I've blown my engine last night. So i'm trying to get all the parts togehter. I'm going to be doing a street port on the intake, but for the exhaust, i'm debating on whether to get the streetable exhaust or the race. I've heard on some places that the race porting gets almost the same driveability as the streetable port. But on the racing beat site, they say that it's not recommended for the street. Could anyone kinda point me in the right direction? I have an S4 TII and it's going to be a daily driver. Thanks in advance.

 

My out of boost suffered, but car sure is a rocket in boost and the higher rpms...

 

but then things like idle, cruise, and such are ok right? I don't think the size of the exhaust port affects any of that does it?

 

the size of the port matters. i dont know how they port it, but the more overlap, the not-as-great idle. you may have a perfectly fine idle, but overlap can cause problems if done at great extents. PPorts, for instance, are well known to idle much higher. they have gobs of overlap. half-bridges, for instance, idle pretty well, but if i were marketing them, i wouldnt sell them as a street-friendly port. this may be the same case with the racing beat port, i'm not sure. also, the name "race" is good for marketing in its own right. would you rather choose from "street1" / "street2" or "street" / "race" if you were building a racecar? "race" markets better. i'm not sure if this is the case, just sorta rambling.

 

With a stock turbo, I wouldn't port up and/or much larger

 

im getting just a small prt on my s4 TII, the builder sayed that it probobly woulnt be very streetable if he ported anymore. I would have also had to upgrade alot more to keep it safe

 

A port doesn't have to be huge to make great power. If you've got a stock turbo you'd be better off with the street exhaust port. The race port involves removing the exhaust sleeves and making those suckers huge. You don't need them this big. Better flow is one thing but port timing is hugely important. A stock turbo is a huge exhaust restriction. There is nothing efficient about it. This exhaust backpressure will just force more exhaust gasses back over to the intake side on a huge exhaust port. This will hurt your power. It will hurt your off boost response, gas mileage, and kill emissions. You also don't need this much flow since your stock turbo can't flow that much anyways. I know it is tempting to port it big while you are there but bigger is not always better. Know when to say when.

 

im getting just a small prt on my s4 TII, the builder sayed that it probobly woulnt be very streetable if he ported anymore. I would have also had to upgrade alot more to keep it safe
you would get alot of high end but your low end would suffer

 

Thats funny you say that, my intake ports are just cleaned up and my exhaust is past the sleeve by around 1-2mm, so 3mm up etc... Against a stock port s5 t2 that I tuned his haltech more aggressive than mine I beat him running a whopping 6psi less! from 40-140. My car can make up to 13psi in 1st gear @ 8500rpms, maybe its a fluke but I've never been a stock turbo t2 anywhere near as fast as mine.

 

What do you mean by "cleaned up"

 

Backcut the inner radius of the port runner, and beveled the closing edge of the port.
Cleaned up the casting of the ports, and the runners thats it. No real material was removed.

 

i elongated my streetable streetport template from RB and it did take my off the line power from me but when the boost kicks in you know it is on!


as for idle, you can set a full glass of water on my engine idling at 900 RPMs and it won't spill a drop.

 

I'm not saying it won't work. Yes it will work (wonderfully as you have experienced), but you shift the power curve up. The turbo will have a hard time keeping up with the flow of the engine at higher RPM's.

 

hrm. i may just go streetable exhaust then. Even though I will be upgrading the turbo in the future, i'm sure it will be sufficient for it.