Tuning Screamer Pipe

[tomharrison]

I'm sure you will all have different opinions, but i could use your help. As the title shows i want to fit a screamer pipe to my Fiat bravo 1.4 t-jet sport, i have put a cat-back exhaust on it and remaped to around 200 Bhp with all the other mods, Im pretty sure the turbo has an external waste gate and i was hoping somebody could give me some dimensions, i was looking at a 38mm Pipe, does anybody know what angle or size i would need and any advice on fitting it thanks!

 

[fingers99]

The FIAT documentation clearly shows an internal wastegate for the Bravo T Jets. So, if you have the stock turbo a divorced wategate is the best you could do.

 

[tomharrison]

So I will have to get an external wastegate, any ideas how much and how difficult and costly they are to fit? Thanks for your response

 

[fingers99]

This looks good. Note that these folk sell them, and recon that they don't improve performance!

Fitting can be tricky -- you'd have to block off the existing wategate, Tig a mount for the new one on in such a position that it "sees" enough gas flow (or it simply won't work properly and you'll end up with boost creep which will destroy the engine, and which is why people fit external wategates in the first place) and do that in what is, in a stock implementation, a very restricted space.

The A.Graham Bell Forced Induction book (amongst others) discusses divorced wastegates. These use the stock turbo and wastegate, but effectively seperate the flow of the exhaust gases after the turbo, the idea being to get better exhaust flow, and hence more power. You could "scream" the post wategate pipe (mind you, you might well get nicked!).

 

[tomharrison]

Thanks for the post, helped a lot, I'm going for a turbo back with a 3" downpipe at longlife, just enquired to see if the can make a custom screamer pipe off the standard wastegate, another question is a screamer pipe illegal? I know they're ridiculously loud ( that's why I want one) so can they nick you for having one?

 

[fingers99]

Well, they could! The big questions are the noise and that -- for it to be effective -- you'd be by-passing the cat, which might create difficulties for the MOT and VOSA.

Generally the length of the pipe (which will "usually" re-merge with the exhaust before the silencer) is pretty long -- 20" or so. The angle of "merge is critical too -- should be as shallow as possible.

Some pics here, the quality varies, but at least one shows "divorced as screamer".

 

[tomharrison]

Thanks a lot fingers, appreciate your help on this, so the one hole in the down pipe is coming from the turbo ( so its a de-cat, which I'm getting after my mot in march) and the left hole is for the waste gate, if this being true that means that for a professional custom exhaust maker e.g. longlife, it shouldn't be much trouble to install one when i get my custom decated down pipe?

 

[fingers99]

Should be easy peasy. But you do need a blocker section between the wategate exit and the "real" exhaust exit for it to be effective. Any machine shop could make one up -- ideally out of stainless.

 

[tomharrison]

Awsome, Thats what I'm going to do then, Really appreciate you help on this thread Fingers, look forward to more of your help!

 

[tomharrison]

And ill post a video in a month or so with the results!