182 ff cup packs
test 3 is same set up as my car, it does make a difference that you can feel, better torque and stronger revving
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De-cat truth
- Thread starter lasimone
- Start date
The air coming out your engine is cleaner than the air that went in.
Sunglasses_Ron
ClioSport Admin
So anyway, what's the truth?
People misunderstand torque. Torque does not equal acceleration at all. If anything it's the exact opposite.
Torque = work done. Power = rate of work done. You need both to make a fast car. A lorry has plenty of torque, so it can haul 40 tons, but it can't do it very quickly because it doesn't have the power (relatively). Therefore it doesn't accelerate very quickly. Take a tank transporter as an extreme example. If it had 10,000bhp, it could pull that tank from 0-60 in 5 seconds. If it had 10,000bhp but no torque, it would be able to do something similar until you added the tank, and it wouldn't be able to move.
Extremely simplistic but that's the nuts and bolts of it. Motorbikes can get away with little torque because they don't have to do much work. What work they do, they do it quickly through lots of power (again relatively) at very high RPM.
Torque = work done. Power = rate of work done. You need both to make a fast car. A lorry has plenty of torque, so it can haul 40 tons, but it can't do it very quickly because it doesn't have the power (relatively). Therefore it doesn't accelerate very quickly. Take a tank transporter as an extreme example. If it had 10,000bhp, it could pull that tank from 0-60 in 5 seconds. If it had 10,000bhp but no torque, it would be able to do something similar until you added the tank, and it wouldn't be able to move.
Extremely simplistic but that's the nuts and bolts of it. Motorbikes can get away with little torque because they don't have to do much work. What work they do, they do it quickly through lots of power (again relatively) at very high RPM.
DC2 TypeR / E36 328i
Ermmm "torque does not equal acceleration at all" - I'm sorry but yes it does
Torque is the turning force applied - power is the speed it is applied. To get a static object to move you need force, once its moving you need speed
You only need to push a car off your driveway to know it takes a LOT of torque to get the car moving and then when it's up to speed you need to be able to run faster to keep it increasing in acceleration
Exactly the same with your engine and car - for acceleration off the line you need torque - to go faster top end you need bhp
Which is exactly what has been said - if you want a bit more top end speed then a decat will give you a few more bhp and free up a bit more speed
But if you want to be quick from the line or quick out of a slow corner then the standard cat will give you a few more torques and will give you better acceleration
Phil, torque does not equal acceleration. It is a necessary factor, but it must be coupled with power. At its bare bones your statement is incorrect. (refer to my post about steam engines; torque probably into 4 figures moving at 1mph).
Power is relative to energy (rpm).
I understand what I think you mean though, but who would deny that more torque is a bad thing?
I haven't done energy principles for a while, I'd like to brush up tbh.
Just out of interest is there any conclusive proof that decats give a drop in torque, aside from the controversial and lollable 2s/lap claim? (mapped and unmapped).
Power is relative to energy (rpm).
I understand what I think you mean though, but who would deny that more torque is a bad thing?
I haven't done energy principles for a while, I'd like to brush up tbh.
Just out of interest is there any conclusive proof that decats give a drop in torque, aside from the controversial and lollable 2s/lap claim? (mapped and unmapped).
You need both - but for acceleration you need more torque to move a static heavy object than you do bhp
The only reason steam engines and lorries are slow is because they are geared to produce maximum torque and no bhp. That's because they both need to move a lot of weight from a standing start.
It's a very exagerated scenario to a car setting off - it weighs a ton and you need to get it moving - so you need torque
But if you had all torque and no bhp it would move easily but slowly. If you had all bhp and no torque it wouldn't move.
In an ideal world you'd have lots of torque loads down and lots of bhp high up - but that's not really very achievable.
I wonder if I can keep this thread going into January?
The only reason steam engines and lorries are slow is because they are geared to produce maximum torque and no bhp. That's because they both need to move a lot of weight from a standing start.
It's a very exagerated scenario to a car setting off - it weighs a ton and you need to get it moving - so you need torque
But if you had all torque and no bhp it would move easily but slowly. If you had all bhp and no torque it wouldn't move.
In an ideal world you'd have lots of torque loads down and lots of bhp high up - but that's not really very achievable.
I wonder if I can keep this thread going into January?
all this torque talk makes me glad to have a gearbox.
Give me a lever long enough and a fulcrum on which to place it, and I shall move the world.
Archimedes
Give me a lever long enough and a fulcrum on which to place it, and I shall move the world.
Archimedes
I agree with your technical definition of torque and horsepower - I totally disagree with the statement above
You're pretty much saying torque doesn't produce acceleration - which it does
Plus I'm bored shitless - and winding people up into week long arguments on here is my only entertainment
I have re-read it now. Understand. Agree.
BHP is merely torque with engine speed anyway. You can't get BHP without torque.
As we're not talking about changing the RPM of the engine or the redline of it - then losing torque is losing acceleration.
Gaining torque is gaining acceleration
If you were gaining torque and losing RPM then yes you'd be losing acceleration but that's not gonna happen with a decat.
"Torque wins races, horse power sells cars" - Carol Shelby
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I don't think it's practical to run one all the way to the arctic circle
Not least because by the time the "arctic" air gets to your car it'd be the same temperature as all the rest of the air in Cheshire (or wherever you are)...
...principle of thermodynamic equilibrium n all. If however you were to attach a calf rearing bucket on the end of your induction hose... wait, no. Nope it definitley would not make any difference whatsoever.
I'm amazed this thread lasted 10 pages before descending into OT chat. I mean at least the 2 second a lap gain, steam engines and power/torque arguments were all on topic!
1995 Renault Clio 1.8 16v
Brilliant read, so... Does a de-cat make much difference then??
Cant believe im here again posting on this thread.... I did have my ass kicked.... In my personal opinion....
Decat... definitely more free revving, and appears easier to stall (i dont do that much) - Less backpressure I guess, oh and more noise. No difference on mpg for me though
Cat... the opposite......
But no difference with mpg either way
Decat... definitely more free revving, and appears easier to stall (i dont do that much) - Less backpressure I guess, oh and more noise. No difference on mpg for me though
Cat... the opposite......
But no difference with mpg either way
1995 Renault Clio 1.8 16v
Jokes aside, I wanted a decat but the last one I bought a decat for was a valver about 6 or 7 years ago, an it made it stink to high heavens, constant headaches from fumes!
Wondered if the 1*2a were any different, but sounds like they stink too!!
Don't want a stinky car, no de-cat for me then
Wondered if the 1*2a were any different, but sounds like they stink too!!
Don't want a stinky car, no de-cat for me then
1995 Renault Clio 1.8 16v
Oh yh wasn't all the time, but when windows were down it would suck the smell inside, was really unpleasant
Renault clio 172
My 172 had a decat when I bought it but I took it of and put the cat back on as it was to noisy for me personaly I've haven't felt any change in power or revs or any thing mentioned apart from noise( don't get me wrong I like a nice sound but it was just too noisy) I left the magnex cat back system on and that's enough for me, anyone with a magnex system will probs agree that they give a nice sound rather then outright noise, my mate has a yozza system and Christ what a racket, excellent build quality though lol, oops I'm speaking crap again sorry
Chris205
ClioSport Club Member
Many Things
My experience with de-cats is you lose a little on the bottom and gain a little on the top. Both weighed up if you're looking for peak power figures and rev the nuts off the car a lot, go with a de-cat. If you want the car to be more usable lower down the range, keep the cat in for more torque.
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