Help: External Wastegate On Stock Manifold?

[217/r33]

ok i've been looking around for aftermarket manifolds for the rb25 with no luck.

im looking for something that will fit the turbo in the original "side mount" position that could allow me to run an external gate. so i thought why not drill a hole in a stock one? but i've been told that the welds might crack? my budget is not so big and a custom manifold is not an option at this stage.

has anyone done this? i would like to hear from people who have tried it, any other suggestions are welcome.

[axe s]

ok i've been looking around for aftermarket manifolds for the rb25 with no luck.

im looking for something that will fit the turbo in the original "side mount" position that could allow me to run an external gate. so i thought why not drill a hole in a stock one? but i've been told that the welds might crack? my budget is not so big and a custom manifold is not an option at this stage.

has anyone done this? i would like to hear from people who have tried it, any other suggestions are welcome.

I've done it before...

I got my brother to do the cutting and welding for me, not that hard just get to 90 degree butweld fittings, cut the hole in the back of the manifold, scallop one 90 degree to fit on the back of the manifold, line up the other fitting and weld... make sure you bold it down when heating the manifold so u don't warp it...

[217/r33]

I've done it before...

I got my brother to do the cutting and welding for me, not that hard just get to 90 degree butweld fittings, cut the hole in the back of the manifold, scallop one 90 degree to fit on the back of the manifold, line up the other fitting and weld... make sure you bold it down when heating the manifold so u don't warp it...

thats great info mate, thank you. a few questions

1. how did you drill the hole?

2. do you need to heat the manifold red hot before you weld?

[rb26s13]

thats great info mate, thank you. a few questions

1. how did you drill the hole?

2. do you need to heat the manifold red hot before you weld?

as for the whole.. pre heat the metal than oxy cut the whole.. than die grind the rest would be the easiest

not red hot.. just cast needs to be pre heated and post heating after welding.. around the 200degreeC mark should do it before welding to avoid cracking.. and it needs to cool down very slowly... so no dipping it in water after its been welded!

[axe s]

we tried an oxy first but the cast is sh)t so it was a pain in the a$$ ended up gouging it out...

we didn't preheat or post heat, just mig'ed it up.... only problem was warping which is why i said bolt it down when cutting and welding...

[217/r33]

as for the whole.. pre heat the metal than oxy cut the whole.. than die grind the rest would be the easiest

not red hot.. just cast needs to be pre heated and post heating after welding.. around the 200degreeC mark should do it before welding to avoid cracking.. and it needs to cool down very slowly... so no dipping it in water after its been welded!

we tried an oxy first but the cast is sh)t so it was a pain in the a$$ ended up gouging it out...

we didn't preheat or post heat, just mig'ed it up.... only problem was warping which is why i said bolt it down when cutting and welding...

ok i dont have an oxy how about drilling it? then get an exhaust place to weld a pipe and connect it to the dump pipe, or i can borrow a friends welder.

if not how hard will it be to make the bends in the pipe my self, im good with tools just dont know how i'd bend the pipe into the right shape.

[R31Nismoid]

You cvan go 3 ways.

1. Spacer plate inbetween the manifold flange & turbo flange with a gate hole

2. Off the manifold (as shown already)

3. Off the turbine housing itself

All 3 ways have been done before, and i cant think of any disadvantages to any.

Depends on the setup your working with, size of turbo, size of gate as to what would best suit your needs as everyone is different.

Cheers

[217/r33]

You cvan go 3 ways.

1. Spacer plate inbetween the manifold flange & turbo flange with a gate hole

2. Off the manifold (as shown already)

3. Off the turbine housing itself

All 3 ways have been done before, and i cant think of any disadvantages to any.

Depends on the setup your working with, size of turbo, size of gate as to what would best suit your needs as everyone is different.

Cheers

thanks nismoid, i'll be definatly doing it from the manifold. do you think i'd be able to drill the manifold instead of having to do it with an oxy?

[R31Nismoid]

Not sure, never been involved with that myself... although there are a few different ideas so far in this thread.

spacer plate would be my choice though (if i could fit it in). Each to thier own

[paulr33]

#3 is so ghetto

[axe s]

Putting a wategate off the exhaust housing can cause turbulence... you could drill it but it would take a long time as u'd have to use a small bit and drill about 30 holes to do the circle, also the manifold is split in the middle so 3 cylinders/runners per side, i'd mark it out and take it to a Fab or engineering shop and get them to oxy or gouge it out, also u'll need them to scallop the wastegate pipe that goes over the back of the manifold as it's not a circle it goes down the back a bit, buy the buttweld fittings from Bunnings should cost less than $15 for both...

[217/r33]

#3 is so ghetto

sure is, however ive seen it on a r33 years ago and the guy didnt have any issues from memory.

Putting a wategate off the exhaust housing can cause turbulence... you could drill it but it would take a long time as u'd have to use a small bit and drill about 30 holes to do the circle, also the manifold is split in the middle so 3 cylinders/runners per side, i'd mark it out and take it to a Fab or engineering shop and get them to oxy or gouge it out, also u'll need them to scallop the wastegate pipe that goes over the back of the manifold as it's not a circle it goes down the back a bit, buy the buttweld fittings from Bunnings should cost less than $15 for both...

sounds like i'll need to get the pro's on this then? any ideas of costs?

would it be a better idea just to take my manifold, turbo and dump pipe to someone who can do it in one hit? suggestions on places would be great. located in sydney.

[axe s]

Measure it all up then take your manifold wastegate flange and buttweld fittings to somewhere that can do it... wont need your turbo or dump...

after you have it all done take it to an exhaust shop to go from the wastegate to your dump (thats if your not running a screamer pipe... well you'll need them to make that for you anyway.)

an advantage to this way is that the exhaust gas is been flowing into the wastegate without restriction, as it's in the exhaust gas flow.

Edited September 24, 2008 by axe s

[217/r33]

Measure it all up then take your manifold wastegate flange and buttweld fittings to somewhere that can do it... wont need your turbo or dump...

after you have it all done take it to an exhaust shop to go from the wastegate to your dump (thats if your not running a screamer pipe... well you'll need them to make that for you anyway.)

an advantage to this way is that the exhaust gas is been flowing into the wastegate without restriction, as it's in the exhaust gas flow.

thanks for all your help mate, i'm now clear on what needs to be done

what do you guys thing about ceramic coating the manifold after its all done, does it cost alot?

[axe s]

I think it'd be about $100 not sure but