UniqueTII

I was thinking $3K on your car, $3k on mine.

I need some major suspension work...one of the other reasons I say it's going to be a busy winter. I am even thinking of replacing all of my bushings, which is a major job time-wise.

rico05

Yeah, for suspension, I want KYB AGX, RB springs and sway bars, Cusco front strut tower bar, Cusco rear triangulated strut tower bar, RB pillow ball mounts, and BF Goodrich KD tires. I think then, I will be a VERY happy little boy!!!

UniqueTII

No ****...that's exactly what I want minus the tires and with the addition of rear-steer elimination. I bet you get it first, though...my financial situation is kinda sketchy right now.

Aaron Cake

iTrader: (1)

Will everyone please get it through their heads that a boost controller cannot lower boost.

Boost creep happens because the wastegate is not large enough to bypass enough exhaust gas from the turbine. Thus, the turbine begins to spin slightly faster, generating more boost, generating more exhaust gasses, spinning the turbine faster, etc.

The only way to cure boost creep is:

1. Port wastegate
2. Install external wastegate
3. Generate less airflow (restrictive airbox or exhaust)

rico05

Good call, rear steer eliminator bushing are a MUST. Then, if I can save up enough $$$, either a Kazz or Cusco LSD in the future. I just need to do a little more paperwork, and the $$$ is mine!! MUWAHAHAHAHAHA!! But one thing Unique, yours will still look a lot cooler than mine!!

rico05

Aaron, how much porting is needed to be safe?

UniqueTII

Mine looks great, rust and all...lol. Good old northern cars. Aaron...thanks for catching my slip-up. I hate posting incorrect stuff.

Aaron Cake

iTrader: (1)

You can port the wastegate as much as you want, even larger then the flapper door itself. If you do port it larger, make it quite a bit larger (at least a MM on each side) to prevent the flapper from getting stuck.

rico05

Can a dufus like me do that w/ a dremel in my drive way? You wouldn't happen to have any pics of a ported stock wastegate would ya?





Mabye I should have been nicer to ya Aaron, you DO in fact know everything

UniqueTII

I have heard about porting the WG bigger than the door...does that increase lag, because the air would always been escaping?

UniqueTII

http://fc3s-pro.com/TECH/MODS/TURBO/wg.htm

rico05

Thanks Unique. Yeah, how would it being bigger ported than the flapper work? Also, would you port both passages on the Kouki w/g, or just one? If only one, which?

Aaron Cake

iTrader: (1)

A dremel will work fine as long as you have a good bit. The porting itself is rather trivial. The real bitch is removing and disassembling the turbo.

The Kouki turbo has a much better wastegate than the Zenki unit, and if you port it, you may in fact then need a boost controller to bring it back up.

Porting larger than the flapper doesn't really increase lag because of all the airflow created by whatever is causing the creep in the first place.

UniqueTII

I need a boost controller to get mine above 6...I feel like I'm wasting the potential of the upgraded turbo.

rico05

SO I should just let a shop do it for me I guess, since I want a B&R stage II or III anyway

Aaron Cake

iTrader: (1)

That's a good thing. It means your wastegate is working properly. A cheap boost controller is easily made with an aquarium air valve and vacuum T. I plan on making one pretty soon...Once I get used to that, I'll get something pretty like the Apex'I AVC-R.

Supermac 7

Awesome info guys, and all correct too . Rico, a profec B is probably the best bang for the buck as far as electronic boost controllers go. Myself, I am building a manual one that will allow me to control wastegate creep as well as boost level.

Anyone, as far as porting the kouki wastegate ( I am about to do it, turbo is off), I have to take the exhaust housing off, correct? I wont mess anything up too bad will I?

Also, if you port beyond the flapper door, boost will not come on near as hard, will it, because of the added wastegate creep?

Thanks,
Jameson

Aaron Cake

iTrader: (1)

If the shop will have your turbo out and disassembled, have them port the wastegate. They may even do it without asking...

rico05

How exactly does a boost controller work? I read the article in SCC last month, and I just got lost. Aaron...you rock!!

UniqueTII

Yeah, I was thinking of a $5 DIY check valve...Home Depot racing...lol.


There's a company that sells some pretty decent ones for $30, for those people who don't like to build things.
www.boostvalve.com

Aaron Cake

iTrader: (1)

Alright everyone, repeat after me: a boost controller cannot lower boost nor control boost creep. That is function of the PHYSICAL WASTEGATE. The ONLY way to control boost creep is to modify/replace the wastegate, or push less air through the turbo.

Yes, the exhaust housing has to be removed. You shouldn't mess anything up if you are careful. The hardest part is removing the turbo.

If you are experiencing boost creep and you port beyond the flapper door, you will not notice much lag because of the increased airflow through the turbo. It is already overwhelming the stock wastegate, so a little gas leakage won't make a big deal.

UniqueTII

Bleed valves decrease the pressure that the wastegate sees, so it stays closed until a higher boost level than stock is reached.

Check valves don't open until a certain psi (like a pop-off valve) so the wastegate doesn't see any boost until the limit is reached.

Aaron Cake

iTrader: (1)

Boost controllers simply alter the boost pressure the wastegate actuator sees. The more the wasgate actuator is restricted from seeing boost, the more boost will have to be made to start moving the wastegate actuator.


Well duh.

rico05

THANK YOU!!! Finally, someone who can explain this stuff even to a moron like me!!! This is one of the most informative threads I have ever read/started.

NZConvertible

Boost creep and boost spikes are two quite different things. Boost creep is just as has been described, boost jumps up to the right level but when the wastegate’s capacity is reached it starts to rise again. A boost spike is when the wastegate can’t react fast enough to a sudden increase in airflow and boost overshoots the set point and then comes down as the wastegate catches up. This isn’t necessarily a bad thing, as it usually happens at lower revs so the fuel system can cope with higher boost because the airflow is much less. So you get a nice mid-range torque spike! There’s no doubt that at high flows the stock intake components are a restriction, but I have seen in excess of 500hp made using them, so they can’t be that bad! Saying they can only move X amount of air isn’t strictly correct, you just have to push much harder as airflow increases.