1937 248 Hp Increase

[Jack Worstell]

We have installed a Lloyd Young overdrive in a 1937 series Special

 

Now  we  would like to squeeze a little more Hp out of the 248 so as to take  better advantage of the overdrive.

.....how far can the heads be shaved ?

.....how much can the compression ratio be increased without getting into an exotic rebuild ??

  ...other things that can be done to squeeze out more Hp ?

 

Thanks   Jack Worstell    jlw master@aol.com

[LAS VEGAS DAVE]

YOUR GEARING SHOULD GO BACK TO STOCK AND THE CAR WILL GO FASTER.

[Ben Bruce aka First Born]

????? Explanation, please, Dave.

 

  Ben

[critterpainter]

I believe that that is about the last of the low compression engines before the new piston was introduced.  In 37 the compression ratio was 5.75  B 1938 the compression ratio was  6.35 to 1.   I believe the change was due to piston design.

   If you are running factory 1937 pistons, then replace the pistons and you should pick up more horsepower.

 

Las Vegas Dave   Without the overdrive engaged, he is running the the stock gearing.  Thats the advantage of an overdrive.

      

[DonMicheletti]

Upping compression ratio would probably do more than enything else. There is an article in the old Torque Tubes about it (somewhere)

[Jack Worstell]

Critterpainter......is there a source for the higher compression pistons ?

 

Dave....you might be referring to the 3.9 axle ratio. The car had 3.9 when my buddy bought it ( it took us a while to discover this ).

 We were aware of this aspect before installing the OD and will live with it or switch back to 4.4

Either way....we want more Hp

 

Don ....thanks for reminding me of the old Torque tube articles.....I should have started with these.    Just quickly scanning this source I already see a number of promising articles.

 

Jack Worstell

[nzcarnerd]

I doubt you could put '38 pistons in a '37 engine because of the shape.  

 

[MCHinson]

Actually, you can use the 1938 Domed Pistons from Egge in a 1937 Special engine.

 

Egge recommends it and Chris Ritter, AACA Librarian, has done it successfully in his 1937 Special.

[Jack Worstell]

The Egge   1938 domed pistons...if used in a 1937 248........about what will the increases in Hp   and  compression ratio be ?

[MCHinson]

I don't know but I suspect if you call Egge they would know.

[37_Roadmaster_C]

I connot confirm the piston swap for a 248, but I can for a 37 320.  We just did it last year during the engine rebuild for the phaeton, no problems at all.  Call Egge and ask them for a recomendation.  It might even be possible to go with newer piston design and gain even more compression.  We put 38 pistons in our 37 320.

[critterpainter]

I am going off my feeble memory here, but I think 37 is the last year of the flat-top piston.  Changing to the later domed piston such as Egge supplies should wake the engine up.  There was one year that the head may have had an interference problem, but my memory fails.   The cure (if the pistons hit) was to install a newer head.    The Guru's on this forum would know the details but I believe it is just a piston swap.  The domed pistons are cheaper than the flat top pistons from Egge for some reason.

 

Bill

[LAS VEGAS DAVE]

On January 27, 2017 at 4:23 PM, First Born said:

????? Explanation, please, Dave.

 

  Ben

 

Ben, I believe Jacks car has 3.90 gears in it. Stock gears are 4.44. With an overdrive the motor has enough power to pull the car along with the overdrive engaged if it has the stock 4.44 gears on a flat road or a not to steep hill. With the 3.90 gears in it and the overdrive engaged the stock motor probably does not have the power to pull the car in high gear to its redline. You can't just keep raising the gear ratio on a car and have it go faster and faster, there comes a point at which the motor does not have enough power to pull it. The overdrive ratio has probably caused Jacks car to exceed the power needed to reach its optimum speed. You can either  add more power or lower the gear ratio, either one will make the car go faster.

[MCHinson]

And if the car does not need the 3.90 gears due to the overdrive, those gears could easily be sold to another Special owner who does not have or want the overdrive. That is a very popular conversion for a Special. Those gears are difficult to find due to the relatively small number of Centurys manufactured compared to the number of Specials manufactured.