BXProject

Such as 50-70mph etc - anyone know how these are done, i.e. do you potter along at 50mph in 5th and then just boot it, or boot it at 45mph and start the clock when you hit 50?
I've been doing a few this morning and wanted to compare them to Citroen's figures and road test results of the time...

The magazines have electronic timers now but you can do it with a stop watch and someone else driving ( not Vanny and not on your back road)

You hold it at whatever speed you are going from in that gear and then boot it till you reach the appropriate speed and clock it.
Ideally it should be done on a levelish road, like an old airfield.

Philhod wrote:You hold it at whatever speed you are going from in that gear and then boot it till you reach the appropriate speed and clock it.

Yeah, that's what I did - this will be obviously a longer time due to turbo lag. Difficult to find a level road around here though. Trouble is 2 people gives extra weight to the car.
For what it's worth this is what I got (1 run only)
30-50 (3rd) 3.5 secs
30-50 (4th) 5.5 secs
50-70 (4th) 6.6 secs
50-70 (5th) 7.9 secs

That is still better than some old road test figures I was reading last night, the bizarre thing is the difference between models (all with the same 1769cc TD engine) over the years the BX was produced! I'm assuming it's different weather conditions/production tolerances/amount the engine has been run in etc.

there is an iPhone app for this, it 'senses' the gear change with its twin accelerometers.

Ooooh, I'll have to see how mine compares to yours (oooo errrr). Mine struggles a bit in 5th TBH

Don't you have the valver 5th gear?
TBH, having another look at the figures achieved in road tests from the 90s I'm suspicious that I may have been going slightly dowhill or had a tailwind!
30-50 (4th) 7.3 secs
50-70 (5th) 10.4 secs
(Figures for an estate)
I'm expecting mine to be a bit quicker than standard, but I think to be a fairer test it needs to be the average of say 3 runs, or maybe 2 runs in the opposite direction. Wish I'd tried it with the original engine now...

I did these in the 19n/a about 8 years ago on a flat surface.
I've been looking for them since you first posted

30-50 3rd 3.4

30-50 4th 5.6

50-70 4th 6.1

50-70 5th 8.0

So not all that different really.

Well, that pissed on my fire! Are you sure that was an N/A? Or were you heading towards a large magnet?

No. That was with 2 up for accuracy too. It also only had about 80 thou on it then too. The 19 n/a is much quicker away than the turbo.
It's only once you get a good spin on the turbo that it picks up.
If you drive the 2 back to back round town, it's very obvious. The n/a is much more sprightly.
It's only at speed on the m/way that the turbo has much more in gear punch.
The later multi angled vanes like the one in my Picasso rectify this, although I think my HDI would improve with an I/C.

Philhod wrote: 30-50 3rd 3.4

30-50 4th 5.6

50-70 4th 6.1

50-70 5th 8.0

Those are quick times - looking at a magazine group test from 1989 (that had the BX16v against an Alfa 75 3 litre) it would appear that an BX 1.9 non turbo diesel is faster than both... Are you sure you've got the decimal point in the right place?

Alfa = 5.1/7.0/7.1/9.9 seconds
Valver = 4.8/6.9/7.1/10.9 seconds

It also makes a mockery of my figures, as I used to have a 75, and it felt considerably faster than my BX!

Well those are what Derek recorded, with me driving. I have his card here in front of me in his writing.
Mine's a 93 TXD, one of the last ones made, if that makes any difference. It even has the GTI dash and interior, like all the last batch.
I'll tell you what. When I have finished the refurb, I'll do it again and you can operate the stopwatch

Philhod wrote:Mine's a 93 TXD, one of the last ones made, if that makes any difference.

Ahhhh, that could be it 'cos you have 71 bhp rather than the 65 bhp of the early ones.

Philhod wrote:I'll do it again and you can operate the stopwatch

Cool, but not after I've been making any cocktails...

Err... especially traffic light coloured ones. and it has 72 BHP cheeky

They were same engine as in the xant, with the fuel filter over the thermostat and the longer oval inlet tracts. Oh and it has Pug alloys on it too! wow.

mat_the_cat wrote:

Philhod wrote:You hold it at whatever speed you are going from in that gear and then boot it till you reach the appropriate speed and clock it.

Yeah, that's what I did - this will be obviously a longer time due to turbo lag. Difficult to find a level road around here though. Trouble is 2 people gives extra weight to the car.
For what it's worth this is what I got (1 run only)
30-50 (3rd) 3.5 secs
30-50 (4th) 5.5 secs
50-70 (4th) 6.6 secs
50-70 (5th) 7.9 secs

That is still better than some old road test figures I was reading last night, the bizarre thing is the difference between models (all with the same 1769cc TD engine) over the years the BX was produced! I'm assuming it's different weather conditions/production tolerances/amount the engine has been run in etc.

hmm, I've never timed my TD, but would guess it would be a little better than that..
It is a tad tuned mind, and it's not an estate..

It now has that cylinder head on that you gave me Doc and I've never blasted it since.

It's not got a cam in it that you had a play with by any chance.........

mat_the_cat wrote:Don't you have the valver 5th gear?

No, it's a std Td 5th gear but with a GTi diff - so, longer legs but not as quick. It struggles torque wise to turn the 5th. It's ok, still accelerates ok for the motorway. It could do with the Garrett T15 a la Xantia. A Zafiara has what looks like the right housings.

The other thing to do is to steal Doc's idea and put the 2.1 block with the BX head/turbo on it. Whilst I like the apparent 'sprintiness' of the 1.7, I drive it and expect it to behave more like it's big diesel. So 2.1 I may as well!

Regarding your times and thinking you had a tail wind etc, you're not comparing like for like are you? You have a Xanty 1.9 TD which has more torque than the 1.7 TD non?

If you stick the 1.9 head on a 2.1 block, what does the compression ratio rise to?

If it gets much above 25:1, won't it start to affect the swirl chamber inserts?? I mean, they have a tendency to crack with age anyway.

can't say I've worked it out on paper to be precise, but I suspect the difference in compression ratio would be next to fuck all, if anything I'd say it would be just an insignificant amount lower.
Personally if I'm going to the trouble of pulling a head then I'd replace the swirl chambers anuhow since yes they tend to crack a bit when they get older, although I've seen some REALLY fucked up chambers and they never seem to part company with the head.

I hadn't thought of C/R issues, but as the head what where the valves seat is effectively flat, wont the C/R remain unchanged?

Well yes the head is flat but the pistons have a recess shaped like 2, 2 pence pieces, joined by a square and not much deeper than the coins either.
It's only as I was writing this that I realised Doc is right. If the 2.1's piston has slightly larger recesses, then of course it would drop the CR a bit, not increase it.

Well hush my mouth