871 vs 1471 blower?

[jeffroe]

i have a chance to trade a guy my intercooled kuhl 871 blower for his intercooled 1471 unit. my motor is a 468 w/oval port cast heads and 7.5 compression it makes 8psi running 1 to 1 pullies, it runs max rpm at 6500 in my jet boat. is there a big advantage going up to the 1471 or am i over killing my set-up?

[BOOGEYMAN]

I would say over kill dude!!! That blower is not even worth bolting on just to spin 8 or even 12 lbs.

[P-Money]

14-71 = spin slower for same amount of boost
Spin slower = less heat and expansion
Less heat and expansion = pack more air in cylinder
More air in cylinder = more hp
Plus there is the "cool factor" of having a 14-71 and the extra inches hanging off the back of the motor. A big benefit of an intercooler is you can throw a 14-71 on and not have to worry about the distributor being in the way as the intercooler gets the blower above it.

[jeffroe]

8psi puts a big grin on my face :crossx:

[MAXIMUS]

Stick with the 8. Its hard to beat a good 871. I have both & the 14 is overkill for 10 lbs of boost. It weighs a friggen ton. On that squirt boat of yours weight equals speed & et. You will get a better power curve with the 8 unless you start stepping up to high psi #'s. :)

[Smitty19]

what about about the 14 on a 555 ? I had a 10 at 18% over making 10-11 lbs
tried to step it up to 26% added more fuel and it didn't pull any harder no rpm
increase this is in a 19' daytona has an intercooler as well..

[Bobby Knight]

I think what everyone has said so far is correct, but no one has mentionsed the amount power it takes to turn the blower. I don't remember the exact #'s, but its amazing. The bigger the blower, the harder to turn, unless its super loose. IMO, the only gains youll get fromthe big the big blower is if you want relatively big boost. On 468 inches w/ a cooler a tight 8=71 should be plenty

[jeffroe]

good point i really don't plan on making much boost about 8psi, because it's a ski boat/cruiser not all out racer. well i havn't called him back guess i'll hurry up and wait :cool:

[DMOORE]

Unless your trying to make big boost, it's just going overkill. As someone else stated, it takes a LOT of power to turn a 1471. I would bet, you would make less power with the 1471, at the same conservative boost level your looking at, due to parasetic loses.
Darrell.

[Schiada76]

Why does it take it more power to spin a 14?
Isn't the HP used a function of the boost level and/or the blowers tolerences?
They spin the same by hand and a 14 isn't that much heavier than an 8.

[cfm]

SC is too big for your application.
Call any SC company and they'll tell you the deal.
All SC have an effeciency range. You'll be under that rpm with a 14:71.
A 6:71 - 8:71 should be fine.

[Robbie Racer]

It's been my experience with both the 10-71 on my 580 and the 14-71 on my 604, that roots type blowers (on gas) don't give you much more power much above 14 psi. They seem to heat the air intake a bunch. In fact, it takes a lot to get them to make additional power above around 12 psi. Screw type superchargers (like PSI or Whipple) seem to work better at the higher boost levels to keep on making power as you go above 14 psi. Just my 2 cents anyway. RR

[Bobby Knight]

An equal tolerances 8-71 spins easier than an equal 14-71. It takes more energy to spin, push, move etc. any object that is larger. When they heat up under loaded condtions, you have a tight seal on even more surface area. There is a 10 pound difference between the two.