Reply With QuoteA. Just the plenum body itself.Originally Posted by andrew_mx83
B. Bigger is better, 150% is fine though as you only get rapidly decreasing returns with larger ones.
Intake plenum theory
bloody xmas week has come around waaayy too quickly and i need to have my plenum design finalised today so it can be welded up before the bloke shuts up shop til mid-january
its a real simple design i just need to make sure it is in the right ballpark for volume.
currently it looks like being 11ish litres on an NA 3lt so im guessing way too big
2 questions i still have after a bit of a google:
a) does the "plenum size" include the runners and ports all the way upto the valve or is it just the plenum area before it splits off into runners
b) 150% of engine displacement seems to be the going rate, im shooting for mid-range and top end out of the setup. so plenum should be around 4-5 lt?
Last edited by andrew_mx83; 20-12-2009 at 05:19 PM.
Re: Intake plenum theory required asap (this afternoon)
A. Just the plenum body itself.
B. Bigger is better, 150% is fine though as you only get rapidly decreasing returns with larger ones.
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Re: Intake plenum theory required asap (this afternoon)
cool thanks mate. i dropped the drawings off this afternoon.
total volume will be around 5.5 litres
Re: Intake plenum theory required asap (this afternoon)
pics when done?
Re: Intake plenum theory required asap (this afternoon)
too late, but i reckon i wouldve kept it bigger
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E46 M3 Nürburgring Nordschleife - 8.38
Re: Intake plenum theory required asap (this afternoon)
plenum size = 150% of engine capacity- any bigger and intake velocities slow down and rob powah i take it?
does this still stand for forced induction applications?
Re: Intake plenum theory required asap (this afternoon)
yeah will post pics up once ive polished it etc.
they are just making the box for me, i have to drill all the port holes etc
i was under the impression that bigger = more low down torque
and smaller = more peak HP
Re: Intake plenum theory required asap (this afternoon)
got any pics of the 11L design? Must have been a tight squeeze
Re: Intake plenum theory required asap (this afternoon)
I get guys coming through for ali to make plenums all the time the going piece for a starit 6cyl seems to be approx 600-700mm of 100 O.D tube with a 3mm wall and then they frankenstein everything to that.
Wish I had a F#%ken awesome toyota.. saving for the goodness now.... stay tuned....
Re: Intake plenum theory required asap (this afternoon)
mine is 450 long 100 high and 150 wide all made from 6mm plate (so i can tap holes in it)
it is being folded out of sheet then welded into a rectangle section, with 2 endcaps welded on from there
apparently its only gonna set me back about $100 -i thought that was pretty cheap!
no pics of the design unless u look inside my head lol and find it filed under "crazy ideas volume 4"
Re: Intake plenum theory required asap (this afternoon)
that is cheap dude. 100 od pipe is about $30/m and if u can weld you can make it look smick as.
Wish I had a F#%ken awesome toyota.. saving for the goodness now.... stay tuned....
Re: Intake plenum theory required asap (this afternoon)
thats what i thought. as i cant weld ally (or have anyone to do it for free) i figured if i buy a piece of rectangle section (cant get that size anyway) id be up for at least $50 to weld the endcaps on so really i cant complain
it was originally $75 in 2.6mm but ive since decided to go fro 6mm so its stronger and i wont have to use nuts anywhere, can just tap straight into it. the bloke said only another $15 to go 6mm.
he seems pretty reasonable and ill be getting a quote for a 30lt fuel cell when i pick the plenum up
Re: Intake plenum theory required asap (this afternoon)
when talking about plenums on NA engines, the only intake velocity you should care about is the one in the port runner.
the plenum is there to balance out flow/air supply to each individual runner, thats all. you can make a really fancy plenum that actually uses acoustic tuning to help feed the runners in an active sense, but thats farking difficult. generally if you can get an NA plenum to work the same as open atmosphere, youve done well.
plenums like the one below i generally hate. flow quality and character is bad. acoustics are bad, port balance is bad. all bad. anyone can weld a bunch of runners to a 100mm tube of ally, doesnt mean its going to work right.... then again, theyre often building a turbo engine, and they dont care about such meaningless details!
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tech moderator
E46 M3 Nürburgring Nordschleife - 8.38
Re: Intake plenum theory required asap (this afternoon)
even the 'pros' dont care that much about plenum design... idjots. boost pwns all
../delete/ban
tech moderator
E46 M3 Nürburgring Nordschleife - 8.38
Re: Intake plenum theory required asap (this afternoon)
even the 'pros' dont care that much about plenum design... idjots. boost pwns all
../delete/ban
tech moderator
E46 M3 Nürburgring Nordschleife - 8.38
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