From: Glenn Shaw (mpmutt@mtaofnj.us)
Date: Sun Apr 25 2004 - 08:39:22 PDT
Hi
Sorry but you were mislead. It is not based on any of the old wives
tale stories of how it came to be. It is not based on the 5.7 Chevy,
the 5.7 Olds, BOP's, 454 Chevy, 502 or any of them. If you look into it
for yourself (forget the numerous self styled experts) and read the
documentation from the Detroit Diesel/Allison Corp, Div of GM at the
time, you will find that it was and is a totally new design from the
ground up by DDA. It has no cracking problem history at all in the main
web area. As a matter of fact it was specifically designed for extra
high strength in that area and given thick walls and webbing, heavy duty
4 bolt main caps and forged crank. It was designed for longevity in
light duty diesel service with its forged cam and roller lifters, and
good fuel economy with its precombustion chamber indirect injection
system. It did have a history of cracks in the heads in the valve aea
which turned out to be a non-problem in most cases. To be fair it also
developed cracking near the head bolt bosses in the area of the #8
cylinder when it was turbo supercharged later on as the 6.5 version in
the quest for more power. This tendency was corrected in a later block
change on the 6.5l. The 6.2l and the NA 6.5l. Did not normally exhibit
this issue.
Later
Glenn
MVPA
MTANJ
-----Original Message-----
From: Colin M Rush [mailto:chesnimnus@juno.com]
Sent: Sunday, April 25, 2004 2:59 AM
To: Military Vehicles Mailing List
Subject: Re: [MV] Chevy turbo diesel exhaust
What I was told a couple years ago by a guy that runs an engine rebuild
company is that the 6.2 diesel was based on the Big Block GM motors, not
the SBC. I believe he said it was a variation on the 502, which itself
was a larger version of the 454 that most folks are familiar with.
Problem with them is that the block is just not strong enough to handle
the torque that either the 6.2 or the 502 put out, so they have cracking
problems in the main webbing. I would find a big block Chev manifold
and look at it. -Colin Rush
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