Thread: need a tuner
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boxermania boxermania is offline
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Join Date: Oct 2006
Location: Baton Rouge, LA
Posts: 143

Don't have a turbo, but I can read and diagnose dyno curves, or so I think.

I am very much concerned at the bottom of the rpm range, right around 3200 rpm, when it appears that the turbo starts building boost big time, unfortunately, it goes south a couple of hundred rpms later and becomes very lazy.

On another note, the A/F ratio seems to be right around where these engines like it, a touch fat, leaving some HP on the floor but in the ballpark to protect an air cooled engine. Good fuel presure, but looking at the E temperature not changing with increased load, I can't help to wonder where it is being measured as it is of no use to a tuner. I would have measured EGT at least on the two banks.

I would say, based on the curves and the output that the engine is flow restricted, partially open throttle valve, at the exhaust or something of the kind. Timing does play a role but more so on the top end and the problem surfaces down low. I wonder if the cams are indexed right....there are so many possibilities.

I would hope that some of the more attuned turbo experts on this forum will take an interest and share their oppinion, I'm sure something will come up.

BTW, what is the build sheet for the engine, as that would help.

Good luck to you.........
Al Morales
77 911 S (930 steel conversion)
88 BMW M3
79 Honda CBX
Old 04-16-2008, 01:36 PM
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