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I Still Like Pushrods, They're Still Viable

Engine tech, for those engines, products, and technologies of yesteryear.

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nicholastanguma
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I Still Like Pushrods, They're Still Viable

Post by nicholastanguma »

Fair warning: long post, maybe not for the faint of heart.

I'm a luddite, but not an unreasonable one. You can like what you like, that's cool with me...but it's not okay for you to try forcing your likes to be my likes, too. We can disagree agreeably. I think electric everything is blind ideology, you think carburetors are for neanderthals--we can still be 100 percent courteous to each other.

Technology always progresses, and therefore marketing must always progress commensurately. Or, when not commensurate in their progress, sometimes the tech or the market will helpfully nudge along whomever is being slow at the time.

I'm heavily involved in the vintage air cooled auto and moto cultures, old VWs and Porsches and Hondas and NSUs and Fiats and Triumphs and all of it, all the air cooled carbed stuff makes me happy all day long (vintage air cooled cars and bikes are a RELIGION here in California). So I still like pushrod engines. I don't dislike overhead cam engines at all, I like 'em just as much as pushies, it's just that in the vintage air cooled world pushrod tech tends to be more prevalent than overhead cam tech. Way more Porsche 914s out there than NSU TTs, for instance. Admittedly, in the moto segment the prevalence of vintage Japanese powerplants makes things a pretty even split, you can just as easily find an old Honda CG or BMW airhead as an old Honda CB or Suzuki Bandit.

Here in the real world, where there exist stoplights, stop signs, police enforcement, speed limits, pedestrians, speed bumps, pot holes, school zones, and just general consideration for other road users traveling at their own paces...having to rev an engine way up high to get into my power curve simply doesn't make sense. The real world is not a race track.

Marketing is sexy when the copy reads "redlines at 15,000 rpm" and "makes 200 hp at only 600cc size" and other such sexiness (all of which I do appreciate, as long as the engine is carbed and air cooled), but if you're not a professional racer on a dedicated race track this marketing copy and this technology are just jewelry.

A hot rodded pushrod boxer four connected to a five or six speed transaxle is more real world usable torque and horsepower than any sane motorist can use without maiming or killing himself or others on the road or trail. Many scoff that a hot rod pushrod boxer in a VW or Porsche is "only making 200hp," but with five or six gears to play with on trails and roads that aren't dedicated racing courses that 200hp is real world fun as long as the sun is shining.

A hot rodded Sportster or Bonneville mated to a five or six speed transmission is exactly the same.

Restomodding old autos and motos with weight reduction and frame bracing and modern suspension and modern carburetion and modern gearboxes and other such upgrades is wonderfully emotionally satisfying, while keeping the pushrod engine's lower-hp-but-more-useable-torque powerband in place for real world fun. Where are you safely going to rev over 9000rpm on public trails and streets?

Your CRF450 or 350Z makes way more peak hp than a restomodded Honda CG250 or VW Beetle, but you're not actually a pro racer and your vehicle's peak hp output doesn't actually make you a sexy beast. Your machine is not you and you are not your machine--you are still fat or bald or ugly or stupid or dull or poor or whatever no matter how sexy your machine is. A poser with a Kawasaki H2 is just as cringeworthy as a poser with a straight piped Harley-Davidson.

So I continually find myself burrowing deeper and deeper into the vintage pushrod lair. I very very very much enjoy track days! But I do not live on the track, either motocross or autocross. Back in the days when air cooled engines were still being mass produced in automobiles, most vehicles, auto and moto alike, had three or four speed transmissions. But today transmission technology allows us to use 5 or 6 speed gearboxes in any ratios we want, so the fact an air cooled pushrod engine can't usually rev to 9000 or higher rpm is no longer relevant.

Again, I absolutely endorse and enjoy overhead cam engines, especially of the air cooled variety, it's just that aside from vintage Japanese motorbikes, the use of pushrod tech is more prevalent in the air cooled world.

Anyone else find they still enjoy hot rodded old pushrod engines for real world fun? Anyone else found endless emotional satisfaction in restomodding something obsolete into something actually usable for real world trails and roads?
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Re: I Still Like Pushrods, They're Still Viable

Post by miniv8 »

Our future is less bright, if we ignore history.
We can not look back at the classics with the demands and ideas of modern MotoGP or Formula1, and snicker at the designs.
Its what got us here.

Soon enough, this whole forum, and the whole industry of the gofast concept and everyone in it, will be the steam engine to the jet engine.
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Re: I Still Like Pushrods, They're Still Viable

Post by MichaelThompson »

I feel you brother, only I’ll go you one step further. I don’t even like pushrods. I’m a side valve freak. Mainly a Flathead Ford V8 guy but I do love all those early side valve engines. Who doesn’t like the 308” Hudson six with “Twin H Power!”??

Now now fellas don’t kick rocks at me. I realize the V/E disadvantage I’m facing but understand the attraction here. I dig an engine that is capable of doing a job with the bare minimum of moving parts.

Another example of where I’m coming from is I’d much rather ride a slow motorcycle fast than ride a fast motorcycle slow. Only a very few talented people can wring all the performance out of today’s sport bikes. I’m not one of them.

Back to flatheads. As time progresses we get so impatient for the next new thing. I’m as guilty as anyone. If we think about it our physical bodies haven’t changed much since the dawn of the automotive world. But we have gotten used to the “extreme” in many ways. We are accelerating ourselves in unimaginable ways today. Anything from a modern steel roller coaster to a 10,000hp fuel car.

That’s ☝️almost irrelevant to an old pee on like me. Let me put it like this. In the 1920’s the kids were having just as much fun doubling the horsepower of their 20hp Model T’s and 40 horsepower Model A’s as we are now with 1000 horsepower “street cars”.

It’s progress and it must happen of course but at some point (after a few close calls or some broken bones) that a fella might say to himself, “hey I made it this far, why don’t I move the decimal point back a couple spots and revisit having fun the old fashioned way?”

I never had the means to go very fast so I found a way to have all the fun without breaking the bank. Don’t get me wrong in a lot of ways it would be easier to just sell off my hoard of Flathead stuff and buy a store bought performance car and go faster stock than I ever have in a Flathead Ford powered car. My next door neighbor has a 480 horsepower stock Mustang for gosh sakes.

Yes it would be easier but would it be more fun? I don’t think so.
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Re: I Still Like Pushrods, They're Still Viable

Post by PackardV8 »

Yes agree with all of the above. No, none of the above is new or novel . Those who ride, own, breed, race their horses, have been saying this for a hundred years.

As to pushrods, gotta give GM credit. When the entire automotive world went OHC, GM debuted the LS and took a crapload of criticism for being behind the curve. Today, the LS platform is the standard of our industry and a hundred are built for every one OHC. It's light, compact, efficient, easy to understand and inexpensive.
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Re: I Still Like Pushrods, They're Still Viable

Post by MichaelThompson »

PackardV8 wrote: Sat Apr 17, 2021 11:07 am Yes agree with all of the above. No, none of the above is new or novel . Those who ride, own, breed, race their horses, have been saying this for a hundred years.

As to pushrods, gotta give GM credit. When the entire automotive world went OHC, GM debuted the LS and took a crapload of criticism for being behind the curve. Today, the LS platform is the standard of our industry and a hundred are built for every one OHC. It's light, compact, efficient, easy to understand and inexpensive.
Yes and Chrysler stuck to the hemi concept as well. They have really made a difference for themselves by using a hemi like gasoline V8 and by capitalizing on the Cummins 6 banger diesel phenomenon.

Ford lost their way I think a little. Much like they did after the Flathead era. They could have simply built an OHV engine in the same envelope the Flathead V8 came in. The Y-block was a good deal more robust but it WAS NOT a cheap engine to build and it DID NOT fit in the same hole where a Flatty once sat very easily.

The 5.0 Ford engine of the 80’s and 90’s caused the LS motor more than anything I think. I believe for the first time since the sbc they (GM) saw their edge in popularity start to shrink if ever so slightly.

Meanwhile Ford was looking down the road at emissions etc. They concluded small bore longer stroke was the way to go. This produced an engine with unusually tall decks and cylinder heads. Sub-300” V8’s that were as large width wise as big blocks.

Of course the brilliant Coyote became the ultimate fruit of this detour from the norm. I also must add that only the Ford engines were never equipped with bandaid solutions like “displacement on demand” which is the Achilles heel on both the LS and Gen III hemi.
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Re: I Still Like Pushrods, They're Still Viable

Post by frnkeore »

Michael, I suppose you can blame ALL this "modern Tech" on Peugeot and it's Indy and Grand Prix cars of 1913 - 1919, with their 4 valve, DOHC engines.

It's said that all race engines copied that tech, from then on, including our own race engineer, Miller.

It is fairly simple. Valves (more than the FH per cyl) actuated by buckets, instead of the FH's "push rods" and a gear driven camshaft. They just made the mistake of putting the cam in the head, instead of the block. But, it worked out in the end.
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Re: I Still Like Pushrods, They're Still Viable

Post by Nikolas Ojala »

A pushrod V8 is still very compact, no matter how you turn the numbers. Measure outside dimensions and compare with the inside dimensions (engine displacement). Or someone would rather compare engine weight and power. I remember when the new and credible rumors about mid-engine Corvette arrived, I thought "probably they go DOHC all the way and that will be bye-bye for the old pushrod V8." But no, it is still the same compact pushrod engine. It has been pretty much the same since 1955. Yes there has been evolution during generations, but the basic concept is the same.
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Re: I Still Like Pushrods, They're Still Viable

Post by Ken_Parkman »

I do find it interesting that all 3 major North American manufactures tooled up for OHC V8 engines, and all 3 have gone back to pushrods. It simply is a better design in a V configuration, reduced parts count, compact, good power density, better packaging, lower hood line, better aerodynamics etc etc etc. Add that to the balance and power pulse advantages of a V8 and it becomes natures perfect engine; other than marketing in some circles. With an inline engine it is a different set of equations and there is a lot more logic in an OHC as the packaging is less of a trade off other than hood height.

It also obviously depends on the rules or taxes. If there is a specific output requirement pushrods are bad, but in a free market it should be the best design wins.

I remember an interview with a GM engineer as they were struggling with the marketing of the clearly superior LS replacing the Northstar in Cadillacs and how some perceive pushrods as low tech. Chrysler solved the marketing problem when they dumped the AMC designed excellent small OHC V8 by calling their new pushrod engine a Hemi.

The big problem with a pushrod V8 with todays technology is it is simply not necessary. With todays specific output there is little need for the displacement advantage of a pushrod V8 gives you. The 4 valve OHC technology clearly does give better low end power and a better operating rpm range, and specific outputs of approaching 1 1/2 hp per cu in is quite normal NA while still giving good driving characteristics. That is what is obsoleting our pushrod V8s - they are too good!
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Re: I Still Like Pushrods, They're Still Viable

Post by MichaelThompson »

frnkeore wrote: Sun Apr 18, 2021 3:58 am Michael, I suppose you can blame ALL this "modern Tech" on Peugeot and it's Indy and Grand Prix cars of 1913 - 1919, with their 4 valve, DOHC engines.

It's said that all race engines copied that tech, from then on, including our own race engineer, Miller.

It is fairly simple. Valves (more than the FH per cyl) actuated by buckets, instead of the FH's "push rods" and a gear driven camshaft. They just made the mistake of putting the cam in the head, instead of the block. But, it worked out in the end.
I agree 100%, DOHC’s are nothing new. In fact I just received a wonderful book about Harry Miller because I’m fascinated with his fertile mechanical mind. You’re right too those early Miller’s were inspired by the Peugeot race engines.

I don’t know too much about the challenges of moving and controlling multi valve, valve gear with a camshaft in the block. I realize diesels get away with this but they sign off at maybe 4500 rpm?

I think the best OHC designs were like the ones employed by early aircraft engines with their bevel geared driveshafts. These are no compromise designs if done properly but are expensive to produce.

The beauty of pushrod V8’s is you probably get 3/4 of the performance from an equal displacement for 1/2 the cost.
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Re: I Still Like Pushrods, They're Still Viable

Post by David Redszus »

As much as I may like vintage engineering marvels, time marches on and progress prevails.

Or does it.

Following is a selection of four remarkable engines, produced over a number of years, compared by
their peak torque and peak power BMEP values. BMEP is used to compensate for displacement and
even for alternative designs.

Engine............Year.....Torque (BAR).....Power (BAR)

MB 6.3L*..........1970...........9.85 ...........10.29
Porsche 928S4...1986..........10.86.............9.48
MB S420...........1997..........11.97...........10.28
Porsche 904*.....1962..........12.42...........12.49
*Two valve

None of the engines are pushrod design, all but one are V8s.
All had two or four camshafts.

The largest displacement engine produced the lowest torque but good power, while the smallest
displacement engine produced the highest torque and power. Both were two valve engines.
All engines were fuel injected except one; the highest output engine was carbureted.

The usable rpm range varied from 1100 to 3000 rpm. Two were built over fifty years ago.

The point I would like to make is that to categorically judge various engine designs leaves
room for many exceptions. It is important to understand just what the engine designer had
in mind and what limitations were in place.

For mass production engines, cost to build and cost to maintain are critical design objectives.
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Re: I Still Like Pushrods, They're Still Viable

Post by PackardV8 »

David Redszus wrote: Tue Apr 20, 2021 3:52 pmFor mass production engines, cost to build and cost to maintain are critical design objectives.
FWIW, I've been told packaging comes first. If it won't fit in the space allotted, cost and power are never going to happen. GM has gone to three-cylinders on their entry-level vehicles.
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Re: I Still Like Pushrods, They're Still Viable

Post by David Redszus »

PackardV8 wrote: Tue Apr 20, 2021 4:44 pm
David Redszus wrote: Tue Apr 20, 2021 3:52 pmFor mass production engines, cost to build and cost to maintain are critical design objectives.
FWIW, I've been told packaging comes first. If it won't fit in the space allotted, cost and power are never going to happen. GM has gone to three-cylinders on their entry-level vehicles.
Packaging is indeed a critical consideration. Not just for size, but also for weight which might require
modifications to chassis, suspension, brakes, etc.; sort of a ripple effect.

Conversely, the smaller and lighter an engine can be made, for a target power output,
the lower the cost of the chassis and related components.

Look forward to small displacement, three cylinder, forced induction, engines that make a
lot of power per pound. A turbo can be both economically driven and have large power when needed.

BMW has been working on small, three cylinder truck engines. :shock:
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Re: I Still Like Pushrods, They're Still Viable

Post by Ken_Parkman »

http://www.seqair.com/Other/PFM/PorschePFM.html

Here is an article from the airplane engine thread that really deserves to be read in context of pushrods.

Porsche spent 75 million to make a "high tech" OHC aviation engine and managed to double the specific output of the pushrod engine it was supposed to replace. Sounds good, right? In the real world it was a total dog, heavier, bigger, lower performance, reduced efficiency, reduced payload and more expensive. Needless to say that was a total flop.
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Re: I Still Like Pushrods, They're Still Viable

Post by David Redszus »

Ken_Parkman wrote: Tue Apr 20, 2021 8:08 pm http://www.seqair.com/Other/PFM/PorschePFM.html

Here is an article from the airplane engine thread that really deserves to be read in context of pushrods.

Porsche spent 75 million to make a "high tech" OHC aviation engine and managed to double the specific output of the pushrod engine it was supposed to replace. Sounds good, right? In the real world it was a total dog, heavier, bigger, lower performance, reduced efficiency, reduced payload and more expensive. Needless to say that was a total flop.
The article is an excellent read. It clearly points out that advanced technology, applied incorrectly or
to the wrong problem, will fail no matter how techie it is.

But they only spent 75 million; relative chump change. But then again, it was 33 years ago.

What improvements have been applied to aircraft engines since then?
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Re: I Still Like Pushrods, They're Still Viable

Post by JCR »

David Redszus wrote: Wed Apr 21, 2021 10:46 am What improvements have been applied to aircraft engines since then?
As for aircraft piston engines, none. Late in life Keith Duckworth was interested in a modern design for aircraft piston engines since they are archaic pre-WWII designs. While technically feasible, it not regulatory feasible. So there will be not improvements made due to them being "certified".
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