TZD exhaust modifications give a pleasant boost

[Erikbm]

While I am waiting for someone to source a non turbo camshaft for me, I have taken off the standard exhaust of my 1990 BX TZD and have fitted a straighter system, with a single 2 inch straight through motor cycle exhaust at the end of it. The result has been a significant increase in driveability and a lowering of the revs at which the turbo boost appears.

The turbo boost was only coming in at 2500 rpm with the4 standard two exhausts , whereas now it appears below 2000. This makes it much more driveable. Taking off in first is now OK, whereas it used to be embarrassingly slow before.

This is a relatively simple modification, although in South Australia we don't have any annual inspections to pass. Even if the MOT people frowned on this, you could still keep the original and bolt it back on to pass your annual test. It is still just as quiet as before.

Regards, Erik from OZ

[kiwi]

Dont suppose you got a picture of this set up?

I was thinking the other day on how the exhaust systems on my two petrol 1900s sound differant well to be more accurate I suspect a baffle is loose in the TZS judgin by the unique noise it makes coasting down hills using the engine for braking. Its been like that since I have had it but then I also recall an exhaust specialist telling me that my exhaust on our none BX would nly last another 6 months! That was 5 years ago

A question though is would a loose baffle in the exhaust affect fuel consumption as well? Reason is the TZS is thirstier than the TRS.

Hence why I am keen to hear more on the modifications possible!

[Vanny]

given how short the first gear is, i can't imagine a TD BX ever being described as slow! With a 1.9td engine that was incorrectly setup for the BX i would happily pull away in second and still smoke away anything trying to out drag. I guess the question is, how slow is slow to begin with?

I guess by the sounds of the intended mods that the engine has been blue printed and becnh marked? What was its original torque output like?

[Kitch]

i would happily pull away in second and still smoke away anything trying to out drag.

Including an Astra VXR?

[DavidRutherford]

have fitted a straighter system, with a single 2 inch straight through motor cycle exhaust at the end of it.

Is that the only silencer on it at all? IE, no cross-box? If so, that's a fair reduction of weight too. I'd be intrigued to see a picture of this set-up too.

I suspect it would only be applicable to a TD engine, as the turbocharger itself does a fair amount of silencing, so is less reliant on the silencers to keep the exhaust quiet. Doing this on a non-turbo engine would make a lot more noise.

[Erikbm]

In reply to a few more responses:

- My description of the standard setup when I first got the car is that the turbo works and it pulls strongly from 2,200-3500 rpm, but is quite gutless below this. Taking off in first is embarrassingly slow and I doubt I would manage it in second without stalling, but I haven't tried it.

- I haven't blueprinted the engine for BHP etc because I hadn't thought of it and I don't know who does that sort of thing. Is that a dyno job?

- From doing a search of this forum, it seemed that TZD owners often complained of a poor response outside of the fairly narrow turbo range, so I assumed the engine was behaving normally.

- I have indeed removed the cross box from the exhaust and I will post some photos when I get it back up on a hoist a bit later. The weight saving is not the factor, because I am still carrying around an extra spare tyre in the boot. I am told by the aussiefroggers that the turbo does silence the exhaust output a fair bit, so this setup may be too noisy on a petrol version, but it was certainly far too noisy with no exhaust at all. I am also told that the UK has something called a 'devil's elbow' that can be fitted instead of the cross box, although this would still give you an unneccessary extra set of bends in the exhaust setup.

- The turbo now seems to come in at just below 2,000 rpm and will pull nicely up until 4,000. It is much more driveable now and first gear no longer seems sluggish at all. It also no longer dies when changing from 1st to 2nd. I am actually quite happy with its performance now, although having traded a Peugeot series 1 Mi16 for this BX, I don't think the BX would be a close match yet. Maybe if I fit a non-turbo cam to the BX it will start to get close?

Any more ideas are welcome, as there aren't any other of these cars that I know of in Australia to go and have a drive of. Compared to a 1.9 TD in a Peugeot 405 I would say that this is still a little slow, but it is getting closer.

Photos will follow, but be patient. I have to load them onto my daughter's facebook first and then copy them across - or is there a way of getting them straight off my camera???

Regards, Erik

[mat_fenwick]

Simply changing the cam for a non turbo version won't bring it close to 16v performance, but it is fairly simple to increase the boost level (and fuelling to match), which should bring a smile to your face.* I've done this to the 1.9TD engine in mine, and I beleive that the next weakest link in its performance is the exhaust, as it sounds strangled at high revs/high boost.
*I should add that it's a completely different kind of performance from a TD to a valver, and I do sometimes find it frustrating when I run out of revs at 4k rpm!

A turbo does remove a lot of the noise from the engine, as demonstrated by this video of my van running with just a straight pipe from the turbo, no extra silencing at all. I probably would have been able to use it like that on the road without attracting attention.