by Usquanigo on Thu Jul 03, 2008 9:31 pm
Positive displacement blowers are "harder" on the engine than turbos - they take a lot of power to generate boost, and they heat the air more as well, making detonation more of a problem.
However, they are cheaper than turbos and easier to bolt on. If you're dealing with a V8 and only need a slight huff to get the power you desire, blowers are better. They also deliver more N/A-like linearity to the torque curve.
However, Turbos, modern turbos, are almost vice free, in terms of operation. They can be sized, used in multiples, or even "smart" (VNTs and such) so that lag is non-existant (especially with some plumbing wizardry). They create no back-pressure (to speak of), and they even eat much of your exhaust noise so that you don't need such a restrictive muffler. It's also much easier to intercool the intake charge, and that allows one to run more boost and get more power.
The trouble is in their price, and plumbing. For V engines you normally want to hang pairs, and you always want to intercool when you can, so you better have a LOT of room in the engine bay.
Also, their power delivery is peaky. It's not nearly as bad as it used to be, but it's still not exactly N/A levels of linearity.
Generally, unless you are married to an engine, I'd say FI is the wrong way to go. Reason being - cost, installation headaches, worsened fuel economy, potentially peaky power delivery, and of course, engine strain.
Let's be real for a second here. 500 flywheel hp on a street car is MORE than enough. Get yourself an LS1, a good cam and heads package, a good exhaust and a good tune and you're pushing over that amount. And it's infinitely streetable, with far less strain on the engine. (Sure, you can get that power out of a small engine with FI, but you aren't saving fuel, there is a bfsc/hp ratio that you can't avoid, and you can't argue with the stress on the engine - if you try, Gale Banks watched a 1.something litre 4 banger with an Offenhauser turbo generate 1200hp on the dyno...... just before they painted the dyno cell with parts when it came apart on them - more boost means less engine life, likewise with rpm.)
