How much can it take?

[blueroo]

Hey all,
I've been tossing around future mods for my 170 and I was considering a turbocharger among other things. I'd like to "push the envelope" more as time goes by and I wondering how strong the bottom end is. I know the seven main block is stronger, but would the added strength of the 7 mains justify the added weight in something that will be meant to be a strong performer, but still a relatively tame and economical street engine?

 

[xctasy]

The 170 has a heavier crank than the later engines. At really high revs, there would be more crank flex, but turbos don't do really high revs.

7 bearing cranks are lighter, but the blocks are heavier. Running four bearings on such a short stroke engine isn't going to break anything.

All Ford 144/170/187/188/200/221/250 sixes are over designed, with a huge factor of safety. Heck, running fewer bearings may help you find an extra couple of horse power, and the small bore engine has nice water jackets to keep it cool. Only worry I've got is the pistons. I'd say any turbo engine is going to suffer piston damage at some stage, so think about the quality of your psitons and stick with no more than 9 pounds of boost, and wind the total advance back so you never run into any detonation.

 

[rbohm]

8) i agree with xecute(few of us dont). these engines are hard to kill. personally i would prefer a 7 main engine when running a turbo or supercharger, though the 4 main engines can handle a fair amount of boost. i would also run forged pistons, and use a boost retard system, xecute indicated, to prevent detonation.

 

[Anonymous]

... but turbos don't do really high revs.

This is not true. At high revs the turbos are still producing boost. If the turbo is not sized to your engine properly, then yes it wont do much. If your turbo can supply enough flow to keep up with what the engine is eating then it absolutly will "do" high revs. 'course it is at this point that you begin to have traction issues at 85mph .