351C 2V HP rating
351C 2V HP rating
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From: East Bend, Carolina, U.S
A 1973 4V 351C was rated @ 264 HP. I think with your cam, headers, aftermarket intake, carburetor and better ignition you are easily in the 300HP plus range. If you were to raise the compression ratio a bit higher than the 8.0:1 your 1973 engine has, then the HP can be even higher.
A 1972 2V 351C had 8.6:1 compression ratio, so one year made quite a lot of difference in compression ratio alone. I can't say what the HP rating for a 1972 2V 351C is, but it is higher than the 159 HP that a 1973 2V 351C has just because of the compression ratio differences.
A 1972 2V 351C had 8.6:1 compression ratio, so one year made quite a lot of difference in compression ratio alone. I can't say what the HP rating for a 1972 2V 351C is, but it is higher than the 159 HP that a 1973 2V 351C has just because of the compression ratio differences.
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From: Austin, Tx
Don't know too much about engine internals. How do I raise engine compression? My engine is a 2V so then it was a 159 hp engine. It felt very strong when it was stock before the overhaul. The reason I decided to do the overhaul was because I was gona restore the mach and decided to start with the engine. Since I moved, that plan has died and now the engine is going into a '74 truck for now. It did not smoke and basicaly ran very well but now I've spent about $2.5k to $3k just on parts an machine shop. Parts for this engine are very hard to find.
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You also have to be careful due to the fact that it was in that time frame that Ford (and everyone else) switched from "gross" horsepower ratings to "net". Makes a big difference when you factor in accessories. I would think the difference between the 230 hp and 159 would be that the 72 was rated gross and the 73 rated net. A little over half a point of compression wouldn't effect it to the tune of 71 horsepower. My money would be on net vs. gross.
Last edited by CJJTulsa; Mar 10, 2004 at 06:18 AM.
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From: Austin, Tx
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I thought so.....
Scroll down to the years you need:
http://home.pon.net/hunnicutt/history_eng.htm
The 240 hp vs 177 hp are gross vs. net.
http://home.pon.net/hunnicutt/history_eng.htm
The 240 hp vs 177 hp are gross vs. net.
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From: East Bend, Carolina, U.S
There was a drop in hp from 72 to 73 because of compression ratio changes and not from net hp ratings.
The biggest drops in hp in the 1970's engines were the results of lowering the compression ratios alone.
The biggest drops in hp in the 1970's engines were the results of lowering the compression ratios alone.
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1970 and 1971 still used gross hp ratings - the 1970 closed chamber, 10.7:1 engine was rated at 300 hp; the 1971 open chamber (CJ), 9.0:1 engine was rated at 280. The CJ did have a more aggressive cam, but it is still only 20 hp less with 1.7:1 less points of compression.
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From: East Bend, Carolina, U.S
Lets compare apples to apples. A 4V 351C and a 351 CJ are very different and is like comparing apples to oranges.
All of the 2V 351C engines are very comparable in the cams, intakes, exhaust systems and carburetors used. This is a very stable area to make comparisons. The hp losses are relative to drops in compression ratios.
Now when comparing the CJ, Boss and HO engines you are going to find a variety of differences in cams, heads, intakes and carburetors. Even with all of these differences they all had hp drops relative to drops compression ratios.
CJJtulsa,
What else is so common to all of these engines to cause the loss of hp?
All of the 2V 351C engines are very comparable in the cams, intakes, exhaust systems and carburetors used. This is a very stable area to make comparisons. The hp losses are relative to drops in compression ratios.
Now when comparing the CJ, Boss and HO engines you are going to find a variety of differences in cams, heads, intakes and carburetors. Even with all of these differences they all had hp drops relative to drops compression ratios.
CJJtulsa,
What else is so common to all of these engines to cause the loss of hp?
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"What else is so common to all of these engines to cause the loss of hp?"
The common thread is the way of rating the horespower.
http://www.geocities.com/mini-ss/mach1.html
Notice that in 72 Ford started with net hp ratings; and between 72 and 73, the 351C 2V went from 8.6:1 to 8.0:1, and lost 9 hp at a .6 point loss of comression, and were rated by the same standard. As you can see, the difference in power between 71 and 72 is 77 hp at a .4 point loss in compression - the biggest difference is in the method that they were rated.
The common thread is the way of rating the horespower.
http://www.geocities.com/mini-ss/mach1.html
Notice that in 72 Ford started with net hp ratings; and between 72 and 73, the 351C 2V went from 8.6:1 to 8.0:1, and lost 9 hp at a .6 point loss of comression, and were rated by the same standard. As you can see, the difference in power between 71 and 72 is 77 hp at a .4 point loss in compression - the biggest difference is in the method that they were rated.
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From: East Bend, Carolina, U.S
Somehow there must be a difference in our sources for engine specifications. I see 177 hp for a 72 2V 351C and 159 hp for a 73 2V 351C. That is a drop in 18 hp for a compression ration drop of .6. If this isn't correct then I apologize in advance for having an invalid source of engine specs.
Anyway you slice it or dice it, the compression ratio drops caused lost hp in engines that were victims of the EPA during the 70s. Basically the 335 series engines went from compression ratios as high as 11.7:1 to a low of 8.0:1. The method of measuring hp on a dyno could have been the same for all of them and a major loss of hp will still show up.
Emissions equipment had a part in the hp loss too, but not all vehicles were required to have this eqipment. It will be hard to make a valid comparison of hp losses throughout the Ford cars and trucks based on emissions equipment, so I'll leave that one alone.
I'll take a stock 1970 2V 351C equipped car to the drag strip and take on any stock 72 and up 2V 351C, 351M, or 400 equipped car. Dare to guess which one will win in a big way? Just ask anyone who drove these old cars around much back then and see which one they would bet on?
Anyway you slice it or dice it, the compression ratio drops caused lost hp in engines that were victims of the EPA during the 70s. Basically the 335 series engines went from compression ratios as high as 11.7:1 to a low of 8.0:1. The method of measuring hp on a dyno could have been the same for all of them and a major loss of hp will still show up.
Emissions equipment had a part in the hp loss too, but not all vehicles were required to have this eqipment. It will be hard to make a valid comparison of hp losses throughout the Ford cars and trucks based on emissions equipment, so I'll leave that one alone.
I'll take a stock 1970 2V 351C equipped car to the drag strip and take on any stock 72 and up 2V 351C, 351M, or 400 equipped car. Dare to guess which one will win in a big way? Just ask anyone who drove these old cars around much back then and see which one they would bet on?