Hi all. Do you think that increasing the volume capacity of the plenum, without altering the runners or the inlet side, would offer any improvements over the standard plenum?

speak to EZ Boy. he is the forum guru on manifolds mate! :D

yeah ezboy has designed a complete brand new manifold from scratch, looks horn and makes a lot of noise, theres a thread going on in magna mods i believe

Will pm him i think. Thinking of the possiblilty of enlarging the plenum chamber with a do it yourself style mod for those who might not be able to afford his new plenum straight up.
Cheers.

Re-read my manifold thread(s), there is HEAPS of useful info there. Just remember the stock runners bog down below 3k and equipping it with a larger plenum will only raise the rpm to 3300-4000, like on some manifolds that have been tried with larger plenums and bellmouths.

I've made at least 7 prototypes, but you're welcome to have a stab at it. ;)

If you want more top end then make the plenum bigger, want more low end make the runners smaller. The oem manifold was poorly configured in that its plenum is small for low end but the runners are huge bore for top end - neither of which the motor does well with the stock manifold in place. Stupid pos really.

^^^ you sure showed them who's boss at making plenums :doubt:

yes he is the boss when it comes to manifolds

yes he is the boss when it comes to manifolds
yeah i know lol
:bowdown: EZ Boy

Well that sorts that one! No need for a second manifold thread I'm guessing! Thanks Ezboy.:)

If you want more top end then make the plenum bigger, want more low end make the runners smaller. The oem manifold was poorly configured in that its plenum is small for low end but the runners are huge bore for top end - neither of which the motor does well with the stock manifold in place. Stupid pos really.

EZ - did you every think of making one with variable length inlet runners (al la MVIC) to get the best of both worlds?
I'd love to have a stab at this one day.

-Dan

EZ - did you every think of making one with variable length inlet runners (al la MVIC) to get the best of both worlds?
I'd love to have a stab at this one day.

-Dan

Yep, but whose going to pay for asking price for it! Then there's the electronics, butterfly machining, gaskets, shafts etc etc etc.... :doubt:

There's always a slight lag too as the air changes direction in the variable inlets. I've driven several variable inlet cars and can't say that I was particularly impressed. Only the runner length is changed - not the plenum or runner diameter. So for the all the extra engineering it's still loaded to the brim with compromises.

Stupid pos really.

What? Nooooo....... :bowrofl: :bowrofl:
U mean, car manufacturer spent millions and came with such inferior product???
Can't be.... :bowrofl:
Std Plenum in Magna isn't prolly even a compromise - I think it's just pile of 6 pipes and a chamber. But, what do I know. :cool:

Can't wait for your product to be ready.

Comes down to bucks and volume.

Basically the inlet manifold plenum design have carried on from the 6G72 to the 6G74 motors in that they look almost the same and have to fit in the same space in the engine bay.

If you want to play around with the design, surely the best way is to get your hands on the Lotus Engineering software package.
Then do an enormous amount of research and measurement to get enough data about the existing engine design.

Then I suspect you would be in a position to do a series of "What If?' changes to some of the major variables.
The following come to mind.
a) Inlet tract diameter
b) Inlet tract length
c) Inlet tract to plenum transition
d) Plenum volume
e) Plenum far wall to inlet track distance.

The desired outcome is always a compromise.
Do you tune for low down power and response.
Do you tune for high end power.
Can you get a desired positive resonance to occur at low engine speed and that resonance harmonic to provide some benefit at high engine revs as well.
Gerry

Hi all. Do you think that increasing the volume capacity of the plenum, without altering the runners or the inlet side, would offer any improvements over the standard plenum?

Yes it will. I have basically what you are talking about with an RPW plenum. They use the factory runners. Like EZY said although there is a definite improvement below 3000rpm, it could be better. I did pick up around 6-7kw atw.

Well that sorts that one! No need for a second manifold thread I'm guessing! Thanks Ezboy.:)

I'm not trying to shut anyone down who's keen for some hands-on, that's how I got started. If you've got some time and materials go nuts, what's the worst that could happen? I've spent 20+ hrs making a manifold from mild steel with laser cut flanges only to lose power everywhere, despite replicating engineering principles from an online cai supplier who was boasting huge gains from their designs. F'd if I know how. :cool:

^^^ you sure showed them who's boss at making plenums :doubt:

That thems fightin words! :shock:

The current manifold works and works well, plenty of members to verify that. The final prototype will be out next wk if the foundary gets it right.

The proto dyno'd on Brad's car a few months back picked up plenty of low and mid range gain but choked up after 4000. The runners have since been enlarged and the runner merge area now has very smooth integration angles.

Happy modding.