Pushrods vs DOHC

[BoomBoy]

Pushrod is an older tech. Sooner or later, GM will have no choice but to go DOHC.

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[JimmyTwoTimes]

As mentioned before the beauty of the LS motor is the compact size and all of the weight being down low. There's a reason why every RX7 and S13/14 puts a LS motor into their cars over a Coyote motor.

There's also cost, crate LS motors are cheap!

Why on Earth would anybody ever want to get rid of that amazing turbo rotary in favor of a small block Chevy? That's like trading in your Buggati for a Scion.

 

[Trackaholic]

Why on Earth would anybody ever want to get rid of that amazing turbo rotary in favor of a small block Chevy? That's like trading in your Buggati for a Scion.

Mostly they want more power and greater reliability.

-T

 

[slythetove]

Pushrod is an older tech. Sooner or later, GM will have no choice but to go DOHC.

This always comes up in these type of threads and really ... it's not that much older.

The first OHV engine was around 1902
http://en.wikipedia.org/wiki/David_Dunbar_Buick

The first OHC engine was around ... 1902
http://en.wikipedia.org/wiki/Overhead_camshaft
Jump to "Early Use"

The first DOHC engine was 1912
(same wiki same section)
http://en.wikipedia.org/wiki/Overhead_camshaft

Discussing the differences is always interesting but making it seem like DOHC technology is "new" is just misleading.

 

[Strokerswild]

Hell, Ford built DOHC 32-valve V8s for Sherman tanks back in WW2 (GAA engine). Definitely nothing new.

 

[Wblv17]

I love both my 5.0 Modular VCT ford and my Modular VCT ram 5.7 hemi

 

[Norm Peterson]

Why on Earth would anybody ever want to get rid of that amazing turbo rotary in favor of a small block Chevy? That's like trading in your Buggati for a Scion.

Maybe more like a Cross pen vs a Montblanc.

5.3, 5.7, 6.2, or more liters of a Chevy pushrod motor has more than enough torque everywhere in the rev range without being tuned to some hand-grenade-with-the-pin-pulled level, has good aftermarket support at reasonable prices, isn't going to be caught off-boost, and when it finally does break you just go to the junk yard and get another one. Aside from non-originality, what's not to like?


Norm

 

[midnite9150]

the fun part is when people try to push pushrods (ohv) engines as old technology and ohc as new technology, when really ohc engines have been around since the 20's and 30's

 

[midnite9150]

Why on Earth would anybody ever want to get rid of that amazing turbo rotary in favor of a small block Chevy? That's like trading in your Buggati for a Scion.

boost in,

apex seals out

 

[Hack]

This is tricky though, because many of those companies are from Europe where displacement taxes used to be common. Also, many like to leverage their racing heritage, where displacement is limited. Finally, they typically are more expensive, which allows greater freedom in parts cost. Those limits incentivise smaller displacement engines, which necessarily need to rev higher to make the same power as a larger displacement engine, forcing the use of a DOHC design.

Point being, there are many factors that impact engine choice, and if you compare an SBC to many world class engines from the likes of BMW and Porsche, the GM offering is pretty great, at least in the USA. Maybe won't be as culturally acceptable in Europe due to its large displacement, which has a stigma of being inefficient (even if the Vette gets pretty great fuel economy).
-T

I agree with some of the points in your post. I'm only going to address what I disagree with here.

You bring up cost and taxes, which really aren't factors for the ultra-wealthy people who are buying the highest performance, most expensive cars out there.

If the SBC pushrod architecture were better, do you really think BMW, Audi, Mercedes and Porsche couldn't and wouldn't build something with pushrods that was just as good or better? Especially being that the cost to produce is lower?

You are fooling yourself. I get that you're a fan, but those points just don't make any sense.

 

[Herr_Poopschitz]

I agree with some of the points in your post. I'm only going to address what I disagree with here.

You bring up cost and taxes, which really aren't factors for the ultra-wealthy people who are buying the highest performance, most expensive cars out there.

If the SBC pushrod architecture were better, do you really think BMW, Audi, Mercedes and Porsche couldn't and wouldn't build something with pushrods that was just as good or better? Especially being that the cost to produce is lower?

You are fooling yourself. I get that you're a fan, but those points just don't make any sense.

Why are you making German companies some kind of benchmark? Who cares what they do?

 

[JimmyTwoTimes]

If the SBC pushrod architecture were better, do you really think BMW, Audi, Mercedes and Porsche couldn't and wouldn't build something with pushrods that was just as good or better? Especially being that the cost to produce is lower?

You know what type of engine the Bentley Mulsanne has?

 

[Sinister]

Pushrod is an older tech. Sooner or later, GM will have no choice but to go DOHC.

I've seen this drum being beaten ever since Ford popularized the DOHC design with the '03 Cobra and later the Shelby. 12 years later the OHV Vettes, Camaros, and Caddys are doing just fine.

 

[Cascadia_302]

Why are you making German companies some kind of benchmark? Who cares what they do?

Really? When Ford goes global with cars like the Mustang and Focus they compete with cars from Germany. And when they go racing they compete with cars from Germany, not to mention other foreign cars. "What wins on Sunday sells on Monday"

24 hours of Le Mans records "endurance racing"

Wins: 32 Germany / 4 USA (Shelby American)

Who would you benchmark when you develop a car like the Ford GT? You always BM against the best and other competitors for that matter.

 

[Old 5 Oh]

Torque largely correlates to displacement.

All things equal, torque will be closely proportional to displacement but your statement is incomplete. Cam timing and overall engine breathing affect total torque and where torque peaks, RPM-wise. In general, a DOHC engine breathes MUCH better than an OHV engine, and will find its peak torque and power values much higher on the tach. (Remember the old Taurus V6 that was 3/4 of a 5.0 V8? It had such a tiny cam and heads that the torque peak was at 1600 RPM, and peak power was a paltry 140 HP.) Now, there are really deep-breathing OHV engines (the Chrysler Hemi and GM Gen V small blocks come to mind) but even so they are not turning the 7,000 RPM the Coyote does with such ease.

There is just nothing so smooth and melodious as a DOHC V8. It may pay a little weight penalty to an OHV engine, but the payback in power, revs and smoothness is huge. That explains why the world is down to the two OHV V8s mentioned above, and everyone else has gone DOHC.

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