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Ben Lipman Goo Roo SA Soarer TT manual, plus TT track car, plus a spare shell
Posts: 4019 Reg: 04-2006
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Sunday, March 27, 2016 - 08:30 pm, by: Ben Lipman(Ben12a)
Cheers Tim,
I have learnt a lot from this experience. Normally I do a lot of research before I commit to something and have a good understanding of the issues/potential issues surrounding the item. In this case I did not do that, so I have actually been reading to put my issues in context. It is an uncomfortable way to learn. Too often during the last 5 months I have had no idea what Glenn, Kurt, or the tuners have been talking about and had to run away and google it.
For example: If I knew about the pressure ratio across the turbo, would have known I needed uprated wastegate actuators as high flows can often have issues here. (the ideal pressure ratio for a race car is 1:1.5 intake manifold to exhaust manifold pressure, 1:2 for a street car). Not a problem unless temps start to rise or you reach a point where the exhaust cant get away as fast as the engine needs it and the system gets 'choked'.
I also did not know about WOT surge. I only knew about closed throttle surge. Closed throttle surge, whilst not desirable, is actually not that bad except in higher boost applications, and as we all know is easily solved with a BOV. WOT surge can destroy turbos and engines.
I also learnt that Turbosmart, makers of many styles of BOV, actually prefer and recommend recirculating systems because they need no tuning. (There are gains to be had from atmo style BOV though)
I learnt that Dump pipe entry should be approximately the size of the exhaust wheel to keep velocities up, and where possible wastegate pipes should be completely separate from exhausts, or at least not rejoin the exhaust for approximately 18 inches (45cm). I also note this is hard to do on a internally gated turbo, and is one of the reasons why an external gate will always outperform the same size internal gate.
All this and I still have one more turbo design and application textbook to read.
Then I need to become an expert on camshaft specs and application...
