Indexing a crankshaft

[Fred Elsass]

Can anyone out there tell me how much HP would be gained by indexing an after market crankshaft from a reputable company?


I understand that indexing a crankshaft is to assure that each and every journal on a V8 engine is exactly 90 degrees apart.


Would this not be tantamount to attempting to build a Formula 1 engine to run Stock Eliminator?


Sarge

[Billy Nees]

If I needed to get a crank done from scratch, I would probably have it stroked and indexed. Otherwise, I wouldn't bother. Not for a (relatively) low HP and low RPM engine.

[1347]

Take what your engine makes in hp and divide it by cubic inches, now figure out the displacement increase and plug the hp per cube into the new formula. That should give you a start. It may increase more due to the compression increase also. Thats what was explained to me many years ago by an old time.class racer.

[cordoba13]

stock crank yes, could be up to .005 off, high quality aftermarket most likely no increase

[Alan Roehrich]

Originally Posted by Fred Elsass

Can anyone out there tell me how much HP would be gained by indexing an after market crankshaft from a reputable company?


I understand that indexing a crankshaft is to assure that each and every journal on a V8 engine is exactly 90 degrees apart.


Would this not be tantamount to attempting to build a Formula 1 engine to run Stock Eliminator?


Sarge

Yes, INDEXING assures each rod journal is at 90 degrees (assuming we're discussing a V8).


If I bought even a relatively expensive aftermarket crank and the journals were not correctly indexed, I'd be annoyed, and return it.


If you're talking about STROKE, then, no, if I had not paid for the extra 0.014", I would not bother with it.


When you correct an OE crank, you should go for proper index first, since that relates to camshaft and ignition timing.Since you usually have to grind it to get the correct index and correct journal size, then you also go for the stroke. You often cannot approach the full 0.014" allowed while getting the index correct and maintaining decent journal size (I don't like going too small on an OE crank).


Hope that helps.


One or two crank manufacturers will make you a new crank with the 0.014" built in. Be prepared to pay through the nose, and wait until you retire before getting it.