Pushrods vs DOHC

[Hack]

Guess it depends on your definition of 'best'. Personally, since I don't like horrible resale due to known long term reliability issues, I stay away from German stuff. If you consider expensive parts for failures that shouldn't happen in the first place 'best', well, there's no conversation to be had. ?

If money is no object you by definition do not care about resale value. I don't think you are trying to argue that 'vettes are better than the best sporty cars made in Europe, are you? :lol:

I don't see a lot of 200k mile junkyard German engines being turbo'd to produce 800, 900, or 1000 hp.

Has no bearing on the topic.

Seems as those who are anti-pushrod have limited racing knowledge or no engineering background...coincidence?

I'm not anti-pushrod and I'm a mechanical engineer. Heck, my emphasis in school was in ICE. I don't work in the industry, so I'm mostly just a fan with some educational background and time spent thinking and reading. One of my favorite engines of all time is the Cleveland 4V, which is arguably the originator of the current NASCAR engine architecture and of course is a pushrod design. I have some practical experience with building my own engines as well.

One of my strengths is an open mind, I believe. That's why I proposed the clarifying method of thinking about this question in the first place. Theory is something you can go around and around about, but practice is where the truth really comes out.

So - take it for what you will.

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[Herr_Poopschitz]

I know of A 30 yr old TT P 928 S4 that makes 964 RWHP.
Link? I said 'a lot', not 'a'. Big difference.

Did you know that the fastest OEM car uses a vesion of the Ford 4.6 DOHC motor? koenigsegg 1200 HP TT. Oh yea and the current fastest standing mile production based car is; A Ford GT TT 5.4 DOHC. Not sure of the validity of the Koenigsegg claim as I think it's just conjecture at this time. Also, these items you present still do not refute the fact that pushrod engines are just as capable of making big power. In the case of junkyard LS engines, they can also do it for WAAAY less money than a Ford equivalent, much less something from Deutschland.

Bring it. Yawn.

 

[Herr_Poopschitz]

If money is no object you by definition do not care about resale value. I don't think you are trying to argue that 'vettes are better than the best sporty cars made in Europe, are you? :lol:

Powertrain? As I stated previously, hell yes. It's also arguable the C7 is superior to European cars in it's price range, as well as significantly above.

Has no bearing on the topic.

Sure it does...it's a good example of longevity of the design. No advantage of DOHC here...or some mystical German supereriority.

I'm not anti-pushrod and I'm a mechanical engineer. Heck, my emphasis in school was in ICE. I don't work in the industry, so I'm mostly just a fan with some educational background and time spent thinking and reading. One of my favorite engines of all time is the Cleveland 4V, which is arguably the originator of the current NASCAR engine architecture and of course is a pushrod design. I have some practical experience with building my own engines as well.

I just don't understand the unlimited funds argument as a justification for declaring one 'better' than the other. European and Asian regulatory standards are different than what we have...of course their engines will be different...whether inexpensive econoboxes or hypercars. The example I tried to give w/ the Venom GT exemplifies this, I believe. There are no inherent advantages. They each have their place.

One of my strengths is an open mind, I believe. That's why I proposed the clarifying method of thinking about this question in the first place. Theory is something you can go around and around about, but practice is where the truth really comes out.

The way I see it, the practice has shown there to be no distinct advantage for either in the kinds of ways I will use my cars. I don't design for emissions. I like an engine that will spin high rpm...so valvetrain stability of DOHC wins. I also like a hard kick in the pants, where larger displacements (pushrods) win.

As an engineer, you certainly understand that you design to a set of criteria...there is no 'best'....every design is full of compromises.

 

[comagt]

Engineers don't always have full control over the design either. Marketing says we have to use X type of motor, because market analysis says it will sell more. I don't care about your science and technological reasoning, just do it cause $$$.

This thread is evidence that you can't win in either scenario, someone will want the other green lawn.

I've driven both and I like both for different use cases. However, for a daily driven street car, I will take DOHC every single time, because I prefer it.

Just to lighten the mood a little - [ame]

I swear I can see this happening with every engineer in the major corps

 

[cosmo]

Oh god, that video is so accurate it hurts.

 

[Herr_Poopschitz]

What I get out of that vid is that in any scenario, only 20% of those involved have a f'ing clue...which seems a bit optimistic from my experience.

The mgmt role is dead nuts on.

 

[Hack]

Powertrain? As I stated previously, hell yes. It's also arguable the C7 is superior to European cars in it's price range, as well as significantly above.

Yes right if getting a cheaper car is important then the "bigger hammer" becomes more attractive than the highly engineered and elegant solution. By the way, I'm not trying to criticize you at all with this statement. I'm cheap and I want to buy the least expensive car that will get me my acceleration fix. So even the 'vette is expensive to me and I would love to buy one. Maybe I will someday. But I'm a relative pauper compared to those buying the real top sports cars out there. And I can see that the top stuff isn't using big displacement pushrod engines.

I just don't understand the unlimited funds argument as a justification for declaring one 'better' than the other. European and Asian regulatory standards are different than what we have...of course their engines will be different...whether inexpensive econoboxes or hypercars. The example I tried to give w/ the Venom GT exemplifies this, I believe. There are no inherent advantages. They each have their place. .

The Venom GT is more of a hot rod than a production car. It's pieced together from parts bought from actual car manufacturers. It does prove that a pushrod engine can make big power, which we all knew anyway.

The way I see it, the practice has shown there to be no distinct advantage for either in the kinds of ways I will use my cars. I don't design for emissions. I like an engine that will spin high rpm...so valvetrain stability of DOHC wins. I also like a hard kick in the pants, where larger displacements (pushrods) win. .

You are adding displacement to the equation, which is really cheating. If you are asking whether pushrods or DOHC are better, compare a 5.0 pushrod engine to a 5.0 DOHC engine. Of course more displacement can make more power, but there are a number of limitations to pushrod engine design (I know you are aware of them from your past posts) that give an edge to DOHC IMO. Like I've said, I'm no expert - but I do trust what I see from large corporations building the best cars they can.

As an engineer, you certainly understand that you design to a set of criteria...there is no 'best'....every design is full of compromises.

Yes generally that is true, but there are innovations that win. The whole reason for patents and the concept of IP in general.

 

[Herr_Poopschitz]

Yes right if getting a cheaper car is important then the "bigger hammer" becomes more attractive than the highly engineered and elegant solution. By the way, I'm not trying to criticize you at all with this statement. I'm cheap and I want to buy the least expensive car that will get me my acceleration fix. So even the 'vette is expensive to me and I would love to buy one. Maybe I will someday. But I'm a relative pauper compared to those buying the real top sports cars out there. And I can see that the top stuff isn't using big displacement pushrod engines.

The Venom GT is more of a hot rod than a production car. It's pieced together from parts bought from actual car manufacturers. It does prove that a pushrod engine can make big power, which we all knew anyway.

You are adding displacement to the equation, which is really cheating. If you are asking whether pushrods or DOHC are better, compare a 5.0 pushrod engine to a 5.0 DOHC engine. Of course more displacement can make more power, but there are a number of limitations to pushrod engine design (I know you are aware of them from your past posts) that give an edge to DOHC IMO. Like I've said, I'm no expert - but I do trust what I see from large corporations building the best cars they can.
Yes generally that is true, but there are innovations that win. The whole reason for patents and the concept of IP in general.

Seems there are a lot of definitions that need to be established.

A Venom is a hot rod, but a Veyron or Koenigsegg is considered a production car?

The addition of displacement is 'cheating', yet having multi-valved heads w/ variable valve events on both in and ex isn't?

I'm starting to get it...it seems the rules have been written in favor of DOHC from the start.

I'm not sure what is 'elegant' and 'highly engineered' about DOHC vs pushrod. The whole process is quite frankly an awful mess...that, or completely beautiful. Again, neither is better or worse, just different.

What is a 'real top sportscar'?:shrug:

As I pointed out, Corvette Racing seems to do quite well w/ their inferior pushrod engines and their cheap, underengineered Corvette chassis against the likes of 'real sports car manufacturers' Ferrari, Porsche, BMW, etc.

Ultima Evolution is pretty badass too...but clearly it's too boutique and excluded from contention to be a 'real sports car'.

Basically, nothing w/ pushrods seems to satisfy your narrow/limited definition of what a sports car seems to be...

 

[Shanghai Dan]

Seems there are a lot of definitions that need to be established.

A Venom is a hot rod, but a Veyron or Koenigsegg is considered a production car?

The addition of displacement is 'cheating', yet having multi-valved heads w/ variable valve events on both in and ex isn't?

I'm starting to get it...it seems the rules have been written in favor of DOHC from the start.

I'm not sure what is 'elegant' and 'highly engineered' about DOHC vs pushrod. The whole process is quite frankly an awful mess...that, or completely beautiful. Again, neither is better or worse, just different.

What is a 'real top sportscar'?:shrug:

As I pointed out, Corvette Racing seems to do quite well w/ their inferior pushrod engines and their cheap, underengineered Corvette chassis against the likes of 'real sports car manufacturers' Ferrari, Porsche, BMW, etc.

Ultima Evolution is pretty badass too...but clearly it's too boutique and excluded from contention to be a 'real sports car'.

Basically, nothing w/ pushrods seems to satisfy your narrow/limited definition of what a sports car seems to be...

Precisely. For many here, there is only DOHC and nothing else.

Never mind that 4V pushrod engines exist.

Never mind that pushrod engines run well above 8K RPM.

Never mind there are highly successful race cars running pushrod engines.

Never mind the most hard-core production vehicle in the US (Corvette) uses pushrods.

Never mind the most powerful ICE engines in the world (top fuel dragsters, close to 10,000 HP) run pushrods beyond 8,000 RPM.

Pushrods will never equal DOHC performance in any platform...

Both technologies are great. Both can work really well. There is really no inherent advantage of one over the other, it's all about what you want to achieve, and what you have available to use.

 

[Catfish]

Engine Masters Challenge allowed Ford DOHC Engines, said engines mop the floor with the push rod engines, said engines are banned from future competitions. LOL

http://www.enginelabs.com/news/amsoil-engine-masters-rules-released-ford-mod-motors-need-not-apply/

 

[Sinister]

I don't see a lot of 200k mile junkyard German engines being turbo'd to produce 800, 900, or 1000 hp. I know of A 30 yr old TT P 928 S4 that makes 964 RWHP.

Also, I'd say the Venom GT does a pretty good job as a world-beater w/ it's inferior pushrods. Did you know that the fastest OEM car uses a vesion of the Ford 4.6 DOHC motor? koenigsegg 1200 HP TT. Oh yea and the current fastest standing mile production based car is; A Ford GT TT 5.4 DOHC.

Seems as those who are anti-pushrod have limited racing knowledge or no engineering background...coincidence? Bring it.

Pushrod engines can go 0-330mph in less than 4 seconds...

 

[Brent302]

Pushrod engines can go 0-330mph in less than 4 seconds...

Pfft DOHC is weak I have a TOHC

 

[Herr_Poopschitz]

Engine Masters Challenge allowed Ford DOHC Engines, said engines mop the floor with the push rod engines, said engines are banned from future competitions. LOL

http://www.enginelabs.com/news/amsoil-engine-masters-rules-released-ford-mod-motors-need-not-apply/

That's a political...as in sales...maneuver. Nothing else.

I responded to this in a previous thread about it. Kaase comes in w/ exotic parts...worked over Cobra R intake ($$$), worked over Ford GT heads that had already been prepped by Yates for a Daytona prototype ($$$), and the most unique headers that would never fit any car ever ($$$) and as you say, mops the floor.

How does the average guy building an engine in his garage relate to a build like that? If they have too many builds featured like that, people would lose interest and no longer buy the magazine. Be glad there are sponsors willing to fork over money and time for something like EMC...if it went to all 4V, all the funding would go away. No one makes aftermarket stuff for 4Vs...there's no real money in it compared to everything else. Maybe if 4V swaps were even remotely as popular as LS swaps you'd see them included. Facts don't lie...they just aren't. Hell, seems the most popular combo right now for cheap thrills is an LS powered Fox...best chassis for the $, meet best engine for the $...

Also, how many guys really do internal mods to their 4Vs? Not many are taking them apart...most are bolt on and/or blown and that's it.

 

[Shark77]

In the purist sense, if you're slamming fuel and air into a cylinder and clearing its exhaust out, it's hard to argue that being able to manipulate more cams and valves are not more beneficial. And the more RPM you add to the equation, less material between valve actuation is always better.

If there was a mechanical advantage using pushrods, F1 engines would have them.

 

[pietran30]

You are adding displacement to the equation, which is really cheating. If you are asking whether pushrods or DOHC are better, compare a 5.0 pushrod engine to a 5.0 DOHC engine. Of course more displacement can make more power, but there are a number of limitations to pushrod engine design (I know you are aware of them from your past posts) that give an edge to DOHC IMO. Like I've said, I'm no expert - but I do trust what I see from large corporations building the best cars they can.

This is a fallacy people have when comparing these engines. Sure the 5.0 DOHC will make more power than a 5.0 pushrod. The DOHC will also have significantly larger dimensions and weight. The DOHC will be so much larger than a pushrod of equal displacement.

Here's one for you. What if we compared hp/lb from the engine, rather than displacement. Your DOHC makes less hp/lb than a pushrod. It's the same principle.

By only comparing hp/L, you're handicapping the pushrod. Just some food for thought.

The only question left I have is, if we were to design and build a pushrod motor to the dimensions and weight of the 5.0 coyote to place in your mustang, would it make a faster mustang?



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