Plenum size?
Turbo Mini Forums

Ive got a peice of ally tube that has an area of 1191cc's that im thinking of using it as a plenum. Would this be sufficient for a 1293cc engine, as ive heard many mixed opinions of size/shape?

I seem to recall the figure 1.3 times engine capacity, but not sure if this needs to be stuck to 100%, Ive also got 4 outlet pipes to connect to this so they will make up about another 200cc's, bringing the total to 1391 ish?

Cheers
Matt

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

I have heard contracitory thoughts on this, fom 0.8-2.5 engine size....

I think as long as you make it big eough it'll be fine, I think its probably impractical to make one thats to big as it'll end up massive.

assuming this is fora K head? I'd say just use a bit of 2.5" tube or make a box big enough, it'll probably end up about 2-2.5 liters.

Also treat the runners and plenums as seperate items.

The only place I can think of fitting it is in between the rad and block, and becuase of the alternator it'll have to be quite short.

The tube ive got is 85mm ID X 210mm, so fairly large!

Ive been trying to think of a way to combine a plenum and intercooler as space is tight, but don't think thats gonna happen...lol

Have you worked out how many cc's your plenum has on your 7port?

Edited by matty on 15th Aug, 2007.

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

sorry for the tj...

Why do you need a plenum chamber? Have looked at a few vw turbo conversions where they haven't been used. Just wanted to understand what the purpose of them is.

The plenum i made was about 90 dia and about 45cm long, so come out about 2.8liter. main reason for this is the webber spacing, making the tube really long.

I'd say your tube is the right sort of dia, pessonally i'd add a bit of length to make the volume about 1.5liter.

I also thought about combining the intercooler an plenum, kinda having an end tank with 4 outlets, but the statremotor was in the way, with the shorter K110 plenum it could work though.

As far as i understand the plaenum is basically a reserviour to store the air so you get the same amount of air passing through each TB (illiminates charge robbing). The problem doesn't seem to be as bad if you have the feed to the plenum in the centre, but space won't allow! lol

From what ive read you need enough air in the plenum to be able to fill all 4 cylinders + a bit more (amount seems to differ everwhere ive read). But thinking about it...technically your only drawing in 2 cylinders at anyone time?

Stand to be corrected though?

What shape intercooler were you thinking of using for your intercooler/plenum? Im guessing the end of the intercooler would have to be fairly central to the TB's to keep the individual hoses as short as possible?

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

I was thinking of having a TB on the inlet side if the intercooler and just having an end tank with 4 outlets to couple straight to the head.

This was inspired by a pic of a R5 Maxi engine in tuning forced induction engines by A Graham Bell.