I have an 87 fc turbo 11. Its all stock, my first upgrade will be the exhaust. I really like the corksport, so. My question is what effect will it have on the performance of my car if I remove the cat and run a 3" down pipe straight pipe into the muffler? Any info or suggestions are appreciated.

 

Your car will boost-creep and you'll blow your engine.

 

Or you might not. But the boost will creep, unless you port the wastegate or keep the silencer in the exhaust. Corksport is loud. I was running 3" turbo back with rtek 1.5 creeping to 12-15 in third, in fourth had to let off, fifth could barley boost would shoot to +15... so. I'd suggest you look into Rtek before putting your foot down with a 3" straight thru exhaust.

 

Fuel, fuel control, ported wastegate...THEN fully open exhaust.

 

So my best bet would be to keep the cat. What about a downpipe should I leave it alone

 

well

keep the cat, then everything should be ok.

dont go corksport. go something quieter, such as the rx7.com dual exhaust that they make. its superb and quiet.

 

Your ear performance will be negatively affected. Put a muffler where the cat used to be.

 

I want it to. Be loud but I don't want to lose power if anything I want to gain. And I know the cat restricts power.

 

pocketlogger.com for rtek 1.7-2.1

upgrade injectors to appropriate cc depending on which rtek ecu upgrade you get.

Port wastgate, then get boost controller.

corksport exhaust or whatever you choose with no cats and issues (i have had no problems for 2 years so far with ssautochrome motoria exhaust, well a couple of tickets for noise...)

Drive a completely different vehicle.

john ny

 

The stock cats do restrict power, but you'll still see big gains if you use a high-flow cat, downpipe & cat-back system.

The S4 wastegate is tiny though, so I wouldn't be surprised if even this kind of setup produces some boost creep. Look into porting the wastegate or having a shop port it (S4 will need a larger flapper welded on). Even buying a stock S5 turbo will help since its wastgate has 5x more area. www.fc3spro.com has a writeup on porting.

 

Wastegate?? Do you mean BOV? Where is the wastegate.
I know I know. I'm new its my first rotatry,and turbo

 

No, not the BOV.


The wastegate is an internal door that opens to allow exhaust to bypass the turbine wheel in the turbo, and therefore limit how fast it spins (faster = higher pressure). When this passageway is too small, the turbo will continue to increase in speed, even when the wastegate door is open.

Take a look here: http://fc3spro.com/TECH/HOWTO/ZWG/zwg.html. The S4 writeup (Zenki) only shows a small port job, which is not enough at all. It really requires a much larger opening and new door.

 

Not trying to be a dick, but if you have to ask...

I think before you do anything, you should do some reading up on turbo system basics, and do someresearch on this forum about porting the wastegate (it's fairly common). Once you have a firm grasp on what the car is actually doing, then start modding.