Intake Manifold Fabricator?

[Butch Dassie]

Does anyone know an Intake Manifold (IM) fabricator in Cape Town?

Would a design like this be possible to knock up, affordably – preferably in aluminium and preferably not in mild steel?




I'd like to lose some weight and improve the flow of air.

We have a massive lump called the EGR. All of the arrows point to it.


I think this is our IM.

If you look inside the tube where the intercooler charge pipe connects with the EGR pipe, it looks like there is a throttle plate inside. Diesels don't have throttle plates. At least, I don't think this is a variable length IM as there appears to only be one path. To me, this is a massive restriction. The air snakes its way through the EGR including through a water jacket intercooler. It then does a 180-degree bend entering a tube with four ports that bolt onto the motor. This is a very restrictive and inefficient design for getting air to our motor. IM should evenly distribute the charge to optimise volumetric efficiency and performance.

The EGR's coolant piping would need to be rerouted and there is either an oil line in the EGR, or more likely nearby, as I had a slight oil leak after I had my exhaust manifold welded (blanking the EGR), which had to be sorted.

Ideally, the ram tubes would need to immediately angle up 90 degrees. The plenum can sit above at the back of the motor. A 90-degree bend of the charge pipe from the turbo's intercooler could feed the end of the plenum.

I don't have the software to optimally design the runner length for 2,000 rpm.

[Butch Dassie]

Intake manifold's ram tubes (runners) should be port size matching. The length will vary according to the optimum rpm where you want the most impact. Rule of thumb is that longer tubes are for lower rpm, lower resonant frequency and increased intake flow speed (C.L. Lee 1997). The idea is that as the valve closes, it bounces (propagates acoustic wave) back the compression pressure (shock) wave column of air. If you get the length right, that shock wave will then return to the plenum (chamber / box), bounce and emphasize (sum amplitude of) the wave going to an adjacent tube's opening valve (rarefaction wave). However, this length is impractical in a vehicle as it would be several feet / meters long where length introduces frictional loss of pressure. Bends, valves and port entrances introduce minor, but significant losses. So, typically eight wave harmonics are calculated. To me, this means an eighth of the strength.

A plenum acts as an air storage device, buffer, helps equalise pressure and can assist with silencing induction noises (think of pipe organ). A plenum's shape can be a rectangle, circle, elliptical or curve. The purpose of a tapered plenum (narrower at the farthest runner) is to increase the air speed towards the far cylinders for equal flow.

In IM design, performance of the engine is closely related to the air motion within the intake manifold. Hence the flow phenomena inside the intake manifold should be understood in order to achieve higher volumetric efficiency, torque increase, fuel economy and better emission control.

Uniform distribution of air and fuel mixture in the each cylinder is the important criteria for good intake manifold.

Considerations include turbulence, fluid dynamics, ram and Helmholtz (resonator) theories.
The formulas for IM sizing include the port size, runner diameter, shape and length, cam closure, desired rpm, intake valve's closure duration, intake curvature radius, diffuser length, plenum shape, motor displacement, volumetric efficiency, etc.

Pressure and velocity are inversely dependent upon each other (Bernoulli's Principle).

You want a turbulent (not laminar) flow to improve the swirl (and tumble) effect in the chamber for better atominsation and broad flame front for a more efficient burn.

The plenum's volume should be equal (or greater) than the maximum capacity of the motor (say 1.5 litres in my case).

[Francois Theron]

Self deleted

[Andre N]

Basically your whole Post 2 refers to things that matter for N/A motors.

I think, you are way over thinking all of this for a Turbo Diesel motor.

But to answer your actual question, just google for a local race car builder.
Nothing fancy to the Manifold you are looking for, and any half decent race car builder should be able to knock that out.

[Buggyfan01]

You can try Rowland Manifolds
Rowland Manifolds
021 939 0004

https://www.google.co.za/search?clie...=sh/x/kp/local

[Butch Dassie]

That's definitely a turbo on the left and a tapered plenum on the right. However, it has short runners due to tuning for high revs.

[TLC70]

If your runners are straight you may want them slightly tapered (~4 degrees) so that it can 'find' it's best length, however as said, for a turbo there's hardly any gain here.

[Butch Dassie]

If your runners are straight...

In my OEM IM the runners are just ports in a tube. For my ideal IM, yes, the runners are straight and a taper would be great.

My concern is the OEM IM size is limiting my motor's output. I've upgraded the piping to and from the IC to 50mm. After the stall plate, the 90-degree bend is 43mm. As 42mm will allow for 225bhp, I'm not too concerned about this elbow. What does bother me is the 38mm EGR piping to the OEM IM. As there is a water IC inside the EGR, I don't know how restrictive it is either.

[mullerza]

That's definitely a turbo on the left and a tapered plenum on the right. However, it has short runners due to tuning for high revs.

be very careful with a fabricated boxed aluminium airbox, especially on a turbo car. On/off throttle results in significant boost level changes which means you are effectively inflating and deflating that manifold which can lead to cracking in the aluminium if its not properly designed and fabricated.

[Butch Dassie]

That's probably why some have chosen a plenum that resembles a diver's air tank.

[mullerza]

That's probably why some have chosen a plenum that resembles a diver's air tank.

I have made 2 custom intake manifolds both for turbo cars

First one I was lazy so found a cast aftermaket manifold for an evo that was the shape I wanted, cut and rewelded the runners to fit my engine (SR20DET) That worked flawlesly for years (the thick casting does not flex so no stress on the welds)

Then I designed one out of folded and welded ali, even with 3mm ali it kept on cracking on the welds and even adding stiffner tubes to the boxed section it still cracked after short use.

[Butch Dassie]

Experience appreciated.

I'll look for a suitable cast plenum. Unfortunately, you are too far away from me even if you were offering.

[Butch Dassie]

Does anyone know anything (good or bad) about WOT Racing in Triangle Farm, Bellville, Cape Town besides their Facebook page having 10K likes / followers?