2650 pulley size/boost combo

einehund

Well-Known Member
Established Member
Joined
Jan 20, 2008
Messages
1,801
Location
Wentzville, MO
I have seen the 2650 advertised boost reference by pulley size, but those all are assuming stock crank size. Is the 3-4psi increase with a 10% lower still the same on this blower, or does the larger size increase the psi to say 4-5? Also, is the safe psi still 19psi on pump gas, regardless of the size of the blower? I ask as the larger blower should be turning slower for the same CFM airflow, thereby reducing heating, resulting in the ability to run a bit more boost. I am just trying to figure out what combo I need.
 

DaFreak

Active Member
Established Member
Joined
Feb 18, 2010
Messages
1,055
Location
Oregon
Also running an IW 10% and wondering the same. Seems this forumn might be dead?
 

Catmonkey

I Void Warranties!
Established Member
Premium Member
Joined
May 20, 2011
Messages
3,854
Location
Louisiana
Here's how I approached it. If my old setup was a 10% with a 2.5 upper, I calculated the liters per crank revolution. Blower diameter / upper pulley diameter x blower displacement in liters = 7.81 / 2.6 x 2.3 = 7.19.

With the 10% lower and a 2.8" upper on the 2.65, you get 7.81 / 2.8 x 2.65 = 7.39.

With the 10% lower and 3" upper on the Gen 3, you get 7.81 / 3 x 2.65 = 6.90.

I ended up using the 2.8" pulley. Jury is out on boost til I get it back on the road, but that's how I got to my starting point. DaFreak, realize your IW 10% has a larger diameter than an ATI, and more like a 12% overdrive.
 

einehund

Well-Known Member
Established Member
Joined
Jan 20, 2008
Messages
1,801
Location
Wentzville, MO
I ended up buying a gen2r on black friday. The lack of info for this combination was one of the deciding factors i picked the gen2r over the 2650.
 

Catmonkey

I Void Warranties!
Established Member
Premium Member
Joined
May 20, 2011
Messages
3,854
Location
Louisiana
Honestly, unless you're running aftermarket cams and/or e85, I think it's a better choice on the 5.4.
 

Tighteyes

Active Member
Established Member
Joined
Jun 19, 2017
Messages
267
Location
NC,Sc
23psi with 10 percent lower 2.6 vmp gen3...... at 2.8 It looks around 19-20 depending on temperature outside. for me on a 5.4 built big cams livernois heads
 

Users who are viewing this thread



Top