Inlet manifolds

[simon718]

the vast majority of custom inlet manifolds i have seen are made from aluminium - i had planned to make a manifold in the near future, but was planning on using stainless. is this alright? and what is the reasoning behind using aluminium, weight?

thanks

 

[madkayaker]

many are cast i think and ali is easy to cast. Stainless might crack @ welds due to flex from heat

 

[simon718]

the custom aluminium ones i have seen are definatly welded. have seen a few stainless ones but not many. i really don't have the money for an AC tig

 

[madkayaker]

i might be thinking of the wrong bit then

 

[Chipper]

What's it for, what sort of layout; and what's it got to carry, carbs or throttle bodies. There's plenty of mild steel inlets custom made, e.g. for bike carbs on cars or TBs, short runners seems OK. Saw a pic of one for a Rover V8 the other week, great big runners crossing over the valley, looked for sure like they were crack-prone. May have been braced, but it didn't look it.

 

[simon718]

bike carbs on a zetec - long term plan is a 2.0 zetec but was thinking of putting a set onto the 1.6 thats currently in it, haven't really done much research yet but it would have been a non starter if it had to be alu

 

[Chipper]

The stubs will be short, the rubber will help isolate vibes from the carbs weight too. Dunno about stainless, seen mild home-made ones though.

 

[simon718]

mild would be fine mate, stainless is shinyer though cheers

 

[Robotstar5]

mild would be fine mate, stainless is shinyer though cheers

Hole in the bonnet with perspex window?

 

[Chipper]

Hmm, stainless would look lovely

 

[simon718]

Hole in the bonnet with perspex window?

im not that bad stu

 

[wyn]

It should be straight forward enough to make one in mild or stainless.

I have been bodging one together today, a mixture of steel and aluminium. Using steel elbows.

This is a 2 stage compressor and the vee in the middle was just asking for something to fill it up.

 

[Robotstar5]

im not that bad stu

I know, otherwise you would have pretty blue lamps illuminating the manifold behind the window

 

[madkayaker]

leave the bonnet of si will go faster with less weight

 

[davenport]

i`m in the process of making one as it happens...

i`m using ally purely for the reason that the flange will need to be flap wheel`d out a fraction to match the port in the head..

the downside to ally as i see it (apart from expensive welding equipment) is creating a nice tight radius in the ally tube (its very prone to collapsing) i also found i had to anneal the tube before bending it..

with stainless you`d probably be able to buy some swept dairy bends in a suitable diameter and just cut a nice radius piece out of a 90degree elbow...

the amount of bend you`ll need obviously depends on your engine and engine bay room..

my ally flange cost me 25 quid i provided them a cad drawing and it ws laser cut in 10mm ally..

 

[davenport]

also i noticed your planning bike carbs?? i used to run some R6 units on my 106.. the new manifold is its going on gsxr throttle bodies now...

you`ll need to create some sort of lip on the end of the tube so the rubber joiner can "grip" i had these spigots machined up and i`ll weld them on the end of the tubes once there levelled off..

dont be tempted to use blue silicone tube to join them unless its the mega expensive fluro lined stuff the petrol will rot it.. i found out when my carbs suddenly became rather floppy..

enjoy the conversion.. awesome noise and low MPG awaits you!!

 

[simon718]

leave the bonnet of si will go faster with less weight

i wouldnt be able to see then from the oil leaking from the rocker cover hitting the windscreen.... really do need to fix that

thanks davenport, i was thinking zx6r carbs? hadn't realised about needing a lip, as i said before i really have done very little research on the matter but can take the gutlessness of the car no more. mr fungus from here put the idea in my head

and i wouldnt dream of putting hylomar or anything like it near an inlet, surely thats just asking for trouble! nice jig you have there btw. was thinking of getting flanges water jet cut, to avoid distortion, but im thinking the price may make me

oh and mpg (or lack of) really doesnt bother me i just want a more enjoyable drive

 

[davenport]

aye most of the 600 sports bikes can be used as donors...

as for water cutting my local place has only just got a flowjet we had some 60mm ally cut for work and it wasnt that accurate quite a lot of deflection from 1 side to the other..

i cant see a stainless one of say 6 or 8 mm distorting through cutting so as long as you bolt it down for welding it should stay flat... certainly nothing a big belt sander cant cure..

the noise alone is more than worth it...

 

[simon718]

aye most of the 600 sports bikes can be used as donors...

thats good cos have my eye on a set for £35... would give them a full strip and rebuild anyway as a matter of course. i know you have to have them jetted, need to find out where the nearest person that can do that is...

have a choice of plasma, water or laser cutting locally, whatever would be best really.

have a selection of belt sanders and if i manage to warp it too much (wouldnt be like me) can always get it skimmed, quite regularly past a well respected place that does skimming

 

[davenport]

i went to a place near manchester.. congleton??

mikeanics.. great bloke and great service. bogg brothers are yorkshire based there also very experienced in jetting them..