Plenum Theorum

[Guest newl]

I'd have to say that this thread has indeed provided quite a bit of info, albeit a little sketchy for some of us (such as myself) without alot of the knowledge of the mentioned variables, but overall very informational. Thanks guys!

[GTjake]

This topic has really sparked my interest and Im keen to learn more.

Can anyone recommend any good books or websites on intake and plenum design?

Or any modelling freeware ?

I understand there will be conflicting theories and different design trade-offs, but any advice would be great.

Thanks fellas.

[Muzza]

I'd have to say that this thread has indeed provided quite a bit of info, albeit a little sketchy for some of us (such as myself) without alot of the knowledge of the mentioned variables, but overall very informational.  Thanks guys!

←

I agree, this thread has brought out alot of the right people to get a informed debate on one of the most asked quetions.

The improved plenum not just in the design gives the ability to remove the heat soak & restrictions in the plumbing which alone reduces boost drop from turbo to plenum.

Simon what sort of boost drop do you get from turbo to a nizpro plenum compared to stock? At what engine boost?

If we can keep the debate on track we will all benifit.

Muzza.

[Guest]

Nick surely you must be rolling around the floor laughing.

I am.

Its difficult to disagree here with out looking like I’m trying to do a sales promotion for our plenum.

Do a sales promo.

But I would be amazed if one person with one, would not have felt the befit is off boost response. In fact when testing this plenum on a N/A engine it makes 27 hp more than stock, with the standard throttle body.

All this with no tune!!!!!! and how much torque did it loose?

Guess what, when fitted to a T engine it doubles this increase at 1 bar. So if you wanted too, you can now fit a larger turbocharger for more top end. As we all know the trade off would be some kind of a loss in the bottom end, although the fact the N/A part of the engine is more efficient, the bottom end losses would be reduced. Having the cake and eating it to, so to speak.

I guess your saying airflow doubles at twice the pressure????

have we not determined that longer runers give better bottom end???

most plenum's use std or shorter runners!!!!

Edited 09/09/06 01:04 PM by Adam

[ebs_4l]

I guess your saying airflow doubles at twice the preasure????

it certainly should

[phildub]

I think DW has missed a number of key points. Firstly there is no intercooler plumbing on a N/A engine so all the 27 hp Simon is talking about must come from the change of the Plenum.Do you really think 1 test was done with an untuned engine and then they fitted the plenum and tuned to gain the power.As he has said in other posts this is why they test on N/A engine's first so there is no influence due to intercooler plumbing and so on. It would then seem that they confirm what was first tested on the N/A engine with a turbo engine.

Edited 09/09/06 12:41 PM by Adam

[Guest]

I guess your saying airflow doubles at twice the preasure????

it certainly should

shows how much you know about flow dynamics through an engine then!!!!!

[ebs_4l]

I guess your saying airflow doubles at twice the preasure????

it certainly should

shows how much you know about flow dynamics through an engine then!!!!!

no... u are getting confused with volumetric efficiency... which of course, unless volumetric efficiency is doubled, flow will not double..

in simple terms, which you seem quite familiar with... if pressure difference through an object doubles, then flow will be double... eg through a pipe.

in your comment regarding "I guess your saying airflow doubles at twice the pressure??????" I do not see any reference there to it being about an engine

and yet you say to me "shows how much you know about flow dynamics through an engine then!!!!!"

[Guest]

I think DW has missed a number of key points.

Again reread my posts not just the last and put them all into context!!!

Firstly there is no intercooler plumbing on a N/A engine so all the 27 hp Simon is talking about must come from the change of the Plenum.

omg really I would never have guessed.

Do you really think 1 test was done with an untuned engine and then they fitted the plenum and tuned to gain the power.As he has said in other posts this is why they test on N/A engine's first so there is no influence due to intercooler plumbing and so on. It would then seem that they confirm what was first tested on the N/A engine with a turbo engine.

Which post I see no mention of him doing so first.

Edited 09/09/06 12:44 PM by Adam

[Guest]

I guess your saying airflow doubles at twice the preasure????

it certainly should

shows how much you know about flow dynamics through an engine then!!!!!

no... u are getting confused with volumetric efficiency... which of course, unless volumetric efficiency is doubled, flow will not double..

in simple terms, which you seem quite familiar with... if pressure difference through an object doubles, then flow will be double... eg through a pipe.

in your comment regarding "I guess your saying airflow doubles at twice the pressure??????" I do not see any reference there to it being about an engine

and yet you say to me "shows how much you know about flow dynamics through an engine then!!!!!"

can you please tell me if the topic of discusion is flow through a plenum/engine to increase performance with economy hence also volumetric eficiancy as you state?

I see no reference to flow throgh a pipe!!!!

and even then through a pipe doubling preasure in practice does not exactly double flow!!! (I say exactly as in certain conditions it may come close!!! these conditions are never seen in an engine in real life)

once again stop wasting my time!!!!

the best theory has been posted for value for money results take them or leave them your choice!!!

for those just reading this now for the first time:

yes use a plenum if it suits your needs

it will allow for increase in power

dependant on design it will either increase or reduce n/a performance(runner length)

if using std bottom manifold ensure all 12 ports are radiused un like some plenums as this may in effect reduce air flow

using the plenum allows for shorter cooler plumbing and better cooler designs

hence better airflow reduced heat in the intake charge allowing for better burn eficiency which inturn allows for more power from the same amount of fuel!!!!

the main design criteria should be:

to not reduce runner diameter

to have radiused runners

to not restict flow to the runners

to have at least 6-7 litres of volume

and finally the difference in manifold volume is not critical unless you are striving for perfection in which case you need spend lots of time in r&d as simon posibly has I have and others too!!!

these so called other theories don't effect a turbo vehicle as much as you would be led to beleive!!!!!