Cheeky Cheapy Trumpets

[Darren]

Shameless take from t'internet - I saw this and thought it would work well for my throttle body install. The problem with using throttle bodies from a bike rather than stripped out carb bodies or jenvey throttle bodies is that there is no straight forward method of attaching trumpets. Most of the inline 4 Jap bikes use an airbox where a rubber coupler is used to 'extend' the bell mouth into the airbox.

This isn't a straightforward method and I'm still working on it, but for the outlay (3 quid for a pair of 'trumpets' even if it doesn't work, then it's not cost me anything!

Started with this -
http://lancisti.net/photopost/data/904/thumbs/P190409_16_01.JPG (http://lancisti.net/photopost/showphoto.php?photo=8379)

A bit of work with a sanding disc
http://lancisti.net/photopost/data/904/thumbs/P190409_16_03.JPG (http://lancisti.net/photopost/showphoto.php?photo=8383)

Spin round the other way and you get
http://lancisti.net/photopost/data/904/thumbs/P190409_16_03_01_.JPG (http://lancisti.net/photopost/showphoto.php?photo=8384)

First fix to the injection body with an un-modified unit
http://lancisti.net/photopost/data/904/thumbs/P040509_18_05_01_.JPG (http://lancisti.net/photopost/showphoto.php?photo=8367)

Another angle - a bit more sanding and blending required though.
http://lancisti.net/photopost/data/904/thumbs/P040509_18_06.JPG (http://lancisti.net/photopost/showphoto.php?photo=8368)

If you haven't guessed already - they are egg cups! ;o)

What do you think?

[1,6 HF]

Bloody clever, if you ask me.

The only possible downside is that the short, rolled profile will favor high-end power at the expense of low-end response. But if that works for you, it's brilliant.

[DJ]

Lookout, Will! Your Mr. Wizard title may be in jeopardy!

[Darren]

Lookout, Will! Your Mr. Wizard title may be in jeopardy!

Nah, Will's title is still safe - his ideas come from him - mine are taken off the net and maybe adapted a little!:D

[Darren]

Bloody clever, if you ask me.

The only possible downside is that the short, rolled profile will favor high-end power at the expense of low-end response. But if that works for you, it's brilliant.

- Hmmm, I'm more interested in low-end response tbh - so maybe I'll try it without them and see how it goes and try it at a later date, once it's all up and running. What's a better profile for that?

Cheers

[DJ]

- Hmmm, I'm more interested in low-end response tbh - so maybe I'll try it without them and see how it goes and try it at a later date, once it's all up and running. What's a better profile for that?

Cheers

Just taller/longer I think. Longer intake tract.

[1,6 HF]

- Hmmm, I'm more interested in low-end response tbh - so maybe I'll try it without them and see how it goes and try it at a later date, once it's all up and running. What's a better profile for that?

Cheers

It's a rough generalization but, typically, longer intake runners and trumpets improve low-end response, while for high-end you want the shortest runners possible, and short trumpets with broad, rolled profiles. There's actually a way to calculate optimum runner/trumpet length (and exhaust system collector length) based on the pressure waves, but I tend to glaze over whenever I read an explanation of this...

[Darren]

Just taller/longer I think. Longer intake tract.
- ok, I'll look out for some larger and taller egg cups! ;o))

[Darren]

It's a rough generalization but, typically, longer intake runners and trumpets improve low-end response, while for high-end you want the shortest runners possible, and short trumpets with broad, rolled profiles. There's actually a way to calculate optimum runner/trumpet length (and exhaust system collector length) based on the pressure waves, but I tend to glaze over whenever I read an explanation of this...

Thanks for the info Ed - I'll pass for now I think and concentrate on getting running again first and add it to the list of things to do....later!;)