What am I not thinking of?

[mcantar]

So I'm building a streetfighter Busa for a contest on another forum, and a TD04 turbo just kinda landed in my lap. So, on it goes. One of the big aspects of the build is DIY and cost savings (not to be confused with cutting corners, mind you). That means kits and pre-made stuff is off the table for the most part.
Anyway, I plan on fabricating the header out of SS or Ti, the plenum out of Al or CF, I have an intercooler core in mind that I'll have to fabricate the tanks for, and I'll take an idea from a budget turbo write up I saw and run a T-fitting off the oil sensor for the feed line.
I've never done a turbo build before, what am I not thinking of that I'll need to address?

 

[Boosted Cycle Perf]

If it's an internally gated turbo you'll want to change that. Td04 turbos (I'm thinking is a 16g mitsu turbo) are known to boost creep bad. An external gate will greatly help with that.

I'll need an oil return, but that's no big deal.

What about fuel system? What you thinking about that?

 

[POWERHOUSE]

If it's an internally gated turbo you'll want to change that. Td04 turbos (I'm thinking is a 16g mitsu turbo) are known to boost creep bad. An external gate will greatly help with that.

I'll need an oil return, but that's no big deal.

What about fuel system? What you thinking about that?

Porting the turbo properly will help with the boost creep issue greatly, although an external gate is preferred, and you want to be sure to position the turbo itself high enough so the drain will gravity feed . . .

 

[mcantar]

Thanks for the input.
Yep, it's off a 3000GT, not sure what year though. Internally wastegated, but from everything I'm seeing I shouldn't have a problem with boost creep at the levels it'll be running (7-10psi). I'll run it and see, and if I notice it creeping we'll throw an EWG on there.
As for fueling, I'd like to be able to run pump piss and stock components, with ECU flashing and tuning done by a local shop. This is going to be a daily-ridden street bike that will likely never see the drag strip.
Plan is to keep it as high up as possible, but how high does it need to be to gravity-feed? On a similar note, am I correct in my thinking that I can run the oil feed off a T-fitting on the oil sensor outlet and then run the return into the front of the oil pan?

 

[Boosted Cycle Perf]

It's a mitsu turbo, it's gonna boost creep. They all do.

What year bike is this on?

Yes you can do an oil feed off the oil sending unit like you described.

The bottom fitting of the turbo must be over the level of the oil. With such a physically small turbo that will be very easy to do.

 

[OZBooster]

Yep lower boost levels creep , high boost gets enough back pressure to be less troublesome
and something built to take high boost levels doesnt care much about a few psi creep but a stock motor trying to run a only few psi sure does
easy to do it once do it right ...

 

[mcantar]

BCP this is on an 08 with 11.5k miles.
Higher than oil level... alright, I guess that one was pretty obvious. Sorry for the basic questions here.
So it sounds like external is pretty much a must do then. I have some research to do on this then, but the first question that comes to mind is what to do with the internal wastegate. Fabricate a bracket of some sort to lock it shut, or leave it alone and forget about it?

 

[mcantar]

So another probably basic question, but this is one I've been googling unsuccessfully. The bearing housing has some extra holes in it and I'm not sure what they're for. One is obviously the oil feed, and the one opposite appears to be for a boost gauge but could potentially be the oil return. The other two faces are identical to each other and have two holes per, one plugged and one tapped on each. I've heard that some TD04's run water in addition to oil, but I'm not sure if mine does. I've also heard that the water-cooled are fine running just oil, which would be great as I'd rather not have to deal with water lines.
So, what are all the ports for, and if it's a water cooled unit can I in fact run it without the water?

 

[POWERHOUSE]

BCP this is on an 08 with 11.5k miles.
Higher than oil level... alright, I guess that one was pretty obvious. Sorry for the basic questions here.
So it sounds like external is pretty much a must do then. I have some research to do on this then, but the first question that comes to mind is what to do with the internal wastegate. Fabricate a bracket of some sort to lock it shut, or leave it alone and forget about it?

Actually, the center line (impeller shaft) of the turbo situated above the engine's oil level will do the trick. Doing an external gate on a Mitsu involves removing the flapper completely, opening that hole and running your external wastegate pipe into it. Porting the turbo from the flange down to that opening should be done as well.

So another probably basic question, but this is one I've been googling unsuccessfully. The bearing housing has some extra holes in it and I'm not sure what they're for. One is obviously the oil feed, and the one opposite appears to be for a boost gauge but could potentially be the oil return. The other two faces are identical to each other and have two holes per, one plugged and one tapped on each. I've heard that some TD04's run water in addition to oil, but I'm not sure if mine does. I've also heard that the water-cooled are fine running just oil, which would be great as I'd rather not have to deal with water lines.
So, what are all the ports for, and if it's a water cooled unit can I in fact run it without the water?

Many cars water cool the turbo . . . you don't want that on a bike, it will overheat, your cooling system can't handle it. Your oil drain will be at 6 o'clock . . . straight down. That is how you want to "clock" the turbo. Those other holes in the housing you can ignore, your system and turbo will be fine without the water . . .

 

[mcantar]

I appreciate the insight.
Hmm... that position would put the exhaust inlet at 6 o'clock as well. I'll have to see if I can clock the housings at all.

So removing the IWG flapper... I'll need to weld up the hole in the side of the housing, obviously. If I'm understanding you correctly, I'll need to weld the pipe to the EXG directly to the hole that the flapper covers?
Now the porting from the flange to the IWG hole bit... do you mean shaving it down so that the housing is flush there and closing off the exhaust outlet with a divider to make a new flange just for that outlet?

 

[POWERHOUSE]

I appreciate the insight.
Hmm... that position would put the exhaust inlet at 6 o'clock as well. I'll have to see if I can clock the housings at all.

So removing the IWG flapper... I'll need to weld up the hole in the side of the housing, obviously. If I'm understanding you correctly, I'll need to weld the pipe to the EXG directly to the hole that the flapper covers?
Now the porting from the flange to the IWG hole bit... do you mean shaving it down so that the housing is flush there and closing off the exhaust outlet with a divider to make a new flange just for that outlet?

Once you bolt your turbo to your head pipe, you want your center (cartridge) section clocked so that the oil drain is at it's lowest point: straight down, at 6 o'clock. And yes, the flapper shaft (pivot) hole needs to be welded closed.

 

[mcantar]

Sounds like the clocking shouldn't be an issue if it's that straightforward.
So for the EWG conversion... shave the flange down to flush with the IWG hole, weld a block-off plate to seal up the exhaust outlet/create a flange for the exhaust pipe, and then weld a pipe directly to the IWG hole in the housing to run to the EWG. Am I on the right track here?

 

[Boosted Cycle Perf]

Don't need to grind down the flange to the port. Simply remove the flapper, and weld the flapper pivot hole.

Get a regular exhaust outlet flange, like what you would by if you were making your own down pipe/dump pipe. Weld your wastegate tube directly to that flange.

 

[Boosted Cycle Perf]

Forgot to mention too, if it's a stock 08, you can only get away with 4psi. That being said, it's imperative to put a proper gate on the turbo, and port it well.

 

[mcantar]

That makes much more sense, thanks. Still unclear on the porting bit though... what exactly needs to be ported?

I've been under the impression that I can hit 10psi without doing anything to the engine... clearly that's not the case. With proper tuning, what power can I expect to see with 4psi? The goal for the build is +/-220hp on pump gas.

 

[mcantar]

What about running the internal gate, but adding a splitter plate to divorce it from the main exhaust outlet? Might that solve the boost creep issue?

 

[Boosted Cycle Perf]

That makes much more sense, thanks. Still unclear on the porting bit though... what exactly needs to be ported?

I've been under the impression that I can hit 10psi without doing anything to the engine... clearly that's not the case. With proper tuning, what power can I expect to see with 4psi? The goal for the build is +/-220hp on pump gas.

You'll blow the head gasket, and drop valves before long at 10psi. High compression, and titanium valves/springs don't like boost that much. You can see 220-230hp with 4psi.

As far as porting goes; the wastegate port is at a hard 90 degrees from the incoming exhaust. Aside from the flapper already being too small, the exhaust has to make a sharp turn to get through the wastegate. This causes turbulence in the exhaust housing, slowing down the exhaust before it goes through the turbine. Because exhaust velocity is getting slowed down, you start to build back pressure. Once back pressure rises, at that point it purely fluid dynamics, the exhaust gases will follow the path of least resistance, in this case continuing forward, and going through the turbine instead of going out the wastegate. This is actually what causes boost creep.

As far as porting you'll have to open the gate hole up. But also while doing so essentially make a scoop in the port to help the exhaust turn more easily. Do an Internet search for porting and converting mitsu turbos to an external gate. There's no easy way to explaine it, you just have to see pictures to understand.

What about running the internal gate, but adding a splitter plate to divorce it from the main exhaust outlet? Might that solve the boost creep issue?

You'll just add more pre turbine turbulence, and make it worse.

 

[mcantar]

Alright well that makes sense. And I'm glad to hear 4psi is enough to bring the bike to it's target power.

So what if the wastegate port was further upstream and completely circumvented the turbo? Maybe I'm not correctly understanding this yet, but it seems that the turbulence issue could be solved by a pipe coming off the header just before the turbo at 30-45° from parallel to feed the wastegate. Seems much easier than reshaping the path in the housing.

 

[Boosted Cycle Perf]

You could put it on the header, however it needs to be directly in the merge otherwise you'll run in to the same issues.

But the catch 22 is, with as compact the header will have to be to keep the turbo high enough to drain oil, there's space to put one in a proper position.

 

[mcantar]

Alright. I'll do some mock-ups and measuring, I think I may be able to design it so there's just enough room at the merge to throw it on there. We'll see. I'll post up how things go as I progress through this.
I appreciate you guys sharing your wealth of knowledge here.