Tier 2 flywheel with offset keyway vs. Tier 3 flywheel

[slowpoke]

I was just wondering if anyone had an opinion or possibly tested both tier 2 flywheel w/offset keyway and tier 3 flywheels alone to get a good comparison of which setup would be better on a tier 2 GX120 engine.Aside from the fact that the keyway is cheaper than the tier 3 flywheel, Supposedly they are equal but I am sure someone has a good comparison they would share.

[sprintcar39]

I dont have any facts to back it up....but I was told by an engine builder that the tier III flywheel is better than the key.   FWIW

Eric

[Swartz]

They are not equal. The offset key has a fudge factor built in to allow for dimensional differences in the production of the flywheel. In QMA you are not allowed to alter the key so in one engine it may give you 18.5 timing an 19.5 in another. In USAC the rule is 20 degrees. Period. Put a timing wheel on the thing and make sure you are getting everything you are allowed.
Myron

[miketsmith]

We tested both with exact conditions (tires, temp, track, driver, and etc) and only gained .03 seconds. Not much of a difference.