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DOHC and SOHC SBC and SBF articles


datsun40146

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I was looking over the great expanse of the inter-web and came across some information that I thought you guys would like to read. These short books are scanned on the webpage and cover what Buick and Chevy did with experimental engine designs in the 70's. We are talking about over head cams, aluminum blocks and heads, fuel injection the works. They are a good read check them out!

 

http://www.cadvision.com/blanchas/54pontiac/BuickEngines.html

 

http://www.cadvision.com/blanchas/54pontiac/ChevyEngines.html

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Whoaaaa...

 

It is neat to see the brand names that we all know today featured so prominently in a magazine four decades old.

 

One thing that relly does bother me is that none of this engineering has ever been produced for the engines these guys were tinkering with(the same engines we all like to play with today).

 

For God's sake, The new Corvettes still have only the most basic implementations of these old school ideas.

 

It seems to me that if we have a member here that can create a dual overhead cam head for the L-series Datsun engines...

...with none of the foundry and developement tools that the major US car makers have to work with...

... What the 4uck have the people in Detroit been doing all these years. They have obviously NOT designed any engines since the 1950s.

 

Ohh.. I see.. They have been hiding under their half century old drafting tables while the rest of the world moved on without them.

 

Simply disgusting....

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That was a great read, thanks for sharing!

 

Bjhines, what you wrote is 100% true. Fortunately though, the US car producers began applying the today's technology to the new models - just a little bit of twitching resulted in fabulous cars like the C6 Z06 and the ZR1...

 

By the way, double overhead cams were introduced in America as early as in 1913 by Peugeot...

 

If I remember correctly, there were actually several heads available for the Ford Flathead. There were the Ardun overhead valve heads, and numerous SOHC and DOHC conversions, all left in the prototype stage. I imagine they would be hot sellers today if they had been produced back in the day.

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I think the American companies just found it more economical to expand the displacement rather than change valve designs. Nothing wrong with that. Its cheaper and easier to upgrade. If they are making 400-500 hp right now, what benefit are they going to see by going DOHC? Broader power band probably, but is it really worth it? I personally appreciate the low weight and compact dimensions of the OHV setups... not that I wouldn't consider DOHC in a heart beat. Just saying that neither route is better for a production car, they are just different.

 

Also, remember the Corvette ZR-1's in the early 1990's... Aluminum block SBC with DOHC heads. Its not that the technology isn't there... they just choose not to use it, which makes sense considering it isn't exactly necessary. I understand why one would go either way.

 

EDIT: Also I think it is interesting to note that they refer to the 3.6L Cadillac V6 as "High Feature". That acknowledges the fact that the DOHC setup is indeed a feature. Not knocking it at all, it IS superior for power production. It is not necessary though, when you are not displacement limited. Thus it is a feature, an option.

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Though the american companies might be "behind the times" by many people's standards I don't think they ever STOPPED evolving, and I think that's key. A company should always move forward, and if there's a fuel crisis and they need to make something economical, imrpove what you have, don't restrict it.

 

We're seeing the most efficiant motors of all shapes, sizes, and types this day in age.

 

The chevy LS series continues to prove that the OHV setup has life left in it yet.

 

Ford's mod motors have taken new height for the DOHC V8 in the Ford GT and GT500 (with several 1000+ wheel HP GT cars on stock longblocks).

 

Dodge has a funtioning cylinder disabling system that's actually working reliable (been done in the past, but never well from what I've been told, seen, and read).

 

To me this looks to be the brightest time ever for engine technology, and I don't see the americans as being slouches in all of it. Not leaders, but definately not slouches. Though I do find it funny when people talk about the "super technologically advnaced japanese engines" and I kinda giggle. I don't expect them to know that ford had a DOHC engine engineered and produced for nascar, and also even saw a small production run. I shouldn't expect them to know that there were several experiments between the big three with technologies they now call "high tech".

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We have to keep in mind that the more advanced valve-trains and the greater HP/ci also add up to more efficient engines.

 

The foriegn manufacturers have been producing affordable, advanced designs for decades. They are ahead of the efficiency curve by miles over American post WW2 technology.

 

It is true that the new Corvettes manage impressive HP numbers and definitely turn heads with performance. But the OHV design just keeps throwing more cubic inches at the problems caused by lack of sophistication.

 

The gas shortages in the 1970s should have been the wake up call in Detroit(It was for everyone else). Yet nearly 4 decades later they still haven't gotten the memo. Do they really think that 7liters, or 8 liters, or 12 liters displacement is going to keep up with the rest of the world's designs...???? Forget it. They have their heads stuck in the sand and will continue to do so until the day they finally close up shop.

 

It is sad to think that people of the future will see that the defining innovations made by Detroit were accomplished generations ago. They just coasted on the work of their forefathers until the day they ceased to exist.

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I still don't see the LS motors as that archaic. People with LS swaps here tend to have:

 

More HP than most

Cleaner swap due to size

Better MPG than most

 

Honestly here, how many NA engines are getting 400+ wheel hp and still able to manage solid consistant high 20mpg maybe even low 30mpg ranges? The SR guys can, but they're turbo'ed so it's not a fair comparison.

 

I doubt a 400 wheel HP VK56 would get 30mpg in a z. But maybe I'm wrong.

 

Another HUGE thing to consider is that smaller displacement motors tend to be a lot more expensive to build, and the american companies are having a very tough time competing with the japanese and koreans for price, and can't compete with the germans in quality. Maybe we shouldn't assume they don't want to give us more advanced designed, but maybe they simply can't due to their situation.

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I'm sorry for getting too political. I am just frustrated with the situation.

 

Economy aside, The SBC is a marvelously small package for a whole lot of displacement.

I am building a JTR/SBC Hybrid 240Z. I looked at the other options...

Cost for performance in a package that balances My 240Z nearly perfectly is hard to beat.

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