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Proper Internal Wastegate Installation on a Holset HX35 w/ BEP Bolt-On Housing

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JusMX141

Moderator
15,152
1,268
Dec 13, 2005
Greensburg, Pennsylvania
Thought you guys would enjoy this.

I just wrapped up building an internally-gated HX35 for a customer of mine. Instead of rigging a Garrett actuator on the backside of the HX35 cover as some suggest, I simply began with a HX35 from a Dodge truck that has the wastegate actuator provision on the compressor cover. The next step was to modify the existing Holset actuator slightly by shortening the rod a bit and bending a piece of rod that would mount to the Bullseye housing's actuator lever. Here's the end result:
 

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I have no idea what the customer had in the BEP housing; I saw somewhere on here that the housings with an internal gate were going for close to $400 shipped.

Add to that the cost of the HX35 core and the rebuild, and you could spend somewhere in the $800 region for a new turbo that is capable of outflowing and outspooling a Garrett of similar size, as well as being 100 times more reliable.
 
hows that wastegate working, can you get over 22psi at redline?

Bump on that, hows the internal wastegate? I plan on doing this in order to keep my stock fan. By the way Jus, once I get this BEP Housing I will have it sent to you and buy hx35 with you as well! Just saving up. Hopefully before Christmas!

BTW That looks real nice! Good job!
 
Very interested in this reply as I saw in numerous thread that the internal gate on the BEP could'nt hold boost under 20-22 psi.

I'm very interested in the internal gate as I could keep all the factory heat shields for road racing insted of going external.

Ask Bullseye yesterday an the are BO
 
Very interested in this reply as I saw in numerous thread that the internal gate on the BEP could'nt hold boost under 20-22 psi.
Do you mean under or over?

Most guys are using the Garrett-style actuator that Bullseye provides on their internally-gated HX35's. What I've done here is incorporate the factory Holset actuator, which has a MUCH stronger spring tension, to help hold the flapper shut under high boost.

This same actuator head has been used to hold 24psi to redline with plenty of room to spare on MHI turbos with 34mm flappers that couldn't hold over 20psi with a MHI actuator. The Holset actuator also holds boost well into the 30's on factory HX35 turbine housings which use a very small internal wastegate.

I have no real-world results with the max boost level achieveable on the 38mm Bullseye flapper, but I'd imagine it to be well into the 20's using this actuator. Obviously boost control is not going to be as good as an external gate, but generally speaking no one buys an internally-gated housing with thoughts of running 25+psi in mind anyway...this mod simply illustrates that it's possible to use an internal gate to get a HX35 a little closer to it's efficiency range and well beyond the limit of stock head gaskets and bolts.
 
Would the internal actuator be ok with 23-25 psi? Or would external be better. Not trying to spend $500 extra if I dont need to.
 
It should be, but keep in mind the internally-gated bolt-on housing costs more than one that has no flapper and is set up for an external gate off the o2. You may spend an extra $150 to make the turbo internally-gated while $150 more would set you up for an external gate off the o2.

A Punishment o2 housing and a knockoff wastegate will work better for boost above 20psi....Talondave was holding 30-32psi at the end of last season with his HX35 and XSPower 38mm external wastegate once it was properly sprung.

This thread was simply to show the proper technique for fabbing up an internally-gated HX35.
 
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