^^^It's not...it's like saying Turbos, Superchargers, and the like are new concepts. It's more like it hasn't been effective by design, manufacture, or by cost to implement it effectively.

A DOHC engine is generally a lot more complex than an OHV engine and requires a lot more working in sync than otherwise. Take this back to, say, the 60's, and try to mass produce this with 60's technology and either the price would be prohibitively high, or the failure rate great.

Hell disc brakes were made before drums if i'm not mistaken, but because of the complexity of trying to make a non-floating caliper design return properly, and boosting the brake force neeted without a vacuum booster, the self-servo action and the ease of implementing drum brakes made them popular until the floating single piston caliper came about.

Same with CVT's. They're not new--it's just now they are more viable.

Plus, you also have to factor in the current consiousness of the consumers and the government. Back then with OHV reigned king, you gould be getting 18mpg highway and it would be considered economical--along with leaded gas.


Goodbye Callisto & Skaði, Hello Ishara:
2022 Kia Stinger GT2 AWD
The only thing every single person from every single walk of life on earth can truly say
they have in common is that their country is run by a bunch of fargin iceholes.

Which one is in my GTP? I like that one.

Which one is in my Sierra? I like that one too.





**there is only one true love in my life... and my girlfriend has learned to live with it**

HEE HEE HEE thanks GM for the timing.....

Quote:

-New for 2008 is the industry’s first 2-Mode hybrid system, which makes its debut with a new 6.0L V-8 in GM’s full-size sport-utility vehicles. The Chevrolet Tahoe and GMC Yukon hybrids will deliver up to a 40-percent improvement in city fuel economy over non-hybrid versions and up to a 25-percent improvement overall. GM will expand this application to the Cadillac Escalade and GMC Sierra and Chevy Silverado crew cabs in 2008. The 6.0-liter V-8 is GM’s first use of the legendary small-block V-8 in a hybrid package. The engine features an aluminum block, Active Fuel Management cylinder-deactivation technology, cam-in block VVT, late-intake valve closing and a higher 10.8 compression ratio. It delivers 332 hp (248 kW) and 367 lb.-ft. (497 Nm) of towing-friendly torque.

I don't know why so many people have a hard time grasping the concept of a vvt ohv motor. they just take the same thing you get on an ohc vvt motor and stick it on the timing chain of the ohv motor. all you really need is a bigger timing chain cover and provisions for the wires and oil lines.


as far as the thread......it totally depends on the car and its intended use. for instance, if you have a small displacement 4 cyl motor in a small car you might be better off taking the better airflow of dohc. however, if you take that same car and try to cram a larger dohc v motor be it 6 or 8 you might just be better off with the more compact, easier to work on, lighter ohv motor.(they have stuffed ls1's in miatas, 240z's, rx7's, and the mallat solstice so this argument is legit) the ford 5.0 has also found its way into some miatas and 240's btw. and don't get me started on the v8 fiero's

I dunno if any of you have actually seen a 5.0 ohv heads and block next to a 4.6 dohc heads and block (ford, just making sur we are all on the same page) on engine stands, but if you did you would clearly see how the size, simplicity, and wight differences could come into play. especially since you can work the 5.0 out to 408ci. try that wiht the 4.6.

another example is if you are working in any displacement restricted class. lets say indy car, the better top end flow of dohc will be where its at becouse irreguredless of engine size or complexity, at the end of the day you are going to need more air in, and more air out



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when you beat someone in a civic people wine and make excuses
when you beat someone in a cavalier they pull over and check under thier hoods

You should have compared SOHC with pushrod motors, same number of valves.

Each have their advantages...

Pushrod:
+Fewer parts, somewhat simpler
-More moving mass, possible valve float at high RPM
+Usually smoother, less valve chatter
+Using a low-maintenance chain becomes possible
+Slightly lower center of gravity
-Usually more difficult to replace camshaft

SOHC:
+Less reciprocating mass for higher RPM
-More parts
-More weight near the top of the motor
-Distance from crank often means a belt must be used
+Usually easier to replace camshaft
+DOHC headswap may be available

Neither is really obsolete. There's a reason every single new car isn't DOHC.

2002 Cavalier 2200 5spd

^^^ a pushrod engine doesn't have fewer parts than a OHC engine. WTF



Pushrod engine = timing chain, cam, lifters, pushrods, rockers, and valves.

OHC engine = timing chain (or belt), cam, tappets, and valves.

Thats 6 to 4. I know I left out things like springs, retaining clips, and tensioners.... but you get my point.

Even with a DOHC your just adding another camshaft and a few more valves.

OHC and DOHC engines are much more simple than pushrod engines..... they are just harder to tear apart.

DOHC inline 4's and Quad Cam V6 and V8's outperform most anything else.... they are just better in pretty much every way except for the fact they are harder to work on.