manifold pipe size

[gingrass179]

ok so what size do you guys think i should use...it will be a log type?!?! where im using 1.5" on the first two cylinders and go to 2" on the back two cylinders and up to the turbo



this is pretty much what i would be ordering just piece by piece 1.5 on front cylinders and 2" back two and around back up to turbo...what do you guys think


http://www.ebay.com/itm/Nissan-SR20...d=100033&prg=1011&rk=4&rkt=4&sd=110637610012&

 

[riotwarrior]

I'd run all pipes same diameter myself. Why would you run different diameter pipes? I'm not sure of many headers or such that do that. Usually same length and same diameter.

Good luck.

 

[gingrass179]

well theres not enough room to do same length and its in a log configuration so i figured the first two cylinders would have less back pressure than the back 2 considering it will be moving twice as much air back there pushing all 4 cylinders

but keep coming on thoughts its all good here

 

[icanfixall]

Schedule 10 304... Nope.. At least schedule 40 and 316. Or if you want to be absolutely sure use inconel materail and inconel tig weld with tig rod. I understand the thickness of a header pipe but gees. Do it once and do it right is my way of doing something. Don't use the carbon steel flange either. Ever wonder why exhaust manifolds are cast iron most of the time... They breath better. Think of all the heating to 1200 degrees only to rapidly cool down to 500 degree in a minute or so. If you look at several of the stainles steel looking manifolds on the gassers they have expansion joints in them. No matter what you do, the manifolds we use stretch and push the gaskets all over the place on the heads. Where is that thin sch 10 going to move too. Its probably going to buckle and bent creating a leak. I hope this is not telling you to give up but to look deeper than whats on ebay..

 

[gingrass179]

no not deterring me at all...sch 40 is pretty spendy so i was trying to sneak it with the 10...i will just stick with the 40...and the manifold flange itself is 3/8 that im using...as far as the ebay item that was just so you know what type of manifold i would be building in reference to what size would flow good and healthy

 

[icanfixall]

What you might do is cut a bevel on the ends of the elbows trying to point the flow towards the next cylinder in the new log your making. Be watchful of bolt acess too and be able to get a tig torch into the tight areas of weld.

 

[gingrass179]

ya ive thought about angling the exhaust to start the flow in the right direction but a big worry is bolt access...and there is 0 room for equal length piping...lol

 

[racer30]

If you look under the hood of any modern Turbo diesel you would be amazed how small the up pipe's to the Turbo are. The smaller the pipe the faster the pulse reaches the turbo and helps with lag. You might think about using 1.5" for the first cylinder 90* into 2" Log then use 1.5 from the head to the 2"pipe on all the rest I think you will find it easer to drill a hole into the 2" log than to try to bevel all the 1.5 pipe joints. At the rear of the head you will find it very tight to run 2" between the head and the fire wall so make it very tight to the head because its already hot you want to keep the heat away from the fire wall or you will have crispy carpet.

 

[gingrass179]

I've got plenty of room I've already chopped the firewall and had to change the driver pedal some ill put up pics tomorrow.

 

[icanfixall]

Whay not use what Ford already made for the psd engines on the back up to the turbo manifold. One end of those has a slip joint so the tube can grow and shrink with heat. If it works on those high ph high boost engines it sure will work for us too. This way your building in expansion and contraction ablitys. Even might look at what chevy does or Cummins with their exhaust manifolds.

 

[gingrass179]

i have plans to use the flex joint style on the back part behind engine...on the back of my manifold logs will be a v band than the flex joint than goes into the t4 flange welded so my only leak point will be the v band on the back of the manifold

 

[racer30]

I built my own pipes for my Motor Home 7.3 swap...When we put the engine in I found out it hit the frame...So now I am cutting up my pipes and rerouting them for a side mounting of the Turbo. I have half of it done but I need another drivers side manifold to finish the job. I have both a flex joint and a 2" v band on my new pipe setup so I can remove the under pan section for service. I will be ceramic coating again and wrapping the pipes to reduce heat on the pan and save it for the turbo. Get some pics of your setup so we can see it... You can see my build thread for my info... Class A motor Home with Mild 7.3... Over on FTE

 

[gingrass179]

Well I don't really have anything reportable til I get my manifold flanges girdle and cam...I've been buying a few things but I have to have the manifold flanges before I go any further...and money pending I'm hoping to be completely done by December...I'm notdropping thethe motor til everything is complete engine bay included

 

[freebird01]

Inconel? really? its an old diesel truck not the space shuttle!

are you feelin ok Gary?