Tooky
Serious about performance
I've got a strange problem that's been crippling my attempts to get new best runs at the track. This problem seems intermittent but always comes back to haunt me when I last want it to. Stock motor, stock ignition, 22-24 PSI boost with 93 octane and SMC alcohol injection, with chip tuning to lean out the fueling for target 11.4-11.8 AFR at WOT. I use a manual ball-spring BoostValve.com controller on the PT51 turbo with PTE downpipe/WG.
I'll be going down the track and suddenly notice the boost gauge fluttering like a "sine wave" and I can hear the turbo's pitch suddenly varying "ShhhwwwWWWssssWWWsssWW" if you get the idea. I can feel approximate 30-50HP power loss when this happens, and it noses off on Datamaster Dyno as well. My MPH are not what they should be, when this happens.
Here is my truck on a normal run:
The boost control (pink) is just flawless and I've turned on WB02 AFR Datalogging (black line) to show that my AFR's are in check.
Here is a drag strip run, all was going well until the middle of 3rd, it's easy to spot the point where the boost (pink) started acting funny....all the way through 4th until I let off. On this run last year, I had it tuned around 12.0 with single nozzle alcohol.
I added a second alcohol nozzle this year, and here's a run with it doing the same thing just hitting it on the street in 1st gear. It starts around 3rd gear.
Finally, I have a Datamaster file from SyTy member "psmvchaser" and his appears to be doing the same thing! I contacted him to ask if he noticed it, and/or solved it, and I'm waiting to hear back.
I changed plug wires and it seemed to go away for a few days.. then came right back. I'm thinking the plug wires actually had no effect and I was just imagining things. I had UR5 plugs at .027" gap and those have always worked in the past; I tried switching to UR6 at .025" and it was no better. I tried jumping down to UR6 at .022" and no change. The weird thing is, some days it will run just fine!?
A friend of mine owns a turbo shop and he suggested the problem may be the tiny air orifice in my brass BoostValve, and that I just need to drill it out a bit to solve this. Any thoughts? I was thinking fuel or ignition but both seem to be in check.
Thanks for the help guys.
I'll be going down the track and suddenly notice the boost gauge fluttering like a "sine wave" and I can hear the turbo's pitch suddenly varying "ShhhwwwWWWssssWWWsssWW" if you get the idea. I can feel approximate 30-50HP power loss when this happens, and it noses off on Datamaster Dyno as well. My MPH are not what they should be, when this happens.
Here is my truck on a normal run:
The boost control (pink) is just flawless and I've turned on WB02 AFR Datalogging (black line) to show that my AFR's are in check.
Here is a drag strip run, all was going well until the middle of 3rd, it's easy to spot the point where the boost (pink) started acting funny....all the way through 4th until I let off. On this run last year, I had it tuned around 12.0 with single nozzle alcohol.
I added a second alcohol nozzle this year, and here's a run with it doing the same thing just hitting it on the street in 1st gear. It starts around 3rd gear.
Finally, I have a Datamaster file from SyTy member "psmvchaser" and his appears to be doing the same thing! I contacted him to ask if he noticed it, and/or solved it, and I'm waiting to hear back.
I changed plug wires and it seemed to go away for a few days.. then came right back. I'm thinking the plug wires actually had no effect and I was just imagining things. I had UR5 plugs at .027" gap and those have always worked in the past; I tried switching to UR6 at .025" and it was no better. I tried jumping down to UR6 at .022" and no change. The weird thing is, some days it will run just fine!?
A friend of mine owns a turbo shop and he suggested the problem may be the tiny air orifice in my brass BoostValve, and that I just need to drill it out a bit to solve this. Any thoughts? I was thinking fuel or ignition but both seem to be in check.
Thanks for the help guys.
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