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| Turbo car need tuning. https://slantsix.org/forum/viewtopic.php?t=18605 |
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| Author: | finnman1 [ Sun Jul 16, 2006 8:54 pm ] |
| Post subject: | Turbo car need tuning. |
Finnnaally got her going and all the leaks taken care of. Only problem now is she overheats and it acts a little funny under boost when i romp on it. It makes a ppffff sound and acts as if it stops pulling. It will still build boost (had it up to 8 lbs tonite but it was making that sound so i let off) Didn't know if anybody had experience with this. This is all new to me. The turbo is rather small A/R .42 & .48 but ive seen the same turbo work on a different slant. I don't necessarily think the turbo is TOO small to where it's over spinning and cant catch up. Anybody have any ideas? As for the cooling, don't think there's a bubble. I flushed the radiator and block, thermo works, new cap. Maybe it just cant cool it with the turbo hooked up to it. I doubt it. |
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| Author: | Matt Cramer [ Mon Jul 17, 2006 5:19 am ] |
| Post subject: | |
What's your air/fuel ratio doing when the boost builds? |
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| Author: | Dart270 [ Mon Jul 17, 2006 8:07 am ] |
| Post subject: | |
Maybe the pfff sound is a leak in your plumbing under boost? Keep us updated and sounds like fun! Lou |
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| Author: | Tom Drake [ Mon Jul 17, 2006 10:35 am ] |
| Post subject: | |
What type of wastegate and blow off valve are you running. Is it making this sound alll of the time? What pressure is the blow off valve set at? |
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| Author: | finnman1 [ Mon Jul 17, 2006 11:39 am ] |
| Post subject: | |
well, i'm not so sure that it's a leak in plumbing because it's more of a louder defined sound than air leaking through a hose. its as if it's the turbo fluttering or the motor. My o2 sensor is crap so my gauge reads lean constantly. I've yet to replace that. I've tried 66 through 85 jets and it still does it no matter what. (i'm shooting blind for the ratio til i get a new one) i'm using a 4bbl vacuum secondaries which wont open so it's the 2bbls for now. which leads me to wonder if the secondaries are opening a bit and letting some air through the throttle plates since it's a Draw-through setup and there's tons of vacuum sucking into the carb. and i dont have a blow off valve since it's a draw-thru setup but the sound is kind of like that only a constant ppsfffppssffffpsfffppfffspfff. |
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| Author: | finnman1 [ Mon Jul 17, 2006 11:40 am ] |
| Post subject: | |
...when under boost |
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| Author: | Sam Powell [ Mon Jul 17, 2006 1:44 pm ] |
| Post subject: | |
So it is not a steady sound, put a pulsing one? Mine blew the bonnet off the throttle body once, and it made quite a hissing sound. Engine sounded like it was strong, but was very week feeling. Tightening the bonnet back down fixed it fine. Go through and chek all your connections. Any time I finish up a project and hustle it out on the road, I always find something I forgot to tighten.  I haven't killed myself yet though.  It never hurts to go back and check everything.Sam |
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| Author: | mpgmike [ Sat Jul 22, 2006 10:24 am ] |
| Post subject: | |
It might just be too small of exhaust. I did a turbo on my '70 and it had very little power increase and made that sound until the larger pipes went in. Then the corners of the front bumper tilted up a bit as the car just smiled! Mike |
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| Author: | grthigpen [ Sat Jul 22, 2006 6:48 pm ] |
| Post subject: | |
i have seen this before with too small of exhaust tubine...are you running a t3? if so what is the AR on it? could be the problem GRT |
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| Author: | finnman1 [ Wed Jul 26, 2006 3:18 pm ] |
| Post subject: | |
well, i i'm pretty sure its one of the pipes leaking. evidently i thought flex pipe from advanced auto was sealed!! i wrapped it and it had soot when i took it off after a spin. that's good to know. yes a t3 is .42/.48... it's basically a straight pipe w/ a collector insert to muffle the sound a bit. wish i could get it to stop overheating though!!!!! got the new 02 sensor and it's on the money now! |
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| Author: | panic [ Wed Jul 26, 2006 4:11 pm ] |
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BTW: a reason why many engines run best with stock or very mild cams? Development work was done showing that overlap must be reduced to prevent chamber pressurization from the exhaust. Even the stock cam has too much overlap. How much worked best? Less? None at all? Even less: negative overlap. Both valve are closed for a considerable time around TDC, the intake isn't open yet and the exhaust is already closed. Source: Vizard. |
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