'A-Body Showdown' ~ 273 'Commando' vs. 318 2-Barrel

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69 Cuda 440

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A-Body Showdown

273/235 HP 'Commando' vs. 318/230 HP 2-Barrel

1967 Barracuda 'Fastback' ........ #2940 lbs. ~ 235 HP = 12.51 Wt/HP
vs.
1968 Barracuda 'Notchback' ...... #2893 lbs. ~ 230 HP = 12.58 Wt/HP

Near equal in Weight-to-Horsepower Factors.

273 'Commando'
235 HP @ 5200 RPM's
280 Ft/Lbs. of Torque @ 4000 RPM's

318 ~ 2-Barrel
230 HP @ 4400 RPM's
340 Ft/Lbs. of Torque @ 2400 RPM's

"Let The Fish Begin To Swim"
 
Only way the 273 stands a chance is if it is geared lower and a manual trans IMO.But what do i know?
 
496 polara said:
Only way the 273 stands a chance is if it is geared lower and a manual trans IMO.But what do i know?
Click to expand...


Are you aware,

The 318/230 HP ~ 2-Barrel in the 1968 A-Body {Manual Transmission} was only
available with a 3-Speed.

You could not get it with an 'A-833' 4-Speed.

Automatics, both had the A-904.
 
Since recently we found out 318s were factored to 180 HP by NHRA of course the 273 will win. If you put dual exhaust on the 318 then it might be close.
 
69 Cuda 440 said:
A-Body Showdown

273/235 HP 'Commando' vs. 318/230 HP 2-Barrel

1967 Barracuda 'Fastback' ........ #2940 lbs. ~ 235 HP = 12.51 Wt/HP
vs.
1968 Barracuda 'Notchback' ...... #2893 lbs. ~ 230 HP = 12.58 Wt/HP

Near equal in Weight-to-Horsepower Factors.

273 'Commando'
235 HP @ 5200 RPM's
280 Ft/Lbs. of Torque @ 4000 RPM's

318 ~ 2-Barrel
230 HP @ 4400 RPM's
340 Ft/Lbs. of Torque @ 2400 RPM's

"Let The Fish Begin To Swim"
Click to expand...

NHRA Class ~ 12.50 to 12.99 Wt/HP}
1968 ......... J/S or J/SA
1969 ......... K/S or K/SA
1970 ......... L/S or L/SA
1971 ......... L/S or L/SA

Funny. I don't ever recall seeing a {1968 or 1969} 318/230 HP - 2 Barrel
{A-Body} running in those classes Back-in-the-Day.

I do remember seeing a few 318/230 HP - 2-Barrel Plymouth Dusters hitting the
scene in 1970 and 1971, but they were classed in the {12.00 to 12.49 Wt/HP}
weight break.

1970 Duster 318 ....... Shipping Weight = #2834 lbs. ~ 230 HP = 12.32 Wt/HP
 
The 318 will be out of it's "comfort zone" near the end of the track, just as the 273 is hitting it's stride.

Displacement aside, those motors are almost built as complete opposites on the inside.


...yet you could get a six cyl with a 4 speed on the floor.
 
Abodybomber said:
Gears & chassis mods????
Click to expand...

No Mods .......... Stock vs. Stock

273/235 HP 'Commando' ~ 4-Speed with 3.55 Gears
vs.
318/230 HP - 2-Barrel ~ 3-Speed with 3.55 Gears

Remember, the 273 'Commando' came thru with 'laughable' {9.25"}
'Auburn' Clutch Set-up.

The 318 2-Barrel came thru with a bigger unit {10.50"} 'Borg & Beck' style.

That would make a difference,
 
69 Cuda 440 said:
No Mods .......... Stock vs. Stock

273/235 HP 'Commando' ~ 4-Speed with 3.55 Gears
vs.
318/230 HP - 2-Barrel ~ 3-Speed with 3.55 Gears

Remember, the 273 'Commando' came thru with {9.25"} 'Auburn' Cutch Set-up.

The 318 2-Barrel came thru with a bigger unit {10.50"} 'Borg & Beck' style.

That would make a difference,
Click to expand...

Yes it would,on stock tires...
 
This is the very reason Im looking at a 318 build right now. I find myself searching/learning/enjoying reading thru your threads
Thanks again Paul for sharing your knowledge and experiences in a very cool way.
RIP
 
Nice thread revival Steve. Also curious. I wonder if he was talking 1/8 or 1/4 mile. Torque is the big factor. Didn't realize the 318 had quite that much.
 
Thanks Larry. Im assuming Paul was talking 1/4 mile? No times were posted.
Ive been flipping thru Pauls threads while im doing a sb build. Great cool info.
R4Sedan said:
Nice thread revival Steve. Also curious. I wonder if he was talking 1/8 or 1/4 mile. Torque is the big factor. Didn't realize the 318 had quite that much.
Click to expand...
 
I understand Paul's comparison for the sake of conversation, but this is NOT the way to compare a 273 vs 318. A commando 273 was factory equipped with performance parts. If one would want to see the real comparison, then compare a 273 2bbl vs 318 2bbl.
273 2bbl - 180 hp
318 2bbl - 230 hp
 
318willrun said:
I understand Paul's comparison for the sake of conversation, but this is NOT the way to compare a 273 vs 318. A commando 273 was factory equipped with performance parts. If one would want to see the real comparison, then compare a 273 2bbl vs 318 2bbl.
273 2bbl - 180 hp
318 2bbl - 230 hp
Click to expand...
It just kind of shows how not so great the 273 is....
 
4spdragtop said:
Paul was basically showing stock vs stock. It shows how much work is required in the 273 vs 318
Click to expand...
yeah, it needs a hotter cam, compression and a 4bbl to make the conversation good. But rightfully so, it is giving up 45 cubes in bore, and that's a lot.
 
Having had both, the key post is #5. 318 has no chance. The 318 will get first jump, but the Commando will pass it like it's standing still.
 
66fs said:
Having had both, the key post is #5. 318 has no chance. The 318 will get first jump, but the Commando will pass it like it's standing still.
Click to expand...
yes, the commando 273 beats a 318 2bbl. But really not a very good comparison..... i mean comparing a 4bbl, higher compression, hotter cam 273 to a 318 2bbl is just.... blah.
That's like saying a 318 with a 340 cam, 340 4bbl & intake, 340 exhuast manifolds and duals will beat a 340 with a 318 2bbl & intake, 318 cam, 318 exhuast manifolds and single exhaust. Just really kind of...... ok
 
Hang on!
Before this goes crazy
As at 1980, NHRA rated all 318 2bbls, from 67 to 73, as 230hp, in spite of many different deck-heights and head volumes.
AND the 78 to 80 4bbl engines carried the same 230hp ratings, while making just 20 to 25 hp more than their 2bbl counterparts, namely 205hp. Remember that; 20/25hp in the 4bbls

Now as to 273s; NHRA rated the 2bbl versions at 180/190hp, while the 4bbls were 235.
So here we have the 4bbl making 45/55 hp more than the 2bbls;
Draw your own conclusions...................................

As for me; my 273 is staying in mothballs.Unless somebody here gets 273 fever.
 
318willrun said:
yes, the commando 273 beats a 318 2bbl. But really not a very good comparison..... i mean comparing a 4bbl, higher compression, hotter cam 273 to a 318 2bbl is just.... blah.
That's like saying a 318 with a 340 cam, 340 4bbl & intake, 340 exhuast manifolds and duals will beat a 340 with a 318 2bbl & intake, 318 cam, 318 exhuast manifolds and single exhaust. Just really kind of...... ok
Click to expand...

Of course it's not. High performance will usually beat low performance. It does not mean you have to leave your 318 stock, as you have proven the potential. Some people look at the advertised hp and think there is a chance, when there isn't. You have to look at NHRA factored hp, but Chrysler was factored too much anyway to make them uncompetitive.
 
Last edited:
69 Cuda 440 said:
A-Body Showdown

273/235 HP 'Commando' vs. 318/230 HP 2-Barrel

1967 Barracuda 'Fastback' ........ #2940 lbs. ~ 235 HP = 12.51 Wt/HP
vs.
1968 Barracuda 'Notchback' ...... #2893 lbs. ~ 230 HP = 12.58 Wt/HP

Near equal in Weight-to-Horsepower Factors.

273 'Commando'
235 HP @ 5200 RPM's
280 Ft/Lbs. of Torque @ 4000 RPM's

318 ~ 2-Barrel
230 HP @ 4400 RPM's
340 Ft/Lbs. of Torque @ 2400 RPM's

"Let The Fish Begin To Swim"
Click to expand...

Assuming identical cars but for engines;the same trannys and rearends, etc:
Check out the the 273 torque at 4000 rpm; namely 280#. If Mopar's numbers were gospel , 280x4000/3450=213 hp. The 273 climbed from barely enough torque to idle, up to 213 hp @4000.
Now look at the teener. With a power peak at 4400, there is a good chance that with the factory cam, she was already making 98% of that at 4000, so225hp.This is 5.6% better than the 273.
Now we all know a teener pulls like a freight-train compared to a 273, so up to this point and a little further the 318 is well out in front, with it's 2bbl. With a 2.76 and a 2.45 low gear, this is about 43 mph.
My guess is that the 318 will continue to 4400, and then to 4800 still at 96% of peak-power. So now we are up to 51 mph, and sitting at 221hp.The teener is done, out front, but is gonna have to shift. And when it does the Rs will fall to 2841,maybe 175 hp.

By this time the 273 is starting to make power, perhaps pulling 94% of peak power, so 221 hp.So now the 273 is catching up, and is not gonna shift until 6200@66mph. So somewhere around 55mph the 273 gets ahead of the 318. Now it has to shift, and the Rs fall to 3670@176hp.
So now they are pulling from the same hp.
But the teener is building power faster than the 273 so it begins catching up some. The finish-line is at about 75/80 mph.The teener may have caught up by then as its power peak comes at 79mph. while the 273 will not reach it's 235 hp until 94 mph.
Unless you are racing to between 55 and 66 mph, I think it will be teener first, thru the traps.
 
AJ/FormS said:
Assuming identical cars but for engines;the same trannys and rearends, etc:
Check out the the 273 torque at 4000 rpm; namely 280#. If Mopar's numbers were gospel , 280x4000/3450=213 hp. The 273 climbed from barely enough torque to idle, up to 213 hp @4000.
Now look at the teener. With a power peak at 4400, there is a good chance that with the factory cam, she was already making 98% of that at 4000, so225hp.This is 5.6% better than the 273.
Now we all know a teener pulls like a freight-train compared to a 273, so up to this point and a little further the 318 is well out in front, with it's 2bbl. With a 2.76 and a 2.45 low gear, this is about 43 mph.
My guess is that the 318 will continue to 4400, and then to 4800 still at 96% of peak-power. So now we are up to 51 mph, and sitting at 221hp.The teener is done, out front, but is gonna have to shift. And when it does the Rs will fall to 2841,maybe 175 hp.

By this time the 273 is starting to make power, perhaps pulling 94% of peak power, so 221 hp.So now the 273 is catching up, and is not gonna shift until 6200@66mph. So somewhere around 55mph the 273 gets ahead of the 318. Now it has to shift, and the Rs fall to 3670@176hp.
So now they are pulling from the same hp.
But the teener is building power faster than the 273 so it begins catching up some. The finish-line is at about 75/80 mph.The teener may have caught up by then as its power peak comes at 79mph. while the 273 will not reach it's 235 hp until 94 mph.
Unless you are racing to between 55 and 66 mph, I think it will be teener first, thru the traps.
Click to expand...

I know you like math, but in real life, that's not how it happens. I shift at 5,500 and only drop to 4,500, still in the power band. X 2. 318 with it's 2 barrel holding it back, is stuck at 4,400 and down to something lower. Commando is easily past, Not theoretical, I had both. The 318 2 barrel does not make 230 hp and is not competitive in stock class racing against 4 barrel motors.
 
66fs said:
I know you like math, but in real life, that's not how it happens. I shift at 5,500 and only drop to 4,500, still in the power band. X 2. 318 with it's 2 barrel holding it back, is stuck at 4,400 and down to something lower. Commando is easily past, Not theoretical, I had both. The 318 2 barrel does not make 230 hp and is not competitive in stock class racing against 4 barrel motors.
Click to expand...
With a stock converter?
 
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