Twin 40 trumpets

[dunova]

I'm not sure if its worth me fitting trumpets on my twin 40's, mainly because there's barely enough room for them and i may just end up reducing airflow if anything. At the moment i have just got K&N filters.

I've been told that the minimum amount of space is 2 inch's between the trumpets and filter top/bulkhead. So if i fitted trumpets with my K&N filters i would just decrease airflow, but at the same time i don't want my carbs to not perform properly. Can i get very short trumpets so that i don't decrease airflow and have the benefits of using them?

Has anyone got any suggestions? What setup are other people using?

Any help appreciated, thanks

[nathan.]

you should have more than 2 inch room matey, look at benji's feature.

you need to use trumpets because if you dont i believe it effects the air flow into and through the carbs.

what air filter(s) you gonna use

hope this helps

[dunova]

I'm using K&N filters. I know trumpets create a smoother air flow but at the same time, you need enough air getting in! I could get trumpets and sock filters but i've heard bad things about sock filters creating air turbulence. If i used trumpets with my K&N filters i'll only have about 1 and a half inch's from the trumpet to the K&N top cover, so i won't have enough air flow.

I'll have a look at some features on here and see what others have done. If i want to use my K&N filters and trumpets the only way i can see of doing it is by using quite short trumpets. Any suggestions?

[nathan.]

i understand what you mean. what size trumpets are they?
mine are 22mm i think and ive got 1 air filter that sits over the carbs. im sure there gonna fit ok, hope so

[Mike]

by the sounds of it, shorter trumpet's is the only way it's all gonna fit properly :|

[Dan]

I think i run 16mm trumpets, what you need is a PIPER X filter for twin forties, for a nova. Yes they do make them (or atleast when i got mine a few yrs ago it was singled out as such).

Here's a pic of the total depth, its an all in one filter which is suited best for 16/22mm trumpets as a minimum requirement is 14mm from face of trumpet to inner face of filter.

http://www2.novaload.net/files/dan/fil8.jpg

I ran that filter from day one with the gte shell, and it never left the engine.

As for trumpet lengths, for what most of peeps use them for there are no real gains regardless of what size you run so dont believe the hype. But as said you must run something to aid air flow into the carbs. Bigger isnt always better

[Snowface]

25mm+ or more is what you need if you are using a K&N or similar which has a metal plate cover.

With a Foam filter, such as RamAir or Piper cross, it has a foam top so it doesn't matter so much, you could probably get away with 10mm because it can draw air from the top of the filter aswell as sucking it from the sides.

Air can't be draw through the metal plate cover of the K&N so it needs more space (25mm+).

Where as the RamAir filter can draw air in through the top so doesn't need as much space.

[Dan]

just to make it clearer (i prob read it wrong but others might also)

Snowface is talking about the amount of room between the trumpet face and inner face of the filter, not actual trumpet size.

[DrivingSpanner]

(all foam)[/color] can draw air in through the top so doesn't need as much space.

Yes that is a very true point which most of you probably havnt taken into accound. However for road use it really isnt that important because you wont be flowing a great deal of air anyway, as a rule of thumb you air box (or area inside the filter) should actually be twice the engine capacity, but howmays cars can claim that, so for a 2.0xe thats a air box with a camacity of 4 cubic litres, and thats huge and unrealistic to fit under most bonnets! so dont get to fussed over it....

You must use trumpets, even if they are only 1/2 inch because if you dont you will end up with a barrier wall effect (which im sure cambridge can explain slightly better tomorrow!), which is basically where the air does not flow into the carbs, like hitting a wall, and rebounds off the sides causing the next lot of air to be disturbed and making the flow worse and worse upto a point.

[dunova]

Okay cheers for the info guys. Looks like i might change my filters for a one piece foam type filter. That way the trumpets will be able to draw in air even if the trumpets are up against the filter.

Shame i didn't post this before i bought my K&N's :roll:

Think i'll still get small'ish trumpets to give them abit of room to breath. Can't wait to get everything fitted, it's going to sound awesome :D