plenum

[dj_djox]

just wondering your thoughts on a custom side entry plenum. good upgrade or not?

[tassuperkart]

No not really.
However makes hooking up piping easier and looks funky!
L8tr
E

[TBON12]

If you want to make piping easier, you can always do what Gibson Racing did to their Exa and just add a 90 degree bend between the TB and the plenum.

[etking]

depends on so many things... a standard motor? no. Highly modified engine and properly fabricated and engineered? yes

[Ash]

no one seems to have played around with inlet runner lengths much with E15ET's.

[Timmzy]

no one seems to have played around with inlet runner lengths much with E15ET's.

Its less critical with forced induction. Its easier to wind in a couple of more pounds of boost with our cars. And our cars are hardly on the limit

I am sure you could do the research, but your time and effort would be better spent somewhere else. I think that's what it boils down to.

Some of the formula cars where modifications are restricted, then this becomes critical.

I am sure our cars could benefit from this research if they were on the limit, etc.

Darren.

[Damo]

no one seems to have played around with inlet runner lengths much with E15ET's.

I have been toying around with the idea of testing out some combo's so I can build a new manifold. There are few pointers to go off to calculate size, but unfortunatly engines arn't all the same so what you make won't nessesarily suit 100%.
Might do something like build a box where the runners terminate into (short), then keep adding length till it makes best torque. Then base the final manifold on the results.

There is stuff like varying plenum volume also.


Damo

[Callumgw]

I have been toying around with the idea of testing out some combo's so I can build a new manifold. There are few pointers to go off to calculate size, but unfortunatly engines arn't all the same so what you make won't nessesarily suit 100%.
Might do something like build a box where the runners terminate into (short), then keep adding length till it makes best torque. Then base the final manifold on the results.

There is stuff like varying plenum volume also.


Damo

Damo, Check out the Jan-Mar editon of RACE magazine, theres a good article in it on plenium/runner design. Also they current RACE has one on airboxes!

C

[BQ.05.TD]

You have to look at the swept volume on the motor, I think it’s the capacity of the motor times 2.7 or some thing like that

I think out plenum volume is ment to be around the 3.7-4l in capacity, runner length determines top or low end power and torque band,

were a lot of people go wrong is with the taper and leaning out ether cylinder 4 and having to much air in 3,4 my self think that the racetech one have pretty much got it spot on but just needs the throttle body facing the flywall on a angle

Look at some of the factory ones, GTiR are a good eg

[BennyET]

i rike a dis won

[etking]

me too gimme gimme gimme!

[jimmyet46]

Here is a pic of the Racetec one

You have to look at the swept volume on the motor, I think it’s the capacity of the motor times 2.7 or some thing like that

I think out plenum volume is ment to be around the 3.7-4l in capacity, runner length determines top or low end power and torque band,

were a lot of people go wrong is with the taper and leaning out ether cylinder 4 and having to much air in 3,4 my self think that the racetech one have pretty much got it spot on but just needs the throttle body facing the flywall on a angle

Look at some of the factory ones, GTiR are a good eg

[tassuperkart]

The gains to be had by tuning the manifold runners are certainly there to be had but are barely worth the drama as the only way to determine if you actuallyvget a gain is subjective and accurate dyno testing.

Its a total black art and there is no absolute strict formula that actually works across the board.

The gains are not that great and really, if it were so spectacular then every manufacturer would have jumped on the tuned length runner bandwagon as Nissan had done with the very funky and successful 300ZX twin turbo inlet manifold.
They spent millions developing the manifold for some gains in low and mid range torque and still actually got the plenum design slightly wrong resulting in some pressure distribution problems.

The ideal volume of the plenum is a mathematical equasion of the capacity of the engine and that particular equasion escapes me as Im not actually interested in it.

Like most other funky tuning tricks, its a compromise as it tends to "rob from Peter to give to Paul"
In that for each incremental increase in performance at a particular RPM, power is often soaked away at other rev ranges.
Its not hard to increase the power at a given RPM but its very tricky to increase the said power without loosing power elsewhere.

This is then the reason for variable inlet designs.
My VG30det has a variable inlet volume thingy. I believe some of the RB series six shooters employ some variable inlet tuning as well but again, my personal "give-a-fuck-O-meter" is reading seriously low!

Sorry guys, once again, on paper it all looks like some magic bullet but in practise and reality, its a very hit and miss affair to actually get it to work beneficially.
I wish you the very best of luck if you wish to frig with such nonsense tho! Your going to need luck, resources and time in bucketfuls to make it work effectively.

As mentioned before, up your boost by 1psi! Problem solved.

L8tr
E

[Damo]

The gains to be had by tuning the manifold runners are certainly there to be had but are barely worth the drama as the only way to determine if you actuallyvget a gain is subjective and accurate dyno testing.

Its a total black art and there is no absolute strict formula that actually works across the board.

The gains are not that great and really, if it were so spectacular then every manufacturer would have jumped on the tuned length runner bandwagon as Nissan had done with the very funky and successful 300ZX twin turbo inlet manifold.
They spent millions developing the manifold for some gains in low and mid range torque and still actually got the plenum design slightly wrong resulting in some pressure distribution problems.

The ideal volume of the plenum is a mathematical equasion of the capacity of the engine and that particular equasion escapes me as Im not actually interested in it.

Like most other funky tuning tricks, its a compromise as it tends to "rob from Peter to give to Paul"
In that for each incremental increase in performance at a particular RPM, power is often soaked away at other rev ranges.
Its not hard to increase the power at a given RPM but its very tricky to increase the said power without loosing power elsewhere.

This is then the reason for variable inlet designs.
My VG30det has a variable inlet volume thingy. I believe some of the RB series six shooters employ some variable inlet tuning as well but again, my personal "give-a-fuck-O-meter" is reading seriously low!

Sorry guys, once again, on paper it all looks like some magic bullet but in practise and reality, its a very hit and miss affair to actually get it to work beneficially.
I wish you the very best of luck if you wish to frig with such nonsense tho! Your going to need luck, resources and time in bucketfuls to make it work effectively.

As mentioned before, up your boost by 1psi! Problem solved.

L8tr
E

JAYZUSE, you are a cynical old kill joy arn't you!

I have an article written by Julian Edgar who either saw first hand or had his hands on muking with a pinto 2ltr in an Esky. They varied inlet trumpets by around 1.5 inches either way of 300mm and got quite substantial variations in the shape and peak torque location in just that small 40mm change. Now, I'm not saying that this will translate to the E15, but if a change is being made, a little R+D could shed the right direction to travel in.
From memory, you start will 8 icnh runners and tune to peak torque by ADDING 1.7inches for every 1000rpm below 10,000rpm that peak torque happens. So, around 16inch's or 400mm from valve to trumpet for 5,000rpm.

The other thing is plenum volume. Most guys recommend massive volumes to counter problems with unstable pulsing in the plenum. The big volume basicly eliminates this, but, it also takes out any chance of resonant tuning of the plenum to the engine.
Most young blokes know how a good calculated ported box can transform a ordinary woofer into a thumping sub, same thing with the plenum, get it just right and there are gains to be had.
The latest 4 banger Mazda 3's have a duel volume plenum which adds volume at a certain switch over point. This would be very straight forward to test. With a second T/B grafted to the opposite end of a log plenum, you could very easily add a sealed at one end tube to the second T/B and test varying extra volumes till optimum torque is achived. May be even handy to bring turb's onto boost a little earlier if the engine is lacking down low (read: turbo is too fucking big!)


Damo



Damo

[Callumgw]

muking with a pinto 2ltr in an Esky.

Julian Edgar was playing with South American Beer from the cooler you say?


{edit: for the uninitiated 2 lt Pinto Engine from a Ford Escort}

This is then the reason for variable inlet designs.
My VG30det has a variable inlet volume thingy. I believe some of the RB series six shooters employ some variable inlet tuning as well

My mister2 has twin entry system that tunes the intake length for two different RPMs, again to aid low end torque. Does it work? The MR has extremely good pick up across the range for a car with no VVT. But they flicked it for later engines, probably due to a combination of cost and laterly, VVT.