Plenum Theorum

[Xtreme F6]

im guessing you are getting those fuel economy numbers from the ford trip computer/consumption gauge??

changing the injectors and fuel pressure will throw the consumption gauge out of whack, basically that reads injector pulse time, so can calculate fuel flow, if you allow more fuel flow per ms, then you reduce the ms you need to open the injectors, hence lower economy reading while actually increasing fuel consumption

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mine reads 15.5 on my trip computer and I average 420 to 450 a tank... go figure

[ebs_4l]

ok, fair enough

[Nizpro]

Dynowog...

if this was the theory toads you would leave it std as that's the main ford emphasis economy and polution thousands more hours and dollars in r&d than all of us put together!!!!!!

power would be my only reason to change it

as to fuel economy its 90% in the tune 10% every thing else over the already good base!!!!!

Nick there are a number of reason’s Ford designed the intake as they did in my opinion. Economy would certainly be one of them. The other would be that this manifold was used way back on the EF and at that stage there was no thought of the turbo engine, so torque at low speeds was a big consideration. They also wanted the largest operating range they could get. So they made a dual length inlet manifold with extra butterflies that would close or open as we know to lengthen or shorten the runner lengths. The longer manifold length would give a torque advantage at low speed and this would also give better economy at low and cruising speeds.

Move forward 10 or so years and the next biggest reason will be cost. Which is fine on the N/A Barra 6 as they still have the same design brief.[economy and low speed torque]. With the T engine and the turbo chosen, low speed torque was no longer an issue, although there was a decrease in fuel economy when compared with the N/A. Some of this will be compression ratio and exhaust pressure having to spin the turbo and other will be the deletion of the butterflies that control the long/short runner.

With the Ford PCM and its great close loop feed back control I would have to disagree in regards to 90% tune 10% mechanical. Any half good tuner should be able to get the injector scaling close enough for the Ford unit to run close loop. I certainly don’t disagree that a terrible tune can cause horrific economy and I have read a number of people talking about this on this forum some time ago. The difference between a fantastic tune and a good one will now come down to a small number of parameters. Cam timing, Ignition advance, lean burn on cruise and just how close to perfect the injector scaling number are. We talk about this in detain at out training seminars ,so there are now quite a number of workshops that are very well rehearsed in this. With all of this in place a gain or approximately 7% can be made in regards to tuning. This figure is reported back to me from my customers who do same same style driving.

So now we get to mechanical, as discussed above the N/A does get better and substantially better economy than its T brother, over half of this is due to the longer inlet manifold that it uses while at low speeds [ highway driving]. Better cylinder filling and exhaust scavenging now becomes the only way to improve economy [engine wise] at this point. During testing we can accurately obtain a figure of 9 % better economy with a stage two kitted car over one of our own stage ones or a standard T. We tested this with two cars following each other at the same speeds over 700 kms of highway driving. The stage two car was in the lead position so there was no befit due to drafting. We did this to simulate real world conditions to back up our results from the engine dyno.

Extractors have a similar effect once again improving cylinder scavenging. A short runner intake manifold will hurt economy at normal operating speeds suited to our road driven Falcons. One only has to watch a video of an engine [N/A] with a big cam shaft and no air cleaner on an engine dyno to observe how badly during a ramp test reversion can be. Some time ago Ten ran a small piece of footage of a F1 engine and you can see the fuel haze exciting the trumpets at various rpm points. The same for V8 supercars which is why they are prone to air box firers, as the fuel can be actually carried out of the inlet track and falls into the air box. This has disastrous effects on fuel atomisation. The correct plenum size is paramount on a road car if great performance ,economy and response is wanted. Boost levels have little effect on plenum volume, It is the runner length that will need to be move for desired rpm ranges.

[Guest]

if its not in the tune how is it some of us enjoy 2-3 litres less per 100klm than with factory tunes?

I beleive you stated at your training day that it was lucky for tuna that the injector bet did not go through as he would have lost!!!!

you previous to that reached 290rwkw with savage d's phoon how is the extra power acheived if not through better use (burning efficiency) of the fuel?

is this not tune???

as to your last paragraph

keeping it in laymans terms

power is torque x speed so you want max torque all the time

to aheive this you need max air flow (oxygen content)

to acheive max airflow you need ideal air speed & density (ideal runner diameter and length)

and finally once you have calculated the ideal airspeed for your engine combo then you can find the volume of your plenum and so the vicious circle starts

I realize nizpro to be one of the top few t tuners and imho one of the most respected but there is always someone out there that can teach me and you a thing or two and it may even be an aprentice on his first day!!!

this can be varified by members I have often told my customers that if I cant be there or if they need to choose another tuner then see dave at nizpro or daniel at hpf as they seem to be good. (yes I know daniel is no longer at hpf)

so realize this I wont post crap for a post count if its serious then its right or I wont post it!!!!

food for thaught have a nice day!!!!!

[SPIKO]

There is no one works for all fomular gentleman!!!!!!!!!

Regards

Spiko

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Spiko, not all of us are willing to put asside a budget that will feed a small nation for 12 months on a car. Hence our having to use off the shelf parts, or try and do something 'different' ourselves..

Results may not be spectacular, but I'm willing to leave spectacular to guys like yourself, and Brian..

I agree with what you're saying though.. ..

Is your plenum a one-off design to suit your unique setup, and can it be purchased for others to use??

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Fair enough

It is a one off design and nothing like the one that is going around now day's.

It can be purchased But it will not fit a standard head!!!!!!!!!! My chambers are much larger on both sides of the engine!!!! Hence I do not see the point, as I said before it has been designed specificaly for my engine.

Regards

Spiko

[boosted_sa]

Got any pics?

[SPIKO]

Got any pics?

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[Guest]

guys as I have said or tried to say here is as long as your manifold or plenum is of at least suficient volume and the runners are decent size

once on boost there is not even a pufteenth in it so

money is better spent elsewhere to acheive the result!

remember though the plenum design will allow shorter plumbing and this improves drivability and power greatly!!!!!

eg std plenum shorter plumbing returned 30+ rwkw

std but reversed plenum with shorter plumbing returned 35+ rwkw

soon to test new plenum with shorter again plumbing on the same vehicle

so yes get a plenum but no need to do your head in designing it as long as there are nice radiuses to every port runner it will be fine

[boosted_sa]

I just want one cos they look good, I'm sure there isn't going to much of an advantage! I just dont like the look of the factor setup!

Spiko you car is very impressive!!! (sorry for stating the obvious) love it!

[Nizpro]

so yes get a plenum but no need to do your head in designing it as long as there are nice radiuses to every port runner it will be fine.

Nick surely you must be rolling around the floor laughing. Its difficult to disagree here with out looking like I’m trying to do a sales promotion for our plenum. 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. 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 am glade that performance car manufacturers don’t adopt the “it will be fine” policy when looking to build and design there vehicles and in fact, after all their theories finally back them up with testing. Keep in mind that almost all facets of car design are now done using computer software modelling. From engine design including inlet manifolding and plenums all the way to crash testing. This would now be the major reason why cars are progressing so quickly in development compared to the old days of lets build it and hope it will be ok.

I don’t believe I will be able to help this topic progress in an appropriate manner from here .I hope my comments up to this point have given some meaning full help in regards to the improvements that can be achieved when designing an induction manifold for your project “Ben and others”

Over and out