Where 'oh where has the OHV gone..

[supton]

Originally Posted By: Silk
Fiat 132. Isuzu 4JG2 and Ford Transit in more modern times. Best thing about a belt driven pushrod engine? Bent pushrods with a broken belt. With a belt driven diesel a broken belt is always a problem, on a pushrod engine it's a just a couple of pushrods...no sweat.


I don't get that. To bend a pushrod means the piston had to smack a valve. I'd always be worried about the valve snapping at a later date. Unless if the valves are perfectly in line with the pistons, which I do not believe is a requirement for pushrod motors (the rocker arms do allow the valves to be canted, the big block Chevy is a good example of using two different valve angles).

 

[SteveSRT8]

Yeah, anyone with an interference engine knows about the catastrophic damage that ensues if that belt or chain breaks at speed.

It sure isn't just a couple of pushrods!

 

[Win]

Originally Posted By: Ben99GT
...

"The net result is a fully trimmed engine that weighs 458 pounds, only 10 more than the 6.0-liter LS2.

For comparison, AMG's all-new 6.3 liter V-8 (it is actually a 6.2 liter V-8, but it will be called a 6.3 liter V-8 to pay homage to the 250 hp 1967-1972 300SEL 6.3) weighs 438 pounds vs. 485 pounds (old 5.4 liter supercharged V-8). The new V-8 has 510 hp at 6,800 rpm and 630 Nm at 5200 rpm."

The AMG 6.3 is a DOHC 4V VVT engine.
The 5.0 4V Coyote weighs 425 lbs per Mike Harrison.


You really need to know what, if any, accessories, fluids, etc., are installed on any of these engines for a weight specification comparison to be meaningful.

The 5.7 litre LS1 OHV engine in my GTO was physically dinky from a volume standpoint compared to the 4.2 Litre DOHC VVT V8 in our '04 Jaguar, or 3.6 litre DOHC VVT V6 in my G8. I don't know about weight - it's usually volume that creates packaging issues and OHC engines have a lot of volume.

The 6.0 Litre SOHC V12 variable nuttin' in my Xj12 could physically crush any of those engines and never know that it landed on anything. It's just HUGE.

 

[bruno]

If you want pushrods look at the diesels in the semis on the highway . Pushrods are fine for low RPM engines that have to live a long time .

 

[mechtech2]

OHC systems use less parts, and have less moving mass.

Much more efficient and much easier on valve train parts.

BTW, timing chains were a bread and butter job with pushrod V8s. Very common to replace them for a variety of reasons.


Basically, we had flat head engines in cars until 70 years ago, now all are OHV.

 

[Ben99GT]

Originally Posted By: mechtech2
OHC systems use less parts, and have less moving mass.

Much more efficient and much easier on valve train parts.

BTW, timing chains were a bread and butter job with pushrod V8s. Very common to replace them for a variety of reasons.


Basically, we had flat head engines in cars until 70 years ago, now all are OHV.


+1

 

[ls1mike]

Originally Posted By: supton
Originally Posted By: Silk
Fiat 132. Isuzu 4JG2 and Ford Transit in more modern times. Best thing about a belt driven pushrod engine? Bent pushrods with a broken belt. With a belt driven diesel a broken belt is always a problem, on a pushrod engine it's a just a couple of pushrods...no sweat.


I don't get that. To bend a pushrod means the piston had to smack a valve. I'd always be worried about the valve snapping at a later date. Unless if the valves are perfectly in line with the pistons, which I do not believe is a requirement for pushrod motors (the rocker arms do allow the valves to be canted, the big block Chevy is a good example of using two different valve angles).

You have not been around too many LS1s, they will bend a pushrod with a mis-shift without the piston hitting the valve. Mechanical over rev will do it those. Swap out the Pushrod and BAM back on the street. I have done it, and I am not proud, twice while at the track. Tons of threads about it on line. Some guys, like me, will leave the stock ones in in case we miss a shift that way you bend a 60 dollar set of pushrods, swap them out and move one.

 

[Cujet]

The variable twin cam timing systems used today can achieve things not possible with simple, pushrod, cam in block designs.

Things such as virtual Atkinson cycle, where expansion is greater than compression. Things such as multi valve engines with high valve lift and duration numbers achieving wide torque curves and impressive peak HP, all while meeting stringent emission requirements.

Sorry, but technology and development prevail.

 

[ls1mike]

Originally Posted By: Cujet
The variable twin cam timing systems used today can achieve things not possible with simple, pushrod, cam in block designs.

Things such as virtual Atkinson cycle, where expansion is greater than compression. Things such as multi valve engines with high valve lift and duration numbers achieving wide torque curves and impressive peak HP, all while meeting stringent emission requirements.

Sorry, but technology and development prevail.


True, and I don't care what you drive, but I will remeber that next time I show a Honda tailights.

"At least his car was more technologically advanced" I am sure the Corvette guys are worried about that to. Power is power no matter how it is made.

 

[Silk]

Originally Posted By: supton
To bend a pushrod means the piston had to smack a valve. I'd always be worried about the valve snapping at a later date. Unless if the valves are perfectly in line with the pistons,


I'm talking about diesels (Isuzu 4JG2 and Transit) and the valves are vertical - they just bend a pushraod, no damage and practically no no load on the valve.

 

[TheBig2003]

Really guys, I have no offense to anybody here, but OHV design has and so far will always be the configuration for developing absolute power. I am running a 5.7 HEMI with 423whp/479wtq on only 7.3lbs of boost (which is extremely low...which we all know is low). I will not mention my Quarter times.

I also have under my belt an '06 Grand Prix GT S/C running a 3.8 Series III with an underdrive SC pulley and a total of 9.45lbs of boost and running an 11.44 1/4 mile and yet still pushing 33.8mpg on the highway.

All-in-all, I would say OHV engines are better in ever way. If would like to prove me otherwise, we can always run the 416 or 417 and see who could make Prescott or Cornwall fastest without a fill.

 

[SteveSRT8]

Originally Posted By: ls1mike
Originally Posted By: Cujet
The variable twin cam timing systems used today can achieve things not possible with simple, pushrod, cam in block designs.

Things such as virtual Atkinson cycle, where expansion is greater than compression. Things such as multi valve engines with high valve lift and duration numbers achieving wide torque curves and impressive peak HP, all while meeting stringent emission requirements.

Sorry, but technology and development prevail.


True, and I don't care what you drive, but I will remeber that next time I show a Honda tailights.

"At least his car was more technologically advanced" I am sure the Corvette guys are worried about that to. Power is power no matter how it is made.


So very true! I laughed so hard I cried on this one!

 

[supton]

Originally Posted By: TheBig2003
Really guys, I have no offense to anybody here, but OHV design has and so far will always be the configuration for developing absolute power.


Never! Bring back flatheads!

We should really come up with a better name for "cam in block", as SOHC, DOHC and cam-in-block are all OHV setups. [Although I'm not sure what you'd call that odd-ball F head that Willeys/Jeep had (intake valve in head, exhaust valve in block) in this argument. Other than dead and gone.]

 

[supton]

Originally Posted By: ls1mike
You have not been around too many LS1s, they will bend a pushrod with a mis-shift without the piston hitting the valve. Mechanical over rev will do it those. Swap out the Pushrod and BAM back on the street. I have done it, and I am not proud, twice while at the track. Tons of threads about it on line. Some guys, like me, will leave the stock ones in in case we miss a shift that way you bend a 60 dollar set of pushrods, swap them out and move one.


Really? Sounds like the valve train is too heavy and/or pushrods are too weak. But I'll buy that.

 

[supton]

Originally Posted By: Silk
Originally Posted By: supton
To bend a pushrod means the piston had to smack a valve. I'd always be worried about the valve snapping at a later date. Unless if the valves are perfectly in line with the pistons,


I'm talking about diesels (Isuzu 4JG2 and Transit) and the valves are vertical - they just bend a pushraod, no damage and practically no no load on the valve.


No damage? As in, 200kmiles after a valve-kissing experience, no dropped valves? I mean, I'll accept it if it's been proven to have no impact on longevity, I just find it hard to believe there isn't any latent valve damage in this case.

 

[SteveSRT8]

Originally Posted By: supton
Originally Posted By: ls1mike
You have not been around too many LS1s, they will bend a pushrod with a mis-shift without the piston hitting the valve. Mechanical over rev will do it those. Swap out the Pushrod and BAM back on the street. I have done it, and I am not proud, twice while at the track. Tons of threads about it on line. Some guys, like me, will leave the stock ones in in case we miss a shift that way you bend a 60 dollar set of pushrods, swap them out and move one.


Really? Sounds like the valve train is too heavy and/or pushrods are too weak. But I'll buy that.


It's a deliberate design strategy. The general knows valvetrain tech!

 

[supton]

GM ought to know what they are doing by now! Heh. Makes sense, I will say that.

 

[itguy08]

Originally Posted By: TheBig2003
Really guys, I have no offense to anybody here, but OHV design has and so far will always be the configuration for developing absolute power. I am running a 5.7 HEMI with 423whp/479wtq on only 7.3lbs of boost (which is extremely low...which we all know is low). I will not mention my Quarter times.


Forced induction changes the game considerably....

There are guys getting close to that from the Ecoboost 3.5 in the Flex. Over on Fordflex.net and shoforum.com there is a guy that has a 12 second Ford Flex which is a 4k lb+ crossover. In the SHO/Flex the limiting factor is not the engine but the rest of the FWD drivetrain.

Not sure what the F150 guys are getting out of the EB 3.5 but from what I remember Ford has tested it to something crazy like 500hp. It's aleready at 4something lb-ft stock. And I'd imagine the RWD/4WD of the truck can handle tons of power.

 

[TFB1]

Originally Posted By: Ben99GT
Originally Posted By: mechtech2
OHC systems use less parts, and have less moving mass.

Much more efficient and much easier on valve train parts.

BTW, timing chains were a bread and butter job with pushrod V8s. Very common to replace them for a variety of reasons.


Basically, we had flat head engines in cars until 70 years ago, now all are OHV.


+1


AMC still used flatheads into the 60s...

 

[mpvue]

Originally Posted By: TheBig2003
...I am running a 5.7 HEMI with 423whp/479wtq on only 7.3lbs of boost (which is extremely low...which we all know is low). I will not mention my Quarter times.


why? are you embarrassed by them?
1/4 calculator is showing 12.7 for you, am I close?

seriously, 423HP at the wheels on a BOOSTED hemi? isn't advertised stock 425hp?
seems pretty low, considering over 500hp in a N/A LS engine is pretty common...