5.2 magnum GT35 to S475

TT5.9mag said

I’d like to know the back pressure:boost ratio on that at 15 pounds or so. It’s probably up in the 3:1 range.

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I think it just about had to be. I ran it around 15.5lbs a couple times and I could tell it made more power than when it was on 3psi but it definitely wasn’t 200hp more. Another example I did some street pulls with a dragy and on 3psi it’d go 80mph to the 1/8 on street tires. I turned it up to 12psi 1 time and it only went 83mph. That’s when I knew I had severely messed up. It was a riot from idle to say 4000. But at 4800 you could feel the car lay over significantly.

I learned a lot about how to do things wrong with this setup which I guess made me better in the long run because it made me study everything super hard. If I were starting from scratch as a guy who had never turbo’d anything I would personally NEVER look at any turbo that had a turbine exducer under 75 or 80mm for even a stock v8.