IInteresting read for the Pushrod vs OHC debaters :)

[Billzilla]

As you'd expect me to say, push-rod engines are pretty poor compared to a modern multi-valve & cam engine.
I wrote a fair bit on it all here -> http://www.billzilla.org/2v4v.htm

The only possible advantage that a push-rod engine has is a slightly smaller head. That's it.

[bathurst-91]

Althought It's well written it is a joke overall.

He brings up teh arguement of engine exterior size in v8 pushrod vs dohc and goes on to say the pushrod is smaller.

If engine exterior size is the main point in regards to pushrod vs dohc. Then get rid of v8's fullstop. Then goes on to talk about better suspension room and weight distribution.

I dont understand the point of the story.

[Bomber2k]

Althought It's well written it is a joke overall.

He brings up teh arguement of engine exterior size in v8 pushrod vs dohc and goes on to say the pushrod is smaller.

If engine exterior size is the main point in regards to pushrod vs dohc. Then get rid of v8's fullstop. Then goes on to talk about better suspension room and weight distribution.

I dont understand the point of the story.

[crYnOid]

[Nick]

Damn the heads on that ford are big, even for a DOHC...

[260BC]

The crucial problem in designing a high efficiency pushrod V8 possibly would be locating the pushrod tunnels. There is not much flexibility there which in turn would not allow much flexibility in locating the valves.

Perhaps the best compramise would a single OHC four valves per cylinder engine. That would make for much more compact size heads and save a bit of weight, friction and complexity.

Really for ordinary road use the twin cam is a bit of a wank

[bathurst-91]

fool! I wasnt saying "get rid of v8s" read my post again. Im saying the general stipulation of the article and of V8 history in general is that bigger is better.

So bagging smaller engines (because of that.. their size) and choosing to stick with an oldschool design then writing and article on how size matters all of a sudden.

Its kind of derivative to the point.

Summary of story;

-V8s rule, smaller engines have no balls and are the sux0r look how big my engine is.

-No smaller engines are more compact and have a better dohc design.

-no they are the sux0r and are for homo's

-cough.

-well pushrods are better than dohc on v8s because they are smaller.

[blimpyboy]

I know it would make bugger all difference but isn't the Ford 4.6 Modular V8 a 90degree V8? What is the 302? 70-something degree?

Nick, this is a common misconception, but windsors, clevo's and all (i think?) big block fords are 90 degree V8s. The last non-90 degree V8 made by Ford was, i believe, the flathead...

[Babalouie]

Ok, here's a hypothetical.

Would a 5.0L 450hp, quad cammed 32V Jap V8 (say a 1UZFE taken to it's potential) be more efficient (BMEP & friction) when mated to a slushbox, pushing 1600kg and mooching around an urban enviroment at predominantly low revs (say 40~60km/h most of the time)....compared to a pushrod 5.0L chunk of iron with small valves?

To keep it fair let's say the 1UZ won't have any VVT. I'm not saying that pushrods are that great either, but when I ran a V8 Soarer I don't think it was any more fuel efficient than my Dad's 304 engined Caprice at the time, and for most of the time around town, the Holden was more torquey and quicker.

Fair enuff when you're up it for the rent, but what about for the way that most brain-dead non-car enthusiasts drive?

[Nick]

Nick, this is a common misconception, but windsors, clevo's and all (i think?) big block fords are 90 degree V8s. The last non-90 degree V8 made by Ford was, i believe, the flathead...

Yeah, googled an found the answer so I edited my post. So it's GM that still use a 70-odd degree V8?

[blimpyboy]

Ok, here's a hypothetical.

Would a 5.0L 450hp, quad cammed 32V Jap V8 (say a 1UZFE taken to it's potential) be more efficient (BMEP & friction) when mated to a slushbox, pushing 1600kg and mooching around an urban enviroment at predominantly low revs (say 40~60km/h most of the time)....compared to a pushrod 5.0L chunk of iron with small valves?

If the 5.0L pushrod engine was also putting out 450hp, I would wager that the quad cam motor would have more low down torque and be more refined and driveable at low revs. All things being equal (which they never are).

[Sturmovik]

Yeah, googled an found the answer so I edited my post. So it's GM that still use a 70-odd degree V8?

GM V8s are all 90 degree too.

(they may have been some 70 degree ones but I doubt they lasted long in production)

[Jim]

See that! Right there! that's a MAN'S engine!! No dinky little wussy toys ya'll heyah!!! :rotflol:

[blimpyboy]

Nick, perhaps you are thinking of the 72 degree (i think?) V6 used on Vectras and what-have-you?

[Bomber2k]

fool! I wasnt saying "get rid of v8s" read my post again. Im saying the general stipulation of the article and of V8 history in general is that bigger is better.

So bagging smaller engines (because of that.. their size) and choosing to stick with an oldschool design then writing and article on how size matters all of a sudden.

Its kind of derivative to the point.

Summary of story;

-V8s rule, smaller engines have no balls and are the sux0r look how big my engine is.

-No smaller engines are more compact and have a better dohc design.

-no they are the sux0r and are for homo's

-cough.

-well pushrods are better than dohc on v8s because they are smaller.

No the history of V8s is that bigger capacity is better, not bigger pyshical size and weight The point that the guy is making is that a pushrod motor is pyshically smaller than an a dohc motor. Eg, that ford motor above is the size of a 454 chev. A 454 chev is 7.4L and the ford motor 4.6L. Depending on the application an old pushrod motor may actually have something going for it.