Engine and Transmission Tech

Hi all again!
To one's who recognised me - i'm alive, okay, doing studies and have too little time for my car.

Got a question. There are two basic types of intake manifolds for V8 with single carburettor:
[speed-eng.com]
[image.popularhotrodding.com]

First of all what is their designation in english? Which of them is better for power, and why? Why the ones have a partition, that divides the flow from diffirent chambers of carburettor, and others haven't?

Thanks in advance.

I'd recommend starting with this article: "Intake Manifolds" by Dan Masters

Dan's article explained the theory behind dual plane vs single plane manifolds in the context of the Buick/Rover V8...

Well, now most of it is clear.

But, here is a single-plane intake of ZMZ 511
[www.zp-avto.ru]
[s3.images.drive2.ru]
As you can see, it hasn't a common chamber under carburettor, and the channels are divided for left and right sides of engine. Rely on article you gave me, i am of opinion that it is made to increase torque at low rpm. Each side of engine works with only one carb barrel, and there is enough flow in each barrel at low rpm. Am i right?

> Rely on article you gave me, i am of opinion that it is made to increase torque at low rpm.

Single plane intakes can have dividers or not. The reason some single plane intakes
have dividers is typically to improve the operation at lower RPM but the mechanism
is different than in a dual plane intake manifold. In a single plane with divider,
the divider is there in an attempt to correct the flow imbalances between cylinders
and/or to decrease the apparent plenum size (or apparent carb size).

In a 90 degree V8 with dual plane crankshaft, there are always a pair of cylinders
that are next to each other in the plenum that fire successively. When a cam has
overlap (i.e. the exhaust and intake valves are open at the same time), flow from
the exhaust stroke of one cylinder can travel into the intake manifold (This is
called reversion flow), fouling the intake charge of the adjacent cylinder. The
thing that separates a dual plane from a single plane with divider is the grouping
of the cylinders relative to the firing order. In a dual plane, 2 of the cylinders
from one bank of the V8 are paired with 2 of the cylinders from the other bank.
In grouping the cylinders this way, the adjacently firing cylinders are in separate
sides of the plenum so the reversion flow effect is greatly lessened.

Be aware there are some errors in the Dan Masters article. He lists the Offenhauser
Dual Port intake as a dual plane. It is not. The dual port design has the runners
split into top and bottom sections, with the plenum split fore-and-aft (rather than
the usual side-to-side). It's essentially two single plane intakes, stacked on top
of each other. The primaries feed the longer path lower runners and the secondaries
feed the shorter path upper runners. When cruising, the manifold operates on the
smaller area, longer path, runners. This provides high velocity flow for good fuel
economy and throttle response. Under high demand, the secondaries open and provide
additional flow through the larger top runner portion.

It's an interesting approach but the packaging required to fit within a carb
intake envelope does compromise the design somewhat. By reputation, it's a
good fuel economy, low end response intake. Makes a good truck intake but
it's not a maximum horsepower design. Once upon a time, David Vizard did a
big intake comparison (on a 350 Chevy but the trends probably apply). The
Dual Port was near the bottom of the list when comparing peak horsepower but
the area under the curve was very wide and the fuel consumption was the best.

Another article with some additional detail on V8 carb intake manifold designs
can be found here:

[victorylibrary.com]

Dan Jones

This makes the possibility of a tunable, single plane, plenum divider easier to facilitate. While we're at it, why not vertically split larger intake runners to increase velocity/torque range ? roverman.



Edited 1 time(s). Last edit at 12/05/2011 12:03PM by roverman.

Thanks Dan, Art, now it's clear.
Do you wanna see, where was installed the engine with this manifold?

Sure we do!

[images03.olx.ru] =)
And in another modification on this:
[www.furgonvolga.ru]
So, you see the problems russian hot-rod enthusiast have to face with. Russia never had enough cheap and powerful V8's

Here are nearly all Buick/Rover manifolds to find:

[www.mez.co.uk]