I've looked around the internet but haven't been able to find the answer to my question. Hoping I can get Bill or Cletus to chime in here with some expert advice I can trust.
I remember Bill talking about the difference between exhaust backpressure vs boost pressure and the associated thrust on the turbo in his post about the WW2 testing. He had mentioned the ratio between backpressure and boost was much improved with the WW2 and higher boost was possible without causing excessive thrust loading of the turbo. At least that's how I remember it.... But I don't remember ever seeing what an acceptable difference was.
So what is the maximum suggested difference in boost/backpressure since that seems to be the controlling limit to prevent turbo damage?
Here's my story(short version?). Bill recommended removing my 38R and replacing with the stock turbo/WW2 combination for my towing setup with stock injectors. I ended up getting the billet wheel from Riffraff due to much lower price and good reviews. So far I've been really happy with going "backwards" by removing the 38R. Now I'm trying to tune in the Wastemaster wastegate controller.
I watch the backpressure with an Edge Insight. Of course this includes the atmospheric 14psi so it doesn't directly match my boost gauge. I can watch the MAP reading on the Insight up to its limit of around 29 and keep from having to convert numbers, but that doesn't really address the max values that I'm trying to tune.
So I take the boost reading and add 14 or the backpressure and subtract 14 for conversion.
I'm getting around 28-29psi max on the boost gauge.
50-52psi max on the backpressure reading. I've been told 52 it the readable limit of the sensor, it flickers between 50 & 52 so I feel like it's right at the limit but probably not beyond.
Converting these values I'm seeing around 8-10psi difference between the boost & backpressure. Is this reasonable or should I try to back it down some?
FYI, recently I've replaced the 6637 filter with the Ford AIS. Loving the new (lack of) sound from my intake suction. It did appear to cut my boost by about 0.5psi at most ranges (cruising & wide open). This intake change did impact the boost/backpressure ratio negatively at least somewhat. Just thought I'd throw that in here for anyone that may be wondering.
Thanks, Jason