Intake trumpets.

Road-race engines and ancillaries - general discussion
4v6
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Intake trumpets.

Post by 4v6 » March 28th, 2011, 5:08 pm

Ive been doing some work to basically put together a set of throttle bodies but I was finding the both the sizes and prices of the various commercially produced intake trumpets a bit of a nightmare to be honest.
In the end I spent most all of saturday playing around with some aluminium sheet, a hobby lathe and resolving with good intentions to make my own.
After some material wasteage and a bit of swearing under my breath I finally developed sufficient skill to be able to make the sizes I wanted ( theyre a one off set) both repeatably and fairly accurately also.
Heres what I managed to do.
P1020266 (1000 x 750).jpg
First intake trumpet. This took a while to get right but it does fit very nicely.
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By the end of the afternoon I managed to make the full set.
Total cost was days time, a piece of 4 inch fencepost and some alloy sheet which was given to me free.
P1020271 (1000 x 750).jpg
5 in a row.
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P1020273 (1000 x 750).jpg
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I have to say, Im very pleased with how these came out and it just shows how you can actually hand fabricate many of the parts you need yourself.

This video was my inspiration, posted with Guys kind permission.
Hope you enjoy it as much as I do, Im absolutely fascinated by this kind of thing!

http://www.youtube.com/watch?v=DGszBVy3cgU
Last edited by 4v6 on April 7th, 2011, 5:17 pm, edited 1 time in total.
Tony Warren. GC #96.

Guy Croft
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Re: Intake trumpets.

Post by Guy Croft » March 28th, 2011, 6:20 pm

I like this post.

It ties in very much with my own philosphy of encouraging folk to learn new skills.

Thanks for sharing, Tony!

G

timinator
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Re: Intake trumpets.

Post by timinator » March 28th, 2011, 6:50 pm

Tony,

That is simply brilliant. Thank you for sharing your new found skill. My lathe is going to be getting some new tooling soon. Just to get me started what gage and alloy of aluminium did you use? What rpm did you find works best for the size parts you made and do you use any lubricant? We are so used to buying things we forget how much fun they would be to make. Thank you again for brightening my day.

Tim

4v6
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Re: Intake trumpets.

Post by 4v6 » March 28th, 2011, 7:42 pm

Thank you Guy, its a little difficult to get the feel of it initially, but once you actually figure out the dynamics of the way the material works and how and when to apply force which isnt much considering ( I had a fair few just rip and tear/deform) then it suddenly just "clicks" and it becomes very much easier.
Ill try stainless before too long but I need to make a brass or phosphor bronze tool or a roller to do it with.

Thank you Tim, I wish I could say it was me who discovered this fine process but alas im probably 200 years or more too late.
Material thickness was 0.9mm aluminium, disc size was 60 mm at start with a small hole drilled in the centre to keep it centralised, the finished height of the trumpet is 55mm but I could have made it a fair bit higher, it stretches absolutely miles and goes thin as paper if you want.
Spindle speed was the highest I could get, I dont know at the moment what that would be but I found that running it slower just allows the material time to ruck up and not flow so well.
Since I wanted a set of identical items, I used a mandrel ( a former) to work the material on to, but its not absolutely necessary if youre "spinning it on air" for pieces that arent critical like a bowl shape.
I made mine from a piece of old pine fencepost, 4 inch square which is what I could find and turned the shape I wanted onto it.
I did use a lubricant- lithium grease which flies everywhere!
The tide mark on my neck and grease in my hair bore witness to the days events.
I will next time use wax though I think.
I've yet to find out what is actually used but I suspect it may be tallow or suchlike just lightly smeared on, not sure at the moment.
Tools need to be rounded and smoothed and polished so they dont pick up on the surface.
I made two, one was just a rounded end the other more bullet shaped to get up close to the starting point at the tailstock end.
I found that if you dont get right in and start it really closely, you end up with a bulge that you cannot get rid of, however if the piece is long enough you could just trim it off when you trim the end anyway.
Absolutely! I agree 100%.
I could have probably parted with around £100 or more for some commercially produced items but then I'd not be any wiser and I'd be lighter by that amount so I'm glad I had a go, I hope your experiments also come to fruition as mine have.
P1020275 (1000 x 750).jpg
Mandrel made from a section of fencepost.
Dont tell the neighbours!
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P1020276 (1000 x 750).jpg
How it fits together.
P1020276 (1000 x 750).jpg (114.5 KiB) Viewed 4212 times
Attachments
P1020277 (1000 x 750).jpg
I wonder if I could make a really big one?
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Last edited by 4v6 on April 7th, 2011, 5:20 pm, edited 1 time in total.
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Boyracer
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Re: Intake trumpets.

Post by Boyracer » March 30th, 2011, 4:57 pm

Most excellent! I had no idea one could form metal in that way.

On my project intake trumpets are made with hydraulic press that forces 50 mm diameter 2 mm thick alum tube over expanding steel mold. Pretty crude and the amount of flare you are able to create is limited but it works...

I have been learning new skills on my build. Progress is slow and sometimes buying the required tools end up coting more than ready made parts from shops but I really like learning new things. In fact, I like building my car more than actually driving it on track! :)

tricky
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Re: Intake trumpets.

Post by tricky » March 30th, 2011, 10:00 pm

Thats very very good, I guess when something is advertised as 'spun' aluminium thats how it's done.
Twice as many valves

4v6
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Re: Intake trumpets.

Post by 4v6 » April 7th, 2011, 4:26 pm

Finally after a lot of effort I've pretty much finished the throttle body setup.
The flange adaptor is made from an existing manifold cut up to give small stubs and a laser cut flange welded on, that was quite difficult with warping and at times some cracking ocurring but I persevered with it ( Guy's "nothing easy is worth having" statement holds true) and finally I'm half happy with it.
I also did another run with with the spinning and found I can also generate quite a nice rolled back edge if I'm careful but more experiments are definitely required to perfect it I think.
P1020379 (1000 x 750).jpg
Finally at the finish on these.
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P1020380 (1000 x 750).jpg
P1020380 (1000 x 750).jpg (144.59 KiB) Viewed 4091 times
Last edited by 4v6 on April 8th, 2011, 1:42 pm, edited 2 times in total.
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TomLouwrier
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Re: Intake trumpets.

Post by TomLouwrier » April 7th, 2011, 11:12 pm

Applause to you!
It's so satisfying to have something like that, made with your own hands.
I'll be following this, let us know about that rolled back edge, please.

thank you
Tom
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Nobby
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Re: Intake trumpets.

Post by Nobby » April 8th, 2011, 11:01 am

Well done! They look great

Could I ask what engine these are for? There aren't many 5 cylinder engines about (unless its a v10 and its for 1 bank). Fiat 20v (2.4 or 2.0) - doesn't look like the manifold would fit as the 20v engines have variable valve circuit on the inlet manifold, so that leaves Volvo/Ford 2.5 engine or perhaps an Audi quattro 2.0/2.2

Chris
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4v6
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Re: Intake trumpets.

Post by 4v6 » April 8th, 2011, 1:46 pm

Thank you for your comments fella's, much appreciated indeed.

Chris, yes an Audi engine is the fitment, specifically the 7A 20 valve naturally aspirated version that used to go in the later type coupe's.
Tom, thank you sir! I'll definitely give an update on the rolled edge as soon as I've made a suitable tool to do them reliably with.
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Re: Intake trumpets.

Post by vandor » April 8th, 2011, 4:39 pm

Nobby wrote: Could I ask what engine these are for? There aren't many 5 cylinder engines about (unless its a v10 and its for 1 bank). Fiat 20v (2.4 or 2.0) - doesn't look like the manifold would fit as the 20v engines have variable valve circuit on the inlet manifold, so that leaves Volvo/Ford 2.5 engine or perhaps an Audi quattro 2.0/2.2
Chris
Just FYI, Acura/Honda also made a 5 cylinder engine for the Acura Vigor, but just for a few years.

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Guy Croft
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Re: Intake trumpets.

Post by Guy Croft » April 8th, 2011, 5:59 pm

Any comments on the type of aluminium alloy you used Tony? Some grades are more ductile than others (and weldable..).

I cold-form tube from time to time for coolant pipes, using a hydraulic bender. Get the wrong grade and it just fractures (won't tolerate bending).

G

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Re: Intake trumpets.

Post by WhizzMan » April 8th, 2011, 6:45 pm

There are good resources on the web if you search for "metal spinning". Soap as a lubrication is mentioned a lot.
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4v6
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Re: Intake trumpets.

Post by 4v6 » April 9th, 2011, 12:07 pm

Guy Croft wrote:Any comments on the type of aluminium alloy you used Tony? Some grades are more ductile than others (and weldable..).

I cold-form tube from time to time for coolant pipes, using a hydraulic bender. Get the wrong grade and it just fractures (won't tolerate bending).

G
Guy, the flange was made from 6082 and I welded it with 4034A rods (tig).

Some of the issues were I'm sure created by the casting that I was welding it to, as even though it was thoroughly cleaned and heated first it still seemed to create a fair bit of mess on top of the weld pool at times, just dirty casting material i think.

Whizzman, thank's for that introduction to the Acura, I never knew Honda did a 5 cylinder!
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Re: Intake trumpets.

Post by WhizzMan » April 9th, 2011, 9:30 pm

4v6 wrote: Whizzman, thank's for that introduction to the Acura, I never knew Honda did a 5 cylinder!
That's Vandor (Csaba) that told you that. Credits should go to him.
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