mmb

Thanks Guys! I try to keep as clean as possible!

mmb

Frick, I am running the 420 Mega Blowers.

Snout - Original 420 Snout
Pulleys - 8mm Set Up
Belt Tension - The Blower Shop


Here is the Belt Tensioner It bolts up with the water pump holes in the block




My Bottom Pulley Set Up




Top Pulley




What it looked like in the boat!

jeff32

so you have 8 mm pulley right? when you say that, I guess it's the size of the blower pulley, not the crank, right?

what sizes pulley are available? you have 8 mm, is there 7 and 6 and 5 and so on?

Is there a rule of thumb like, a 8 mm pulley is 5 pounds of boost, and a 7 mm is a... 7 pounds of boost?

just throwing numbers as example but I don't know sh.t about blowers!

Thanks for teaching me!

CIG3

8mm is the belt tooth design (round tooth). 1.2" pitch is square tooth. Below is a link to a site with raio chart.
http://goodvibesracing.com/Ratio_Charts.htm

mmb

The 8mm Pulley just refers to the cog pulley set up. You either have a 8mm style or an rib style. The Rib is your serpentine belt (like a car) you have have 8 ribs or 16.

The 8mm set up (Cog style) has zero slip... where a serpentine will still slip a little... However the low boost settings on boat engines... either one is perfectly fine.

You get the boost from the size of the top & bottom pulley... either over driven or under driven. My top pulley is a 46 tooth, my bottom pulley is a 54 tooth

The math to figure it out is

Bottom teeth / Top Teeth = Blower Ratio

54 / 46 = 1.17 17% Over Drive


This set up made 6lbs of boost with my old cam.. I have a custom cam now that is quite a bit smaller.... I am guessing the boost will be at 8lbs. But you have to add the chillers back in, that is going to take some boost away. I won't know exactly what the boost is until we run it... Should be between 6-8lbs

Jolley

Great Thread. Thank you for sharing Well Done !!!!!!!!!! Bill

frickstyle

MMB, Awesome, thanks,
That's exactley what I needed. Now, if I can just find the parts.....

Here's a stupid question:
With the cog style belt system, does it not require as much tension as a rib style setup? Looks like you just snug the tensioner up almost by hand. Unlike a rib style, which uses a threaded advance (or similar) to really put the "hurt" on the belt? I guess once it's relatively snug, it can't slip because of the cog drive....

mmb

You run right at 1.5" of slack in the belt.. You can move it 3/4" side to side

If you call the blower shop, they have everything your going to need!

frickstyle

This is probably in one of our earlier posts, what compression ratio are you running at a 17% overdrive? Are you running 93 octane or higher (at 6-8 psi)?

mmb

My compression came in at 8.1 with my new pistons. Yes I plan to run 93 Octane only.