Is Bigger Always Better

[gotriver]

This is a great forum, it is my first post and I was hoping I could get some opinions. LOL
I have just come across a boat as close to the one I have been looking for. It supports a BBC with a 671 blower, I was hoping to find one with at least an 871 blower, but don't know what kind of difference to expect. What are the pros and cons of the two sizes?
Thanks for any help
KM

[Fiat48]

6/71 all you need. 8/71 is fine but really not worth any extra money since between good blowers there is only a couple of pounds boost difference. Sometimes 8/71's are cheaper than 6/71 due to the nostalgia boys going through cores and more demand for the 6's. For lake use you want a loose blower anyway, especially on gas. Forget about 10, 12, or 14/71 blower. Offset mags required, special blower manifolds, not worth the effort for your purposes.

[Liberator TJ1984]

depends on what your gonna do? From what I researched..a bigger blower doesn't have to be driven as fast to make more boost...the faster you spin the blower the more heat it creates as it is beating and compressing the air..heat adds to detonation..bad situation..a bigger blower under driven would be the best choice for the cost difference..also if you upgrade motor,blower will be big enough to accomodate possibly..10/71 on up takes alot of special drives and adapters to make work..8/71 best all round choice..talk to Marv Hinemann @ The Blower Shop(661)299-5483,he has helped me in the past ...good luck !

[Blown Cheyenne Hydro]

i agree 8-71 is the way to go

[superdave013]

An 8-71 has 1 inch longer rotors then the 6-71. If you already have the 6 it will be fine. If starting from scratch you might as well go with the 8 as they were the same price when I bought mine from Littlfield.
BTW a 10-71 will fit on my manifold and clear a my mag with no offset drives or special adapters. You would have to open up the manifold a bit.
Stay away from Whiend manifolds if you plan on running an 8 or larger. They are off set a little more towards the rear of the engine and you will have clearance issues with your mag or dist.

[Blown Cheyenne Hydro]

i have a bds manifold and like it alot

[Fiat48]

Wiend and Crager blower manifolds tend to run the rear cylinder hot also due to their setback and flat floor design. BDs, Mooneyham or Littlefield all have peak floor manifolds that work great and solve this problem.