Note the horsepower ratings used by GMC were SAE net ratings. I have no idea
why this was the case, but the 228 was closer to 100 hp using the more
common gross rating. So the 248 has about 10% more HP, which is about right.
An equal mystery is why GMC did not list torque ratings in those days,
because torque is where a GMC shines.
The 228 and the 248 use the exact same head and valves, so the slightly
larger combustion chamber of the 248 results in a bit lower compression.
Higher compression ratio is indeed better, because it directly increases
torque. I am sure someone can offer a more erudite explanation, but the
bottom line is, you can feel it in the seat of your pants, and with your
right foot, too. Racers always increase compression to the ragged edge, but
they have access to super high octane racing fuel. About 9.5:1 is the limit
on pump gas these days. Though some very high tech motorcycle engines are
back up around 11.5:1 using multi-valve heads.
Jack / Winter Park FL
-----Original Message-----
From: THE REIDS <reidx4@gte.net>
To: Carl Cooley <carcooley@webtv.net>
Cc: oletrucks@autox.team.net <oletrucks@autox.team.net>
Date: Saturday, April 03, 1999 7:01 PM
Subject: Re: [oletrucks] Can anyone HELP!
>
>
>Carl Cooley wrote:
>
>> Now to my questions. On the engine by the dist. is a number. It is
>> C24847169 On the post of the door is Serial Number 102-22-S-2763 . I
>> beleive this is the original engine. Truck is solid and unbutchered
>> except for a now old coat of paint. Also the interior was gone from the
>> heat in the southwest. I have the inside redone. If anyone can give me
>> any informationon the date and location of the build of my truck I'd
>> appeciate it. Thanks
>>
>> Carl 51 GMC ( Got it out and ran up and down the driveway today!)
>>
>> oletrucks is devoted to Chevy and GM trucks built between 1941 and 1959
>
> OK, here's more.
>I checked my owners manual (this and the maintenance manual are reprints
>available from most vendors and more than worth the price), all the 100
>series models (101 & 102) all have a gross vehicle weight of 4,800 pounds.
>Series 150 are 5,800 pounds, therefore 102 must be a long bed 1/2 ton.
>Other things:
>rear axle raio 4.11
>248 displacement 248.5 cu.in.
> bore 3 23/32"
> stroke 3 13/16"
> compression 7.5:1
> S.A.E. horsepower 33.19
> Max recommended RPM 3400
>
>for those of us with the stock 228
> displacement 228 cu.in.
> bore 3 9/16"
> stroke 3 13/16"
> compression 8:1
> horsepower 30.45
> Max RPM 3400
>
>now I have a quesion. The two motors are different, with the larger being
>20.5 cu. in. bigger.
>The horsepower is barely different, why is that.
>the 228 has a higher compression, is that because of the smaller bore?
>I've heard a higher compression is better, why?
>Jim Reid
>'53 GMC 101-22 with a 228
>
>oletrucks is devoted to Chevy and GM trucks built between 1941 and 1959
>
oletrucks is devoted to Chevy and GM trucks built between 1941 and 1959
|