Custom inlet plenum

30th May 2011, 09:27

I want to build a plenum for my jenveys, how would i go about doing this or where i could i get one made?

The only thing im insure of if made one would be the curved bit similar to a dp one id make.
What material-aluminuim?

30th May 2011, 11:08

probs best to make it from aluminium. Start with a base plate and mount the trumpets to that. Then build the plenum from that with the shaped top and bottom then form roll and weld the back as you go to get the shape to the sides.
Unless you can ark weld aluminium to a high standard i would just buy one mate as beginners welds are not the best so wont look very nice and chances are it will leak air in more than one place.

I have also started seeing stainless steel box section used for making inlets and plenums for turbo cars at the mo im not sure on if there any good on flow but they look amazing when all polished up.

30th May 2011, 13:37

The hardest part of making a plenum chamber would probably be the design part, as opposed to the actual manufacture.

There are soooooo many things to consider!

Unless you’re going the do some 3D design work and then some CFD analysis, might be worth just copying a proven design. I'm sure you could make one cheaper than the £987 At Speed are charging for the DP one

30th May 2011, 16:31

+1 im sure if you find some on on here that has one they will let you take some measurments for some sort of payment. the ally would cost you less than 100 and once its all cut to size then the welding would be pretty cheap too.

30th May 2011, 16:46

am sure blocks 85 or somet is running one he's made on his bodies with his turbo set up.

30th May 2011, 16:55

Sorry to hijack but is this basically just to force more cold air into the bodies??

30th May 2011, 17:00

2 reasons for it really mate if your going boost it holds boost pressure and gives you a sort of manifold to join all inlets of the body's into one. The other is to link to a cold air feed and or a filter box so you have cold filtered air.

Its pretty complicated to get equil amounts of air to each cylinder using a plenum thats why most people buy proven ready built ones.

But J222JRA seeing your fabrication skills im sure you could get some measurements and make one pretty easy.

30th May 2011, 17:13

The basic idea is to create a pressure that is greater than that at atmosphere, thus increasing the amount of air going into the cylinders.

But as bedford has said, "It’s pretty complicated to get equal amounts of air to each cylinder using a plenum..."

But they do have their advantages! It's just weighing up the costs and effort for the amount of increase you will see.

30th May 2011, 17:19

As has been said, the design of plenum chambers is impeccably hard. The fd work involved is mammoth and you'd really need cfd software to do it right. and if not done right (as it is with bodies so the map will just take the tps and other sensors inputs but no air mass reading) if one cylinder is starved it will run very rich, and more importantly if one gets high flow compared to the others it will run lean and could cause serious damage. this can be rectified with mapping, but will then sacrifice the performance of the other cylinders. so... tricky

30th May 2011, 18:00

Yeh it aint as straight forward as slapping a box on there.

30th May 2011, 19:00

I have breifly spoken too colin (at speed) about it and he said if i look at the likes of the world touring car ones then wouldnt be too hard to do so but i think similar to a dp one would be best.

30th May 2011, 19:39

So if it isnt made correctly it could basically do more harm than good??

30th May 2011, 19:48

Quote:

Originally Posted by J222JRA

So if it isnt made correctly it could basically do more harm than good??

yes but thats always the case with modding cars.