Twin plenum Intake manifold crossover tube
Twin plenum Intake manifold crossover tube
(OP)
When looking at a twin plenum intake manifold on a Ford V8 with a firing order of 13726548, what is the purpose of a crossover tube between the two plenums effectively coupling them together?
It would seem that isolated plenums without the crosstalk between the plenums would be more effective overall. I have seen examples of the connected plenums on some high horsepower cars. What am I missing? Can someone help explain?
One other question. Would the intake described be able to take advantage of Helmholtz tuning? With the firing order the way it is, it would seem that the oscillations being created from helholtz tuning would be distubed by the overlapping induction cycles. Is this correct or is there still some measure of Helmholtz tuning to be realized?
Thanks in advance for any help!
It would seem that isolated plenums without the crosstalk between the plenums would be more effective overall. I have seen examples of the connected plenums on some high horsepower cars. What am I missing? Can someone help explain?
One other question. Would the intake described be able to take advantage of Helmholtz tuning? With the firing order the way it is, it would seem that the oscillations being created from helholtz tuning would be distubed by the overlapping induction cycles. Is this correct or is there still some measure of Helmholtz tuning to be realized?
Thanks in advance for any help!





RE: Twin plenum Intake manifold crossover tube
Without providing any hard data, I really doubt this has much affect on any harmonic tuning of the manifold as long as the tube is small relative to the plenum. The sound has to travel thru this tube for there to be crosstalk, and what little soundwaves make it through this would be insignificant to me.
RE: Twin plenum Intake manifold crossover tube
The balance tube connecting the two equal phases plenums usually has a variable device such as a throttle butterfly.
What you're aiming to do is match the natural frequency of the container- which in this case is the system of plenum and intkae runners to that of pistons (or the air charge within the cylinder) but also allowing for the valve timing.
As the original poster correctly postulated, this works very well on even firing set ups such as V6s and straight sixes, but not so well on conventional cruciform crank V8s. The Porsche 928 S4 uses a twin plenum set up like this- connecting up equal phase cylinders. The twin plenum set up balnace pipe is usually closed- acting as a twin plenum at low speeds, then opens in the mid range only two become a twin plenum again about about 5000 rpm. The work I saw, didnt show that much benefit using a twin plenum over a well designed single plenum. Certainly, the serpentine runner lay out incurred losses- that effect top end performance such that the twin plenum resonance manifold may be more beneficial to low revving truck like applications- where the runner bend losses will have less of an effect.
The resonace "charge boost" effect from the twin plenum lay out on a V8 of this type is only effective over a relatively small rev range.
RE: Twin plenum Intake manifold crossover tube
Cheers
Greg Locock
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RE: Twin plenum Intake manifold crossover tube
RE: Twin plenum Intake manifold crossover tube
RE: Twin plenum Intake manifold crossover tube
which translates to 12784563 in the conventional system. I will end the hijack here and start a new thread on V8 firing order.