Differences between Flapper and Hotwire?

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The Original Tom
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Differences between Flapper and Hotwire?

Post by The Original Tom »

I've heard of these 2 types of rover V8 injection that was used on Range Rovers.
I believe flapper was used on 3.5's and 3.9's, but the later 3.9's were hotwire?
What are the differences and why is the hotwire regarded as so much better than flapper?


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katanaman
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Post by katanaman »

there are many differences but the main ones are:

Hotwire has a fully digital ECU flapper doesn't and hotwire's air flow sensor is just that a hot wire where the flapper has a big flap sitting in the airflow.

The flapper system is really old now and as such can have a lot of problems purely down to its age. It also cant control the fuel as accurately purely by its very nature. It was a marvel in its day but it is well behind these days. Its also very difficult to alter the fuel curves, where the hotwire can be chipped.

Like I said there are many more detailed differences which all add up to the hotwire being a better system although these aren't the greatest systems these days either in the modern scheme of things.

Should also add I cant think of any 3.9 engines with flapper injection, they are all hotwire unless there are some very rare examples kicking around. Equally there are a small number of factory hotwire 3.5 engines around.
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ChrisJC
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Post by ChrisJC »

The hotwire also has idle speed control.

Chris.
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