Hi all,

Just checking what your thoughts are. TBH I am already half way through this and dont intend in changing the design too much but want to make sure there are no obvious things!

So When I brought the car (4age 20V blacktop) it had the standard rubber trumpets with ITG filters over the top. This catches the sterring colom and has ripped so is not a long term solution. I have a hole in the bonnet already so Im thinking to make a new backing plate to face the TB, weld new trumpets of approx the same lenght as the originals and put them at an angle to get close to the big hole allowing for cold fresh air feed. As I am making the trumpets out of thin-ish ali and the backing plate for the PX600 I am going to add the crucial radius inside the filter space (cunning, I know!) to make sure the air flow is max.

I have read anything that Dave Walker (Emarald ECU) has written to death and spoken to him on the phone to check parallel trumpets, thin ali and importance of length and radius design but he does not know exactly what I am trying to do, no pics given and didnt want to bother him for too long. He seems to be the man in the know and well respected when it comes to trumpet design.

Below is a cut through view vertically looking down on the engine. Front of car to left, obviously!



So I would just like the LCB collective to have a look and pass comment on anything obvious. The angle of the trumpets are purly to get the filter out to cold air and try and make them as long as possible. The engine had approx 135mm long trumpets bent at 90deg as standard so I am thinking this design is smoother and better.

Finish will be gloss black or maybe crackle black to give it an OEM look.

Thoughts?

Thanks.

Pos and neg comments always read, then deleted!!!!

Biz

I'm pretty sure a sharp angle is a no no. Best to form a bend if you can't make it straight

Oh and the curved entry has to be at right angles to the pipe - part from that its fine

[Edited on 20-2-12 by v8kid]

Don't like the angle of the trumpets. Could you curve the straight ali tube to reduce the angle it meets the throttle body?

I thought a lot of the effect that trumpets have was due to standing waves within them. I'm not sure how that would work if they're at an angle like that unless the head has been ported to work with such a system.

Hmm. . . .

I have rolled the trumpets from flat and am getting them welded to tubes. Any simple ways of bending the tubes. I cant think of any simple (or complex for that matter!) way to bend a thin walled ali tube of 50mm dia.

Ideas?

for reference, these are what the standard trumpets look like. Mine are the same but in rubber.





You can see why I am less worried about the angle!!!

Depends if you want to improve on it or not! No point in replacing poor design with poor design.

I used to make very complex sheet metal 2 stroke expansion chambers by welding together two bits of sheet metal and blowing them apart with hydraulic pressure. In my case it was trial and error but some claimed to be able to calculate the shapes. Google it I'm sure some kind soul has posted a how to.

Claire has this doc in her photos if it helps;

ram pipe shapes

Hello Bizzle

Sharp angle is not good, how about some tight mandral bends off ebay?

I can remember looking under your bonnet, all very close, is it possible to adjust the steering column angle and point below the TB's and make a bit more room for a more standard affair?

Also the first TB will get a little more air than the last with that design, better to make a tapered plenum to cover the TB's and duct cold air in if possible, or better still design something so you can add a low pressure turbo and intercooler at a later stage

Regards Mark

[Edited on 20/2/12 by mark chandler]

I run a Silvertop in mine, for which I originally made 115 long parallel sided ramtubes. The engines has very mild cams, COP and a Haltech.

For noise reasons [to get it all back under the bonnet], I replaced them with 75mm tapered ramtubes in a home made airbox. The shorter tubes gave me 5hp more ATW.

Piccies at the bottom of this page :- http://www.locostbuilders.co.uk/viewthread.php?tid=146635

Seems i may need to do more thinking.

Any body know of cheap trumpets for sale or can turn custom ones up?

Ok I have had a think.

I will make up some parrallel (maybe tappered) tubes about 75mm long and round the edges as planned before. Ill make them straight and not worry about the cut out in the bonnet. Ill buy a new one long term.