Flathead 6 horse power

[dgrinnan]

My new project has a 1953 Plymouth 218.  I pulled the head to replace a valve and it appears it only has about 200 miles on a some level of rebuild.  I am not sure what was done but it has over size pistons.  It has been bored out to .040.  Just out of curiosity, how much should that increase horsepower. 

[Plymouthy Adams]

maybe a small burro.....?  .040 bore should be an increase to 223 CI

[dgrinnan]

Sounds like the intention was just to restore a worn engine as opposed to beefing it up.  I am okay with that.  

[Sam Buchanan]

1 hour ago, Plymouthy Adams said:

maybe a small burro.....?  .040 bore should be an increase to 223 CI

 

And maybe a few inch pounds of torque.  ?

 

My 218 has also been bored 0.40 over, it is an angry beast now.

[Plymouthy Adams]

2 minutes ago, Sam Buchanan said:

 

And maybe a few inch pounds of torque.  ?

 

My 218 has also been bored 0.40 over, it is an angry beast now.

probably more of angry beast due to returning to stock combustion and not so much the added cup of yogurt...

Edited November 3, 2022 by Plymouthy Adams

[Sam Buchanan]

I was at a car museum recently and fell into an 'old Mopar' conversation with the local caretaker. He asked what engine I had and he stated that these engines can be sleeved if bored out far enough. I haven't heard that or seen sleeves for our flatties...is this true?

[Sniper]

A good machinist should be able to sleeve it out if needed.  Though doing all six is probably more expensive than just finding a better block.  Unless there is a need to save the original engine. 

 

https://www.melling.com/contract-manufacturing/cylinder-sleeves/

[Sam Buchanan]

Ok...so you're ready to upgrade the flattie but you want to stay with a Mopar straight six.....here is your newest option.....

 

 

 

It's available as a crate motor and up to 550 hp.   

 

https://www.hagerty.com/media/news/detroits-straight-six-is-back-in-a-crate-for-2023/?utm_source=SFMC&utm_medium=email&utm_content=MED_UN_NA_EML_UN_DailyDriver_Thursday&hashed_email=ea7f7c793e5515d5caf7cf5a774caf9774db54b62a135bdd15fddd36832fff0a

[dgrinnan]

Will that mate up to my 1947 3 speed transmission or do I need an adaptor plate? ?

Edited November 3, 2022 by dgrinnan

[Plymouthy Adams]

just a casual glance says that is not a leaning tower of power.....so why the reference to the /6...well that the real OHV inline 6 mopar built.  Other statements in the write up purely wrong also....but that is ok....the fact that the new leader of Mopar is dedicating the Dodge name back to performance is much appreciated by many.....long time a coming...now if they would just dedicate themselves to a few sporty 2 door cars.  Don't get me wrong about a 4 slammer as they have thier place but not for a personal car in my opinion

[Plymouthy Adams]

4 minutes ago, dgrinnan said:

Will that mate up to my 1947 3 speed transmission or do I need an adaptor plate? ?

the mating to the 3 speed would be the least of your logistical nightmare of wiring and monitoring the engine.  Personally I would love to have seen the modern straight 8 prototype debut to the public in crate form. BUT if you truly got to have a bit of a slant....you can get a slant 4 from Mopar

Edited November 3, 2022 by Plymouthy Adams

[Sniper]

It refers to the slant six because, well that was the only OHV straight six Chrysler made.

 

[Plymouthy Adams]

2 minutes ago, Sniper said:

It refers to the slant six because, well that was the only OHV straight six Chrysler made.

 

already covered...

[Sniper]

15 minutes ago, Plymouthy Adams said:

already covered...

Hard to tell from what you actually wrote

[47 dodge 1.5 ton]

 Just bought a new grand Cherokee (2) months ago with a V6, wish this would have been an option. The V6 is peppy, but has been back twice so far, not sure it will be welcome here much longer.

 I really liked the 4.0l engine, wonder why they wouldn’t have built off that?

 “New Hurricane I-6 Now Available as HurriCrate Crate Engines Capable of 1,000 HP”

 Now That’s Dreamy!!

Edited November 3, 2022 by 47 dodge 1.5 ton

[martybose]

The Hurricane I-6 pictured is supposed to put out over 300 horsepower in stock form.  It would be an interesting setup if the installation wasn't such a nightmare with the electronics.

[keithb7]

To the original author:

 

There is a formula to calculate your new displacement.  Take your stock bore and add 0,040 to it. Google search the formula and work it out. There won’t be much HP gain. Maybe a very small amount. If you eat a big buffet dinner the car with a 0.040 over engine will accelerate about the same as stock. Lol. 

Edited November 4, 2022 by keithb7

[andyd]

Chrysler here in Oz from 1970 to 1981 had an OHV 6 that was termed the "Hemi 6" due to a slight angling of the intake/exhaust valves to each other along the centerline of the cylinders.......available in 215/245 and 265 cubic inch capacities, as used in the Oz Valiant Charger the "R/T" version of the 265 was available with triple Weber DCOE 45mm carbies & rated at 302hp........properly setup race versions developed close to 400hp and more........this engine was available in Chrysler Australias Valiant models as well as the Dodge pickups built in the same period......so there was more than one OHV mopar 6 around.............lol...........andyd  

[DJK]

20 hours ago, Sam Buchanan said:

Ok...so you're ready to upgrade the flattie but you want to stay with a Mopar straight six.....here is your newest option.....

 

 

 

It's available as a crate motor and up to 550 hp.   

 

https://www.hagerty.com/media/news/detroits-straight-six-is-back-in-a-crate-for-2023/?utm_source=SFMC&utm_medium=email&utm_content=MED_UN_NA_EML_UN_DailyDriver_Thursday&hashed_email=ea7f7c793e5515d5caf7cf5a774caf9774db54b62a135bdd15fddd36832fff0a

NO NO and NO!!!!!!

[kencombs]

7 hours ago, andyd said:

Chrysler here in Oz from 1970 to 1981 had an OHV 6 that was termed the "Hemi 6" due to a slight angling of the intake/exhaust valves to each other along the centerline of the cylinders.......available in 215/245 and 265 cubic inch capacities, as used in the Oz Valiant Charger the "R/T" version of the 265 was available with triple Weber DCOE 45mm carbies & rated at 302hp........properly setup race versions developed close to 400hp and more........this engine was available in Chrysler Australias Valiant models as well as the Dodge pickups built in the same period......so there was more than one OHV mopar 6 around.............lol...........andyd  

 

Thanks for the reminder.  Oz got some engine developments that never made it to the U.S..  Even Ford had some impressive versions of its inline sixes.  Crossflow head on the same basic engine that didn't even get a separate intake manifold in the states.

[andyd]

Ken, my daily driver now is a 2014 Frod Falcon Ute that has the "Barra" DOHC version of the 250 six, its the lowest HP version at 195kw, the factory XR6 turbo versions did 315kw & aftermarket ones have been shown to get over 700kw........varoom..........lol........andyd

[Sniper]

For those of us that do not speak metric, lol

 

195kw = 261hp

315kw = 422hp

700kw = 939hp

 

I have a handy conversion utility, lol.

[47 dodge 1.5 ton]

All what a turbo can do. 30 years ago, my brother designed and built a 225 slant six turbo for his 68 barracuda. I laughed at him most of time he was setting up that contraction and one day we were at the track paired to my slighty warm 340 4spd demon. I caught a better light and he finished 1st with a 13.10 to my 13.15 et. I had a nice lead at 60ft and he got me by the time I shifted to 3rd. I then had respect for the turbo. Although, does not have that flathead sound?

Edited November 5, 2022 by 47 dodge 1.5 ton

[DJ194950]

Time to build a turbo'ed  flathead 6??  ?

 

DJ

[andyd]

Thanks Sniper..........I'm not a fan of metrics but just used what the advertised power figure was.........I normally tell people that I have feet at the end of my legs, not metres..........lol............andyd