I went to Longlife exhausts in Walsall today- and I'm getting them to do the exhaust tomorrow. He said £600 including de-catting, which I thought was OK. I just have a nagging feeling that someone recently said you shouldn't de-cat an NA. Is this true? or will I get more power?

 

I read that write-up by MTL and I'll have another look- did you say with an NA you have to be careful with the back pressure. Will de-catting it lower the torque at lower RPMs? Will I end up having to rev it even harder to get it going? If the cats are still there, and that raises the backpressure, does that make the car get more power at lower revs? Tell me if I am totally wrong here

 

The bloke seemed to know what he was doing, but I just wanted to check before I went ahead with it.

 

I have to choose the style for the back pipes too- god knows what I'm going to go for. Definately twin exit, but two pipes at each side or just one?? What should I go for?

Ha ha ha ha ha ha

 

Ummmm. just a bit.

 

Thing is I didn't really want it too loud, but it is. It's loud. It hits a resonance at 2000 and it drowns everything else out.

Don't know now how happy I am with the big noise. I drive it to work every day and it WAS quite loud today. I did like the sound of my engine with the stock exhaust, and liked the fact I heard engine not exhaust, so I am wondering whether I should put the cats back in and see how it is on the daily drive- will this decrease the noise a bit?

aaaaaaaaarg, bhp is directly related to torque.

 

 

This is getting as bad as auto v manual. :rofl:

 

You're right, in terms of Physical Systems 101, but the English meaning of "torque" and "power" in these kinds of discussions seems to be:

 

"Torque" - the car pulls from low revs and 3rd is a good overtaking gear

"Power" - the car pulls from low revs, 20-60 in 2nd is monstrous, and 3rd is a good overtaking gear

 

:D

 

The main thing that gets lost in the "English" meanings is that there is a gearbox and a diff to consider.

 

There doesn't actually seem to be a common word for NAs in a high state of tune, where the engine delivers *power* at high revs and you deliver *torque* to the wheels by using the transmission. That's probably because very very few people can bring themselves to drive that way on public roads, and also because you just don't see cars like that most of the time these days. Even the Z has plenty of concessions to town driving. Honda had to invent VTEC just because people want town driving AND big power at the top.

 

The more times I have this discussion, the more I'm tempted to give up on overcomplicated turbos altogether! Mmmm...V-TEC...

 

(Remember Rich's thread when he bought an NA? Once he brought himself to go near the redline he was much happier about the performance of the car. I've only just realised this was his post in the first place. :rofl: )

 

Rich, induction might have as much effect on the engine note as exhaust does, what kit have you got in there?

Induction is standard right now- I am going to get induction sorted ASAP.

 

After a few days of it being decatted I would say the performance difference is minimal. Like I said, I could be wrong and any effects could be all in my head, but nothing else in the car has been changed. What I notice is not power- in fact because of the sound it almost feels like it is more laboured. It seems I have to rev it harder to get the accelleration I had before. It now feels a little flat at lower revs where before I would feel more pull in 2nd and 3rd gear. BUT, like I posted above, it does seem to be easier to drive- easier to change gear almost like I am 'riding' the power between gear changes. It is too noisy for me, and I am going to have to investigate some kind of silencer- someone mentioned this last night but I don't really know what they meant- do you put something in the decat pipes or have the exhaust mangled again to fit boxes in between the cat pipes and the back box?

 

I want the growl not the howl, and there is a nasty resonance at 2000rpm which is getting on my tits. I still am not sure and am considering putting the cats back in and seeing what happens and what I feel it's driving like then. Revving beyond 4k is seriously noisy.

 

Yes- before I had the exhaust done I would say revving it up nearer the redline produced a lot of power. I think the manual helped here because I was able to control just where I revved it to and what power (sorry, torque to the wheels) I was applying. The exhaust sound coupled with the engine sound was right for me. I felt my NA had good torque low in the rev range- it suited me that the 'power band' was quite low like that- in third it pulled well and I felt I could get up to third quick and take off. Now I feel I have to rev harder, with bigger noise and accelleration does not seem so strong.

 

This could all be imagination, maybe because I am not totally happy with the sound, so I'm not pushing it the way I had learned to when I had got used to the car the way it was. I think I'm a bit intimidated by the sound still at the moment.

 

Sorry about the long post. Am I B.S.ing again? These are just my impressions from the last couple of days driving. Anyone got some more info about deadening the sound a bit without putting the cats back on. If I do put them back, will the noise go down?

Rich, I know what you mean about resonance, about 2500 you can only hear exhaust.

 

You could try turning the stereo up more ;) Or you could try some more sound deadening material in anyplace you can fit it.

 

I just find it adds to the character of the car :D

 

BTW, how does it sound near the redline :)

rich,

if u want some inline boxes try jetex exhausts in stratford 01789298989 they do lots of universal parts in diff bores

That's what I don't like- the exhaust taking over at 2/2.5k revs. Turning the stereo up sounds like the easiest answer!

 

I think the thing is I have to relearn how to drive the thing again. To be honest, I have been shitting myself to take it over 5000 revs because it just sounds so loud. I tried staying in a lower gear tonight- staying in second rather than quickly going up to third. I saw an S2000 fleeing along with the engine revving hard which gave me inspiration. I know I am bad for changing up very quickly- just the way I was taught- keep it close to 2000 revs. I just bang it up a gear.

 

The engine actually sounds really good hitting 5k in second. It sounds lovely sitting at the lights. I have been changing my mind about this for days now. I still think I'll go for some small mufflers in place of the de-cat pipes. But I am getting used to not just the sound but the feel of the car too.

 

I phoned Jetex today and the guy said he'd probably be able to help- thanks fairlight.

 

When you're not actually in the car it sounds great. Like I said before or in another post somewhere, I even let her out in it (up to the corner of the road and back!!) just to hear what it sounded like, and it does sound good. Yet again, thanks to everyone whose given me advice on this. I do feel like I've stamped my mark on the car now. I did like it totally stock- I was quite proud of it, but once you start tweaking I guess you are bitten by a bug.

I have been thinking too- talking about Vtec and NAs and revving hard- I would love to have a go in an NSX. Are they fun to drive?

One very last de-cat question (promise)- can I do any damage at all by having it de-catted? Obviously I am aware of the turbo 'problem' of oil leaking into the exhaust, that people say is just bringing on a problem that was there anyway. I just wondered if there was any way at all I could strain or damage the engine by having the cats off.

 

Promise I will shut up now.

De-catting won't do any harm. :dance:

I have been thinking too- talking about Vtec and NAs and revving hard- I would love to have a go in an NSX. Are they fun to drive?

 

They were Evo mag's Car of the Year at some point. I want a go too. :-)