Hot Rod Forum : Hotrodders Bulletin Board - View Single Post - Trivia thread
Thread: Trivia thread
View Single Post
  #6957 (permalink)  
Old 04-08-2013, 01:28 PM
Dave57210 Dave57210 is online now
Semper Gumby
Last photo:
Join Date: Feb 2007
Location: Vancouver, BC
Posts: 360
Wiki Edits: 2

Thanks: 452
Thanked 463 Times in 367 Posts
In a four-stroke engine, any cylinder fires once each 720* of crankshaft revolution. An 8 cyl will therefore fire a cylinder once every 720/8 or 90* of crankshaft revolution.

A 6 cyl should fire a cylinder once every 720/6 or 120*. HOWEVER - a 90* V6 cannot do this unless you make the engine longer by having a separate throw for each cyl. (Draw it up, you'll see) A 60* V6 has no problem with a smooth, even-firing order and lighting one off every 120* (and usually has a firing order like 1-2-3-4-5-6)

Because of the crank design on the original (V8 derived) 90* V6 it could NOT fire cylinders with an even spacing of firing order (oddfire)

Later versions DID use separate throws for each cyl to get the spacing right (evenfire) but this necessitated a whole new block with the banks more staggered than is the case on a V8
Reply With Quote