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Old 06-24-2010, 05:33 PM   #30 (permalink)
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Join Date: Apr 2009
Location: Arkansas
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The Van - '97 Mercury Villager gs
90 day: 19.8 mpg (US)

Lyle the Kindly Viking - '99 Volvo V70
90 day: 25.82 mpg (US)
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Originally Posted by Frank Lee View Post

It has torque down low and doesn't need hp on high.

OHV = more compact. No timing belt to service either.

Cast iron cyls = the best wear characteristics.

Monoblock i.e. no separate cylinder sleeves = the most reliable. And inexpensive.

KISS = Keep It Simple, Stupid.

Civics pretty much aren't getting any better fe than the Coupe.
I love the Tempo myself, but mine was lucky to get over 30 mpg (3 speed auto; I ran 60 @3000 rpms)

The OHV may be more compact, but more simple it isn't. The pushrods only add to the weight and complexity while reducing its power and maximum rpms.

I would say though the weight of the block isn't the problem with a pushrod engine (and timing chains are a PAIN to get to compared to a belt, although the change intervals are longer) but rather the design. Having the cams lifting the tappets directly is much simpler than the cam pushing the lifter which pushes the pushrod which lifts the tappet.

AFAIK, the aluminum block/cast iron sleeve method is straight forward and reliable. My Max has an aluminum block and DOHC run by 4 timing chains, yet there is no recommended interval on changing the chains and this engine is known to last over 500k miles without problems.

When the Explorer did away with the pushrod and went with an OHV, the mileage went up. I know of a guy managing to eek out 30 mpg from a 2wd Explorer with the OHV engine. With a lot of hypermiling and even shutting off half the cylinders on my pushrod Explorer, I managed to get 19 once.
RIP Maxima 1997-2012

Originally Posted by jamesqf View Post
I think you missed the point I was trying to make, which is that it's not rational to do either speed or fuel economy mods for economic reasons. You do it as a form of recreation, for the fun and for the challenge.
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