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Discussion Starter #1
In the last few threads.... everyone is saying GM needs to "catch up" and stop using pushrods and make more DOHC engines.

Why?

Here is an artical that spells the whole thing out to somone that dosn't know much about the difference and just jumps on the band wagon....

Pushrods will ALWAYS be superior then OHC in my eyes ANYDAY.

http://www.v6performance.net/forums/showthread.php?t=27941&page=1&pp=30
 

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1976 Eldorado project
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I like pushrods :)

The ones going into the 500 are 3/8" diameter. Woohoo!


Seriously though,

I don't see any flaw in the pushrod design, therefore I don't understand what is so bad about it. However, I have no problem with OHC engines either. Both are great designs and thats why they are still around and used by many. I guess I'm kind of a neutral.
 

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I've got nothing against pushrods, I just wanna try something new :)
 

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Discussion Starter #4
What about folks that call OHV "old tech" and that GM needs to catch up with the times?

OHC predates OHV.... there is nothing old about it.
 

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1987 Fleetwood Brougham
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It just makes more sense to me to have 1 cam and not 2 or 4. It's cheaper to manufacture and cheaper to upgrade. Sure, the amount of moving parts in the valve train increases, not allowing for high RPM, but how many Cadillacs do you see up at 9,000 RPM anyway? Heck, even the new LS7 only hits in the range of 6500 RPM. Sometimes people forget that street motors are supposed to run on the street. That means low RPM, high torque, cheaper costs. OHV lends itself perfectly to all 3.

I own 4 cars and a motorcycle. All of them are single cam, pushrod, OHV engines. :D
 

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2002 Seville STS F55, 2006 Mazda Miata
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A lot of people these days want smooth highway passing power. OHV engines are a little rough and tend to run out of breath at high speeds. There's exceptions, but its not the rule.

I dont mind them myself. The 3800 is particularly nice for regional and local driving.
 

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94 FWB, 93 SDV, 94 FWB (sold), 90 Brougham (sold)
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Both have their ups and downs. There are simply too many variables to consider to make a judgement stating one is better than the other. Vehicle weight, intended use, normal driving RPM, rear-end gearing, tire-size, the list goes on and on about where an engine needs to make usable power.
 

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Jesda said:
OHV engines are a little rough and tend to run out of breath at high speeds.
That has nothing to do with the valvetrain style; OHV, SOHC, DOHC, suction valves, side valve flatheads, solenoid electronic valves, it doesn't matter. The duration, overlap, and lift of the intake and exhaust valves controls the power band and smoothness of the engine. A modern MAF-controlled car can easily produce a smooth idle and plenty of power at the top of the band with a single cam, pushrods, and OHV

MAP and carbureted cars, well, it doesn't matter what style valvetrain you have. You're going to get a rough idle for power up top or a smooth idle for power down low. There is no computer to fix the fuel mix and ignition curve for your aggressive cam at idle :D An MSD 6-AL can help though.
 

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Discussion Starter #10
Jesda said:
A lot of people these days want smooth highway passing power. OHV engines are a little rough and tend to run out of breath at high speeds. There's exceptions, but its not the rule.

I dont mind them myself. The 3800 is particularly nice for regional and local driving.
the supercharged 3800 in my fathers '99 Grand Prix GTP would end any and all comments about a pushrod having smooth and lots of highway passing power.

Come to think of it, I don't know of any modern pushrod engine that struggles to pass on the highway... only things that come to mind are severly low-power, too big of a car.... cars... like the HT4100 and 307 in 80's Broughams.

my '79 DeVille, '89 Delta 88 and '93 DeVille all have alot of smooth highway passing power....
 

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Discussion Starter #11
FrankieSixxxgun said:
That has nothing to do with the valvetrain style; OHV, SOHC, DOHC, suction valves, side valve flatheads, solenoid electronic valves, it doesn't matter. The duration, overlap, and lift of the intake and exhaust valves controls the power band and smoothness of the engine. A modern MAF-controlled car can easily produce a smooth idle and plenty of power at the top of the band with a single cam, pushrods, and OHV

MAP and carbureted cars, well, it doesn't matter what style valvetrain you have. You're going to get a rough idle for power up top or a smooth idle for power down low. There is no computer to fix the fuel mix and ignition curve for your aggressive cam at idle :D An MSD 6-AL can help though.
yeah... but I'll take the no computer and carburator over all the other crap any day....

Power for power.... a 1970 Chevelle SS 454 gurgling, thumpin and jumpin at idle is SO much more aggressive and flat out enjoyable then a new Nissan 350Z that is quiet at idle, its simple. :) Yeah, it woudln't be practical to drive around as a daily driver... then again... give me a 1970 Chevelle SS 454, and I am sure I could make do :)
 

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My daily until I got the Caddy was a 1967 Camaro SS with a totally aggressive 350 small block. I made due :D

And seriously, SCREW computers in cars. Soon as my wife sells her Trans-Am, the Caddy'll be the only car/bike in my garage with a computer.
 

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Discussion Starter #13
nice! :)

ya know... new cars go better, stop better and turn better then old cars...

but just something about all the electronic and computer stuff.... really kills the spirit of an engine.

I notice this so much between the '79 and '93 DeVille.

the 4.9, while in todays standards is old... but its a very refined engine, smooth, responsive... when starting, driving and anything else, its as if its just this thing in front of me that is in its own world.... hard to explain, its a great engine... but its like the soul of it is gone.

the 425... I like pumping the gas to start it, I like the carburator.... its like when I hit the gas pedal, its connected to something beefy and mechanical, not something full of electronics and wires....

but the same could be said comparing the 4.9 to new engines.... now there is throttle by wire and stuff.... I dunno... I like new refined cars alot.... but I think it would be more for a daily driver, it would take alot for me to get into tuning and moding one over, say a classic big block.

Although with the computer, you plug a lap top in and know EVERYTHING about the engine... also to a more simple degree is the on board diagnostics on the Caddy..... that is just cool too.

So I guess I can say.... I'm glad I have both :)
 

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ben72227 said:
Pushrods suck:devil:

OHC's are better; because HONDA says so:devil::devil::p:devil::devil:
Nyah nyah-nyah nyah-nyah nyaaaaah! :nyanya:
 

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The newest vehicle we own is a '90 0lds 98 regency (my caddy is a 89)- ancient by todays standards in technology. But we travel a bit and always rent a car and so we have sampled some of the newer cars Detroit and Asia have to offer.

There is no question about it, the cars they are making today are great; speed handling, technology; I love it. I read with fascination and awe the latest advances in the cars today and try to imagine what is in the future.

But, my two favorites to drive are my '88 Big Blue Kidney Buster 3/4 ton 4x4 Chevy Pick up and my '68 Pontiac Lemans.

The PU has a 350 with 190K. It has tons of power, the engine and drive train are tight, and it uses almost no oil. A Cheyenne, it has almost no options (the AC was put in later!), and is a brute to drive. The 3" exhuast growls when I stomp on the gas (which is great for scaring little old ladies doing 20mph in a 50mph zone when I pass them). There is absolutely nothing refined about that truck but I love it.

My pontiac is my toy. I love the older style of cars but lets face it, the damn things, compared to the handling of cars today, are almost death traps. The 4 drum brakes are horrible for slowing down quickly at highway speeds, heaven help you if the brakes get wet. The handing and response, compared to todays cars, is like a horse and buggy. It is kinda funny, to me, when I drive the Pontiac most of the time in the summer and then get in the caddy. In particular the gearing for the steering is so different. You have to spin the wheel on the Pontiac so much more when making a turn that I have to be carefull not to turn into the curb with the caddy. The pontiac also doesnt have power brakes so the first time I use the brakes in the caddy, or truck, is kinda funny.

But after those long days at the shop, I put down the top, and all the worlds hassles go away. I enjoy the slight shake of the old V8 under the hood and the low rumble when I come up to speed. Certianly the admiring looks from other drivers is nice for the ego as well.

Push rods, OHV, it is whatever brings a smile to your face that is important. 20 years from now OHV may well be antiquated and 100 years from now..... who knows.

K
 

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OHC is a far simpler design , less to go wrong less weight in the valvetrain ,less friction losses ....

The battle to get the new z06 engine to run damn near 8,000 rpm was won in removing wieght in the valvetrain ...very exotic stuff going on in there ...metals and teqniques that till the past few years werent there or werent cost effective ...

There is most likely more technology in the z06 engine or the new 3.9 vvt pushrod engine than in any present honda engine ...honestly....

weight weight weight ...thats the eninmy of horsepower and freind of torque (to an extent)...cranks, pistons, conrods all weigh one number when still , but spin them and the weight grows expoentially ...
too bad horsepower is purely an advertiseing number , means nothing ...

honda always pulled the big HP numbers , and the big rev numbers , if you look at there stuff its very light ....they pay ALOT of attention to weight , years ago the only way to get the weight out of the valvetrain was to run the cams up top ...they make high winding 4 and sixes , and tell everyone there makeing 240 hp from 2.4 liters ....a number thats great , and something you wont see in a V8 , a factory stock V8 i dont think will ever produce hp per liter numbers as a 4 cyl will , because of all the weight and friction involved ...as displacement and cylander numbers goes up , hp per liter goes down ...and torque goes up ...

NVH in pushrod engines has been an issue , yes there smooth but mathmateicly theres more parts and more surfaces working against eachother ...OHC has less parts less chances that toleraces are out of whack ...and from what ive seen have beatter controll over valve spring bounce ......if you ever get a chance to see the pushrod engine's valvetrain under the rocker covers on a high speed camera youll cringe at how things bounce and float around ...
 

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I'll agree that horsepower is a marketer's best friend, but horsepower does mean something. If I could say I had 400 horsepower in my 90 Brougham, it would mean something special because everyone knows it has a 350 TBI which will NEVER see the likes of anything above 4500 RPM. If people were to say "I have xxx horsepower at xxxx RPM," that would really clear things up. I mean, the only reason the new M5 has 500 horsepower is because the thing has to rev to all high hell to get there, but if you realize that it has 500 horsepower at a little over 6000 RPM, that's still 389 ft. lbs or something like that (just going off of memory).
 
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