In reference to the Rover V8 we all have, this is a direct quote from this forum: the Rover V8 engine is an "old school type engine design!" Often, on this forum, we see posters making similar or same remarks. Educate me, briefly at least, how does the General Motors 1960s designed Buick all aluminum V8 engine, an engine that General Motors later sold rights and some production tooling to Rover, differ from what must be called new school type engine designs? I know that the camshaft, push rod, rocker arms valve train system so common in V8 engines, with two valves per cylinder, is part of these engines, and I know that it has, to some degree, been replaced by more modern overhead valve train systems, with multiple valves per cylinder, BUT, again, what makes our Rover engines so antiquated? Multiple valves per cylinder allows a better breathing engine, something that is generally considered a good thing, but in exchange for the better breathing, we sacrifice more susceptibility to common valve train problems, more parts--more valves and related parts, more friction, more wear and tear, more susceptibility to common problems with valves in general. What am I missing here, what makes our engines so "old school?" The most modern "new school" engine doesn't differ all that much from the oldest "old school" internal combustion engine, they all have valves, pistons, camshaft, crankshaft, etc. Jaguar, designed its double overhead camshaft engine during WWII, 20+ years before the GM designed the V8 so many call an out of date design, so are you all also calling the double overhead design an out of date design?

 

Well, around the time they were designing it a lot of people had finally seen a TV, so I guess they're not THAT old of a design

 

Just because jaguar was ahead of the times doesn't mean that a newer (chronologically) push rod engine isn't outdated.

Overhead cam engines can actually use LESS parts, not more, depending on the design. But even those with more parts usually do it for very good reasons. And well designed overhead cam engines have less wear of those components and the stresses are spread out better.

 

The Rover's flat tappet camshaft is prone to a great deal more wear than a modern rolling camshaft.

Personally, I love the old school design of the engine because it means it's easier to work on.

 

Hummm, so the only thing that makes the Rover engine outdated, is the fact that it has a push rod valve train, right? And the lack of a more modern, more efficient, rolling camshaft is all that makes the Rover engine an "old school design?" Shucks, a guy can buy and/or fabricate rollers to replace the push rod design; they are available for such use, so this would make our Rover "old school" "new school?"

 

It would be difficult and not very cost effective to go from push rod to overhead cam. There were some very rare 427 overhead cam engines in the 60s. They used an idler where the stock cam was and ran chains from it up to the real cams above the heads. You'd also need new heads with more modern valve geometry.

 

I know I'll catch a lot of flack for this, but IMO most anything that isn't forced induction is outdated tech to me. Even the newer N/A stuff doesn't excite me.

 

The design and tooling was based off of 60's tech, most of which has been discussed before. Modifications to meet modern emission standards were added later, but no redesign.


This brings us to the famous Rover issues:


1) It wasn't designed as a 4.0L engine, so over-boring to 4.6 weakens the block, add to the fact the tooling was warn and you get a significant amount of engine failures. Old school isn't bad, bad tolerant old school is bad, which is why we all have ultra-gauges.


2) Economy sucks per power output. I can get 15MPG all day long out of my 2500HD 6.0L Iron-block push-rod truck, it's less exotic than the Rover, cam-in-block, but was designed with modern advances. Nearly twice the power too. My suburban can get 17 easy with the Chevy 5.3, and the suburban is heavier and larger than my Disco.

Both chevy engines are light-years ahead in the reliable department, and yet they are the same basic "tech", but re-designs, rather than "evolution of the same block" like the rover motors.


In the Rover's defense, it's cam profile is SWEET for off-roading. I don't care that it barely has 200HP, the fact that it has a smooth torque curve means I can totally control it off-road. It's one of my favorite off-road motors (next to the old Jeep 4.0 I6 Jeep), only trails the Jeep motor in my mind because it is so fragile in comparison.

 

It wasn't over-bored. The additional displacement is from stroke.

 

I think converting to a rolling cam design would have a profound effect on the way these engines run. You could use a more aggressive cam, the valve train would quiet down, and you'd see horsepower and efficiency increases.

But there are many little things that make these engines old school.

One of the results of a modern multiple valve design is what is essentially a hemispherical combustion chamber, which results in a more efficient fuel burn.

If the engine is designed around a rolling cam, the entire air flow can be designed around larger valves with more movement. This generates more HP per cubic inch. An engine is basically an air pump, and the more air you can pump the more power you make.

Much like other 60s designs, the bore/stroke ratio leans more toward power than efficiency. This site gives a very simple explanation of what I'm talking about. For example, the Rover V8 has a 1.32/1 ratio while a LS1 has a 1.08/1 ratio.

Timing belts, while a PITA, do offer performance advantages over chains.

Those were just off the top of my head; I'm sure there are many other ways the design could be improved without even talking about stuff like the head gasket and sleeve problems.

Big picture is the engine was designed 50+ years ago, and there have been many, many lessons learned since then about increasing engine efficiency. And efficiency doesn't just mean 'mileage' it means more power per CI. It also means you can run normal oil and not have it fouled after 3000 miles.