Hey all, Im going to make a Turbo exhaust manifold for a friend. Its a Turbo 4cyl and the exhaust ports are 38mm but the gasket holes are 40mm so was going to port match the head to 40mm too...
So should I use 40mm ID steam pipe for the manifold? or is there benefits making the runners on the manifold bigger or smaller?
I found a place that sells Steampipe bends... but they didnt sell straight sections? :S anyone know where I could get them?
Turbo Steam pipe exhaust manifolds...
Started by
_Viper_
, Nov 02 2009 09:23 PM
8 replies to this topic
#2
Struggler
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Posted 03 November 2009 - 12:13 PM
I can't remember the exact sizes available but 38mm ID will be fine.
You need to maintain air speed so make the tube as small as possible without being a restriction. Making it too large will only hurt.
You can buy the tube from any metal merchant, it is now black wall steam pipe with about a 3.2mm wall.
Hope this helps.
You need to maintain air speed so make the tube as small as possible without being a restriction. Making it too large will only hurt.
You can buy the tube from any metal merchant, it is now black wall steam pipe with about a 3.2mm wall.
Hope this helps.
#3
Bart
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Posted 03 November 2009 - 07:52 PM
Yeah good point, but since the port will be a little bigger than the diameter of the pipe i would flare/grind out the pipe just at the start of the pipe where it butts on the flange/port.I can't remember the exact sizes available but 38mm ID will be fine.
You need to maintain air speed so make the tube as small as possible without being a restriction. Making it too large will only hurt.
You can buy the tube from any metal merchant, it is now black wall steam pipe with about a 3.2mm wall.
Hope this helps.
Edited by Bart, 03 November 2009 - 07:53 PM.
#4
_Viper_
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Posted 03 November 2009 - 11:42 PM
Cheers guys, one person mentioned to me its better to refer to the valve size rather then the outlet size of the port.... any Merritt to this theory
He did say he did some back to back testing and he did gain 5hp from the larger runners but it did have more Lag... And for a street car ill take the less lag over 5hp....
He did say he did some back to back testing and he did gain 5hp from the larger runners but it did have more Lag... And for a street car ill take the less lag over 5hp....
#5
dattoman
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Posted 04 November 2009 - 12:23 AM
1 1/2" = 38.1mm
No port matching required
No point going bigger than the ports really ...
No port matching required
No point going bigger than the ports really ...
#6
_Viper_
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Posted 04 November 2009 - 07:45 AM
Well problem is they measure steam pipe in a weird way (well I think so anyway) its measured by the Nominal Bore....
http://en.wikipedia....ki/Nominal_bore
So 1.5" NB schedule 40 is actually 40.8mm ID and 1.25" schedule 40 is 35mm ID :S So its either i Go slightly smaller or slightly bigger
The guy I spoke to (who also has a 9 second gemini) said I would find the Turbo housing will be more of a restriction then the runners themself.
http://en.wikipedia....ki/Nominal_bore
So 1.5" NB schedule 40 is actually 40.8mm ID and 1.25" schedule 40 is 35mm ID :S So its either i Go slightly smaller or slightly bigger
The guy I spoke to (who also has a 9 second gemini) said I would find the Turbo housing will be more of a restriction then the runners themself.
Edited by Viper, 04 November 2009 - 07:54 AM.
#7
dattoman
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Posted 04 November 2009 - 09:23 AM
Go the 40.8 then
And let me know the price of the bends
And where to get them from
Have a similar thing to do for someone on a datto engine
And let me know the price of the bends
And where to get them from
Have a similar thing to do for someone on a datto engine
#8
_Viper_
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Posted 04 November 2009 - 11:03 PM
I got the bends from blackwoods... were $7.40 each inc GST
#9
_Bomber Watson_
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Posted 05 November 2009 - 05:40 PM
The bends from blackwoods are cast iron arnt they??
Will most likely need cast iron strait pipe then.
Cast is a bit of a prick to weld with a Mig.
You can weld cast iron to mild steel, but with the different expansion rates and the extreeme heat changes in a turbo manifold im not sure if its a good idea.
I wouldent reccomend using a thick mild steel because of one other thing you may not have considered....Thicker metal conducts heat quicker.
You would be better off making it out of thin walled exhaust tube, if you can make it strong enough to support the turbo through all the heat changes as thick steel will conduct the heat out of the system (you want it to stay in there remember) a lot quicker.
Cast doesnt conduct heat as quick so if your using that you will be ok.
Cheers.
Will most likely need cast iron strait pipe then.
Cast is a bit of a prick to weld with a Mig.
You can weld cast iron to mild steel, but with the different expansion rates and the extreeme heat changes in a turbo manifold im not sure if its a good idea.
I wouldent reccomend using a thick mild steel because of one other thing you may not have considered....Thicker metal conducts heat quicker.
You would be better off making it out of thin walled exhaust tube, if you can make it strong enough to support the turbo through all the heat changes as thick steel will conduct the heat out of the system (you want it to stay in there remember) a lot quicker.
Cast doesnt conduct heat as quick so if your using that you will be ok.
Cheers.
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