S300, hook the wastegate up or not? HP?

[bgilbert]

Well as many of you know, I've been running a S300 from HTT for awhile, the one they call their 'Sled Puller 66'. With their 14cm wastegated housing. Since day one, I never hooked the wastegate line up. I just removed the line from the charger and inserted a pipe plug in the compressor housing, in place of the boost elbow. Well actually if I remember right, I may have run the wastegate for a few passes and seems it was set around 34psi. Once disabled I seen around 40psi, eventually up to 50psi. I figured if I kept the boost below 50psi, why hook the wastegate up? My question is, which may be stupid, is there any horsepower I am losing by not allowing the charger/wastegate to dump off the extra boost/drive pressure?

I figured I'm not losing HP, only allowing high drive pressures at higher boost. Also I'm probly just out of the chargers efficiency range around 50psi, or maybe not. Would it be safe to say I would be making the same HP at 35psi of boost as at 50psi?

[CAJUN 93]

i'm no expert by far on this but it seems to me that volume rather than pressure is what your hunting for. the heads, valves, cam sizing, etc limit the amount of air (cfm) you can move. if your turbo moves that cfm at 35 lbs of boost, anything above that will just stack air and add heat into the system. kinda defeats the purpose of a highly efficient turbo.

i guess whai i'm trying to say is you want whatever boost pressure is needed to move the cfm your engine can use. i think the wastegate hooked up with an adjustible boost controller is the way to go. you can make adjustments while on the dyno and see if it makes a difference.

[gman07]

Based on your dyno video, I think you need more air.

I remember reading somewhere that the map of the 66 was good to a pressure ratio of around 4, which would be 44psi. While volume is more important than pressure, mass is even more important. The way to get more mass flow (higher density) is to run more pressure, assuming you are running within a turbo's map and intercooling.

I think you need twins or a more efficient single.

[wannadiesel]

AFAIK anything over 45 psi out of the Schwitzers is hot air. I'd hook it up and set it to open around 40 and see what that did for me. Talk to HTT and see what they say about the max useful boost.