Re: IML: Dope on The 413

["Brent Covey" <brentcovey@xxxxxxxxxxx>]

Bill in Vancouver writes;

> That 413 with 228 gross HP and 400 torque is actually quite anemic.  I
know
> the truck 413 was available with a 2-bbl carb, but that 228 bhp pales in
> comparison with the 1959 Imperial's 350 gross bhp and 470 lbs feet of
torque
> (4-bbl carb and 10.0:1 compression ratio)

You're comparing apples and oranges, Bill-

The truck engine is the 413-3 ( the car is the 413-1 family) which is a very
heavy duty version of the passenger car engine, it has top quality materials
and a few modifications such as better cylinder head cooling provisions.
Truck engines always used net horsepower ratings and consequently rated much
lower than the gross ratings used in car engines of the pre 1972 period.
This is neccesary for truck engines particularly because trucks must be
spec'd for their actual vocation and knowing the weight, tire size,
aerodynamic demand resistance hp and altitude and grades the truck is likely
to encounter permits a fleet buyer to order an appropriate axle ratio,
transmission and engine to make sure his trucks can handle the cargo and
terrain they're going to encounter. Fudging the engine output would make it
very difficult to know which truck to buy so the ratings need to be pretty
close to the truth in truck engines.

The old truck net ratings are still a little on the high side because they
are corrected to a very cold ambient temp compared to actual underhood air
temps but they're roughly comparable to the system used for passenger cars
after the early 1970's when the cars got net HP ratings finally. You may
recall back in the early '60's a lot of big rig type semis had gasoline
power, GMC offered a 702 V12 that was two 351 V6's basically, and Chevrolet
offered the 409 in a truck version with very heavy duty upgrades.

The actual difference between an Imperial 413 and a truck is about 30 gross
hp, the truck engines operate on regular gas and have lower compression, and
likely a tamer cam profile among other small tuning changes. The net torque
rating will be very close to the car net rating but peak HP will be slightly
lower from the tuning for maximum low speed torque. If you compare the 413-3
rating to the 1973 440 car engine you'll discover its not so bad at all for
output. The lower compression eats about 10% of the power, and the truck
engines arent set up to reach maximum power at speeds over 4000 rpm, like
cars, which inevitably reduces the ultimate max HP you'll see even if its
just as powerful at lower rpm ranges.

My interest in the 413-3 is because it was a wonderful engine in the Dodge
Motor Home Chassis, and I'm the Travco Mailing List administrator. I think
the Travco (also known as the Dodge Motor Home prior to 1965)  was the only
'factory' Chrysler product that cost more than Imperial for every model. The
early models used a heavy duty 318 polysphere engine

For more Travco information visit;

http://mytravco.com/

or join the mailing list

http://autos.groups.yahoo.com/group/travco/

For a wild link taking a look at the 318 Poly engines

http://www.bbc.co.uk/dna/h2g2/A1149266

I think some of the changes in the 413-3 (there was also a 440-3) might be
beneficial in an Imperial used for towing or other extreme duty operation,
just being able to run regular 87 gas might be nice;-) Imperial had a
wonderful reputation as a tow vehicle back then, considerably ahead of
Cadi**ac due to the relatively 'easy to live with' high compression engine
(Brand X pings like a pig when its hot) and the leaf spring rear suspension
made it a very stable towing platform. The excellent 727 transmission is
well suited to trailer towing as well, and Imperial had the largest standard
tires in the industry.

If the Imperial just isnt spacious enough for you and you really would like
extra luxuries hitherto unavailible in Imperial, like a toilet that
incinerates its contents ("Destroilet"), a 220V a/c unit or a hot water
shower, well, have a look at the Dodge Motor Home.

Brent Covey
Vancouver BC





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