UK-POLOS.NET - THE VW Polo Forum

not neccessarily that it'll put out more power up top than the 1.3 (though, if you compare spi to spi, that does hold water... a tiny, vanishing amount hehe) but it will go up the revs easier and will have less inertia/resistance to higher rpms as the shorter stroke means lower peak piston speeds = less momentum

the MK3 has a different down pipe to us GC, its a sortof 4-2-1 setup, sumbody correct me if im wrong, and also the same downpipe can be found on a MK2 1.3 golf.

I am with you on that one polo kris, I dont understand whats the big wow about spi though?? a bigger carb set up is better and less work! My mate whos a vw specialist said that my 1.3 twin choke carb would be quicker than a 1.3 spi.

The spi idea is just for economy really. Oh and the "turn the key and go" benefits to be had with fuel injection.

As for the mk3 dowpipe yeah its sort of a 4-2-1 arrangement; the manfold converts four down to two. and then the downpipe converts two to one. Theyre joining faces are flat and are fastened together with 4 bolts and a gasket goes in-between.

Ive not looked at my mk2's exhaust. All ive done since Ive got it is:

fit a radio with a digital tuner (original one out of my GT)
fit a better speaker upfront
checked the oil
taken the top off the airbox to see if the golf throttlebody elbow would fit (it wouldnt)
replaced a few bulbs and fixed a few dodgy earths on the rear lights

and thats it in 2months of ownership! which is good for me as usually its buy a car and mod it straight away.

Having spent the last 7 hours fitting a new front silencer -very- slowly and even more painfully, I never want to see an exhaust pipe again Still, if I just had the existing downpipe modified to take a lamda I wouldn't need to worry about a new manifold / downpipe anyway.

As for SPI over carb, the main things for me are:
* Getting into a car on a cold day, turning the key and going is a very attractive proposition, rather than spending the first 10 minutes fiddling around with the choke or spending the first 10 minutes having the choke fiddle around with itself (badly)
* Fuel economy is improved
* Less hassle to keep in good order once it's set up in the first place.. tuning carburettors has turned into a nightmare for me..
* Power slightly improved over standard carb setup (ie pierburg 1b3/weber 32tla) - but that's not really why I'm considering doing it.

As with many things though, I suspect this will get stuck on a back burner for a good while yet.. I've still got mods I started planning last spring to catch up on for now

yeah the low end torque is a bit better and you dont have to rev quite *so* high to get that 45hp - even considering the cat

it still plays its face on a truly cold day, but i bet thats just the leads

all in all - fantasticcio!

Gareth_GT_Hatch wrote:Im guessing that that engine is a GK lump. 1272cc, 75bhp 11:1 compression ratio. Never made it over here though. Im guessing thats the standard airbox setup for the GK, it vaguely resembles a GT setup without the airflow meter.

is that all that differant between the MH and GK??

a thought ---

if you put the mk2 head onto an AAU, would that have any benefit (larger ports 'n' etc)??

how is the mk2 underbraked???

all a servo does is help the driver press the brake peddle though vaccum from the intake, it does not put any more pressure on the brakepads that servoless system cant

a mk3 driver would have to rest his foot on the brake pedle to do the same amount of work that a mk2 driver would have to press the pedle a 3rd of the way

The mk3 is also underbraked, you just don't notice it so much under normal use
If you want to see how a mk2 is underbraked, take it up to 70mph, drive until you see a point which you think you really ought to be able to stop in front of (sign post, driveway, whatever) and stand on the brakes at the last minute that you think you can stop in time for it. You'll find that by the time you get to ~40mph the pedal has gone firm and the brakes are doing naff all.. get down to 30mph and try to lock up and you won't be able to, you'll practically roll to a stop.

The lack of servo makes it feel like there's less braking power, as you have to put more muscle work into it. Just a psychological thing (or, a physical thing, if you don't have a great deal of leg strength), like having a sharper set of brakes on your bike. It doesn't make much difference what you have on, until you go down a very large hill or take a trip in the rain, but those which lock the rear wheel up with a few degrees of movement from rest will feel a lot stronger than those which need you to pull it almost until the brake lever is touching the handlebar rubbers.

Discounting that in reverse to that, a servo car has more pedal travel than an unservoed one..... (where my theory falls apart a bit ) ... take a mk3, 4, whatever downhill in neutral and kill the engine (15-20mph will do), give the pedal a few gentle squeezes to exhaust the vacuum effect and then hit it hard, see what the difference in feel is like. Doesn't feel quite as reassuring any more, does it?

In this case, as well as the legwork involved (actual physical grunt, especially in an emergency, as opposed to a fairly gentle, measured application), there's the matter of the initial brake bite. With the servo assistance, when you smack the pedal, you can get them to lock almost immediately - the instant braking force available is nearly 100% and you can get a strong stopping force straight away. Without the servo it can take a good second or so to build up the pressure on the pedal to that same point, which affects the braking feel a lot... and also what distance you can do an emergency stop in. Locking up isn't all good, of course, but you can always take it to 95%, or lock and back off a little, and come to a rapid halt, rather than pushing with all your might and the cylinder still needing time to move against the resistance.

See what i mean now?

I never had a problem with the brakes in the polo, up to the times where it was actually time to have them serviced (worn pads, warped discs... rusted cylinders... etc!). They always brought me to a halt in plenty of time and could be quite fierce if you booted the pedal in an emergency (great for giving it some down the lanes - granted it was a 1 litre, but 60mph is 60mph...) and didn't even fade much from speed. Don't think I ever managed to get the pedal all the way down to the floor...

What was the limiting factor, more than the iddy-widdy discs and fairly naff drums (not much of a problem with such a lightweight car), were the tyres. Any time I felt that the braking power was sending me into the danger zone, it was because I could feel the rubber reaching it's grip threshold through the pedal and steering wheel (such a communicative little car!). The standard stuff really doesn't cut it for anything other than the most docile trotting around to and from the shops, gripwise. Particularly if you're running on crap budget things, and VERY much so in the wet. Going from budget 145/80s to michelin 155/70s made a phenomenal difference to the feel of the steering and brakes. Personally, I would have gone for 165 or 175s instead, had I the wheels to put them on --- yes, even though it was a 1 litre. Even 850cc, dinky toy size Daewoo Matiz's come with 175 section tyres these days, and with good reason!

The brakes are fine --- just get the thing shoed up right!
(If you felt them fading on the mk2, it might be an idea to get them checked out and serviced, unless you were REALLY wellying it - For testing sake, if you have the cojones for it, I reccommend you come off the M6 north at junction 5 sometime, or any similar junction - short sliproad, short steep downhill offramp with a sharp left turn onto a roundabout at the bottom, where you usually have to stop, if the traffic hasn't stopped you before the turn... Done 85-90 off the main carriageway and come to a neat stop on the line before without much stress... even better, the approach from the A452 Collector Road onto the same island, it's almost a straight line but the road is about 15 metres higher altitude than the motorway and drops to the island even steeper, following a blind crest... that CAN be hairy in the polo, if you hit it at 70-80 and there's stopped cars at the bottom, but you survive... just...*)

Something to really be concerned about is if you have a situation like I do with the Astra, which I will taking to Kwik Fit this weekend I think. Nipping up a country lane, just doing the limit or a little under, bloody bird flies up (and hits the screen...)..... I hit the brakes just a little late, but hit them hard..... And have the pedal buried against the stopper in the carpet for a good second or more before any of the wheels lock, and I'm not sure all of them did, even all the way to being stopped - in fact probably just the rear left which was hitting the gravel at the side of the road by then. Most probably outbraked what the polo could have done despite it being heavier (the tyres are mahoooosive, i can barely lift the spare out of the boot) but it sure as hell felt wrong. There's no reason for being able to actually get the brake pedal to the floor (or, did i reach the full travel of the master cylinder piston?).... all four wheels should have locked by then, regardless of how chunky the tyres are. And no - it does NOT have ABS!

* that one quickly learned me to pay attention to the signs and ease off a quarter mile before the crest, get it down to about 40 or 50 (possibly another reason the limit's been brought in on that road!).... consider myself lucky there wasn't a larger standing queue of traffic right after it! Wouldn't be entirely as stupid if i haven't lived in the area for most of my 23 years - and my first 5 weren't spent about 400 yards (almost completely vertical yards) from that same island...

edit: apologies for a big post, but i've been off on a mini holiday... my fingers have got blue balls

Yeah, the tyres are the most limiting thing as standard.. but I've gone up to 175's on the front and 185's on the rear now, and that's when you really do notice the brakes. I've still got plenty of meat on the pads, the discs are under a year old and the drums are in decent condition, but it still fades like hell. Mind you, it's due a fluid flush, don't know when that was last done, so maybe that'll improve things. That can go on the list of things to do after sorting the suspension yet again..

k4lps wrote:

Gareth_GT_Hatch wrote:Im guessing that that engine is a GK lump. 1272cc, 75bhp 11:1 compression ratio. Never made it over here though. Im guessing thats the standard airbox setup for the GK, it vaguely resembles a GT setup without the airflow meter.

is that all that differant between the MH and GK??

different carb (or the same with bigger internals) and different cam as well

GroovyCarrot wrote:The mk3 is also underbraked, you just don't notice it so much under normal use
If you want to see how a mk2 is underbraked, take it up to 70mph, drive until you see a point which you think you really ought to be able to stop in front of (sign post, driveway, whatever) and stand on the brakes at the last minute that you think you can stop in time for it. You'll find that by the time you get to ~40mph the pedal has gone firm and the brakes are doing naff all.. get down to 30mph and try to lock up and you won't be able to, you'll practically roll to a stop.

i'v done that its not very nice when you really need to stop, but thats brake fade underbrakeing would be like brakeing at 30mph -10mph takeing 2mins

Gareth_GT_Hatch wrote:

k4lps wrote:

Gareth_GT_Hatch wrote:Im guessing that that engine is a GK lump. 1272cc, 75bhp 11:1 compression ratio. Never made it over here though. Im guessing thats the standard airbox setup for the GK, it vaguely resembles a GT setup without the airflow meter.

is that all that differant between the MH and GK??

different carb (or the same with bigger internals) and different cam as well

so what carb and cam would i need if i was after the same power as the GK???