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EFI: larger plenum


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  • 4 weeks later...

...this is how a 5" plenum with 5" K&N Filter looks like....powder coat pending

Hopefully a little test-drive this weekend (weather permitting) and see if I need to adjust my fuel table...

Jochem

PS Matt, many thanks !

larger Plenum.JPG

Edited by JochemsTR
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19 hours ago, JochemsTR said:

...this is how a 5" plenum with 5" K&N Filter looks like....powder coat pending

Hopefully a little test-drive this weekend (weather permitting) and see if I need to adjust my fuel table...

Jochem

PS Matt, many thanks !

larger Plenum.JPG

My pleasure! 

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  • 1 month later...

I really do not want to overdo it on this topic, but I remain curious. and I am sure I am not the first one experimenting...

Any ideas or thoughts regarding the outcome of installing such a fan in the air intake, so actively forcing air into the plenum?

The fan would be controlled by the TPS Sensor, so no support during Idle, but rather during driving and WOT.

Jochem

 

PS Picture is a sample, ofcourse it runs with 12V

Fan1.jpg

Edited by JochemsTR
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Nope, the fan will not do it. The size and the position of the K&N is also not optimal. You need a ram-air-system or a charger. 

Without that I doubt that the bigger plenum will bring any significant increase of power.

Edited by Casar66
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2 hours ago, Drewmotty said:

A baby fan isn’t going to shift anything like the requirements of your 2.5 litre “air pump” it will just restrict the inlet.  That’s why we have superchargers. 

Absolutely!  Just do the maths, Jochem!    2.5L at 5000rpm demands just under 16,000 Liters of air!  (2.5x2500)    

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Gross 6250 liter/min for the record at 5000 rpm.

As a boy I tested a large funnel on my moped (Zundapp KS50 watercooled). It gave no noticable difference.

Waldi

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I ran mine up the road without the bonnet on with open inlets to test something once. The intake roar is just unbelievable and will give you goosebumps. It's worth doing just for the hell of it. John, best not try that with the Vitesse.

 

Jerry

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If I do my calculation correctly we will have around 6000 litres air intake because we do not not fill 100% at high revs.

The inlet area with 5" will give 121cm² and with a rate of 100 litres per second it will be only 9m/sec airspeed.

That is pretty low, in the inlet liners the speed should be limited to 80m/sec.

 

So I would be interested to see if just the increase of diametre from a quite low flow rate before will increase power.

 

I found out removing air filter box will lean engine and so wil increase power if properly set but copy this air box is a lot of work and it would be nice to see before if that makes additional sense.

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A mate of mine increased the size of the airbox and made all the parts himself including the trumpets. He found the pick up was very noticeable around 3500 rpm but torque suffered at low rpm. This is on EFI and single throttle body. Maybe back on the rolling road (Emerald) for adjustments on the fuel curve.

Regards Harry

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Fit a turbo with EFI and have done with it!

Counting to ten and looking for a place to hide.

Andy 

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No argument with the statements above, but I'd love to know where they come from/their authority.

TV8 - "the inlet liners the speed should be limited to 80m/sec."

and

trolleybus: "The volume of the plenum should be 85% of the swept volume of the engine"

Can you provide references, please?  Books, papers?

Edited by john.r.davies
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Here is a larger plenum, single throttle body, extended length runner EFI intake featuring heat blocks on each runner. From individual bell inside the plenum to the intake valve is 19.5”. With a TSI cam that is a flat torque curve, this increased torque in the 3200 rpm area at the cost of breathing above 5000 rpm.

A709E8F8-E16F-4A91-93F9-4FEB9D0A5170.jpeg

6AE25DE0-AF87-48CF-816E-BBDA1A69CF8C.jpeg

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