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what should a decat gain me..BHP?

Nafoff

Nafoff

ClioSport Club Member
i am looking at getting a decat for my valver and was just wondering on the gains...

i already have a full magnex exhaust and a pipercross panel in my OE airbox..
 
You wont gain much with a normal engine especially if you have a full system exhaust already. A turbocharged engine can expect 20-25% power boost ( as according to the ppl at powerflow). Basically to get the best gains from a decat you need to shove more air in in the first place
 
it may only be a couple of bhp, but its well worth it. the engine revs much mre freely and feels much better, the pops bangs and flames (if ur lucky) make it all good 2!
 
I always change my decat straight back over after a MOT, would'nt do without it now as I know how much better the car runs with it on. Magnex sounds so much nicer;).
 
mine only gave me 1/2bhp and the same torque increase at peak but throughout the rev range was a constant 5bhp higher and peaking 300rpm lower, so although I was initially not impressed at the 'gains' as soon as I got it out on the road I knew there was a very nice improvement....
 
na lunner mate..its someone from the forum.....but i don't really wanna disclose as i don't want loads of competition..as said if i don't win then i shall probably be coming to you..

matty whats the exhaust gum?
 
Hi Freebone,

I have a standard 182 and about to fit a de cat pipe, I'll see what it does soon!

See other thread "BHP Gains From a decat?"

I wrote;

Why remove the Cat?

Theoretical and minor benefits are (in order - possibly?);

1) slightly more power
2) slightly more reliable
3) slightly more mpg
4) slightly lighter
5) slightly less emissions
6) slightly lower maintenance costs
7) slightly louder
8) slightly wider range of useable fuels

Disadvantages;

1) illegal emissions therefore fails MOT and would fail roadside test
 
My list from experience is:-

1) slightly more power
2) Better reving engine, car pulls better all the way through the rev range.
3) slightly more reliable
4) slightly more mpg
5) slightly lighter
6) slightly lower maintenance costs
7) slightly louder
8) slightly wider range of useable fuels

Disadvantages;

1) illegal emissions therefore fails MOT and would fail roadside test
 
Good luck on e-bay then!
Mines a home-made jobbie.Straight piece of tractor exhaust(lol)& the front joint from an old valver exhaust!
 
Dave finney said:
Hi Freebone,

I have a standard 182 and about to fit a de cat pipe, I'll see what it does soon!

See other thread "BHP Gains From a decat?"

I wrote;

Why remove the Cat?

Theoretical and minor benefits are (in order - possibly?);

1) slightly more power
2) slightly more reliable
3) slightly more mpg
4) slightly lighter
5) slightly less emissions
6) slightly lower maintenance costs
7) slightly louder
8) slightly wider range of useable fuels

Disadvantages;

1) illegal emissions therefore fails MOT and would fail roadside test
Click to expand...

note point number 3. this happens as your engine is running lean on fuel!

from experience of having a decat on other cars be careful with this if you have a primary and secondary o2 sensor on the exhaust as the ECU will think that the car is running too rich, it will then compensate by leaning out the fueling to the engine meaning not enough fuel and potentially causing occasional flat spots in acceleration and over a prolonged period of time can cause damage to your engine.

you can solve this by getting a little box of tricks called an o2 Sim (not the mobile phone) which will fool the engine into thinking its not running rich and the ECU will then run and fuel just as normal.

regardless i would say fuel consumption will increase once you do this as my car went from an average of 30 - 32mpg, thrashing it everywhere to about 23mpg!! be prepared to pay more dosh and also use optimax if you dont already anyway.

Alex
 
bigmonmulgrew said:
You wont gain much with a normal engine especially if you have a full system exhaust already. A turbocharged engine can expect 20-25% power boost ( as according to the ppl at powerflow). Basically to get the best gains from a decat you need to shove more air in in the first place
Click to expand...

20-25% wtf! ROTFLMAO, marketing gone a little mental that one!

All inlet/outlet mods objective is to get the air flowing best through the system, there will always be a bottleneck at some point.
 
Been out for a drive and 1st impressions are a slightly free-er throttle response, though this could be the placibo effect. At full revs felt very similar to before and no difference to noise levels noticed at all.

Spykee, Even if the engine does not fuel any differently than before then more mpg should happen simply because a restriction in the exhaust has been removed, particularly when cold. It's easy to check. I'll have to go down the MOT and have emmissions measured. If Lambda much different to 1.0 then you're right, otherwise no problem at all?

Need to measure mpg over a full tank to be sure of mpg one way or the other.
 
Dave finney said:
Been out for a drive and 1st impressions are a slightly free-er throttle response, though this could be the placibo effect. At full revs felt very similar to before and no difference to noise levels noticed at all.

Spykee, Even if the engine does not fuel any differently than before then more mpg should happen simply because a restriction in the exhaust has been removed, particularly when cold. It's easy to check. I'll have to go down the MOT and have emmissions measured. If Lambda much different to 1.0 then you're right, otherwise no problem at all?

Need to measure mpg over a full tank to be sure of mpg one way or the other.
Click to expand...

well see how you go Dave but the decat on my Civic Type R caused it to lean out too much at first and then after fitting the o2 sim it was running really rich meaning i was averaging 23mpg instead of 32mpg which i got before decatting.

let me know as i would be interested in knowing but usually if you free up air and gas flow in and out of the engine it means: more air into engine = more fuel into engine to balance the mixture = more performance + running richer meaning heavier fuel consumption.......

your thoughts on the car running leaner just dont make sense!

Alex
 
mate i am sure this problem would only happen on the more modern cars..as i don't think the valver has these sensors although i am not 100% sure
 
Gary G, worth the money?

Well it's only a piece of pipe with 3 connectors for about £70 so hardly great VFM (although still one of the cheapest) but have to give a proper run over different conditions to be sure. See if I really think it's faster and see what mpg it gives. Needs at least a full tank (about 350 miles) to make an accurate assessment.

easy to fit? Yes I'd say;
2 X 10mm bolts at manifold (easy)
1 X 13mm bolt to 1st silencer (horrible clamp that needs a bit of f'ing about)
1 X 22mm for 2nd sensor (easy)

Light hasn't come on at all yet, ECU must think alls ok!

Spykee, I know what you mean but seems ok. If restriction in exhaust is removed then, for a certain speed, foot should be slightly less pressed on throttle giving slightly better mpg. The petrol light is on now so need to fill up and I'll reset trip. Then we'll see if the mpg has changed much.

I will try to go to MOT to test emmissions, the lambda reading is important. If it's 1.0 (or VERY close) then the engine is running exactly as it should and won't be causing problems, and I am interested in the "base" reading (no-cat) at least for my own curiosity!
 
Quote:
Originally Posted by Tucks
Prob only a few BHP Neil,Im demanding you put a 2.0 in anyways!
TomS said:
I'm roaring at that comment
Click to expand...

Soz,lol I was emotional when I was writing that.
 
Freebone said:
mate i am sure this problem would only happen on the more modern cars..as i don't think the valver has these sensors although i am not 100% sure
Click to expand...

danm i just noticed you have a valver but i was referring to a post by a 182 owner on this thread but you are right, it only occurs with modern engines. your valver might have one sensor tho depending on its age as my G60 has one and its a 1991 H plate.

with your valver im taking a guess you have a distributor cap? if so, even if you have an ECU and electronic ignition you just need to adjust the base timing on the dizzy by advancing it a bit to add more fuel and your car will run great! you will get noticable acceleration increase but putting it too far in advance you will definately get flames from the exhaust, i am curently running my G60 at 5 degrees advance and i get a pop and a flame quite often! :cool:

Alex
 
cool thought that was the case...how do i change the base timing then and is it really vital.

some ass keeps out bidding me on the decat on ebay..lunner special is looking promising..lol

tucks don't appoligies to tom for the 2ltr comment...thats were the real power is at...lol

no pony trekers in here
 
For the guys who have fitted a decat already on their 172/182s- can you tell me if your engine maagement light has come on yet?
Ive had the decat pipe on my car and its taken four months of seriously hard thrashing and the light still has,nt come on!
 
Dave finney said:
Hi Freebone,

I have a standard 182 and about to fit a de cat pipe, I'll see what it does soon!

See other thread "BHP Gains From a decat?"

I wrote;

Why remove the Cat?

Theoretical and minor benefits are (in order - possibly?);

1) slightly more power
2) slightly more reliable
3) slightly more mpg
4) slightly lighter
5) slightly less emissions
6) slightly lower maintenance costs
7) slightly louder
8) slightly wider range of useable fuels

Disadvantages;

1) illegal emissions therefore fails MOT and would fail roadside test
Click to expand...

If it has less emissions why would it fail???:S
 
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