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1G Hx35 bullseye boost creep

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talonlan3

Supporting Member
60
17
Dec 16, 2013
moline, Illinois
•Hx35 8 blade
•Archer fab manifold
•Bullseye housing
•tial MVS open dump
on 02 housing
• custom 3" side exit
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Boost source is at bottom of wastegate(top port vented) and goes directly to compressor housing. 10 psi or 20psi springs set ups really don't change it. Boost just climbs to 25+ psi at wot.
My thinkings are that I need to open up the wastegate flapper hole, in the bullseye housing, and do some kind of porting. I have no idea how much to go and wondering if anybody has pictures of porting their own.
Any other suggestions besides going t3 would be appreciated
 
You're running a H1C, not a HX35. Similar, but different...the H1 turbos had a weaker thrust system but better-sealing compressor housing (in my opinion) from the factory. The thrust system can be upgraded as I convert these to HX-style thrust plates, but there are no direct-fit compressor upgrades for the H1 turbos at all.

You're definitely experiencing boost creep- likely a result of the side-exit exhaust with zero post-turbine restriction. Usually if I'm building a HX35 to sell I'll get the wastegate hole milled locally to a full 38mm I.D. so there's no chance of this happening regardless of the boost level, but honestly unless you're just trying to break the engine in or something most folks are running these turbos in excess of 25psi straight-away so the time spent milling the housing is somewhat-nullified. Any effort put into gaining boost control at low boost will make it more-difficult to control at high boost.

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Greatly appreciated!
I just built this motor two years ago with absolutely no experience inside an engine. Nearing 1k miles now... So partly been going through a break in. I am also new to tuning cars and have been learning a lot this past year. Im finally at a point I feel confident turning the boost up but am afraid I still won't be able to control boost at 30 psi is all. I don't plan to run boost this low ever. I will try 30 psi and reduced timing this spring and if she still don't hold i will then open the wastegate hole.
Good thing I work in a cnc shop and can throw this in a mill quick and easy
 
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