12 replies to this topic

[danny19boy86]

If I got a custom made inlet manifold made in stainless steel would it flow better the usual cast one with such hif44

[nicklouse]

Ok let's reply to this without sounding like a *******.

If the person making it knows what they are doing then maybe they can. It the person making it does not know what they are doing snipe are partial to their Beer then maybe they will not.

But now now not being a plank if you are limited by the space available as standard then you can't realy do better as the curves need to be about the same.

Edited by yeti21586, 20 June 2015 - 08:29 AM.
Don't try and avoid the swear filter

[JJ1992]

Maniflow can probably make one, i know the do one but i think its mildsteel

[danny19boy86]

I was just thinking of taking my osselli torquemaster to a exhaust fabricator and ask him to duplicate it in stainless. Would there be a benefit being stainless.

[nicklouse]

I was just thinking of taking my osselli torquemaster to a exhaust fabricator and ask him to duplicate it in stainless. Would there be a benefit being stainless.

Not really as they will have fun changing the diameters like the casting.

[JJ1992]

i think the imperfections in the cast are beneficial for the fuel air mix. there are other ways to improve them. its all in vizard's book.

[JJ1992]

i work for a stainless steel exhaust company and toyed with the idea myself but decided there wouldn't be any benefit.

[matty...]

I've made several stainless inlet manifolds up for a couple se7ens, and both have seen power gains over the maniflow inlet.

Many things to consider with gaining more power, length of manifold for said power band, pipe dia, and from recent dyno tests the angle in which the pipes split from single Venturi into 2 had a massive effect.

This is the type I made up. And the mark 2 version.

The surface finish inside the bore will also have an effect...too smooth and you will start getting beading on the walls of the manifold, which will effect mixture atomisation (in a bad way).

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Edited by matty..., 19 June 2015 - 10:06 PM.

[blacktulip]

I personally think its a waste of time and money. why would you want to make one of steel when the aim is to keep the intake charge cooler?

 

if you are copying a performance intake you surely would want it to perform to its maximum capability. unless you are after the bling factor.

[69k1100]

Stainless is less than half as good at conducting heat as mild steel. A manifold from stainless will heat quicker and cool slower compared to a mild steel one.

Good or bad? In exhausts you keep more heat in the gas, quick can be beneficial. With inlet charges you could argue that the stainless gives up less heat to the inlet charge.

[matty...]

Stainless is half the conductivity of mild steel and about quarter of aluminium, so it actually takes longer to heat up. When you have a cold inlet charge running through it, it will give a more cosistant inlet temp as it's not going from hot to cold so quickly.

In the bigger picture the material is no where near as important as the actual design of the manifold. There is no point copying an existing manifold if it is wrong for your engine spec. To gain any benefit you really need to dyno the engine, see where peak torque and power are, decide where you want the most torque to be in the Rev range, and make one to suit, along with a camshaft that will suit those needs, and time that in accordingly.

Generally a standard cast manifold will flow far more than what the standard ports/valves allow, so unless the head is fully ported, there is no real benefit from fitting a high flow manifold, unless you are going to change the length to change the torque curve.

Edited by matty..., 20 June 2015 - 01:43 PM.

[blacktulip]

Generally a standard cast manifold will flow far more than what the standard ports/valves allow, so unless the head is fully ported, there is no real benefit from fitting a high flow manifold, unless you are going to change the length to change the torque curve.

Can you back this statement up? as it contradicts what Vizard says and puts a large part of the concept of stage 1 tuning into disrepute.

[matty...]

The stage one kit is more than just an inlet manifold.

As vizard explains one of the main power gains from changing the inlet manifold is the fact that it is no longer part of the exhaust casting, hence inlet charge temperatures are lower. If you measure a stage 1 inlet port sizes and length it will be near identical to a standard cast aluminium manifold. Any gains to be had from the stage 1 kit will be from the increased scavenging on the exhaust and reduced inlet temps from having a separate inlet.

I'm talking about, if you want to make an inlet to optimise tuning, then there are other things to consider first.

Edited by matty..., 21 June 2015 - 09:21 AM.