Pushrod or OHC

[targa]

Originally Posted by Slicks

I havent heard of any I pushrod engines...

the model T & model A were two-valve OHV push-rod inline4's

[jcp123]

Originally Posted by Matra et Alpine

go pull the camshaft out of an in-block cam OHV engine and then do the same on an OHV
The weight issue is unproven when comparing LIKE with LIKE. Agreed when it's OHCs on a V or DOHCs. But single cam it's LESS weight ( no pushrods or followers ( heavy steel ) for slightly more head casting ( alloy ). See the Ford Pinto engine as prime example.
Maintenance - try to replace a cam follower in a OHV engine compared with OHC when all other factors remain the same !!
Sorry jcp, but the issues of complexity and ease of maintenance are MORE down to 1970s V8 engine versus 2000s OHC in many cases. Take an OHV engine and it is as complex as an OHC for the same emissions.

The BIG differnecs is in an OHV engien you dont' get to see the cam drive belts and tensioners and the followers, buckets and rods. Because on an OHC you SEE all those things it's easy to imagine it's more complex

Well of course anything I say is tinged with the "classic is better than new" thing; I firmly believe that for some things. I have an OHV V8 in a '68 Mustang and naturally it's easier on maintenance than these things they make these days; let's forget that emissions stuff, I don't have it, I don't deal with it, I don't know anything about it. But with the extra width of a V-type OHC engine, that makes things harder to maintain when you can't reach around it. Inlines, okay, it's about even. But as I recall, my 302 weighs a little less than the current 281ci OHC V8 used in the Mustangs, and it's definitely smaller in every dimension but displacement.

Or let me put it to you this way: Pretty much all the cars I like have OHV engines. It's tried and true, and the simplest way to get the torque on the low end, which suits the way I drive (I haven't been much over 60mph in ages, even with the ~1000 miles of freeway driving in recent memory). Case closed for me. Since we're not going to convince each other of anything...let's leave it at that.

[Slicks]

Originally Posted by johnnynumfiv

Save some some money up and do it. You would still learn something, its better than nothing. I've learned a lot just taking apart lawn mower engines and A-series bmc engines, very simple designs but the principles are still there.

Maybe when im not a poor college kid, I dont have the money to go out a buy engines that im going to tear apart and do nothing with, on top of that I have no where to tear them apart or store them, the garage is full.

[Slicks]

Originally Posted by henk4

Just take a look at the pic Johnnynumfy sent.

If you want to tease Matra you might want to tell him that all Alpine A110 engines were Renault based pushrod in-line fours.

Heh, ill keep that in mind

It is just a pity that engine builders fail to read your posts, otherwise they would immediately order there development departments to reinvent the pushrod engine

Please read what I wrote on page 3. Its too late for companies to "start over", DOHC has alreasy been marketed as "high tech" and by switching to pushrod they would be admitting they were wrong, and that GM was been smart for sticking with that design. Whether its better for a certain application or not, the marketing biasness is already there. Think about it, would Ferrari buy an engine from lamborghini, even if it was superior in every way, and would make the car they put it in travel through time? No, because that would be like admitting that lamborghini has done something better, and that would be bad marketing for ferrari, its that simple.

hmm, think about when the big switch to OHC from OHV was done by most companies. Late 70s, early to mid 80s, the time where emissions were killing power for almost every car, and technology was at a "low" point. The OHV design was very restrictive compared to the OHC design of the time. And thats where alot of the biasesness comes from. But the OHV air flow is alot more even to DOHC now than it was then.

[jcp123]

Originally Posted by targa

the model T & model A were two-valve OHV push-rod inline4's

The Ford Model T/A 4-cylinders (and the V8's for that matter) were flathead, not ohv, as were most other engines of the day.

Look at the Chevy inline 6 from the 30's all the way up through the 70's. The GM Iron Duke 2.5l I4. The Chevy 2.2l I4 used in the Cavalier. The Ford inline sixes from the early 50's even into the 80's were pushrod. And almost all volume models from the mid-50's to the 70's had some kind of pushrod, inline 6 (Studebaker, Rambler/AMC, Ford, Chevy, Dodge, Plymouth, etc.). Even those fun lil british roadsters from the 50's and 60's were powered mostly by pushrod-actuated, OHV I4's (or sometimes even I6's)

And think about this: A V8 is basically two inline 4's put together at a 90* angle.

[johnnynumfiv]

Originally Posted by Slicks

Maybe when im not a poor college kid, I dont have the money to go out a buy engines that im going to tear apart and do nothing with, on top of that I have no where to tear them apart or store them, the garage is full.

O well, when you get the chance, it is definetly well worth the money, it probably wont be more than a few hundred for both.

[Slicks]

Originally Posted by Matra et Alpine

I'm ignoring the rest because I'm in a bad mood and you've just demonstrated how little you know and I will likely spend the REST of your post correcting all the other misconceptions you continue to spout forth.

g'night

wow, someone needs to chill, god knows its not like you've never been wrong, and Ive been patient with you.

Well soooory that I havent heard of an I pushrod engine, in that case, yes, I would much prefer an OHC design.

BTW im waiting for that list...

[jcp123]

I think Buick also had an OHV inline 8 in the late 40's/early 50's? I could be wah-rong on that...

[Slicks]

Originally Posted by Matra et Alpine

erm, but they ALL have to have the major components or they wear out VERY quickly.
See you're talking through the orifice on the WRONG end of your body.
You clearly haven't a CLUE what actually happens inside an engine be it OHC or OHV So please refrain from debating the issue as it makes us all feel bad pointing out your stupidity !!

IF you want to know, I'll gladly do a "Slicks camshaft components 101" thread as before

Did I say anything about them not having their "major" components?

Why do you assume that I dont know what happens inside an engine? Yes, I dont know exactly every part, but the design in general yes. (howstuffworks has some little .gifs for example)

Heh, another 101 thread, great, for your reputions sake ill not mention that 20% formula you made up, heh, that still make me chuckle.

[henk4]

Originally Posted by jcp123

I think Buick also had an OHV inline 8 in the late 40's/early 50's? I could be wah-rong on that...

No you are not.

[henk4]

Originally Posted by Slicks

Please read what I wrote on page 3. Its too late for companies to "start over", DOHC has alreasy been marketed as "high tech" and by switching to pushrod they would be admitting they were wrong, and that GM was been smart for sticking with that design. Whether its better for a certain application or not, the marketing biasness is already there. Think about it, would Ferrari buy an engine from lamborghini, even if it was superior in every way, and would make the car they put it in travel through time? No, because that would be like admitting that lamborghini has done something better, and that would be bad marketing for ferrari, its that simple.

I read your marketing hint, but I can tell you that if you ask 9 out of 10 carowners where they think their camshafts are, they would probably look at you as if you were making them an indecent proposal. They simply have no clue what it is. There is not even one company now that would consider reintroducing pushrods. Even GM that could, and I admit it rightly, pojnt at the success of the LS series engine, is not considering in any way to go back to pushrods (" a proud part of the heritage of the small block engine") for any other engine type that they are producing and certainly not for the markets outside the USA. You could also inverse the marketing argument. A Corvette buyer would never go for OHC's because the Corvette needs the small block. (the fact that the ZR-1 was about 30000$ more expensive than the standard version may have contibuted also to its failure)
Finally I very much doubt whether Lamborghini would be willing to sell an engine that would allow time travelling to any one.

[SlickHolden]

GM had there chance to take up a OHC Engine that was as smove as a babys bottom in the 80's. But they closed it down when it was ready, today if that engine was being built they would have something like the rest have if they just let holden get on with it.

[fpv_gtho]

Originally Posted by SlickHolden

GM had there chance to take up a OHC Engine that was as smove as a babys bottom in the 80's. But they closed it down when it was ready, today if that engine was being built they would have something like the rest have if they just let holden get on with it.

And then there was that supposed shut down by GM of Holdens attempt to convert "their" 304 V8 to SOHC in the late 80's.

Seriously, i find it a laugh to shut down a DOHC V8 for its "high cost" in its first use, if GM had kept the LT5 in full production by now the engine would have payed itself off and they'd have a nice, cheap DOHC V8. The thing definately made power, around 400hp IIRC so thats not bad considering the LS6 was making "only" 380hp or so when HSV went hunting after it for the VT2 GTS.

[KnifeEdge_2K1]

pushrod's main advantage is compact space, you dont need huge cams and cam gears ontop of the heads, its just rocker arms (i think thats what they're called) and the .. well push rods

overhead cams however enabls engineers to put 4 valves per cylinder (hard to do with pushrods, and really hard on hemis) which supposedly increases fuel efficiency and power, ohc also feature a certain degree of flexibility since the cams which control the valve timing is readily accesible while on a pushrod engine the cams are deep inside the "V", unless it's an inline pushrod at which point things just get funky

[Slicks]

Originally Posted by henk4

I read your marketing hint, but I can tell you that if you ask 9 out of 10 carowners where they think their camshafts are, they would probably look at you as if you were making them an indecent proposal. They simply have no clue what it is. There is not even one company now that would consider reintroducing pushrods. Even GM that could, and I admit it rightly, pojnt at the success of the LS series engine, is not considering in any way to go back to pushrods (" a proud part of the heritage of the small block engine") for any other engine type that they are producing and certainly not for the markets outside the USA. You could also inverse the marketing argument. A Corvette buyer would never go for OHC's because the Corvette needs the small block. (the fact that the ZR-1 was about 30000$ more expensive than the standard version may have contibuted also to its failure)
Finally I very much doubt whether Lamborghini would be willing to sell an engine that would allow time travelling to any one.

Im not talking about asking car owners where they're cams are, but if their engine is the "high tech" "DOHC" or "pushrod", some may not know, and most wont know what that means, but the fact that the engine is marketed at "high tech" will most certainly attract more buyers.
GM is still making pushrods other than the LS series, and are introducing VVT in a 3.9L V6(OHV) they are working on.
The next step up is computer controled valves, camshaftless engines.

The ZR1 was also 2-300lbs over the base LT1 Corvette, hmm, I wonder what add all that weight... Both the LT1 and LT5 (based off the LT1) were aluminim engines, but the LT5 weighed 100lbs more than the LT1, what could have added all that weight, technology?
The fact remains that the C6 Corvette is a 400hp, 400ft-lbs car, and the pushrod works perfectly fine for that.

Other than the price of the Zr1 making it fail, it gained about 2-300lbs over the OHV version... I wonder why...
BTW Ill say it again, the LT5 was 100lbs heavier than the block it was based off of, the LT1. Hmmm, why is that?