4 cylinder 20V engines - why no more???

C_Audiboy

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• Jan 15, 2007

• #1

I was just wondering why Audi (VAG more to the point) seem to have dropped the 5V per cylinder configuration on the new 4 cylinder engines?

I'd have assumed that it was 5V for a good technical reason and I assumed it to be an improvement over 4v per cyl. But we are now back to 4V per cylinder in the new 16V FSI units.

Anyone know the reasons behind this?

I don't claim to know **** about how engines work....... I'm just curious!!!

 

icenutter

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• Jan 15, 2007

• #2

They probably found that the benefits didn't outweigh the costs (weight and money). You can get away with any old rubbish if you are turbocharging an engine

 

smitch

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• Jan 15, 2007

• #3

Dunno, but i used to have a 90 20V which was 5 cylinder with 4 valves per cylinder and wondered why they went to 4 cylinder with 5 valves per cylinder!?!?!?!

 

Ess_Three

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• Jan 15, 2007

• #4

I seem to recall that in order to get the FSI injector into the head, there wasn't room for all 5 valves...so they reverted to 4 valve heads, plus a direct injector and a central single spark plug.

At least I think that's the reason...

BYW...this 5 valves are better than 4 is ******** anyway...on a road engine with properly designed heads, there is no reason why a 5v flows more than a 4v...so don't go looking at it as a backward step, 'cos it isn't.

 

Beerzo

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• Jan 15, 2007

• #5

Yup plus the valves maybe bigger now, so they may not have needed the 5.

 

Ess_Three

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• Jan 15, 2007

• #6

The inlet valves will be larger...they were pretty small on the 5v heads.

 

Caesium

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• Jan 15, 2007

• #7

5 valves per head is no better than 4 if the 4 are designed properly. The use of turbos on a lot of cars now also negates the need for the extra valve.

Also the extra engineering needed has clearly been dropped as it offers no more in the way of performance or economy.

 

J

joost

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• Jan 15, 2007

• #8

And there's me thinking there might have been a shortage of valves...