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Top 10 Engines of All Time (#6): Chrysler 225 Slant Six


Editor’s Note: This series counts down the Top 10 engines of all time—see how the voting was done by reading our initial post.

Chrysler 225 Slant Six engine

In a hot rodding world dominated by V8s, many of you decided to think outside the V…er, box.

At #6 on your Top 10 engines list, you’ll find the first gasoline-based inline engine of the group: the Chrysler 225 Slant Six. While it doesn’t possess the cylinders or overall displacement of the other engines, the Chrysler 225 Slant Six makes up for it by delivering gobs of torque and a cockroach-like lifespan.

You just can’t kill ’em!


First produced in 1960, the Chrysler 225 Slant Six replaced Mopar’s old Flathead-style engine.

The inline engine was given the Slant Six name because of its unique, 30-degree tilt toward the passenger side of the vehicle. This design was implemented for several reasons, according to Chrysler’s original 1960 press release:

  • The center of gravity is much lower than in upright engines
  • Increased clearance for use with the Plymouth Valiant’s low-profile hood
  • Engine accessories are more accessible

The “slanted” design also allowed for the use of equal-length intake runners and header primaries. The result was improved distribution of the intake air charge and reduced airflow restriction. Combined with a unique internal cylinder design, which featured a much smaller bore than stroke, the improved airflow helped the 225 Slant Six deliver tons of torque. And when the engine’s original one-barrel carb was dumped in favor of a two-barrel carburetor (a common practice among hot rodders), the engine offered even more performance potential.

From 1960-62, Chrysler also offered a Hyper-Pak package, which included a four-barrel carburetor and numerous performance upgrades. This parts combination helped push the Chrysler 225 Slant Six’s power output to almost 200 horsepower—almost V8 range!

Still, the Chrysler 225 Slant Six became most-known for its durability during its 23-year run from 1960-83—as your fellow gearheads pointed out…

Reader Quotes

“Slant Six 225! Bulletproof! –Chris L.

“Not a Mopar guy, but I have never seen anything tougher than a Slant 6 Chrysler!”–Leonard A.

“The Chrysler 225 ci Slant 6—reasonable on fuel, never stops running or wears out, and has loads of torque. My mum had one with over 300,000 miles and it never even had the tappet cover off once!” –Jeff N.

Fun Fact

The Chrysler 225 Slant Six was not only used in cars and trucks, it also provided power for farm tractors, forklifts, and boats.


The original Chrysler 225 Slant Six produced around 145 horsepower at 4,000 rpm and 215 ft.-lbs. of torque at 2,800 rpm.

Aftermarket Upgrades: Six for the Six

Because of the durability of the 225 Slant Six, aftermarket manufacturers continue to offer upgrades and replacement/maintenance parts. According to Summit Racing, six of the more popular parts include:

Editor’s Note: This series counts down the Top 10 engines of all time—see how the voting was done by reading our initial post.

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  1. Graham Kluver (Brisbane Australia) says:

    I have had a 65 AP6 Valiant 225 slant since new (Nov 65). After more than 48 years and over 880,000 KMS on the same engine (same crank, cam,rods and pistons) finally needed an engine rebuild. Still started easily and had plenty of power, but plugs tended to oil up. Had replaced valve seals on two occasions during life time. 30 thou wear in bore and less that 10 thou on crank. Now running it it again. Truly remarkably tough and confirms comments made by others.

  2. Fred Armentrout says:

    I had a 1979 Plymouth Volare 225 slant 6 that was incredibly durable. The car fell apart while the engine still hummed like new!

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  4. Erm…I killed mine.

  5. Just bought a 63 Valiant 200 Signet with a slant 6. Im not a mechanic or gear head. Excited to hear the history of this engine is so strong. 58k miles on my purchase. Sounds like I may be driving it awhile!

    • A good upgrade is the cable throttle linkage from V-8 Valiants. Installs with its metal plate screwed to the firewall in place of the existing plate. Later intakes, 1 and 2 barrel, are already made to accept the cable linkage. Aftermarket 4 barrel setups work horribly poor using the existing linkage with its twisting butterflies. Can be done but I hated it with a passion.

    • Brett – I have been a Mopar/Slant six fan since 1963. Check this out:

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  7. dave meinhardt says:

    Had a 72 Gold Duster and a 70 Scamp- After sitting outside in -20 weather (no garage) it would start no problem when the Brand New Caddy down the street wouldn’t start. Anyone remember that clasic Mopar starter sound? The engine wasn’t too fussy about being super finely tuned, had decent pick up and gas mileage. As a kid a saw a guy who made a v-8 out of two Kawasaki 1000cc motorcycle engines for use in his midget racer. I wonder if you could make a V-12 out of two slant 6’s lol

  8. I have a 69 Valiant slant six 225 that has been sitting for 23 years. My mother was original owner. My daughter and I will be restoring it in the near future. Can’t wait to drive it again

    • Bill OBeirne says:

      Saw your comment on 10 best engines. I too, found a 1972 Valiant in a Garage which it had sat in for 24 years. Driving now, and have put on 10,ooo miles since purchase in November 2015. Fixing the little things and enjoying it a bunch.–Bill

  9. the low hood line of the 1960 Plymouth Valiant is erroneous; in 1960 the Valiant was introduced as a separate line and not a model of the Plymouth line. In 1961 it became a Plymouth. Typical MoPar badging. In 1962 the Desoto was dropped as a nameplate; it lived on as a new model Dodge, the 880, which looked like the classic and currently continued Chrysler much more than the all new Dodge 330/Polara. The 1961 Dodge Dart was a full size car, then the name Dart was dropped, then revived in 1963 as a rebadged Dodge Lancer.

  10. As far as the production run of the slant 6 is concerned, they were used in pickups until 1987, when the v-6 came out. My first truck was an ’84 D-100 with a “leaning tower of power” and a four speed manual. Frame rotted through but still even had the original clutch. Biggest repair I ever made was a rebuilt carburetor and a new fuel pump.

  11. Just bought a Plymouth Volare Wagon with a Slant Six. Put some new plugs and wires on her she she purrs like a kitten. Absolutely shocked at how nice the car runs.

    • my parents had an ol s\6 volare wagon lol…. fond memories of that ol car. would be interested in buying if ur interested in selling.

  12. gene martin says:

    One of the greatest engines ever built. a true shame that Chrysler will not bring it back. re done with EFI and high energy ignition it would meet all smog tests and run forever. Are you listening Chrysler?

    • A-men I have a 1980 dodge 2door diplomate only 62,000ths miles onthe225 engine given to myself by #1 owner great car chrysler should do better.

  13. Ossi Keitaanranta says:

    Have this in my 1966 Dodge coronet, works fine and fuel saver too.

  14. why are superchargers so trash

  15. I killed the engine and not the car. started it up in a blizzard pulled out didn’t let it get warm and 6 miles later blue and purple smoke filled the car. 59.995 miles on engine. called my dad… he came and got me drove the car 26 miles home and the engine locked up. 🙁 My mom’s 1972 duster bit the dust. because of my stupidity.

  16. Carl St.clair says:

    I had the 225 Slant Six in my 1976 Dodge Aspen 4 door sedan It was one of the best engines I had ever seen as it outlasted the body at that time I bought the car in 1981 it had 120,000 miles on it and my complaint was they should have built a better body.

  17. Amirmahmood shasti says:

    Yesterday i bought a 1974 duster, in first day after running about two hour engine fell apart and connecting rod cracked and bearing moved, and block damaged and cracked …its a record as i think

  18. Ha d a 61 Valiant V20 tradede in on a 69 Charger RT Boy do I wish I had both

  19. As a Dodge store employee most of us would put our teenagers in something with a slant 6.
    We use to say with a slant 6 that oil and coolant was optional !

  20. Have used my 1987 W100 225/4 spd ” Dodger1 ” for hunting/fishing for 25 years… ” Creepy_Crawler_Mode ” good ‘ol 4 low… this truck will not stall no matter how steep the hill, without tending the gas pedal, the slant 6 stroke is soooo long! Pulled out more dead/stuck trucks/cars/quads than you can shake a stick at… drove over trees, through rivers, piled game in the back… finally last year the clutch disk cracked/separated… apart now, up on blocks, having a bit of trouble finding a clutch… sad to see My_Dodger1 like that… Yeseree, it’s all about forcing you to buy new these days… I’m sure if Dodge did bring the slant 6 back, it would be so over engineered you probably wouldn’t even be able to see it… 😉

  21. We had hundreds of them in Dodge SixPass pickups in the USAF….and they were unbreakable. Cruised at 90 mph on the Autobahn for hours on end. Smooth, too.

  22. But with no mention of the Buick V-6, the list is questionable. Over 25 million were built!

  23. I had a 73 Dart Sport with a slant 6. Threw a rod less than 100K.

  24. Christopher McCarthy says:

    I have bought a 1964 Plymouth Valiant 200 with the super six 225ci. When I started out as a mechanic the first tune up I did was on this same model year and the first motor I rebuilt was also a 225 slant six. 52 yrs later and this car I found in a scrap yard is also most ready to fire up. My hope is that the cold compression I found to be still in tolerance will be even better after it warms up. When I found it it only had 80,000 miles on it and had not been driven since 1980. The mice had taken up home keeping and the fuel is bad. I also had to hammer out the oil pan that was full of sludge. But after close inspection the bearing look still in good shape the cam has very little ware, and the cylinders have no scoring so with luck after I plastic gauge them and re-torque them, rebuild the carb and she should fire right up for my first road test. Replacement parts are hard to come by and I have rework what I have but it nothing I’m not used to after being in the Army for almost 18yrs. It makes me feel like that kid just starting out again.

  25. I’ve owned 4 slant sixes, still drive one to this day. When I was a teen, our “handme down” car was a ’66 dart 4dr with a 225. It lasted through my mom, and then 3 teen agers. They are superbly tough, overdesigned is what my dad always said, and he was a mopar mechanic for 40 years. When they quit making them, he was upset. He liked the power of the new v6s when they came out, but he knew those would never last as long as the old leaning tower of power. He had a saying “when it starts ticking, you should probably put a couple quarts of oil in it, or a gallon of water”. That was the honest to god truth.

    • Oh forgot to mention, the combined total of miles on those 4 slant sixes I’ve owned, would be slightly more than 3/4 of a million miles. That’s low because my current has less than 100k on it, and I don’t drive as much anymore. Avg. economy was around 17 honest mpg(city/hwy combined) for all of those(2 were trucks). Yearly maintenance was less than $50 a piece. Even my current one.
      You basically just got tired of driving the damn things and gave them to someone elses kid for a couple bucks, or someone Tbones you and totals them out.

  26. What a great engine,the 225 slant six.I bought the Valiant Safari Stationwagon in 2006 and drove it on until one cylinder began to give problems but it still worked tirelessly.I had the whole engine redone in 2015 and have just done less than 2000 km since.I look foward to pull this great car to Limpopo (RSA) in June(2017).I love the power and smoothness of this car.

  27. I had a ’66 Dodge Dart w/ a 225 slant six and a 727 Torqueflite transmission. That combination was Chrysler’s one-time claim to fame for building quality machines, a reputation long gone with the junk they’ve make recently. The 727 Torqueflite was as “bulletproof” as was the slant six. I also later had a ’73 Dodge D100 pickup truck w/ a 225 and a manual transmission. I wish I still had it instead of the miserable ’07 Dodge Dakota 3.7 L six that I own and hate today.

  28. David M Norris says:

    I had a slant-6 for 14 years and 168,000 miles. The car rotted but the engine was always solid

  29. Tom Andtews says:

    I owned a 1979 dodge Aspen bought brand new in the middle of the might be going out of business days, and it was a great car. It was a two door sport model with a 225 super six engine. There was no blind spot in the rearview, and it was a really good looking car. I got it for a song. The fools at brake check did a brake job . On the way home after leaving the shop my brakes failed and the best car I’ve ever had got totaled. She was silver and black with a rear spoiler I ordered. Damn fine car. I sure don’t know why Chrysler won’t bring it back after the success of the 4 liter AMC fuel injected straight six engine. That could be the shot in the arm Mopar is looking for. Just saying.

  30. Brian Eastman says:

    I love the 2 barrel carburetor in the SUPER Slant 6 cylinder engine in a 1976 Plymouth Fury salon 4 door.

  31. betty murray says:

    my work truck was a 1983 ram 1500 slant six 727 torqflight.drove it 17 years everyday.very little maintance.

  32. I had an 80 Aspen wagon and couldn’t wait to get rid of it as it couldn’t get out of it’s own way.

  33. James Kingston says:

    Have the slant six in my RHD Barracuda 1966 great car.

  34. I have a barn find 40000 mile original 68 Plymouth Valiant Signet with the Super 225 Slant Six, what a smooth running motor at 50 years

  35. Brandon Heisler says:

    I have an 81 Dodge Ram d250 3/4 ton pick up it’s white and it’s got a 225 slant 6 single barrel carb four on the floor and it only has 26,045 original miles on it my grandfather bought it new back in 1981 with a thousand miles on it and he drove it back and forth to work for 11 years and then used it to haul water for the garden and salt for the road and it still looks great he passed away 5 years ago and my aunt said that she is going to scrap it and I told her know that I want the truck I’ll give you $500 for it and bought the truck put a starter solenoid in and a new battery and it started up with 5 year old gas and now with a few maintenance things done it purrs and runs like new

  36. Brandon Heisler says:

    By the way if you guys want to check out the truck go on YouTube and search Mopar man and is a white 81 Dodge Ram you’ll see a picture of me sitting in the truck

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