I’m trying to nail down the pulley combo for my car without having to buy a ton of pullies. I thought I had it figured out but it looks like all the data I was looking at were for older gen 2’s and gen 3’s. The gen 4 is supposed to make 1-2psi more with the same pulley than the gen 3, not sure what the gen 2 to gen 3 difference were or if there were any as far as pulley and boost numbers.
I’ve got a ATI 15% lower on the car and the 3.25” that came with the Whipple. Plus my car has longtubes and I’m at sea level. Whipple tech support says the gen 4 2.9 makes 16-17psi with the 3.25” and stock manifolds and the guy I spoke to said he heard 4lbs for a 15% lower. Everything I’ve read says 5-6lbs for a 15% and 3-4lbs for a 10%. I believe they also gave the same boost estimate with the gen 3’s from the old sales pages I’m finding so I don’t 100% trust their figures.
Regardless, if we say 16-17psi - 2psi for long tubes + 5psi for 15% lower it’s 19-20psi total. Maybe as much as 21psi if the 15% does make closer to 6lbs or if the longtubes don’t quite knock off 2lbs.
Can any 2.9 gen 4 on 5.4’s owners chime in with what they’re seeing with what pulley combo and also please note if you have longtubes, cams or head work.
Also even if you don’t have a 2.9 gen 4, if you have another generation 2.9 or a 3.4 or a similar size KB and you ran with both a stock lower and a 15%, how much boost increase did you see?
Thanks.
I’ve got a ATI 15% lower on the car and the 3.25” that came with the Whipple. Plus my car has longtubes and I’m at sea level. Whipple tech support says the gen 4 2.9 makes 16-17psi with the 3.25” and stock manifolds and the guy I spoke to said he heard 4lbs for a 15% lower. Everything I’ve read says 5-6lbs for a 15% and 3-4lbs for a 10%. I believe they also gave the same boost estimate with the gen 3’s from the old sales pages I’m finding so I don’t 100% trust their figures.
Regardless, if we say 16-17psi - 2psi for long tubes + 5psi for 15% lower it’s 19-20psi total. Maybe as much as 21psi if the 15% does make closer to 6lbs or if the longtubes don’t quite knock off 2lbs.
Can any 2.9 gen 4 on 5.4’s owners chime in with what they’re seeing with what pulley combo and also please note if you have longtubes, cams or head work.
Also even if you don’t have a 2.9 gen 4, if you have another generation 2.9 or a 3.4 or a similar size KB and you ran with both a stock lower and a 15%, how much boost increase did you see?
Thanks.