lotusmadandy
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| posted on 15/8/11 at 06:48 PM |
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Inlet plenum opinions please.
Hi all,
I am just about ready to weld the 'log' onto my inlet manifold
but need some opinions from the house please.
As it is ATM the runners are poking into the plenum around 4-5mm.
Do you all think this will be fine,or should i shape the ends of the runners
to match the inside of the tube?
I will try and post a pic now to show you all what i mean.
Andy.
[img]]http://locostbuilders.co.uk/upload/8inside.JPG[/img]
HMM. That didnt work,i must learn.
[Edited on 15/8/11 by lotusmadandy]
[Edited on 15/8/11 by lotusmadandy]
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bonzoronnie
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| posted on 15/8/11 at 06:54 PM |
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Heres the picture
Hope that helps 
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lotusmadandy
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| posted on 15/8/11 at 07:04 PM |
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It does indeed.
Much obliged sir
Andy
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flibble
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| posted on 15/8/11 at 07:23 PM |
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I'm sure I read a thread on here some time ago where the concensus was that having them poke through a few mm is the best way, I shall go look
for it!
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mark chandler
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| posted on 15/8/11 at 07:24 PM |
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You should buy some nice trumpets and insert from the inside, then weld the to the runners
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sebastiaan
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| posted on 15/8/11 at 07:34 PM |
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It will deffo work like that. Trumpets will make it better though.
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lotusmadandy
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| posted on 15/8/11 at 07:40 PM |
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Thanks guys.
I agree that trumpets would be the best option but the problem is
that they will be bigger than the holes in the plenum,so it won't fit over
the top of them.
I think i will just leave it as is and weld it up.
Andy
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big_wasa
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| posted on 15/8/11 at 07:41 PM |
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What he said but I dont see an easy way of attaching bellmouths inside the plenum.
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sebastiaan
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| posted on 15/8/11 at 07:45 PM |
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It might be worth looking on ebay for some rubber bike TB trumpets that fit. If you let the runners poke through a bit you might just be able to put /
glue / sikaflex them on before you weld on the plenum end caps. If you see what I mean....
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lotusmadandy
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| posted on 15/8/11 at 07:53 PM |
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Indeed Wasa,
The only way i could fit steel trumpets,is by cutting the
plenum and i dont fancy that very much.
Sebastiaan,
I do see what you mean and you may just be onto something
there.I am intending to make the plenum double ended with a blanking plate,
so the throttle body can go on either end.It is made from a 4" tube so if both ends are
open it should be easy to fit them.
Andy
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bi22le
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| posted on 15/8/11 at 08:30 PM |
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Hi,
Dont mean to hyjack but I have a quesiton as I am going to be doning the same fabrication in the next month or so.
Why are trumpets better than straigh tubes? Shape is better for air flow? Lips are rounded increasing air flow?
Thanks
Biz.
I will be using a sausage filter so have the luxury of using pre fab trumpets if they are THAT much better.
Track days ARE the best thing since sliced bread, until I get a supercharger that is!
Please read my ring story:
http://www.locostbuilders.co.uk/forum/13/viewthread.php?tid=139152&page=1
Me doing a sub 56sec lap around Brands Indy. I need a geo set up! http://www.youtube.com/watch?v=EHksfvIGB3I
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lotusmadandy
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| posted on 15/8/11 at 08:42 PM |
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Maybe i should have mentioned, i will be fitting a turbo
as well. I dont know if it will make any difference to
the flow into the headers?
Andy
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sebastiaan
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| posted on 15/8/11 at 08:48 PM |
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No difference. The trumpets increase airflow on boosted and N/A engines equally.
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lotusmadandy
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| posted on 15/8/11 at 08:50 PM |
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Cool. Thanks Sebastiaan.
Andy
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DIY Si
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| posted on 15/8/11 at 09:14 PM |
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ram pipe flow
This is a fairly accurate guide of what trumpets can do to airflow.
“Let your plans be dark and as impenetratable as night, and when you move, fall like a thunderbolt.”
Sun Tzu, The Art of War
My new blog: http://spritecave.blogspot.co.uk/
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snapper
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| posted on 16/8/11 at 05:17 AM |
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Sikaflex is not fuel resistant, ask me how I know.
I eat to survive
I drink to forget
I breath to pi55 my ex wife off (and now my ex partner)
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MikeFellows
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| posted on 16/8/11 at 10:42 AM |
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im no expert here but it doesnt look right to me
if the inlet is at one end, wont the pressure difference between the trumpets be all over the place, you could solve this by making it conical in
shape so that as the pressure dropped across the trumpets the cubic capacity also dropped increasing the pressure?
there must be a fomula for this, but like i say im no expert and i could be talking bollocks
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The Black Flash
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| posted on 17/8/11 at 10:23 PM |
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Mike - don't think so, providing the plenum volume is big enough. I think that ideally the plenum volume is such that the inlets don't
really "see" the fact that they're in an enclosed chamber at all. (Yeah, I know it's a *bit* more complicated than that...)
The OEM plenum on my Alfa engine is a constant size all the way along, so it'll definately work as is. ISTR that it's best to have
narrowing plenums for FI engines though.
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atomic
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| posted on 18/8/11 at 12:28 PM |
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quote:
Originally posted by MikeFellows
im no expert here but it doesnt look right to me
if the inlet is at one end, wont the pressure difference between the trumpets be all over the place, you could solve this by making it conical in
shape so that as the pressure dropped across the trumpets the cubic capacity also dropped increasing the pressure?
there must be a fomula for this, but like i say im no expert and i could be talking nutsack
Mike, are indeed correct. The fixed diameter plenum will work but is not the most efficient design. Some if it's drawbacks can be worked around
using individual cylinder trim etc but if you are fabricating a intake manifold/Plenum changer from scratch then why not take this into account.
not the most detailed source of info but it may help out.
http://autospeed.com/cms/title_Breathing-Deeply/A_107771/article.html
[Edited on 18/8/11 by atomic]
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MikeRJ
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| posted on 18/8/11 at 01:08 PM |
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quote:
Originally posted by atomic
Mike, are indeed correct. The fixed diameter plenum will work but is not the most efficient design.
Honda use a small, constant diameter plenum on their B16 engines which produce 182bhp from a 1.6L engine straight from the factory (in the Type R).
Clearly it's not worth worrying too much about.
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lotusmadandy
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| posted on 18/8/11 at 06:44 PM |
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Thanks for all the info fella's.
I have been busy with a file creating nice radius on the inlet runners,to try and smooth
out the air flow.I am going to go with the plenum shape as it is,it will be a very
similar size to a griffin manifold.Ad to this the turbo boost that will be blowing through
and it should be fine as it is.
Andy
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BaileyPerformance
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| posted on 18/8/11 at 08:51 PM |
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quote:
Originally posted by lotusmadandy
Hi all,
I am just about ready to weld the 'log' onto my inlet manifold
but need some opinions from the house please.
As it is ATM the runners are poking into the plenum around 4-5mm.
Do you all think this will be fine,or should i shape the ends of the runners
to match the inside of the tube?
I will try and post a pic now to show you all what i mean.
Andy.
[img]]http://locostbuilders.co.uk/upload/8inside.JPG[/img]
HMM. That didnt work,i must learn.
[Edited on 15/8/11 by lotusmadandy]
[Edited on 15/8/11 by lotusmadandy]
Hi Andy, hows the motor going?
If would go for throttle bodies, then make a plenum chamber to feed them from the turbo.
Let me know if you need any help, as you know we have done several zetec turbos
Cheers Dale.
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NOTE:This user is registered as a LocostBuilders trader and may offer commercial services to other users
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beaver34
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| posted on 19/8/11 at 04:09 PM |
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where does the throttle body go? was wandering as didnt know if that effected how efficent the setup was as no1 would see the air first and 4 last if
it was on the end
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lotusmadandy
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| posted on 19/8/11 at 05:26 PM |
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Beaver,
How efficient the plenum is going to be,i dont know.What i do know is
that there are a lot of cars with that type of plenum fitted as standard and
they seem to work ok.The thrittle body
fits on the end of the plenum,griffin style.
Dale,
I will be in touch with you when i come to fitting my MS1.
To start with i am thinking of having an MS2 Daughter board fitted
and you will be my first port of call.I will no doubt be in need of tuning advice
to get the motor up and running anyway
Cheers,
Andy
[Edited on 19/8/11 by lotusmadandy]
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mark chandler
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| posted on 19/8/11 at 05:37 PM |
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Better if you can weld some wedges in, so oval where the TB sits, tappering down to the last cylinder
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