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914World.com _ 914World Garage _ Fuel Injection intake

Posted by: jhadler Apr 27 2009, 01:11 PM

So... I'm just thinking...

I've got this set of independent throttles sitting on a shelf in my garage, but my understanding is that they're not necessary for a basically stock motor. That being said, at what point do independent throttles become useful?

Cam? What kind of cam will limit the stock manifold?
Bore? How much displacement will limit the stock manifold?
Compression? At what point is more flow needed?

I know that the very first answer form Mr. Raby will be "it's all in the combination", and that makes perfect sense. But I still would like to get some ideas at what will limit the stock intake plumbing.

Example: What about a 2056 with an FI cam? Will individual throttles be needed at all? Or would the stock manifold be sufficient? Would there be any gains to going to ITB's even if the stock manifold was sufficient?

Thanks all!

-Josh2

Posted by: underthetire Apr 27 2009, 01:47 PM

None at all, i'll take those from you so you can clear up some shop space !

Posted by: Bleyseng Apr 28 2009, 06:46 AM

All depends if you are trying to use DJet or not. If you are going to aftermarket FI then the stock manifolds make no sense to use...switch it over to independant TB's and go with a better cam .

Posted by: kwales Apr 28 2009, 07:10 AM

Think of it as how much air can you suck.

A 2050 sucks a little more air than a stock 2.0 so a stock system, and the stock system should handle it well.

Be aware that the FI cam is a match for the stock manifolds, and works best with it.

Add throttle bodies to the FI cam, and it's like running a FI cam with webers- a mismatch.

The length of the intake manifolds has a distinct effect on performance. It's a reflected pulse thing and depending on manifold/throttle body/vellocity stack length, you can shift the max power point up and down the RPM range.

For example, if you use throttle bodies, there are short manifolds and long manifolds and different power points for each. There are also different lenghts of velocity stacks and they shift the power point too.

So, it's all in the combo...