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Discussion Starter · #1 ·
Spawned by a recent CL debate, I thought I would start a poll.
Which engine design do you think is superior? DOHC/OHC or OHV
DOHC/OHC - camshaft(s) mounted directly above cylinder head
OHV - camshaft mounted in cylinder block
To be specific, modern production vehicles
I prefer......


Modified by CannuckCorradoVR6T at 1:21 AM 7-23-2006
 

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Re: (gotapex)

Quote, originally posted by gotapex »
Depends on the individual engine design. Each config has its advantages and disadvantages, it just depends on how well the manufacturer takes advantage of those qualities.

x2
 

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Re: DOHC/OHC vs OHV (xdre)

umm since I like revving, and like technology too, I go for overhead cam designs. OHV is an old, outdated technology. Very old.
I can't tell you how many cars with an OHV design I heard that the rods floated.


Modified by Seanathan at 5:21 AM 7-23-2006
 

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Re: DOHC/OHC vs OHV (Seanathan)

Quote, originally posted by Seanathan »
umm since I like revving, and like technology too, I go for overhead cam designs. OHV is an old, outdated technology. Very old.
I can't tell you how many cars with an OHV design I heard that the rods floated.

Modified by Seanathan at 5:21 AM 7-23-2006


OVC is just as old as OHV, and just because an engine is one or the other doesn't mean it's going to rev higher. The redline in my 6L GTO is exactly the same as it was in my 2.8L VR6.
 

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Re: DOHC/OHC vs OHV (jeremyc74)

Quote, originally posted by jeremyc74 »


OVC is just as old as OHV, and just because an engine is one or the other doesn't mean it's going to rev higher. The redline in my 6L GTO is exactly the same as it was in my 2.8L VR6.

The 1967 Pontiac Firebird had an OHC straight 6 that leaked enough oil to make an Arab cry.
The only "outdated" valve design would be flathead.
 

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Re: (gotapex)

Quote, originally posted by gotapex »
Depends on the individual engine design. Each config has its advantages and disadvantages, it just depends on how well the manufacturer takes advantage of those qualities.

+1
i wonder how long before this becomes a flame fest.


Modified by munkey at 3:12 PM 7-23-2006
 

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Re: DOHC/OHC vs OHV (Seanathan)

Quote, originally posted by Seanathan »
umm since I like revving, and like technology too, I go for overhead cam designs. OHV is an old, outdated technology. Very old.
I can't tell you how many cars with an OHV design I heard that the rods floated.

Modified by Seanathan at 5:21 AM 7-23-2006


OHC is actually an older technology than OHV. OHV engines were designed to save space by reloacting cam down in the block. OHV is actually more sophisticated than OHC (especially when you compare the new VVT OHV engines to VVT OHC engines of today)
 

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There is no *inherent* reason why OHC would give "better efficiency and fuel economy". NONE.
Case in point: the GM 3800 V6 is well known for being a very efficient design ... complete with pushrods and 2 valves per cylinder. But it WORKS, because someone did their design work properly way back when.
Having said that, DOHC is an "enabling" feature for other efficiency-boosting systems like Honda's VTEC, numerous manufacturer's variable-valve-timing schemes, and BMW's Valvetronic. None of those things are realistically possible using a single cam buried in the engine block.
BUT ... Pushrods are an enabling technology for Chrysler's MDS (multi displacement system) and GM's similar Displacement On Demand system. Yes, it is POSSIBLE to do that with overhead cams, but it's more complicated.
 
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