Spank wrote:Ok, so I've got a turbo from a 2.2 shelby and it's 466298-0004 which googles to a TB0335. The A/R is 0,48 whereas our current unit, the TB0329 has an A/R of 0,25
The A/R (area Ratio) determines how the turbo .. responds to the exhaust gases on the turbine side (hot Side) and the on the compressor side, how it compresses the intake air.
Small A/R wheels in the turbine tend to spin up faster. For a given engine a .25 A/R will spin up faster than a 0.60 A/R. But the Small A/R will max out in speed vs exhaust sooner. If you draw your volumetric flow rate on the turbo map (have to calculate how much air your 998cc engine sucks av various RPM) you'll see at some point for a small turbo, you will go to the right and off the map. That means the turbo is maxed out and providing all it can provide.
Similarly, on the compressor side a small turbo wheel will start to pressurize sooner vs a big wheel. But the small wheel will also reach its limit and then you'll hit the surge line (left edge). The bigger turbo wheel will spin up slower, but when it starts to make pressure, it will make more pressure.
So the idea (if your doing this correctly) is to a) figure out the RPMS you want to have boost for, b) figure out the volumetric flow rates, C) pick a turbo and plot the V flow to see where you land. Optimally you want to go right through the middle of the bullseye of the map and not hit the Surge line or fall off the map to the right. If the "map" is not wide enough (you fall off the curves to the right), you need to go to a bigger turbo. If the map is too wide, smaller turbo. If you hit the surge line, right size, different A/R. etc........
For Lemons you'll want mid range boost, that should probably max out just below redline, unless you run your engines to redline (YEAH baby, BOOM!), So a smallish turbo is better than a big Turbo. I would just guess that a T3 is too big for your 1 Liter. Try looking for Diesel engined turbos, since they are designed to spin up a lower Engine volumetric (lower RPM) ranges
Try running this online calculator for your engine and the different turbos. You'll have to fool it a bit on injector size (just put in 280cc or bigger)
http://www.squirrelpf.com/turbocalc/
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