UK-POLOS.NET - THE VW Polo Forum

Hi there. From what I know Germany taxes their cars based on horsepower so what they do is give smaller bhp values to their cars than what the engines actually give.

So i was wondering if anybody had ever actually heard of a dyno on a 1,4 16v 75hp model. Based on my having a bash at a few stock 106 mk1 rallyes, the results justify more than just 75hp

The output is rated at the minimum octane the engine is designed for, printed in the filler flap. Any engine that has a knock sensor is capable of producing more as the octane goes up, because higher octane means better detonation resistance = more compression = more mixture = more power. Its not quite that simple because your engine cannot alter the compression, only the timing, but you will get more power usually in the single percentages. If you want more you'll have to bugger about with valve timing but that will screw up the torque at the bottom. Or you could have variable valve timing, which I think the GTi and 100BHP models have (not too sure).

Stick Optimax in and you'll probably be getting significantly more than 75Bhp. The 75Bhp model is designed for more torque lower down the range than the other models which is why it has a lower red line and better fuel economy even than the 60Bhp.

(Forgot to mention, the minimum octane of 91 is not available in the UK, we have much better fuel 95 normal to 97 super unleaded to 98 optimax - thus you probably are getting more than 75BHP) My dads plane runs on 100LL Avgas which is 100 octane low-lead - unfortunatley you can't use it because of your cat - but it did make my old beetle go like stink on the raceway!

Thanks for the swift reply.

VW doesn't have a VTEC/Vanos/VVTi etc. system.


Actually I was just asking whether someone had put their car on a dynamometer to see what it's output is, not what i can do to increase the bhp althought that is something I'm seriously considering doing.... (read below) Personally I only use Shell's 98+ or BP's 99+ unleaded fuel. As regards Avgas, I've heard a lot of different things about it. I would be tempted to de-cat although I'm pretty concerned about reliability issues. My engine is only 20k kms old (young) and I don't want a prematurely aged engine on my hands.

I really want to up the performance of the engine. I've asked around and there are many differences between the 75 and the 100hp model. It's not just ECU and cams.

Although I'm a die hard supporter of naturally aspirated engines, I sometimes envy the "easy" horsepower that turbo freaks enjoy. At the moment my whole car is stock. But what I'm eventually after is this. First of all I want instant throttle response. I mean lightning! Secondly 3rd and especially 4th gear is reeeeeeealllllly long. So I'm thinking that I want the mid range to significantly pick up in order to counter this. With this in mind, i don't mind sacrificing some of the low end, but I have to REALLY gain in my mids and highs. (edit: obviously the ecu will have to change which is a great thing cos of the red line under 6k and that freakin' annoying thing it does with the "pre-rev limiter throttle limiter" on 1st and 2nd gears...not to mention cutting the throttle if you try to left foot brake)

An engine swap isn't in the picture cos my current engine is practically brand new.

With this in mind.....can anybody suggest any specific mods they've tried out on their polos? As I've mentioned before, I come from a 106 mk1 rallye so the things I had on that would be very different to what I'm going to have to do to the polo since they are two very different cars. Therefore, I'm effectively a novice once again.

Pretty certain the only thing you can do is to get more charge in the engine, either force it or cool it, or both. The other thing of course would be to rev it higher.

What were the rev-limiting artefacts you were refering to? I've noticed it flattens out before you get to 6000RPM, you never seem to be able to crank it up to exactly 6000 then change. I sometime left foot brake when coming up against the sppedbumps in my road to take the backlash out of it, I think it does affect the overrun, shortening it a bit, is that what you meant?

These all seem to be software limitations built in for reliability, like you say, they can be reprogrammed.

I've mentioned these two things before when I first joined the forum to ask whether it was just my car.

Left Foot Brake....Say i'm on full throttle (or any other throttle position) at 4500rpm (or any other rpm) and i so much as touch the brake pedal while the throttle is pressed. The rpms will drop cos of braking and then for about 1,5-2secs the rpms won't rise.

Pre rev limiter throttle limit........ Red line is just before 6k. Probably around 5950. There is no way to keep accelerating constantly to the red line in 1st or 2nd. 1st gear as soon as i reach 5200, it suddenly stops accelerating as hard. as if i've only got quarter throttle open. it'll still reach the redline but only a lot slower which is hell cos this is a torquey 16v engine which is quite promising cos you get the torque in the high lows/early mids, and the 16v's help you out up high. So if you're going at it with a fiest for instance they'll be redlining it through 1st and 2nd, and you'll be missing out on about 700rpm in first and around 300rpm in 2nd. 3rd,4th and 5th are ok. They are free to redline.

As you mention it's cos of reliability. If i wanted reliable, i'd go buy a bike! I want enjoyable!

daffy wrote: So if you're going at it with a fiest for instance they'll be redlining it through 1st and 2nd, and you'll be missing out on about 700rpm in first and around 300rpm in 2nd. 3rd,4th and 5th are ok. They are free to redline.

As you mention it's cos of reliability. If i wanted reliable, i'd go buy a bike! I want enjoyable!

I must admit it never redlines when I get distracted and boot it, like my old one would, so maybe it is doing this a bit, but its not as aggressive as yours. I guess then, you're probably looking at chipping it then. Its twin cam, hydraulic lifters, I don't foresee many problems with reving it to about 6.5k. The torque does drop off, so you will not be getting that much extra power but 90 - 100HP ish should be possible with the right fuel, warm engine.

Its always nice to play but if I wanted that extra performance I'd probably get a different car.

With regards to the left-foot braking, I remember reading something that the majority of VAG group cars cut the engine power if you brake with throttle on. Obviously this is possible due to the fly-by-wire throttle the Polo has.

Out of interest at what rpm does the 1.4 16v produce its peak power?

Its in that specification book that came with your car next to the manual. I believe the 75BHP has peak torque at somewhere like 3800 and peak power at 4400 with 80% of that torque through 2000 - 5000 RPM.

Its that range that makes it feel far more pokey than it should. I didn't feel mine had enough poke, but now I changed the air filter, I realise that it does! My filter was bocked with oil after VW overfilled the engine. I replaced it with a stock filter, but I'll get a K&N or pipercross if I get round to it.

My dad swears by K&N filters, we put one on the aircraft he reckons it reduces his take-off run by about 75ft, and gives him about 6% better economy at cruise. Pretty good because that thing drinks fuel.

daffy wrote:VW doesn't have a VTEC/Vanos/VVTi etc. system.

Erm. Yes it does! On the GTi! It has variable valve timing on the inlet manifold... I read it in the handbook

Si_GTi wrote:

daffy wrote:VW doesn't have a VTEC/Vanos/VVTi etc. system.

Erm. Yes it does! On the GTi! It has variable valve timing on the inlet manifold... I read it in the handbook

Yeah - I thought I'd read it somewhere too.

Yes it does

So I was right then.

The GTI does have variable intake timing as do the newer vw 6 cylinder and above engines. its quite a distinct change when it comes in as can be seen on a dyno.
the left foot braking is the same on any DBW car (drive by wire, as a pose to cable throttles) its a safty feature as the potentiometer can fail (used to happen on early impretzas and then they reverted to WOT (wide open throttle)) so if the throttle does revert to WOT then it can be over ridden by pressing the brake

Seems sensible, after all, you can just detect the digital signal that the brake is applied with little cost and it wouldn't affect many drivers, but its still another complexity that can cause adverse effects. I've seen a couple of cars driving around this year with the brakelights permanently on, from one fault or another.

Well you learn something new everyday i guess. VW with a Variable Valve Time. I think it was about time they started using it. They've been left donkey's years behind. Personally I don't like VW much as an engine manufacturer. No imagination whatsoever.

As regards a playful car JWC, my previous one was a 106 Rallye so as you can imagine......the difference is a bit more than obvious. But you would think that it would do the basics. Thinking of changing my airfilter too cos the one that it has now is totally smothered. It intakes from somewhere in the front right arch. I'm more than happy with the car's range. Revving it to 6,5 as it is now (stock) won't do much anyway as you already mentioned.

By the way, I definitely need lowering. How far down does the GTi go in relation to the 75hp? I'm not going to lower it so far that it'll effect handling. So the question is......how low do you go on 15'' wheels so that handling isn't affected?