Alfa Romeo Forum banner
1 - 20 of 22 Posts

·
Registered
Joined
·
20 Posts
Discussion Starter · #1 ·
Hi,

I own an 1.8 8v with a Scorpion DTM exhaust fitted.
Next Saturday I am going to take out the catalytic convertor and replace it with a straight pipe.

What is the increase in BHP expected please?

Is it true that one can expect up to 5 BHP ?


Thanking you,
Eric.
 

·
Registered
Joined
·
447 Posts
I've even heard about a better increase, but those are just rumors, it may have to do with the fact that when your car has run lots of km's the cat fills up wich decreases the bhp output so when you remove it it gives a big increase
 

·
Registered
Joined
·
550 Posts
HI JACQUES, INSTALL A STRAIGHT PIPE OF MILD STEEL OF 2 INCHES.
CHEERS AND GOOD LUCK
 

·
Registered
Joined
·
20 Posts
Discussion Starter · #5 ·
Hi,


I removed the Cat.

That's much better, i am really happy!!
Noise improved and car more willing to rev perfect !!


Regards,
Eric.
 
G

·
Unfortunately it is illegal :O(

As long as you put it back for the MOT you can quite happily get away with it. :O)

wahoo!
 

·
Registered
Joined
·
20 Posts
Discussion Starter · #8 ·
Fortunately here in Malta we don't have an MOT which also tests the emissions !!

The Police Alfa 155's are all de-catted !!

Regards,
Eric.
 

·
Registered
Joined
·
20 Posts
Discussion Starter · #11 ·
Hi,

As regards running the car without airfilter......

Will you be doing any damage to the engine etc....

And will improve performance please ?


Regards,
Eric.
 
G

·
Not something to do Eric but apparently they sound GREAT!!! My 1997 1.8TS 16v appears on the parts cd as a Carabinieri car. It doesn't realise just how lucky it was to find me and to be a regular sight on the wonderful backroads of Bedfordshire...! (And also to find Alfa in a mood to bestow lashings of Alfa Red paint, a sport pack and ample electrical goodies :D )
 
G

·
Hi Eric

where did you do the job here in malta.
When i tried to de-cat mine, nobody seemed to find big enough flunges.(i hope you checked out the size of the flunges first)
I'm telling you this cause the guy at MSG SILENCERS was going to use a much smaller flunge. Obviously the flow wouldn't be the same

regards ian
 

·
Registered
Joined
·
20 Posts
Discussion Starter · #14 ·
Hi Ian,

Sillatu garage fitted the scorpion exhaust and de-catted my car.
They're wonderful people ! Really helpful.


Regards,
Eric.
 
G

·
Living here in the Isle of Man, we don't have an MOT either, so no emissions tests to worry about.

My exhaust is on the way out and I'm looking at a Supersprint system (money allowing) or having a Powerflow system made. I hadn't considered removing the Cat until I read some of the comments in the forum. I had no idea such horsepower increase could result from such a simple job. I wonder if fuel economy will also improve?

For those of you who've removed the cat, have you had any problems with the Motronic engine management? And you'll have to excuse my technical ignorance here, but how is the lambda probe affected by having no cat? I can't help wondering whether I will have problems in the future by taking away something the car was designed to have from the start.

Come on, put my mind at ease.

John
 

·
Registered
Joined
·
715 Posts
The good thing about the 155 is that the lambda sensor is mounted at the bottom of the downpipe before the cat, so you can just take it out and put it to one side!! If it wears out, it is over £500 for a new one!!!

With regard to exhausts, I think the Supersprint would be a good buy as the custom exhaust I had made is very noisy compared to the Supersprint. The 155 has a very heavy breathing engine and really needs some well engineered silencing. I would not recommend the Powerflow exhaust as it hasn't been engineered correctly, like any custom exhaust. But then again, the Supersprint isn't cheap either!! Jetex and Peco do a back box for it.
 
G

·
Thanks for the info Henry. I was in two minds about the Powerflow (not sure if I trust the local fitter) but you've made up my mind. Supersprint it is.

Just spoken to Alwyn Kershaw in York. Seems the prices for Supersprint are fixed in the UK so no one can offer huge discounts. Best they can do is offer free postage to the Isle of Man. Anyway, I'll get saving and the Supersprint should be on by next summer.

One question though. On previous postings, people have discussed replacing the cat with a straight through pipe from the downpipes to the centre section. However, on the Supersprint web-site they show part no 752702 as the cat replacement.



The part appears to be cat shaped. I'm assuming this has something to do with the flow of air into the exhaust and tricking the engine into thinking back pressures or whatever, are the same. Someone mentioned something similar on another posting when talking about replacing the cat on a Q4 as this has a pre-cat box which needs to be retained.

I don't mind forking out the cash if this thing is going to make a difference, but a piece of straight through pipe is going to be a lot cheaper.

Anyone any ideas :confused:

John
 

·
Registered
Joined
·
35 Posts
I repleced my cat with a Supersprint one. Last wednesday my 155 1.7 8v has been on a performance test and it puts out 125 bhp instead of 115. So it's a difference of 10bhp. After fitting a chip of Squadra tuning it is increased to 134bhp.

Richard
 
G

·
Henry, what is wrongly engineered about the Powerflow Systems? I've one and it seems OK...on your custom one did you retain all three of the silencers? :confused:
 
1 - 20 of 22 Posts
Top