CJ 304 HP and Torque vs. 225 - Off-Road Forums & Discussion Groups
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post #1 of (permalink) Old 05-25-2002, 11:18 PM Thread Starter
 
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CJ 304 HP and Torque vs. 225

According to everything I can lay my hands on, the early 304s had 150 hp and 245 ft lbs of torque. Most of the Buick 225 V-6s had 160 hp and 235 ft lbs of torque--at approx the same rpm. Bore is the same, stroke slightly longer on the V8. However, we hear stories of how AMC had to start boxing the front part of the frame because the 304s were cracking them. Granted the V8 is heavier, but only slightly more torquey, so why is this? I know that AMC sold the 225 tooling back to Buick, so this probably accounts for some of why they used the 304, but other than that, wouldn't this indicate the 225 was a better engine overall for a jeep than the 304? Especially considering the weight savings and fuel economy? Is there some other factor I'm not considering? Granted, I'm not planning on yanking my 304 out to replace it with a V6 (I'm looking at a 401 actually....), but it seems to me that the V6 might overall be a better choice for replacing a worn out 304 than another 304. Opinions on this? Am I overlooking something? (Besides the cool sound of a V8 exhaust--"coolness" doesn't help performance)
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post #2 of (permalink) Old 05-25-2002, 11:43 PM
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Re: CJ 304 HP and Torque vs. 225

I know what you are saying there. Kind of makes some sense. But then you have to think of how a V8 can be built in comparison to a 6 Cylinder. With a little work on the 304 you can get yourself another 50-60 hp fairly cheap and easy. Sixes are buildable but you will cost you a lot more to get it to V-8 numbers. Remeber the old cliche, there is no substitute for cubic inches when it comes to getting power.
post #3 of (permalink) Old 05-25-2002, 11:53 PM
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Re: CJ 304 HP and Torque vs. 225

Here's a simple answer. The 225 was rated before 1973 and the 304 was rated after 1973. You're comparing apples to oranges. This is from <a target="_blank" href=http://www.motorera.com/dictionary/car-dics.htm>this</a> site.

SAE horsepower: A simple formula of long standing is used to determine horsepower. The formula is: (bore diameter) squared times (number of cylinders) divided by 2.5. This formula is used primarily for licensing purposes and is not very accurate for determining actual brake horsepower. Also called rated horsepower. Compare SAE gross horsepower and SAE net horsepower. Also see horsepower.

SAE gross horsepower: A production engine's actual power available at the flywheel or output shaft (usually crankshaft) as tested with an absorption dynamometer. It differs from SAE net horsepower in that many of the accessories (such as alternator, water pump, etc.) are not attached. Engines before 1973 were primarily measured with these "gross" numbers. Since 1973, "net" figures were published. This confusion caused many people to suppose that their engine had been seriously de-tuned when they saw that the same engine in 1972 had 400 hp but in 1973 had only 235 hp. (This example is from the Cadillac 500 cubic inch engine). Compare SAE net horsepower. Also see brake horsepower and horsepower.

SAE net horsepower: The brake power (power available at the flywheel or output shaft -- usually the crankshaft) of a fully equipped engine fitted with all the accessories necessary to perform its intended functions unaided. In 1973, automobile manufacturers began publishing their engine specifications in "net" horsepower and "net" torque instead of "gross" figures. In many cases the published numbers were significantly lower in 1973 than in 1972. Some of the decrease was attributed to the addition of pollution equipment, the lowering of compression, and the use of regular unleaded gasoline instead of premium leaded fuel. However most of the decrease in number was a switch to "net" figures. Compare SAE gross horsepower. Also see brake horsepower and horsepower.

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post #4 of (permalink) Old 05-26-2002, 03:17 AM
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Re: CJ 304 HP and Torque vs. 225

exactly as will explained i had both a 71 cj5 with a 225 and a 74 with 304, the six is not as compareable as your misleading performance stats would have you think,and some will prob disagree but reliability on the buick was not as good either ,with a worse oiling system then even the amc v eights.
post #5 of (permalink) Old 05-26-2002, 10:09 AM
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Re: CJ 304 HP and Torque vs. 225

In defence of the Buick, it is still in production today, of sorts. The GM 3.8L FWD V-6 is a relative of the 225 Buick. The 225 was bored out slightly in '75 to 231 cubic inches or 3.8L. In mid 80's a turbo version was available. Late 80's a FWD 231 replaced the RWD 231. Now even a supercharged 3.8L is available on Buick Regals and Pontiac Bonnevilles. Was available on the Riviera, but that car has been discontinued. AMC V-8's are no longer in production, however the I-6 still is in the form of the 4.0L. But back to the original post, it was the fact that mid 70's cars changed from rating gross hp &amp; torque with no accessories to net hp &amp; torque with accessories.
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post #6 of (permalink) Old 05-26-2002, 02:15 PM
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Re: CJ 304 HP and Torque vs. 225

they stopped makin sb chevys too does that make the buick the better platform?sorry couldnt resist i have a foul taste for buick sixes after working for a gm garage in the late 80s and early 90s.those grande nationals hauled booty but they almost folded buick up from waranty claims.
post #7 of (permalink) Old 05-26-2002, 08:38 PM Thread Starter
 
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Re: CJ 304 HP and Torque vs. 225

Thanks Will, I kinda figured it was something like that, but wasn't sure on the date when they changed the ratings. I knew my 304 had more balls than my buddy's CJ5 with the 225, but sure didn't look it on paper.
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post #8 of (permalink) Old 05-27-2002, 12:05 AM
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Re: CJ 304 HP and Torque vs. 225

I wasn't aware that SBC's were out of production. Seems to me that you can still buy a brand new new one in several flavors. I think they may not be used for new vehicle installations, but are far from out of production.
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post #9 of (permalink) Old 05-27-2002, 10:15 AM
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Re: CJ 304 HP and Torque vs. 225

you got me, miss worded that one a smidge
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