Black BX 19 GT MK1 FOR SALE

[docchevron]

Not sure what you mean by a narrow power band on the gti? It can rev easily upto the redline whilst the td runs out at about 4.5k. There is a 35bhp difference to a stock td to a Gti, & in a lightweight car thats a massive difference.

Erm, right, well...
the petrol engine developes maximum power through a fairly small rev range, whereas with the TD it's less about the horsepower and much more about the wave of torque the turbo provides.
Whilst the horsepower difference between the petrol and diesel is quite substantial, the TD doesn't so much use power, it's all about the torque.

Couple that to not only the differences between the gearing, but the final drive aswell, and the TD is quite a formidible weapon (well, I mean, one that really works well)..

Your'e right doc, there is a misconception that the 8v has more torque than a valver, you quite correctly pointed out it doesnt, the difference between them isnt that much & in the valver it comes in much higher up the rev range than the 8v.

Again, we need to seperate torque from horsepower.
A valver doesn't come on to cam until you hit the magic 4.5K revs, which is lower in the 8V, but lb/ft for lb/ft of torque and the valver still wins, assuming said valver has a No. 3 inlet and No.2 Exhaust pulley.
Which mine does.
Ok, thats the way I set mine up for a reason, I like the fact it has lots of bottom end torque, this is slightly to the detriment of top end power, but I'm not one for screaming the nuts off it everyday. It's still more fun than sex when it does bounce off te rev limiter...
But wqually it'll pull very strongly from 25mph in top gear, which works for me..

I think the 8v gets a bit of a dis-service, td's are much more fuel efficient, but once you get into 4th gear performance is leisurely in td whilst in the 8v its still going strong. The gti also feels a lot more nimble to drive for some reason, is the diesel lump quite heavy in comparison?

Yes the diesel lump is heavier than the petrol engine, not by as much as you might think, but it does make a difference.

I'm not sure the 8V gets a disservice TBH, I think it's a lovely engine, and it's no slouch by any means.
IT'll never be as good on fuel as a diesel, as you say, but then that was rather the point of the diesel engine in cars!
Which is why things like the Golf GT TD seems a bit silly to me..

Equally, if you say your TD feels leisurly in 4th then I would suspect it aint running aswell as it could.
Dependant on what related road speed we are talking about here of course.

[Tim Leech]

I'm not sure the 8V gets a disservice TBH, I think it's a lovely engine, and it's no slouch by any means.
IT'll never be as good on fuel as a diesel, as you say, but then that was rather the point of the diesel engine in cars!
Which is why things like the Golf GT TD seems a bit silly to me..

Doc you welcome to have a go in my GTD any time if your not convinced, 65mpg on the motorway and with 168bhp will show a clean set of heals to most cars and spins its wheels in third yet the emissions are low so cheap on company car tax, I see the point in that.

[sdelasal]

Horse power is actually defined as torque multiplied by speed. A diesel, turbo especially, makes gob loads of torque at low RPM and then across the rpm range - but at 4500RPM approx it's all over. Diesels don't rev. Therefore their power, torque x speed, can tend to be lower simply because of the limited RPM range. A petrol on the other hand, will make peak torque around 2000-3000 RPM, i.e. crusing RPM and most efficient engine breathing via CAM design, but rev to 6500+ RPM - hence potentially much higher power.

So, in terms of acceleration around town, it's torque & gearing that matters - TD diesel will tend to give you more torque at lower RPM, compared to petrol, and therefore has to be worked less. When you are at Vmax, then you need power to overcome road load, dominated by aero drag. By virtue of being able to rev higher, a petrol will give you more power. In fact the first thing the providers of the 'tuning chips' do is raise the engine RPM limiter, put there by the manafactirer to protect the engine, so as to raise engine power & hence Vmax. Steve

[MULLEY]

You make some interesting points Doc. My td whilst nice i would never describe as being quick, even when the torque comes in, its over so quick it really doesnt make that much difference. Drove the Gti today & there is no way my td could keep up with it in a million sunday's.

I think i need to have a spin in someone else's td to compare, i think thats the only way i'm going to be convinced that they are similar.

[ken newbold]

They are all different, my white TZD estate was very quick, Shaune's Hurricane ain't bad, but that white L reg TZD of Shaune's was frighteningly quick, certainly the fastest BX I've come across, mind you, the headgasket has been bubbling away since he got it, maybe that makes the difference.

[MULLEY]

I've heard that performance also differs depending upon what pump is fitted?

[Tim Leech]

They are all different, my white TZD estate was very quick, Shaune's Hurricane ain't bad, but that white L reg TZD of Shaune's was frighteningly quick, certainly the fastest BX I've come across, mind you, the headgasket has been bubbling away since he got it, maybe that makes the difference.

Could be, that 19TGD auto which you bought off me had a stuffed headgasket but went like the wind, the green hornet was/is proper quick Phil, check the headgasket!

[docchevron]

I'm not sure the 8V gets a disservice TBH, I think it's a lovely engine, and it's no slouch by any means.
IT'll never be as good on fuel as a diesel, as you say, but then that was rather the point of the diesel engine in cars!
Which is why things like the Golf GT TD seems a bit silly to me..

Doc you welcome to have a go in my GTD any time if your not convinced, 65mpg on the motorway and with 168bhp will show a clean set of heals to most cars and spins its wheels in third yet the emissions are low so cheap on company car tax, I see the point in that.

You misunderstand Tim.
I know they are bloody fast, infact IIRC faster than the current at the time GTi, which rather misses the point of the diesel in a car really..

Leaky HG's can lead to better performance, which is why water injection in diesels came about.

I've heard that performance also differs depending upon what pump is fitted?

Not just the pump, the turbo too.
The best option is a Bosch and Garrett.
Both easily tunable.
As Ken rightly says though, I've nevr driven two the same, some seem quite pedestrian, others are utter rockets.

Bit pointless trying mine, it's as far from spec as it gets without a cast iron head.

[mat_fenwick]

The best option is a Bosch and Garrett.
Both easily tunable.

Even I managed it! I had a look at the KKK turbo off the engine, and imagined trying to adjust the boost in situ. No thanks...

My td whilst nice i would never describe as being quick, even when the torque comes in, its over so quick it really doesnt make that much difference.

Maybe in the lower gears, but IMO the ratios are pretty well chosen to allow usability over the powerband in the top 3 gears. It may be that the diaphragm in the actuator has gone a little soft over time (less boost), if you're only seeing leisurely performance in 4th?

[cavmad]

Ken, did you ever drive Sleepy's BX after the engine transplant? That was only a 1.9 n/a diesel but went like a rocket for what it was.

[mountainmanUK]

I would imagine, from my very limited technical knowledge of these things, that the gearbox fitted would make some considerable difference to the overall "feel" of the car's driveability?
I know my TD seemed to me to go faster and smoother across all the gears when it had it's original(?) box fitted. Since I stuck this other box on last year, the gearing seems to be a lot shorter in 1st and 2nd.

I am presuming that this box (unknown history!) came from a petrol-engined car, and therefore is incorrectly set up for a TD?

I wonder just how many of our BXs are still running on their original factory-fitted gearbox?? Not many, I bet!

[MULLEY]

Matt, having driven you tuned derv beast, i would describe that as being genuinly quick, even though it was a short drive at limited speeds, my td felt for all its worth, just an old diesel in comparison, so perhaps that diaphram in the actuator is knacked as you suggest? I wont know until i get a replacement engine head, which is looking doubtful as no one seems to have a spare that they want to part with

[jonathan_dyane]

I've got a XUD9TE lying around, which was very healthy, and with minimal alterations (fitting the BX cam and blocking up the vaccum pump oil feed) would drop straight in...

[MULLEY]

Thats very good of you Jonathan, trouble being i have limited mechanical knowledge, as it was just doing the head, was going to be an experience & a half, let alone a whole engine swap Now on the other hand, if i was given help to fit it i'd certainly be interested as long as we could come to a mutually agreed number of beer vouchers etc

[jonathan_dyane]

To be perfectly honest, I think (although it might seem more intimidating) an engine swap is easier than doing the head, as removing and refitting the engine just requires undoing lots of things then hoisting it out, then the reverse, whereas doing the head needs a degree of mechanical knowledge with regard to checking for flatness, selecting correct gasket according to piston protrusion (although some just bang the thickest one on) and torquing up the head bolts spot on. The BX TD headgasket is a bit of a pill to do in situ anyway, and tends to result in somewhat grazed knuckles...

Anyways, it's there if you want it (subject to the motor in my dads new TXD not being fucked).