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Originally Posted by Mike Gayner
Oh yeah that's why you see so many turbo charged top fuelers, right? :rolleyes:
Why would you want to bother boosting a Focus? I mean, they're an okay car for a shopping trolley but why would you even bother trying to make it go fast?
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Top Fuel are obviously rule-limited to roots type. It is an effort to slow them down. Roots are the most inefficient form of forced induction. You get 'contstant boost' but you also get extreme levels of heat and extreme levels of parasitic loss. It takes 800hp to drive the supercharger on a Top Fuel dragster - that's an 800hp power gain alone from going roots -> turbo, if they were allowed to, they'd all do it.
As for why would you bother boosting a Focus... it's a small light car, it doesn't need much power to be exceptionally fast. The Focus weighs 1218kg (2680lbs) with a full tank of petrol... now lets add, say, a 100kg driver (1318kg or 2900lbs). With 190kW (255hp) and assuming you get a good run, that's a 13.7 - 13.8 @ 95 - 100mph. So on average, low 14's, from a little FWD hatch. Power/Weight is a good thing. It needs only 300hp to run 13 flat. What's a big, heavy Falcon do with 300hp? 350hp and its running 12.3 - 12.4's etc etc.
Turbocharging is definitley the way to go, Roots yeilds too much heat and parasitic loss, and extreme expense and difficulty to intercool properly, Twin-Screw is the same, just not as bad.. and Centrifugal is only really good if you wish to be different or have little to no underbonnet space. It's simply a crank driven turbocharger. Centri's are really screwed because they get the deficiencies of a Supercharger and a Turbocharger rolled into one package. You get the parasitic loss of a Supercharger (being crank driven), yet they need to spool up, just like the turbo, so you lose the whole "constant boost advantage" that Superchargers have.
Besides, a properly setup turbocharger system will have little to no lag, and make bucketloads of power from low rpm to redline.