34mm flapper on small 16G NEEDED?

tsi_turboawd · 09-03-2003, 08:23 PM

I was wondering if it's worth getting a 34mm flapper mod on a small 16G turbo?

If i not then ill just keep the stock flapper and port the WG hole. I just dont want boost creep and have to do everything over again. I have a 2.5" DP along with 3" N1 catback and will be upgrading to a 3" sometime next spring.

thanks for the space

sidoze · 09-03-2003, 09:43 PM

my evo3 big16g creaps when i downshift sorta rough from 5th to 3rd.i have the 34mm flapper, evo o2 housing, 3 inch downpipe and catback.

some times things will creep no matter what you do

but id do it for one reason, you will get bored one day and it will be nice that its already been done when you get it swapped to a 20g. atleast i know im going to upgrade mine at a local turbo shop once i get done with all the fuel mods.

95GSXracer · 09-05-2003, 05:13 AM

The key to eliminating boost creep is ALL in porting the turbine housing. If you put a 50mm valve in there and dont do any porting, youre still screwed. If you keep the stock flapper, you can still get boost down to pump gas levels by proper porting. Its all in the vfaqs really. Another thing to consider is if you get a larger flapper, forget about running high boost efficiently. Bigger flappers blow open easily. Many people that think the boost dropping as rpm goes up is because they are outflow the turbo are actually see the WG blow open. I did the experiment, search this site for a thread named wg blowing open info for an experiment I did to confirm this

Hope that helps.

mitsugsx95 · 09-05-2003, 02:25 PM

A larger flapper will help, but if you dont open the wg passage to let the air go through faster, theres no point. Before you do anything, take a hard look at your turbine housing and see where the air is going to go through the wg passage. Even if you get a huge flapper, its still going to be hitting the wg hole wall either way.

dcskater82 · 09-05-2003, 07:42 PM

get the 34 mm flapper...my boy had a small 16, with a 3"turbo back, and crept like a mother####er, i have a big 16 and the 34mm flapper, and havent crept at all, my boost has been stickin on 16 solid, no creep no shit...i love it.

asian312 · 09-05-2003, 08:05 PM

I know it's noisy, but have u considered a wastegate dump. 95GSXracer findings are well in thought with my theory. I'ld rather dump it to atmos where there is ambient pressure to comabt with rather than what may be built up in the exhaust track. I run a fairly large internally gated turbo and experience no creep. And still use a stock flapper. Just a thought.

tsi_turboawd · 09-05-2003, 08:11 PM

It would be annoying for a small-early spooling turbo like a 16g to be o2 dumped wouldnt it. Thats like every gear before shifting, it will dump loud. But its not that i dont like o2 dumps.

Rob Rohr · 09-07-2003, 10:33 AM

Quote:

Originally posted by 95GSXracer
Many people that think the boost dropping as rpm goes up is because they are outflow the turbo are actually see the WG blow open. I did the experiment, search this site for a thread named wg blowing open info for an experiment I did to confirm this
Hope that helps.

This is VERY interesting and not something I've heard discussed before. I have a big 16G and ported Evo O2 sitting here ready to go in and I just bought a 34mm WG valve. I really, really don't want ANY boost creep so I was going to install the 34mm. Are you saying it is a bad idea? I wil NEVER run more than ~20psi and the car will live 99% of the time on 91 oct at ~16psi. Will I still experience the WG opening and dumping bost with the 34mm valve at that level of boost?

Thanks!
Rob

m1k3 · 09-07-2003, 11:10 AM

Just get a stronger wastegate actuator if it starts blowing open the wastegate.

95GSXracer · 09-08-2003, 11:35 PM

In my case boost would drop to 20 psi. In other cases i have seen it drop to 19 psi. After I wired the WG shut, I held 24 psi to redline

If you only plan to run 19-20 psi, you should be fine. The larger actuator is always a good idea, but there really arent any simple, inexpensive bolt on options. People have tried helper springs and the like, but it never seems to work well in every circumstance. If you are willing to make it work for your setup, start looking around for springs or other actuators. But dont follow what other people do, it often wont work on another car. Another thing I am not a big fan of is adjustable actuators. When I would set mine loose enough to get boost creep below 20 psi, I couldnt hold over 23 psi. If I tightened it up to get over 23 psi, it would creep to over 20 psi. Very small window of adjustment there. A stronger actuator spring is really the only way to go. Only use adjustable rods for setting preload properly (done on typical mitsu actuators by bending the bracket). I would start with Mike at SBR, I've talked to him extensively about this, and he has several actuator options that may or may not bolt up without maing new holes. Or you can talk to your favorite turbo vendor that has good success in offering internal gates. The important thing to discuss is the range of boost YOU intend to run, not that other guy that says "I have X turbo with an internal and it works for me" lol Hope that helps.