Looking for a STRONG Internal Wastegate Actuator?

[JusMX141]

Anyone who's attempted to achieve more than 22-25psi on an internally-gated turbo knows this can be an extremely difficult task- especially on MHI turbos, and turbos with upgraded (larger) wastegate flappers. I've found a simple and cost-effective actuator which takes the guesswork out of buying a stronger actuator....use an actuator from a Holset HX35 or HX40 turbo. The internal spring is so strong the actuator practically cannot be pulled out on it's own.

I got the idea recently when a buddy of mine absolutely couldn't get over 22psi out of the Garrett actuator and 34mm flapper combo on his SBR G60. The Holset actuator has the same two-screw mounting system as the Garrett, so it literally bolted right into his Garrett actuator mount. The rest was as simple as some bending / cutting / drilling to get everything to line up, and his first run out he made 28psi before we did a little fine-tuning with the actuator adjustment and MBC to acheive his final desired boost level of 25psi.

I'm in the process of building one of these to fit the 18G that is going on my FWD, as I'm shooting for a target boost level of 28-30psi with a 34mm flapper. When I get the finished product, I'll post back here with pics as well as step-by-step instruction on how it was done. It will take a little welding to make the Holset actuator work properly on a MHI turbo.

 

[talonalex92]

Cut it open, put a stiffer spring in and weld back together? That's my plan. I need to finish my recircd o2 housing first. So I can leave it disconnected if I need to drive it.

 

[FonZ454]

Really...

How much work do you think it will be to make it fit a MHI turbo?

Would give me another excuse to not put on my external. I'd like to try this out.

My car will spike to 27psi, and be at 20psi at 6000rpm and up. I've tried shimming the gate more, and the boost will stay, but that's also at a point where the gate is just shut and won't open, so that means that there is still boost to be had.

I'd like to run a stronger internal and keep the car quiet then an external.

 

[JusMX141]

Cut it open, put a stiffer spring in and weld back together? That's my plan. I need to finish my recircd o2 housing first. So I can leave it disconnected if I need to drive it.

That's not a feesable solution in my opinion. I mean, I'm sure it works fine....I just don't want to be hacking apart the actuator and trying to weld it back together, possibly burning a hole in the diaphragm. My solution is much simpler than you think.

Really...

How much work do you think it will be to make it fit a MHI turbo?

Would give me another excuse to not put on my external. I'd like to try this out.

My car will spike to 27psi, and be at 20psi at 6000rpm and up. I've tried shimming the gate more, and the boost will stay, but that's also at a point where the gate is just shut and won't open, so that means that there is still boost to be had.

I'd like to run a stronger internal and keep the car quiet then an external.

I don't think it will be much work at all.

You'll need a base from an old Mistu actuator, as well as the end that connects to the flapper lever....I have more than enough of these laying around to experiment with.

The Holset actuators control boost up to the mid-30's on Cummins applications, although the Holset turbine housings use a wastegate flapper that is smaller than a Quarter, so I'm sure it's easy to hold shut at high boost.

Essentially I'll be building something that looks like this, only with a Holset actuator instead of a Garrett one:

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What you're running into sounds like the same issue we had with my buddy's internally-gated Frank 5 20G. The first actuator we had was too weak and wouldn't hold more than 18psi- the external dump and the fact that we didn't even run a vacuum line to the actuator confirmed this. The next step was to pick up a stronger actuator....but it would have to be short, as there is not much room between the flapper lever and the backside of the compressor cover to mount an actuator. What I built was a one-off creation with a custom mounting plate using an AGP actuator from an SRT4 that I found on eBay:

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This setup works great, but still could use a stiffer spring. One of the issues we have is if you preload the actuator too much, it will become slow to respond as you'll have to build up more air volume in the actuator head in order to move the diaphragm through it's travel. The result is boost that will spike and settle.

It took a lot of fine tuning between the adjustable actuator and the MBC....too much tension on the actuator causes slow response and spikes; too little tension causes a lower achieved boost level. The end result is boost that will spike to 23 or 24psi, before settling at 22psi and holding it rock-steady to redline; that's something we're both happy with!

 

[andy4g63]

Good find Jus. I'll keep that in mind.

 

[Mike Marnik]

ima have to keep an eye on this thread. i can get my car to hold any more than 20psi with an initial spike to 26psi and im trying to run 28-30 psi oh and this is on a fp 18gsl2 that i had upgraded to a 20g compressor wheel. I really dont wanna have to shell out for an external set up.

 

[JusMX141]

I probably won't have any real-world results until spring, but I wanted to get the thread started and the discussion going while I'm in the process of building the actuator and can get photos of the setup while it's off the car.

I'd go with an external gate but I want the car's engine bay to absolutely look as stock as possible yet have the capability of producing 30psi. Some of my stealth mods include porting a 1G o2 housing to the same spec as an Evo III housing (I would buy the Evo III housing but it won't fit my downpipe), and running an 18G compressor wheel inside a 14B cover. My goal is to literally beat the crap out of Mustangs and Honda guys on the street, and make them think they just got their ass handed to them by a stock DSM.

 

[dsm-onster]

Good stuff on getting the most ot of an internal setup. I've had many a MHI turbo blow open the wastegate even with the tiny stock wategate hole. This is good stuff.

 

[JusMX141]

I honestly think internal gates are fine at regulating boost on smaller turbos. The only time they need tweaking is if your exhaust system is too unrestricted (causing boost creep), or in situations where you're trying to push the internal gates farther than their design threshold.

I can't imagine Mitsubishi thought there would be crazy bastards like us trying to run 30psi on an internally-gated turbo when they designed their wastegate system!

 

[Auto RS T]

This could be what I'm looking for to hold a little more boost. Way to keep thinking.

 

[talonalex92]

I think I just don't understand what this does essentially. Preloading the wg? I would like to hear more about this. My wastegate blows open at almost no boost at all. Talk about irritating..

 

[JusMX141]

The Holset actuator has a stiffer internal spring, which will work much like changing the spring in an external gate to a stiffer one to achieve a higher boost level.

It's normally safe to figure you can just about double your spring's holding pressure by using a manual boost controller- anything above that will require a stiffer spring. The MHI actuators are rated around 10psi on their own with no controller, making 20psi or so the maximum you can run without the flapper blowing open. This number will be less if you have an upgraded (34mm) flapper.

I'm trying to overcome this by using an actuator with a much stiffer spring. Sure I'll never be able to lower my boost under 15psi or so with this setup.....but then again, why would I want to?

 

[jking29]

You will probably not even get it down to 15. The actuator that came on my hx35 is a 18lb actuator, but most of the Holset actuators are rated for 20+psi.

 

[JusMX141]

Even better!

Honestly, the lowest boost number achievable will depend on how big the flapper is and what the leverage of the flapper arm will provide (the Holset flapper arms are a different size / angle, and they have very small flappers). If it never goes below 20psi I'll be happy with that....as long as I can get to 28-30psi on an internal gate without spiking / dropping boost problems.

 

[Weapon-X]

Nice idea............................

I definitely am interested in seeing how the final product works.

I myself run high boost on an internal gate and know the kind of work involved with getting a good working system together.

I'm currently using a Mitsubishi actuator that is re-sprung with a stiffer spring. I sealed the actuator back together and am using a V-band clamp on it. I didn't like the idea of possibly damaging the diaphragm while welding it back together either.

It's probably hard to picture, but it works great, and it's honestly not some hack looking job either.

The other route I almost took was using a Forge wastegate actuator. Only reason I didn't was because of price.

They can be pre-assembled using their red spring which they state is a 17.5 to 20 pound rating.

Definitely keep us up-dated on any and all progress.

 

[FonZ454]

Where can I find one of these actuators cheap?

eBay shows nothing. I'd rather not buy new either.

Cummins forums?

 

[JusMX141]

Probably Cummins forums. I can't believe eBay doesn't have anything....there were (4) or (5) on there when I looked a few weeks ago when I originally got the idea to do this mod. I figured they would be one of those items that are constantly there.....I guess I was wrong. Stuff like this is so hit or miss on eBay.

 

[jking29]

Where can I find one of these actuators cheap?

eBay shows nothing. I'd rather not buy new either.

Cummins forums?

PM me. I'm not going to use mine since I'm going external.

 

[FonZ454]

Alright, I got my actuator in, thanks to John (jking29).

I have a 14b here to use as mock up. I'll report back with progress.

 

[RyAn007]

The internal gate on my hx35 holds 28 pounds consistent with no drop once so ever.

 

[JusMX141]

Finished the prototype tonight. It turned out quite well, and the spring tension seems more than double the Mitsu actuator it replaced.

Making the actuator work was simple. I took a bad Mitsu actuator, cut the actuator bracket off flush with the base. Using the Holset actuator bracket as a guide, I marked the holes to be drilled on the Mitsu base, then drilled them using a 5/16" bit. I removed the adjustable end from the Holset actuator, and trimmed about an inch off of the threaded portion of the rod to meet the length requirement of the Mitsu setup. The next step was to trim the end off the Holset adjuster, leaving the threaded barrel adjuster by itself. I welded the end of the Mitsu actuator arm to the threaded Holset barrel, then threaded completed end to the Holset actuator, and here's what I ended up with:

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[fwdmaster]

Great job on the prototype jusmx141

 

[Weapon-X]

Nice job Justin. Looks great. Very clean for sure.

How does that Holset actuator compare in size to a Mitsu one? Physically it looks like it may be a hair smaller.

If your able to get a chance, could you snap a pic or 2 with the actautors next to each other.

I ask only cause I'm running into some slight clearance issues with my actuator set-up wanting to occupy the same space as my dual FAL slim lines.

If there's any clearance to be gained from using a Holset actuator, I may look into picking one up myself.


Thanks.

 

[JusMX141]

The actuator head is much smaller, like a Garrett. The throw of the Holset actuator is much longer than the Mitsu actuator, opening the flapper almost a full inch versus 3/8" or so with the Mitsu actuator...although the flapper opening isn't really what I'm worried about. I'm more interested in keeping the flapper closed. At 30psi, the flapper opening 1/4" or so should control boost just fine.

I'll try to snap some more pics as requested....although I'm not sure I'll be in the shop tonight. It may be a day or so, but I'll get them posted.

 

[Auto RS T]

I picked up an extra Mitsu actuator and modified the base today. Now I just need the Holset part of the deal... The prototype looks very nice (to any non-dsmer; would look stock). I'm eager for everybodies results.