I've been searching this issue pretty heavily on the forums lately. But, it seems theres a lot of different thoughts about it.
I have a street ported 88 TII with stock fuel system. I have a 3" dp and racing beat FCD about to go on; as well as a 3" single exhaust.
My car already will max out the boost ( stock gauge ) by 3-3.5k. If I go to 5k the car just cuts off from the fuel cut.
I plan on getting a walbro as soon as possible. I keep reading that the FCD isn't going to help and I need to get a MBC and port my wastegate or get an external wastegate.
I have no idea. I just don't want to be putting a new motor in it next month. So if someone can tell me, will the car be ok with just the fcd, stock fuel, and open exhaust? Will a fuel pump & secondary upgrade solve everything? Or do I have to get my wastegate ported?

Thanks

 

A fuel pump is needed, yes, but you still want to port your wastegate to help prevent the boost creep. A boost controller is of no help. They can only raise boost levels, not lower it. You want to port your wastegate to about 95% of the flapper area(So that the flapper cannot get stuck in the whole..) Or weld on a larger flap, and port larger. Boost creep is especially an issue on the S4 due to its relatively small wastegate.

 

I am in the processing of doing a TII swap into my 87 NA. I do not know anything about the turbo systems yet. I have read a thread in regards to porting the wastegate (see attachment) , but I am not clear where to take it or what instructions to give them. Could some please help me?

 

Is that a pic of your turbo? That is a S5 turbo, not a S4. basically when you have the turbo off, you want to serperate the comressor housing from the rest of the turbo. Disconnect the wastegate actuator rod, and remove the 6 13mm bolts in the center that hold the 2 sides of the turbo together. Then you can pull the exhaust side off. Then you need to remove the back plate that is covering up the wastegate holes. (the part where the downpipw bolts to) This will also be held on my 13mm bolts. Once you remove the backplate, you will see a flap covering a hole. (one hole on a S4, 2 on a S5 as pictured above) basically you just want to make this hole as large as the flapper itself, so that more exhaust gas can flow through..

 

Not it is not mine. It is a pic I downloaded so that I could show it to the machine shop.

Thanx 87turdo2 for clearing that up cause I had no clue.

 

So I should be OK with just porting the wastegate and getting the walbro? Is the FCD still needed after porting the wastegate?

 

Yes, You need the FCD. the FCD is what eliminates the fuel cut that you are getting. I hope you arent letting your car hit fuel cut, as it is very hard on the engine.

You should be ok with the pump and wastegate porting, but if it still creeps you may need to do something about it. Put on a high-flow cat instead of the mid-pipe, or use stock intake. Or convert to a external wastegate. That all depends on how well your ported wastegate can control the creep though.

 

Ok thanks. The RB FCD should be here no later than Monday. I'm putting it on 1st, then if all is OK. I'm outting the dp and full exhaust on.

 

you NEED to port the wastegate larger than the stock flapper... i made my hole about 11/16 in size with a new flapper welded on, and its still not enough. you have to cut into the sidewalls if you want a good port, about 1" round. i still creep to 12-13, and thats too much.

only other way to deal with it is to port it mild, and then cope with it by adding fuel... the best way to go with an S4 wastegate is with a good fuel pump (better than walbro, like a supra pump, or the comp pump from teamfc3s.org store), and a Rising Rate FPR, that will give you enough fuel untill you decide to get larger secondaries, or a better turbo setup.

-chad

 

Don't just port to the edge of the stock flap. Have a turbo shop replace the tiny stock flap with a much bigger one and then port to the edge of that. You'll have much higher flowing wastegate and better boost control than you would with the stock flap.

 

the first thing you need is a real boost gauge!!! don't do anything else till you get that.

then buy a bigger fuel pump and put that in.

once you put the FCD and exhuast on. just make sure it doesn't go over 10psi. you might not be able to floor the car. and you might have to constantly let off the gas or only push 3/4 to keep it under 10 psi.

if you go over 10 or so chances are you'll need a new engine...

if so you need to port the wastegate to lower the creep under 10.

 

LOL, GOOD point...

yes, get THAT first... before ANYTHING!