Too much boost :(

"StudyStudyStudy" (jesterjin) 03/12/2018 at 12:30 • Filed to: None

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Just a bit of whinging really. My car is making too much boost.

Had a whole fiasco trying to figure it out, but now with a manual boost controller set to full open and functioning properly at lower gears, it is very apparent - the wastegate is too small. The spring is set to 9.4lbs, if memory serves, and in 1st and 2nd it pops open nicely and maintains that number as far as I can tell on my boost gauge. Starting with third gear though, the car hits my ECU controlled boost limit of 17lbs seemingly immediately if I give it more than half pedal. So boost creeping like crazy. Can’t even imagine 4th or 5th really.

I’m happy with how the manifold fits and the turbo sits with the routing of the oil lines and all. Unfortunately being made out of thick cast stainless this is going to really really suck to try and remedy.

I have to get a bigger wastegate, no doubt about that. That means I have to adapt or weld on a bigger flange for the bigger waste gate. I have a 39mm waste gate on a treadstone cast stainless steel manifold. Adapting seems to me like it would not solve a problem as the orifice leading to the wastegate would be the same internal bore as the 38mm flange. That leaves boring it out and welding on a V-band. That in turn means finding a way to bore out a hole in solid thick stainless, I’ve killed tons of bits trying to just drill a tiny pilot hole in stainless plate, I don’t even know what to do to try and do something to drill a 2 inch bore in something that thick.

Long-Voyager > StudyStudyStudy 03/12/2018 at 12:45

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1. Slow your drill way down, feed it heavy. Stainless cuts hard and wears out drills quickly, so slower rpm/heavier feed usually helps. That’s assuming you’re set on doing it yourself.

2. Take it to a machine shop and have them machine it to the correct diameter.

If you’re around WI I could sneak it in ;)

OPPOsaurus WRX > StudyStudyStudy 03/12/2018 at 13:39

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#1stgearproblems

StudyStudyStudy > Long-Voyager 03/12/2018 at 14:30

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I mean I would like to, I can use an angle grinder to grind down the flange to make an easier surface to weld on the 44mm vband setup, but enlarging the hole seems fairly daunting. Is it easier to enlarge a hole then it is to drill one? Last time I tried to make a new hole I ended up cutting the pieces and repositioning an existing hole after about an 15 minutes of slow drilling with oil and lots of pressure got me maybe 1 or 2mm deep with supposedly the correct bits.

Long-Voyager > StudyStudyStudy 03/12/2018 at 16:06

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It is easier to enlarge a hole than drill one. Drills don’t really cut on their tips, which leads to a lot of pressure needed to cut. When it’s cleared for the tip, they cut much easier (aka drilling out an existing hole), this is why when drilling a large hole you “pilot” the hole with a smaller drill first.

Either way, machining it out would be easier by far.