460 lb-ft @ 4100 rpm. That's a not so shabby 67.7 bhp/L.

If you implement a DOHC 4-valve setup, it should at least rev to 7000 rpm and make it's peak power at close to 7000 rpm (like GM's 90 bhp/L LFX V6) or preferrably do what Honda did 22 years ago with the B16A 1.6L which makes 160 bhp @ 7600 rpm with 111 lb-ft @ 7000 rpm and a 8200 rpm rev limit. Anything less and a DOHC valvetrain is simply not worth the weight, the bulk, the cost, the complexity and -- if you don't care about any of the above -- the extra parasitic drag and fuel economy penalty. The problem with all the extra high revving designs is that they have emissions, tractability and/or efficiency issues down low which really takes a cam switching valve train to properly address. Over the years manufacturers had, instead, simply watered down their DOHC mills by reducing passage sizes, valve lift, valve overlap, etc. to make them civil and efficient at typical driving conditions. In doing so, they had also made the entire design choice moot. But, by now, they are so used to it that they carried on the tradition anyhow.

Edited by dwightlooi

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Use clips from this video:

"Some auto makers like to use all sorts of complicated tricks to try and squeeze extra power out of their little engines. With our integrated cam system, you get more engine, better fuel economy, and better reliability with out all of the (cue clip of some V6 blowing a timing belt) .... fuss. Integrated Cam, just part of the Simplicity System by General Motors."

How about...

Vrrrrmmmmhhhhh.... (Corvette Stingray Cut Scene)

0-60 mph 3.8 secs.

30 mpg (EPA Hwy MPG)

Single Integrated Cam

Because simple is simply better

Edited by dwightlooi

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