Boost keeps building

[90mitsu3clipse]

I just bought a big 16g from forced performance, I have a manual boost controller. When I set the boost around 11-16 or what ever I set it at it still raises above 20. What causes that>?

 

[gdmbat85]

I highly discourage ANYONE from doing the divided housing mod. Do a search on it at a minimum before you go destroying the turbine housing and decreasing the performance of your turbine. And I'd like to see how long it'd take someone to do that port job with a dremel and grinding bit. If you're going to try to fix the problem with porting, do as the others said, and read up on the porting articles.

If you can cure the creep, you can stick with your current configuration at whatever boost level your fuel system can stand without knocking. Upgrade from there.

If you can't cure the creep, you can port, get an external or O2 wastegate, or get supporting mods to run 20psi. The last option is fine if you can afford the required parts, and it won't require any porting or oversized flappers or hacking dividers.

I really dont see any reason as to why the undivided housing mod will decrease performance. Maybe you can explain why it would. As far as the porting itself, I've ported my throttle body elbow and fully polished my dual piston calipers, brackets and throttle body with a dremel, so i don't need to read any articles to tell me about porting. It's really not that bad. You can get a porting cutter bit such as the one dejonpowerhouse.com offers if you really want to make it quick. they say it's best for aluminum, however if it's truely a carbide bit, it'll go through just about anything; trust me on that, I'm a Manufacturing Technology major. Another alternitave would be to get a tubular o2 housing for like 50 bux off ebay if you don't feel comfortable porting out your housing.

 

[kenamond]

I really dont see any reason as to why the undivided housing mod will decrease performance. Maybe you can explain why it would. As far as the porting itself, I've ported my throttle body elbow and fully polished my dual piston calipers, brackets and throttle body with a dremel, so i don't need to read any articles to tell me about porting. It's really not that bad. You can get a porting cutter bit such as the one dejonpowerhouse.com offers if you really want to make it quick. they say it's best for aluminum, however if it's truely a carbide bit, it'll go through just about anything; trust me on that, I'm a Manufacturing Technology major. Another alternitave would be to get a tubular o2 housing for like 50 bux off ebay if you don't feel comfortable porting out your housing.

First of all, this is still being debated, but folks who have run with the divided housing have suspected decreased performance as a result. I don't know if anyone has dyno numbers for it, so it may not be an issue, but the logic below makes perfect sense to me.

When you're at full boost, exhaust is flowing out the wastegate and turbine outlet. The flapper only opens about 45*. If you remove the divider, the wastegate flow deflects off the flapper, across where the divider was, and interferes with the turbine exit flow. This interference restricts turbine exit flow. This raises the pressure at the turbine outlet. This gives you a smaller pressure drop across the turbine which decreases torque on the turbine which decreases torque on the compressor. It's like putting a smaller turbine exit diameter housing on. You want that turbine to flow as easily as possible. That's why folks race with test pipes. So it'd be easier for him to cure his creep problem (if that's what it is) by putting his stock DP back on.

As far as the porting issue, the housing is steel, not aluminum. With a 1/2" double-cut tungsten carbide burr and a die grinder (the correct tool for this job), it would take you 15 minutes to do the job. I find it hard to believe that a grinder bit on a dremel could eat away that much material in a reasonable period of time. But I've not tried it. Flapper wheel bits with 40 grit paper are maybe 50x slower than a burr. Maybe a carbide burr in a dremel like you mention would do the job, though.

 

[90mitsu3clipse]

PORT PORT PORT just port the damn turbo..

I thought you said I wouldnt be able to run high boost with out it leaking?

SO..... Port the O2 housing, then get a 190 fp, and when I get some more money, get some 580s and fuel management//?

I have been reading and it looks like a better tuning device would be the MAF Translator..