273 vs 318

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Slantsix64

Slantsix64

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was wondering would a stock 273 with a four barrel 500cfm carb. would have the same amount of power as a stock 318 with a two barrel. what are the pros and cons example mileage torque. i have read the 65 charger 273 engines with a four barrel made up to 235 almost the same as a stock 318 two barrel. but that is with bumped up compression and a hotter cam. any thoughts and experiences thanks!
 
You're referring to the 273 Commando motor w/10.5 cr, 4 bbl and solid lifter cam. Great little motor, but limited due to the heads! IMO I'd prefer it over any stock 318 2bbl.
 
Favorite saying....There is no replacment for displacement!!
 
What size is the 2bbl on the 318?

I'd like to see that test with the same carb on both engines or with a 500cfm 2bbl on the 318.
 
the 67 4 barrel 273 was rated @ 235hp @ 5,200rpm - - in 68 the 2 barrel 318 was rated @ 230hp @ 4400rpm - - as stated above, splitting hairs. I am mostly responding so I get alerts - this should be a fun one..
 
Larger RPM range and 5 more HP with less reciprocating weight. I'm going with the 273 all day on this one.
 
The first LA was the 273, with a two barrel carb, producing 180 gross hp. Introduced to Americans in 1964, it had a thin-wall casting and simpler wedge-heads and valves, which saved around 50 pounds over the existing A-series V8. The 273 ended up being only fifty pounds heavier than the 225-cid slant six. In 1965, a four-barrel carb and high performance cam could push that up to 235 hp; and, in 1966, a limited edition 273 with a 700 cfm carb and .500" lift cam put out 275 hp.
The 318 (5.2 liters) was brought out in 1967; the main difference from the 273 was its larger 3.91” bore. The 318 was never used as a performance engine by Chrysler; the 273 four-barrel matched it in peak horsepower, and the more performance-oriented 340 was quickly released in 1968. It had hydraulic tappets from the start, but hardened valve seats were not used until at least 1973.
~~all above info. copied and pasted from Valiant.org ~~
 
The 273 is a high rev engine but you would probably get more power per upgrade with the 318. As stated above "There is no replacement for displacement"

And it comes down to cost.

Build either one and put a 340 sticker on it and call it a day
 
Don't matter wich one u get . Both motors will smoke a chubby anyway . Vrroomm vrooommm bitches!!
 
Can't go by the stock hp specs there gross hp numbers and may have no actual relationship with the engines actual power.

And your best bet is to build 318/360 mainly more plentiful and cheaper pistons and bigger bore. And also cause of the torque factor you could gear a 273 more aggressively but most don't want and really no point since just go 318/360. To put it into perspective 4.10 with a 273 would ruffly equal 3.55/318 3.23/360 and 2.74/408.
 
The only reason is a good little revver cause it's got a good intake port cfm to cid ratio.

Add an mild cam like 340 cam and 4bbl to a 318 or better yet go magnum 318/360 you'lll be future ahead.

Just like /6 273 is a labour of love not sense
saying that I might still build my 273 :)
 
I've owned both, both are reliable and for a long time. I'll take the 318 over the 273, but that's me.....
 
I've noticed a lot of lol on here are like me. More love for the smaller sizes due to gas and pride when you smoke something bigger and it's more usually imo due to most drivers not really knowing how to race lol.
I've always opted for the smaller motors. Where as my dad argues with me I need to get a real race car. Everytime I talk to him about the dart I got for my missus and my plans for it he tries convincing me to put a 440 in it along with my buddy and most others I talk to. My neighbor is with me and keeps edging me to slap a turbo on it.
I really like when these threads pop up. It not fully about the power but the economy with the wanted power to go with it.
Personally if going for a v8 upgrade for a daily driver I'd probably get the 318. More possible lower with the build. Availability is higher. The extra weight is easily compensated by increased up and take abilities.
I'd take the 360 if I had issues finding a 318 and I was on a tight time frame.
273 probably for gas economy and a possible turbo.
440 if it sat on a trailer or in my garage and only showed and dragged occasionally. But I'm more into drifting and rally racing than going straight. Main reason I gave this car to my fiance. I appreciate the classics to much to smack a wall or such and have to cut it up to fix it. 80 and90s car are just throw away cars, toys
 
I'm trying to overthink this as much as possible, but not any having a luck.:poke:

Mileage? There are some builds out there where some have got some pretty good numbers using the stock 273 and stock cam or similar that torque peaks at 2500ish. The easiest power will be starting with the bigger cubes.
 
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It's easier to get better mileage out of a 273 possibly. But mileage has more to do with performance level take my pervious example. 4.10/273 3.55/318 3.23/360 and 2.74/408 now say each make 300hp. I know no one us gonna build a 300 hp 408 but we are for this example.
Technically each of these combos should have similar performance and mileage.
Each of these combos will put similar torque to the ground at same mph (hp) which is passing the same fuel and air again similar mileage. But obviously 408 is gonna be more streetable vs the 273.

Another way of looking at it you either have to put torque into the rear end with gears or torque into the engine by displacement since most don't want to run deeper than 3.55 the bigger the cid for any given hp wins.
 
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