Inlet manifolds - Alloy vs Plastic?

[Damo666]

Another quick question, I have a choice of inlet manifolds to put onto my new engine. The first is the plastic plenum, the other is the alloy 2 piece plenum.

Does anyone know if there are any differences between the two? I'm thinking that the alloy one might have a bit more longevity with the underbonnet heat and bumps encountered in a rally situation....but on the other hand, it does weigh a bit more, and is a two piece design that could introduce another potential area for leaks.

Has anyone had any issues with either version in a 'performance' situation?

Cheers
Damo

[ernysp76]

According to the blue Bibles there is only one type for each motor respectively, these are alloy. You can't change them to another material according to the rules, you can't even add a heat proof spacer plate. Clearly a plastic one would be better as it wouldn't transfer heat in an area you want things to be as cool as possible but as I said you can't change it to another material.

[HMCA]

I believe that the excels only cam with the Alloy manifolds. The plastic didn't get introduced until either LC1 Accent or Getz.

Do you know what LC stands for?

Cheers mick

[Whitey]

The single CAM had a plastic manafold, the twin CAM is alloy. The two are not interchangeable.

Any manifold from a later model Hyundai ie Accent or Getz is not a standard Excel part and would not be allowed.

[Damo666]

Sorry, to clarify - both my cars are single cam's.

One uses the plastic manifold, the other uses the alloy. The alloy manifold is on my wifes 4-door GLX, the plastic one off a crashed 2-door Sprint. Both are 1995's.

I'd always assumed that the 4-door had the original engine in it, as it came with 6 years worth of rego papers in the glovebox, and had the same engne number on all of them.

Could it be using a twincam manifold? (I thought the ports were different?).

[Whitey]

The twin cam port configuration is different, I thought all single cam manifolds were plastic.

Hopefully Mick Gillett can clarify where the alloy manifold may come from.

[Whitey]

Just got out the service manuals, and discovered that there is an alloy inlet for the single cam.:eek:
There has only been one single cam in NSW and i'm pretty sure it had plastic and two in Victoria, I'm pretty sure they had plastic also (anyone??)

So to answer the original question, as already mentioned, the plastic would probably conduct less heat so would be better. I'd be suprised if there was much performance in it.

[ernysp76]

MRT estimates 5 - 7 % advantage might explain why the single cams can hold their own.

[Damo666]

Thanks everyone - plastic it is then!

[David Marriner]

Just for info the 95 single cam I bought from Paul Batten in vic had the alloy inlet manifold whilst the 97 single cam i bought over here in sa uses the plastic one. Do you really think it would make a 5% difference to horsepower? guess I could always swap them over and see.

[elantraelite]

The earlier X3 Excel's orginally had the alloy manifold. Which is exactly the same as the one found on the 93-95 Scoupes.

At some stage Hyundai changed to the plastic manifold during the X3 single cam production model.

Hyundai then returned to the alloy manifold on the DOHC X3.