Bike throttle bodies inlet length? CGA3

Hi,

I have a question (second question of the day lol), hoping someone can help! :)

Basically I've been using the standard rubber trumpets on my GSXR600 throttle bodies on a CGA3.
Today, I fitted some 35mm longer stainless DANST trumpets and the car sounds soooo much more aggressive, like a proper ITB growl. It sounded pretty cool before but now its much more of a deeper ITB soundtrack.
However, the longer trumpets don't really fit underneath the bonnet so the bonnet has to be kept open, (just locked into the latch but not fully closed).

I'm getting a new inlet manifold made anyway as my current one is damaged. So if I get a new manifold made that is 35mm shorter (so that my total inlet length is still the same as before), then how will that affect the sound?

I guess my question is - is this new aggressive ITB sound coming from the fact that I am using bigger wider trumpets or is it more down to the fact that the total inlet length is longer?

Sorry if I'm not explaining it properly!

Ideally I want the soundtrack that the car has now, but with everything being able to fit under the bonnet.

Appreciate any help!
 
Last edited:
A couple of thoughts, I'd expect the sound to be length dependant all else being equal, that is length from the back of the inlet valve to the trumpet not too the butterfly.
So short inlet runners on long trumpets or short trumpets on long runners of guess the result would be similar.
That said one is a rubber trumpet and probably absorbs more sound, the trumpet shape probably also has a part to play.
Unless you're going to modify your bonnet it would seem you don't have much choice on length, of you've got to make a new inlet manifold anyway you may as well try the steel trumpets as you have them anyway.
 
A couple of thoughts, I'd expect the sound to be length dependant all else being equal, that is length from the back of the inlet valve to the trumpet not too the butterfly.
So short inlet runners on long trumpets or short trumpets on long runners of guess the result would be similar.
That said one is a rubber trumpet and probably absorbs more sound, the trumpet shape probably also has a part to play.
Unless you're going to modify your bonnet it would seem you don't have much choice on length, of you've got to make a new inlet manifold anyway you may as well try the steel trumpets as you have them anyway.

That is all making sense to me, thank you for your advice.

I'll be sticking with the steel trumpets but as you say, I guess I don't have much of a choice on keeping the current inlet length.

The current inlet length is around 410mm, which according to Jenvey, its pretty much bang on for a car that revs to 7.6k but I'll have to take 35mm off this in order to get everything to fit nicely.

Thank you for the help, appreciate it :)
 
Top