Why would you doubt it would work well?? The flow characteristic would be brilliant
If you had a infintely large plenum chamber possibly but you would still have the shadow effect i spoke about. I still doubt it would make more power then the current way of doing things.
Did some reading this is what I noted...
* Plenum capacity can have effect on power output
less = more response less power
more = more power less response
capacity normally = engine capacity
* What works great for NA engines should work well for Turbo applications, turbo applications don't benefit a hell of a lot from venturi design
* One way to increase power and response is a multi butterfly plenum much like what the skyline GTR has, each runner has it's own butterfly and a big butterfly at the entry...
I'm only relaying what I've read, can't put my head on a block for this 🙂
Dahlback racing intake design... rather interesting
also something interesting...
I would have said that those ram tubes are too long and impeding the airflow.
Theory is that you need at least 1.5 diameters clearance
* Plenum capacity can have effect on power output
less = more response less power
more = more power less response
Yes thats correct but you have to remeber the volume of the runners themselves, these would act like a plemun.
now gary,
take vlades picture of the venturi's inside the plenum.
if you had to turn them to face the butterfly, the leading edge would go down toward the base of the plenum, but the trailing edge would have to go up toward the top of the plenum.
so the first venturi would be raised at the back, and this would then be "in the way" or would "shroud" or would "shadow" or "block" the airflow to the lowered leading edge of the 2nd venturi.
and the 2nd venturi would shroud the 3rd, etc, etc.
does that clear it up?
calibrator, is this what you meant?
Yeah VC I get that but the air is flowing through the length of the plenum and then has to change direction to enter the runners which are 90 degrees to the plemun. This change in flow direction is turbulant and disruptive.
Gary57 wrote:
Yeah VC I get that but the air is flowing through the length of the plenum and then has to change direction to enter the runners which are 90 degrees to the plemun. This change in flow direction is turbulant and disruptive.
on an N/A engine the cylinders suck in the required quantity of air, and in a boosted engine the air is waiting at the gates (valves) ready to be forced in.
i think you're over-analysing this whole thing. the plenum is just a feeder tank for the intake runners, i dont think that turbulence has as big a detrimental effect as you're making it out to be. on most setups the venturi's and runners sort out turbulence before the air gets to the valves, so no big deal.
but like vlade said - i'm no expert on this, and my thoughts are merely intuitive!
I was just wanting to see if there was anything "wrong" with my idea, seems not so I am happy. As I said the costs involved in building a manifold like this will out wiegh the power gains.
Gary57 wrote:
I was just wanting to see if there was anything "wrong" with my idea, seems not so I am happy.
but a few people have given you things "wrong" with your idea. so it seems so, not so?
but a few people have given you things "wrong" with your idea. so it seems so, not so?
Nothing to re-think the principle.
Gary57 wrote:
but a few people have given you things "wrong" with your idea. so it seems so, not so?
Nothing to re-think the principle.
ok i concede!
you know whats really funny???
i just recieved the new product brochure for the latest M3 to be launched in SA in September.
its the full brochure with the engine specs, car options, colours, etc... and there is a lovely picture of the new v8's intakes that lie under the plenum.
remember the v8 has individual throttles, and it has venturi-type collectors that are turned towards the air intake hole. fancy that???
Because it has a huge plenum chamber with a hight problem and you will find that they dont point exactly at the entrance.
nah but they close, its about a 45 degree angle. the plenum covers almost both of the heads though, so it is huge.
but looking at the picture, it seems the front ones might starve the rear ones of air - although i'm sure that tons of research went into this, because the car retails without options at 650 000. quite pricey i reckon!!!
i'll get that pic, and post it soon!
That looks pretty good and there are about 20 reasons why that was done like that and much time was spent on development.
2 things to keep in mind here guys...
1 Air is not forced in its sucked in... since its N/A
2 Each runner has its own butterfly...
the only way not to shaddow the venturies is to mount them in V pattern (speaking of the pic above) but then the length of the runners wont be the same...
I'd say the current way with the venturi pointing forward and the sloping of the plunem is the best way, that or a side induction like the old RB motors...
speaking of those RB motors.
the RB25det in its natural form has a intake that comes over the tappet covers.
and if you look closely the runners are all different lengths.
so the design from the factory has been tried and tested and it works right?
but there are people who do the swop into their s13's, and then move the throttle butterfly from the middle of the plenum to the side that faces the radiator. i know its easier and cheaper than lowering the engine to make it fit, or than buying a Greddy manifold for instance, but does it have a detrimental affect on the engine breathing???
are there some cylinders that might get more air than others???
here's pics, first of an original, and second of the mod i am talking about.
over the tappet covers:
new intake position:
The second car is Rezlo's :200sx_confused1:
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