O M G !

[tractor]

cant believe wot a difference getting rid of foam air filter has made got to up the rev limiter cos I just run out of revs so quick there is just so much more power higher up the rev range now it is getting all the air it needs just hope the rolling road session tomorrow will spread the power a bit more

[brumster]

What filter was it that you got rid of?

[tractor]

it was the piper cross sausage one

Edited May 4, 2016 by tractor

[brumster]

Interesting. Not used a pipercross (ITG here) but I assume they have a metal cage inside to stop the foam collapsing (the cable ties are probably not helping!)? It does look somewhat small though, appreciate you've not got much clearance but that probably won't breathe enough for a 2.0 litre... given our longitudinal orientation, of course. Candidate for an airbox right there ;-)

Edited May 4, 2016 by brumster

[Guest preeday]

What have u replaced it with?

[brumster]

I bet he's stretched the missus' tights over the ends of his trumpets

 

ooer missus!

[tractor]

yes it did have the metal cage in it it was the thinist filter I could get cos it used to fit under my 2b bonnet

[tractor]

no air filter now just some mesh

[brumster]

I take it you were testing on the road, moving along, not just standing static on the drive revving it?

 

Obviously once moving you've got a more complex airflow setup in play - probably hot air through the nosecone exhausting through those holes rather than any air being sucked it, due to the higher underbonnet air pressure. Hard to say really without empirical testing, of course, but that would be my guess. But for sure, the old air filter wouldn't have helped, particularly if it was butted up against the bonnet panel. If so, you were effectively sealing it against the bonnet and reducing it's airflow considerably (and restricting it to what it could draw from within the bonnet area, of course). Assuming the holes weren't there before....

 

Either way, sounds like you've got the improvement you was after just don't suck anything in like a nut, washer, pigeon, small child, etc...

[tractor]

been out for a good run this afternoon and all i can taste is fuel the air filter was restricting air flow but it was also stopping the stink of fuel coming back out

[brumster]

Yeah. Not sure whether you mean that literally, but there's a good chance that the negative pressure you've created with those bonnet holes is now drawing fuel out of the trumpets and out of the bonnet - not all the time, probably only at certain throttle openings/engine conditions. Hard to say really just from some photos...

 

Certainly air flow through engine bays is an art, and one that most people in the kit industry completely misunderstand, trying to scoop more air in that getting it out.

[ozz]

No wonder the filter didn't work you had it on upside down ⬆Pipercross⬆

[Guest Pauljordan]

Chris, Dan thinks your sausage looks small...... Ooh arrived missus.

[Guest 2b cruising]

A nice plenum by red 7 engineering drawing the air from the front of the car ahead of the radiator would help performance, and stop it throwing fuel out of the carbs/throttle bodies at the same time.

You might even have room to design forced air with some form of scoop under the car.

Every little helps Chris.

What a clever guy Brumster is.

[jaimo]

+1 for red 7 great phlenum is what i am having done when my bike carbs are fitted