Further thoughts regarding my home made TB trumpets (velocity stacks)
bi22le - 6/3/12 at 06:24 PM
Hi all,
Following on from this thread:
http://www.locostbuilders.co.uk/forum/9/viewthread.php?tid=166686
I have made the below:
Needs final welding and some split and polish but I think its closer to the standard style velocity stacks. I did want some thing more custom made
looking but this will do for now. This is quite over engineered interms of wall thickness and plate used but when I finally get to SCS then I can cut
up and use this to make a cusom plenum. Its all practice!!
Any ways, I wanted to post up a pict to make sure this seems more sensible. I understand that the rad at the stop is quite small but looking at some
online ones its actually not that bad.
Any thoughts?
Cheers
Xtreme Kermit - 6/3/12 at 07:29 PM
Not an expert on this by any means (read that as complete numpty) but shouldn't the backplate be further down he stacks away from the radiused
ends?
mark chandler - 6/3/12 at 08:48 PM
Looking good Biz, how did you roll the ends over?
Good start to the supercharged plenum next year as well 
theduck - 6/3/12 at 10:15 PM
quote:
Originally posted by Xtreme Kermit
Not an expert on this by any means (read that as complete numpty) but shouldn't the backplate be further down he stacks away from the radiused
ends?
This was my thought also.
bi22le - 7/3/12 at 08:08 AM
If you look on the link in the op then you will see a pic supplied originally from clairetoo i think.
this shows a +5.8% increase which is the most beneficial set up over a bare carb.
v8kid - 7/3/12 at 08:24 AM
That is excellent! How did you roll the ends over - it looks very professional I'm jealous!
WRT the increase - increase in what? Clair's sheet only states an increase in flow not power and the two are not necessarily the same.
frequency, overlap and pulse duration are critical here.
Having said that I think your plan is as good as any but the acid test is to compare it back to back with another plan. Makes the whole thing
academical don't it
What matters is if you get a better performing engine and we won't find out until you try - go for it!
Cheers!
Xtreme Kermit - 7/3/12 at 08:36 AM
quote:
Originally posted by bi22le
If you look on the link in the op then you will see a pic supplied originally from clairetoo i think.
this shows a +5.8% increase which is the most beneficial set up over a bare carb.
Ah I see. I was thinking that the radius has to stand away from the baseplate for best effect but it seems not. Interesting.
Looking good by the way.
MikeRJ - 7/3/12 at 08:47 AM
quote:
Originally posted by Xtreme Kermit
Not an expert on this by any means (read that as complete numpty) but shouldn't the backplate be further down he stacks away from the radiused
ends?
It makes relatively little difference. A friends 2.0 Mi16 engine is making over 280 bhp with the backplate attached like this to the trumpets and a
slim Pipercross "sausgage" filter. Interestingly they tried fitting the Pipercross air box to the back plate ducted to a big cone filter to
reduce noise and immediately lost 10 bhp.
DIY Si - 7/3/12 at 08:48 AM
quote:
Originally posted by v8kid
That is excellent! How did you roll the ends over - it looks very professional I'm jealous!
WRT the increase - increase in what? Clair's sheet only states an increase in flow not power and the two are not necessarily the same.
frequency, overlap and pulse duration are critical here.
Having said that I think your plan is as good as any but the acid test is to compare it back to back with another plan. Makes the whole thing
academical don't it
What matters is if you get a better performing engine and we won't find out until you try - go for it!
Cheers!
That pic was originally uploaded by me, I think, and it's from Vizard's A series Book. As you say, all it shows it increases in airflow over
a standard inlet on an SU carb, but it gives you the idea of what to aim for. And whilst it shows increases, it doesn't show how much of that
increase will be held back by either the engine or the rest of the inlet, so just fitting them alone won't give anything like the same rise in
power, although they were worth a BHP or two on an A series, so a good few percentage increase.
FASTdan - 7/3/12 at 09:14 AM
Looks great - what is the make-up of the tubes, are the rolled ends part of them or to be welded? How did you make the rolled ends?
bi22le - 7/3/12 at 10:01 AM
quote:
Originally posted by v8kid
That is excellent! How did you roll the ends over - it looks very professional I'm jealous!
WRT the increase - increase in what? Clair's sheet only states an increase in flow not power and the two are not necessarily the same.
frequency, overlap and pulse duration are critical here.
Having said that I think your plan is as good as any but the acid test is to compare it back to back with another plan. Makes the whole thing
academical don't it
What matters is if you get a better performing engine and we won't find out until you try - go for it!
Cheers!
Thanks for the replies all. regarding above, i am aware that there are lots of things that affect power and engine performance. I used the info to
decide on shape and something to aim for. the tubes are shorter and i hope have better flow. i may get a power rise but i will be happy with no
change. the only reason for this exercise was to get an air filter on my car and test my manufacturing skills, i like making stuff!
the "rolled" edges are infact hand made pieces made from the same plate as the thick base plate. it over 2 hours per one to make and
included drilling, hand saw, jig saw, Dremel, filing and standing!! i will weld them on the end now the air filter base plate is in place. They are a
little untidy but i am happy with them.
i am worried about increased induction noise.
Any other thoughts?
bi22le - 7/3/12 at 10:07 AM
quote:
Originally posted by FASTdan
Looks great - what is the make-up of the tubes, are the rolled ends part of them or to be welded? How did you make the rolled ends?
tubes are 3mm wall 60mm od tube.
there is a ridge or step from trumpet to TB bit after speaking to Dave walker at emerald i thought the step was not much of a concern
DIY Si - 7/3/12 at 10:52 AM
How big is the step? If that's a 3mm plate, then there should be plenty of metal to allow you to smooth the shapes together.
It will be louder than the standard stuff. Hard to say by how much though.