Holset replaces K-14

[Gizmoman]

I think you want to  work on the spring rate more than the  rod  length.    Either  adding some external spring to your linkage,  cutting open & altering the boost can, or using a boost can off something else.
Since the  WG opens gradually, even at lower settings, you MBC will help spool, as  the WG instead of being 10% open at 5 PSI (#s straight pulled out of my butt), it will see no signal till 9 PSI(or wherever you set it) then open abruptly when needed.

Wouldn't changing the length of the rod (making it adjustable - again) essentially do the same thing? As the spring has a "rate", it gets stiffer the more it is compressed therefore making it harder to open (or increasing boost pressure required to open it).
It seems to me that a MBC is just another spring. I admit though, it is definitely easier to adjust.

I suppose the ideal would be to use the pot to resist the exhaust pressure only, then when the boost pressure went to 20 psi, the MBC would push the valve open and add pressure to the pot opening the valve.

As was suggested, I need to get this on a running engine before I worry too much about it. However, making the rod adjustable is pretty simple while it's on the bench.

[745 turbogreasel]

Wouldn't changing the length of the rod (making it adjustable - again) essentially do the same thing? As the spring has a "rate", it gets stiffer the more it is compressed therefore making it harder to open (or increasing boost pressure required to open it).
It seems to me that a MBC is just another spring. I admit though, it is definitely easier to adjust.

I suppose the ideal would be to use the pot to resist the exhaust pressure only, then when the boost pressure went to 20 psi, the MBC would push the valve open and add pressure to the pot opening the valve.

As was suggested, I need to get this on a running engine before I worry too much about it. However, making the rod adjustable is pretty simple while it's on the bench.

Changing the rod is  good to adjust against it blowing open, or a couple PSI change, then the arm is just in the wrong place.
Your MBC may be a spring... mine is an adjustable spring loaded pressure relief valve as sold by Graingers.
With it  set below factory boost setting, I reach  full boost about 500 RPM earlier, but I do get more PSI than I need at cruise, somewhat more EGT and less MPG.  I imagine a 2 stage setup would be better on a daily.

[Gizmoman]

Wouldn't changing the length of the rod (making it adjustable - again) essentially do the same thing? As the spring has a "rate", it gets stiffer the more it is compressed therefore making it harder to open (or increasing boost pressure required to open it).
It seems to me that a MBC is just another spring. I admit though, it is definitely easier to adjust.

I suppose the ideal would be to use the pot to resist the exhaust pressure only, then when the boost pressure went to 20 psi, the MBC would push the valve open and add pressure to the pot opening the valve.

As was suggested, I need to get this on a running engine before I worry too much about it. However, making the rod adjustable is pretty simple while it's on the bench.

Changing the rod is  good to adjust against it blowing open, or a couple PSI change, then the arm is just in the wrong place.

Your MBC may be a spring... mine is an adjustable spring loaded pressure relief valve as sold by Graingers.
With it  set below factory boost setting, I reach  full boost about 500 RPM earlier, but I do get more PSI than I need at cruise, somewhat more EGT and less MPG.  I imagine a 2 stage setup would be better on a daily.

My MBC is a ball and spring and doesn't vent - just sends air to the gate when the set pressure is reached. On my k-14, I had adjusted it to open at 15-16 psi and it seemed to work just fine. I suppose I could add a slightly stiffer spring (or stretch out the one that's in it now) and get it to go to 20.

What kind of turbo are you running?

[745 turbogreasel]

A stock 1983 vintage T3 on a 2.4 6 cyl.

My MBC is the same as yours.  15-16 is probably fine, the last few PSI happen a lot faster than the first 5 or 10

I wonder if your actuator bolts up the same as a Dodge WH1c or HX35?
Those range from 17-23  pretty much based on how old the truck is, and you should be able to find someone  who put on an aftermarket can ~$160.

[Gizmoman]

Trying to move this project along, I am futzing with it after work instead of weekends only (daylight savings probably has something to do with it).

Here are some shots of the custom banjo bolt and aluminum sealing washers - I even made two spares. This will allow me to use the existing oil feed line that went to the K-14. The K-14 threads are 12 mm, the Holset is 10 X 1.25. The original oil feed line banjo body is 12 mm. All the holes in the bolt match the original that fed the K-14.



Here's the bolt and seal rings. It is black (except where I polished the journal) because I oil tempered it. Now it's strong enough to put some torque to it without fear of it snapping.



Here it is installed on the new Holset.



Now all I need to do is work out a new drain line. The previous one was a #8 JIC and I need to bump it up to #10 as suggested by Alcaid. I may cap off the tigged-in one to the pan (#8 as well) and make a fitting for the original drain location on the side of the block (if there's enough elevation).

Am I proud of it? Darn tootin!

Tomorrow I will re-do the boost pot rod so I can adjust it again  

[Alcaid]

Haven't seen your updates since just now, great progress

This specific wastegate actuator is used in 27-29psi setups, depending on preload. Boost pressure will NOT be this high as exhaust pressure will also try to push the wastegate flapper open and at specified pressure the wastegate flapper is open by 0.50-1.04mm and there is lots of turbine bypass happening at even this low lift. Don't remember exactly what they do stock as we always hook up a boost controller and run at least 30psi from these

[Gizmoman]

Thanks for the info Alcaid.
I went back and inserted the adjustable portion into the rod. Too ugly to post but it works.

[Alcaid]

Function before fashion

[theman53]

Alcaid can chime in but on my turbo the return said it should be something like .55" which is in between 8 and 10 JIC as 8 is .5...being that it already has a weird drain angle you probably want it draining as good as can be, but maybe an 8 would work for you?

[Gizmoman]

Alcaid can chime in but on my turbo the return said it should be something like .55" which is in between 8 and 10 JIC as 8 is .5...being that it already has a weird drain angle you probably want it draining as good as can be, but maybe an 8 would work for you?

It's a tough call for sure. After getting oil past the K-14 and into my IC, I'm a bit gun-shy. At lest my Laminova intake drained any oil while it was running - the Frozen Boost IC would become a big oil filled box over time - nasty!

[Alcaid]

.55"/14mm is correct, we have good results with AN10 oil drains, never dared going for AN8, just measure the ID through the actual connectors, restrictive!

[Alcaid]

You said your MBC doesn't went? I hope there is a small hole somewhere between MBC and boost can so pressure can leak off? Otherwise you would open the wastegate once and it will stay open since pressure is trapped! 

[theman53]

You said your MBC doesn't went? I hope there is a small hole somewhere between MBC and boost can so pressure can leak off? Otherwise you would open the wastegate once and it will stay open since pressure is trapped! 

It is a ball and spring, it vents, but not unless it is open. It would be better maybe to say it doesn't bleed pressure all the time like other types.

[RabbitJockey]

?? the ones i have seen all only bleed between the can and the boost controller, so they can only bleed when the wastegate is open, and its such a tiny hole it wouldn't matter anyway.  although i have seen people use some weird *** to control boost haha.

[Alcaid]

Ball and spring type controllers work great! (NXS boost controllers on ebay etc.) but if there isn't a pinhole to bleed pressure between ball/ballseat and boost can somewhere (normally a smole hole drilled in the MBC) the pressure will be trapped between the seated ball and the boost can and wastegate will stay open. Just something to note for those who make their own MBC.