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MG MGB Technical - Maniflo intake manifold

Has anyone out there had any experience with the after market intake manifold ?
Maniflo ?
With a mild competition rebuild. better than stock cam, port & polish, headers, rich carb. needles, 10 to 1 compression, etc ????
Is it really going to help increase HP ?
Safety Fast
Dwight McCullough
Dwight McCullough

According to the people that sell them, yes. ;-)

However I have one on the shelf and plan on using it soon. Last year I ran G Production and they are not legal there (maybe that is a clue) and this year I am running F Production where they are legal but my headers match the thickness of my Huffaker/MG manifold and I have been to busy/lazy to modify them to match the Maniflow. I think there is HP there just by smoothing the air flow where the stock manifold has the big cut-out from the balance tube.

Leland Bradley

Dwight,
I have a maniflow inlet(Weber 45DCOE) and the LCB exhaust manifold. I think this has made a difference on my B. Also the fit between the headers is so much better. feel free to email me if you want more details on bhp etc..
TJ
T J Nicolson

Dwight-
I've had one on the engine of my B for some years now and consider it to be definitely superior to the Original Equipment item. The Maniflow fabricated steel Hy-Flow intake manifold (British Automotive Part# SUB4-2; Maniflow Part# L137) has high flow potential coupled with good port velocity, enabling it to take advantage of the inertial effects of the fuel/air charge to better fill the cylinders at high engine speeds with the added benefit of maintaining excellent fuel suspension within the incoming fuel/air charge. In addition, because of the slower heat transference of steel as compared to aluminum, it conducts less heat from the head into the incoming fuel/air charge, thus making for greater fuel/air charge density and hence more power potential. Polishing and chrome plating the exterior of this manifold will enable it to reflect away radiant heat emitting from the exhaust manifold, keeping it cooler. Jet Hot coating it is better yet. If you choose to use this intake manifold with SU HIF4 carburetors you will need to use either the early version of the UK/European Market SU HIF4 carburetors with the vacuum takeoff fitting on the carburetor body for provision for a ported advance mechanism, or, if you use the North American Market SU HIF4 which lacks provision for a vacuum takeoff, Advanced Performance Technology also offers the option of welding in a nipple on the crossover tube which would allow the use of a manifold vacuum-advance distributor. If you wish to run an anti-run-on valve and do not have the carbon canister of the 18GK and later engines, you will need to use the thinner Advanced Performance Technology?s phenolic carburetor spacers (APT Part# MFA338) which come suitably modified to provide fittings for a vacuum line, as well as the later exhaust manifold (Casting# 3911) as both have a mounting flange thickness of 7/16". This phenolic spacer with the vacuum takeoff incorporated into its design is a Maniflow item intended to be used with the Maniflow intake manifold which has no provision for vacuum takeoff on its crossover balance tube. A companion unported phenolic spacer of the same thickness is also available from Advanced Performance Technology, although a second spacer with a vacuum takeoff may be substituted to allow the use of a vacuum-assisted servo for a power brake system. Because both the angle of this intake manifold is higher (20°) than that of the Original Equipment intake manifold in order to enhance its flow characteristics, and variances in production tolerances of the bodyshell of the car, in a few cases longer and larger diameter aircleaners will not allow the installation of an underhood insulation pad, hence the thinner design of the Advanced Performance Technology?s spacers.
Why not stay with the OE intake manifold? Due to the sudden change of cross section that occurs in the area of the balance tube intersection, the airflow within them is markedly disrupted into a vortex effect. The resulting turbulence causes the fuel/air mixture to condense somewhat and also impedes airflow by causing the mass of the fuel/air charge which has been vectored into the upper section of the intake manifold to swirl 180° towards its bottom. When the fuel/air charge reaches the turn into the throat of the port, its inertia then causes it to careen into the opposite wall of the throat of the port instead of flowing along its contour as it should, thus impeding its own flow past the intake valve into the cylinder. While smoothing the cast surface of the inside the manifold and blending the change of cross section, as well as making a .250" radius at both the leading and trailing edges of the balance tube can reduce this vortex effect, such efforts can't take the place of the better design of the Maniflow intake manifold.
Steve S.

Whew!
That's alot of 'stuff'
Well what I understand is, ceramic coating will help this manifold even more. More power, better mileage, smoother idle, etc.
Thanks for the good reply.
Well just as soon as I get enough $$$$$$$$$.
I a' gonna' get one.
Safety Fast
Dwight McCullough
Dwight McCullough

This thread was discussed between 17/08/2004 and 25/08/2004

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