Comments on: The Fuel-Injection CORVETTE http://blog.modernmechanix.com/2009/02/01/the-fuel-injection-corvette/ Yesterday's tomorrow, today. Sun, 22 Nov 2009 01:28:09 -0800 http://wordpress.org/?v=2.8.4 hourly 1 By: hwertz http://blog.modernmechanix.com/2009/02/01/the-fuel-injection-corvette/comment-page-1/#comment-1065469 hwertz Tue, 03 Feb 2009 04:34:31 +0000 http://blog.modernmechanix.com/?p=6972#comment-1065469 "However, the automotive fuel injection system developed at General Motors at present is only a distant cousin of the diesel system. This new system, though providing a fantastic advance in performance, does not explore the full and expensive properties of diesel injection, which someday may make it possible to run a 12 or 15-to-1 compression ratio engine cooler and more effectively on a poorer grade of fuel than we have now. But that’s tomorrow. Before we get on with today, let me qualify that last statement. When the fuel is injected at the last instant, as it is in a diesel, or at the top of the compression stroke, all possibility of pre-ignition is eliminated. In today’s so-called fuel injection engines, such as used on the Corvette, high-octane fuel must still be employed. The fuel goes in on the suction stroke and must ride out the compression stroke to the end without bursting into flame first." This is JUST being addressed now. Some of the newest cars are just getting Direct Injection, which does in fact inject high-pressure gasoline directly in the cylinder, like a diesel. The gasoline cannot preignite -- the gasoline is simply not injected ahead of time so it can't ignite early. I think there are a model or two up to 12:1 compression now, on regular gasoline, due to this. The newest thing being worked on, GM calls it HCCI (Homogenous Charge Compression Ignition) and Mercedes is called it DieseOtto. Under heavier load conditions the spark plugs are used. Under light load conditions, the fuel is injected very lean and under tightly computer-controlled conditions, autoigniting just like a diesel. I think this may involve variable compression. This really does run like 15:1, and has diesel-like efficiency gains using regular gasoline. (Diesel is still higher since it actually has more energy per gallon, but HCCI apparently gains about 30% mileage over spark ignition... overall increase is expected to be more like 15% since HCCI can't be used under heavy load, or quite yet at idle.) “However, the automotive fuel injection system developed at General Motors at present is only a distant cousin of the diesel system. This new system, though providing a fantastic advance in performance, does not explore the full and expensive properties of diesel injection, which someday may make it possible to run a 12 or 15-to-1 compression ratio engine cooler and more effectively on a poorer grade of fuel than we have now. But that’s tomorrow. Before we get on with today, let me qualify that last statement. When the fuel is injected at the last instant, as it is in a diesel, or at the top of the compression stroke, all possibility of pre-ignition is eliminated. In today’s so-called fuel injection engines, such as used on the Corvette, high-octane fuel must still be employed. The fuel goes in on the suction stroke and must ride out the compression stroke to the end without bursting into flame first.”

This is JUST being addressed now. Some of the newest cars are just getting Direct Injection, which does in fact inject high-pressure gasoline directly in the cylinder, like a diesel. The gasoline cannot preignite — the gasoline is simply not injected ahead of time so it can’t ignite early. I think there are a model or two up to 12:1 compression now, on regular gasoline, due to this.

The newest thing being worked on, GM calls it HCCI (Homogenous Charge Compression Ignition) and Mercedes is called it DieseOtto. Under heavier load conditions the spark plugs are used. Under light load conditions, the fuel is injected very lean and under tightly computer-controlled conditions, autoigniting just like a diesel. I think this may involve variable compression. This really does run like 15:1, and has diesel-like efficiency gains using regular gasoline. (Diesel is still higher since it actually has more energy per gallon, but HCCI apparently gains about 30% mileage over spark ignition… overall increase is expected to be more like 15% since HCCI can’t be used under heavy load, or quite yet at idle.)

]]> By: Rick http://blog.modernmechanix.com/2009/02/01/the-fuel-injection-corvette/comment-page-1/#comment-1065445 Rick Mon, 02 Feb 2009 15:58:31 +0000 http://blog.modernmechanix.com/?p=6972#comment-1065445 Yep. Get your kicks on Rt. 66! Rick Yep. Get your kicks on Rt. 66!

Rick

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