Boost Creep

[19rslaser911986]

Alright I have a 1991 FWD Turbo Rs Laser. I have extreme boost creep issues. I live close by to Slowboy racing and talked to them about it and have had no luck. They had told me to port the O2 housing and make an inch long X 3/8 inch deep cut inbetween the exhaust and waste runners to inhibit suction to open up the waste gate flapper. That didnt work. I then had a 34mm flapper installed on my exhaust housing, they said that would stop it guranteed. That didnt work either. So I tried pressurizing my wastegate and it only opens half way. So I tried another waste gate actuator, it did the same thing, only opened halfway. So I noticed that the actuator only moves about a half of an inch. SBR then told me to completely take the actuator off and plug the positive line of the turbo, and let the flapper move freely. After trying that and getting past the horrible lag, it held in third gear 10-11 psi clear to redline. So is my wastegate actuator not moving freely or enough to open the flapper the whole way or is there something else that is causing my extreme boost creep. I only have a 2.5 inch turbo back exhaust with a straight through N1 style muffler with no cat. Thanks, if you guys could get back to me as soon as possible it would be great. Phil

 

[daren_p]

It looks like youre not running a cat? If not put a high flow one on, that will more then likely prevent the boost creep. You're wg actuator is more then likely working properly as they don't move enough to open the flapper completely (well it doesn't on my evoII atleast) on top of what you have done only other thing (other then an external wg of course, which you shouldnt need) do some more porting. If you look into the the turbine inlet, is there alot of material above the wg hole covering the opening? If so remove this so the top lip is atleast parallel with the bottom, if not abit more. The look at the wg outlet, if there are any abrupt edges (evo had a huge one) remove them to make a nice smooth transition. I guess you've alrady ported as much out of the wg passage on the O2 sensor housing as you can? Other then that maybe get a 2g sensor housing & port it or a tubular one.

 

[19rslaser911986]

Well as far as porting it has already been ported to its max on all areas of o2 housing and exhaust housing of the turbo. As fas as a cat i know it is only 2.5" press bent and as slowboy had told me i should have never boost creeped in the first place. The only large reason i dont want to put a cat on is because i dont need one because i have no emissions and since its only pressbent i dont want to restrict it to much. Slow boy told me the arm should open up the flapper a little less than the whole way which mine isnt doing. its about half if not a little bits less than half....well anymore input would be greatly appreciated. Thanks ....Phil

 

[19rslaser911986]

Also i completely took off my wastegate actuator and plugged my positive line coming off the neck of the turbo as slowboy had told me to do. Naturally it creeped horrible lag but once it spooled in 3rd gear it held 10-11 psi clear to redline with no creep, so as I am saying there has to be something with my actuator... please help soon...

 

[19rslaser911986]

in the last post i meant it had horrible lag not creeped horrible lag...sorry

 

[daren_p]

Well it looks like you've covered everything else & it didn't creep when you bypassed the wg actuator so I would say you should try a new actuator.

 

[truwarrior]

I'm pretty sure they all only open that far. That's how Mitsu wanted it apparently. What do you have a EVOIII? I didt that slow boy racing thing too (ported 02) and I have 20PSI from 5500-redline. I'm not complaining though (although they said they never had anyone creep with this port job), just need a FMIC and I'm set.

I'd just let the flapper go open until you can get some fuel and other mods...else you'r gonna have to do some more porting...I'm taking the lazy way and getting more mods

 

[DSM_Aruba]

Why bother doing so many mods on the internal wastegate. I am using a Tial 38mm wastegate and have no boost creep issues. You can either install it on the Exhaust manifold (no. 1 runner) or on the O2 housing. The good thing about the Tial wastegate is that it doesn't make that huge noise like the HKS or Turbonetics wg. You can also connect the wg dump dupe to the O2 housing (no open air dump noise)
I have also heard that it performs better than the HKS or Turbonetics (not sure about that).