Surging due to loose wastegate? EXPERTS NEEDED!

[1QWIK6]

I am trying to run low boost (15PSI), to start a low "tuning curve". I have a TE63 and 72# inj and 2 307 F/P's. Base fuel pressure is 40 and I see 55-60@WOT. The problem is at WOT, the car pulls, pulls, pulls, and then fall flat (FP is 55-60), then picks up and pulls, pulls, pulls, falls flat, then repeat. Knock is >5. I do not get this problem at 1/2 throttle. Why is it falling flat at WOT?

I have the wastegate rod turned all the way out. It has 3-4 threads left. Is it possible once I hit 15 PSI and the wastegate opens the loose end (due to too few threads) is flexing and causing the surging? Anyone experienced this? Is this a possible cause? Any suggestions?

 

[azgn]

with that size turbo, and little tension on the wastegate, at WOT the wastegate just blows open, dumping all your boost....

I suspect you may not be able to run under 18-20 lbs boost and keep the wastegate shut under WOT

I guess the solution is some kind of external boost control that will allow enough tension on the wastegate to hold it shut, yet still keep the boost low

I have the same situation, BTW

If you come up with something magic, let me know!

 

[JDEstill]

One possibility is that you are encountering compressor surge. If your engine isn't flowing enough air at that particular boost pressure, it will surge if the compressor is too big. What kind of heads and cam you got? If you crank up the boost and the problem goes away, that might be a good indication that this was the problem. I wonder what a TE-63 compressor curve looks like...

John

 

[azgn]

that too.......bet the curve isn't real purty at 15 psi

 

[1QWIK6]

I have M&A heads and 210/205 cam + ATR headers

 

[Steve Wood]

Is this a stock wastegate actuator or a hd version?

You need about a tenth of an inch of tension on the wastegate rod. Do you have that? What kind of dp? Is the wastegate hole enlarged to fit the puck?

Is it running overly rich?