Buddyworm wrote:Might still have a hard time keeping it from creeping. With externally gated manifolds it's usually a good bet that the WG pipe doesn't have an "ideal" flow path for boost control. Could have the bulk of your exhaust flow blasting right past the wastegate.
It sets exactly opposite of the turbo flange. This is kind of an odd manifold in that it's a divided manifold, but it is NOT equal length. It's a sort of log/divided mixture. The exhaust runners are about as short as they can get, especially #3. I think it's MAYBE 3" long. They also feed into a "plenum" of sorts for each side of the turbine housing, and as such, don't feed into the turbo at an ideal angle. I think HKS's thinking in this was that it was more of a pressure manifold and less for flow. I'm sure given their turbo options at the time, decreasing spool RPM was the highest priority, and so sacrifices were made in regards to ultimate flow. In that regard, if you look closely at the picture, you can see the wastegate flange is exactly opposite of the turbine flange, both of which feed off of the "plenum". Since advancing the timing, I haven't seen more than 8psi, which I think is in the acceptable range. I'm also pretty sure I'm still way off from the ideal ignition timing. And even if it does creep to 8 or 9 psi, I have no intention of ever running it that low once I'm done tuning those ranges of the map, so I suspect any creep issues will be gone once I get the 14psi spring in it.
I think i'm way off from it. E85 likes lots of timing advance due to it's slow burn rate. All I did with the timing was ramp it up from the idle timing of 25°to 40°by 3000rpm. From there, it's just fixed at 40° regardless of RPM or boost. The slight creep I was seeing I'm sure was from the lack of advance I have at the higher RPM's as I know from experience (and as other's have said on the internet) that the timing needs to start to be advanced once you get up in the RPM's or you start to get away from MBT.Buddyworm wrote:It does depend on how far off you are from MBT though...
You may be right. I haven't spent enough time on a dyno to know what it's going to like.Buddyworm wrote:If I had to put a (very) rough number on it I'd say 5-6deg or so retarded from MBT is when you start to put enough extra energy through the turbine to get an increase in wheel speed/boost pressure.