16 valver plenum
Turbo Mini Forums

im just looking into plenum design.

im going to have the throttle body feeding from from one end.

do people think it would be a good idea to introduce some form of baffle into the plenum of a K headed mini to stop the opposit end cylinder running lean.

or will this not be a measureable problem?

In theory you should I guess. In reality, folks have made some outstanding power, with 'supposedly' un-optimised plenums.

I'd make whatever is needed to do what fits inside your engine room, and concentrate your efforts on the rest of the package.

As I understand it, the plenum should taper down in cross section from inlet to the last cylinder.
Don't have any numbers though.
Maybe a google on some formula 3 engines might give you some ideas.
ie fixed inlet diameter and a plenum feeding 4 cylinders.
Regards
Dave

If you look at a lot of production engines the plenum is angled so that the distance from valve to the throttle body is as near equal as possible across all the cylinders.

This is the key, keeping the sonic distances equal so all cylinders see the same harmonic shock waves, thus no single cylinder is either encouraged or discouraged from ingesting more or less air.

Every day is a school day ...........

How fast and how expensive ...... the same question...

The engine will produce more than enough power without having to worry about these little details, Just buld it, get it running and take it from there. That way giving you an idea of whether any mods are worth the effort or not.

Although Sproket is right in what he says ....... isn't the maths part of the fun .... or do I need to get out more??

Every day is a school day ...........

How fast and how expensive ...... the same question...

Alexander Graham Bell covers this area in great detail, might be worth buying his book?

"Turbo's make torque, and torque makes fun"

"did you know you can toast potato waffles?"

The DON works perfectly well without any baffle. Looking at spark plug colours the end cylinder does run slightly and I do mean SLIGHTLY leaner than the rest.
If you are that worried about it fit a cam sensor, run sequential injection, and trim that cylinders fuelling up a touch, the ECU the DON uses is able to do this.
Otherwise do as Sprocket says and don't mither over things of no great consequence.

Ive seen a really interesting design for a plenum that uses a parallel cylinder with a tapered one on the back of it, from what I read its supposed to work really well. May be a bit OTT for our use though?

I'll try and find a pic...hmm

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1/4mile in 13.2sec @ 111 terminal on 15psi

Andy,

have a read through this thread,

it has the type of plenum matty is talking about.

http://www.turbominis.co.uk/forums/index.php?p=vt&tid=121495

cheers good bit of input there.

i think if the DON doesnt need it mine should be ok without, although thats good thinking about the fueling, thats a feature i will have to look for when buying an ecu.

and joe that imp,8-) seriuosly cool. reminds me to try and get some gear to make my own carbon bits!

I think John is working on a production plenum for the bimmer heads.

I knew I read it somewhere...lol

Cheers mini13 for putting me out of my misery, I couldn't think where the feck I saw it.

Looks nice though!

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1/4mile in 13.2sec @ 111 terminal on 15psi

Well i dont think theres anything in it on a turbo motor, Normaly aspirated maybe. Id like to see some one get an equal induction length plenum, a turbo, an intercooler, a rad, a decent sized alternator, an oil cooler, under a round nose with a grille fitted.

Still not convinced it matters that much, I have an OEM plenum that contradicts the theory of equal induction length

Edited by Sprocket on 26th Sep, 2007.

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1/4mile in 13.2sec @ 111 terminal on 15psi

Dont even joke bout stuff like that. LOL

Back once again like a renegade master

hes not, theyre left over from ian-w's nova days

I was persuaded that the end feed to the plenum was not a good idea in this thread:




The discussion starts at the bottom of the second page.

Saul Bellow - "A great deal of intelligence can be invested in ignorance when the need for illusion is deep."
Stephen Hawking - "The greatest enemy of knowledge is not ignorance, it is the illusion of knowledge."

Plenum Origami

How about this shape?


the intake is in the angled square bit. it is quite possible to bend most of it in one go so there is less welding to be done.

That sir, is not rust, it is the progressive mass reduction system

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