Skoda Rally Blog

If you’ve never built a car or messed around with the engine on one, it’s fairly easy to think that they just run without any real effort.  Unfortunately, the cars that you drive every day that start up on cold mornings, run economically and go well when you hit the loud pedal actually hide many, many hours of development.  Not only on the mechanical parts that whizz round the engine for thousands of hours without letting go, but also on the systems on the car that put just the right amount of fuel into the engine, and then light that fuel with a carefully timed spark.  There are many things that can go wrong with this – too much fuel and you’ll have a car that is expensive to run, chokes people behind it and damages the internals of the engine.  Too little fuel and it will run too hot and possibly burn holes in the pistons.  If the spark is too late, you don’t get as much power as you could do.  If it’s too early, you can create massive pressures inside the cylinders and damage the pistons and other parts.  It’s quite amazing that modern engines run as well as they do.

Why am I telling you this?  Well, the thing is if you change any part of the engine’s internals (cam, head, valves) or external bits (exhaust, inlet filter, etc), then it means that all the old settings are now going to be at best wrong, and at worst disastrously wrong!  So whenever a new-spec of engine is built, it’s time for the engine to be set up.  Back in the old days with a distributor and carburettors this was a majorly long-winded process, and always involved many compromises.  But with fuel injection and electronically controlled ignition, it is at least something which can be done without dismantling the fuel system to make a change; all you need is a laptop!

The engine on the Skoda uses two main things to control the fuel – the engine speed and how far open the throttle is.  Once it knows that, it looks up how much fuel to put in.  Fairly simple.  But this isn’t something you can do blindly, you need tools to measure what’s happening at the current time, so you can alter the settings to the correct values.   Handily I already had one of them, a sensor which goes in the exhaust, and from the gases coming out of the engine works out the mixture of fuel and air that was just burned.  All I needed to add to that was something that would measure the engine speed and how far open the throttle was, and then I’d be in business.

Luckily the people who make the meter mentioned above also thought of this, and made a little box which attaches to it, and which can measure several other things at once.  Unluckily, no-one seemed to have them in stock, but an afternoon of searching finally turned up someone who had one in stock (and only one!), and I got that sent down.  £180 which is a lot for a little black box, BUT it should make this job much easier.  In the past we’ve done this by me driving the car at a specific speed and throttle opening with Paul noting down the meter reading on paper, and working from that.  This should mean it can all be recorded just in normal driving.  An hour spent adding a new sensor to a spare throttle body and another hour doing some wiring extensions saw the car all set up and ready to map.

Last time I’d driven the car, it was really not that happy.  This morning I took it up the road just to see how it would go, and it was much better within minutes – I think it was dodgy old fuel that was causing the poor running as once it had warmed up it drove pretty well; well enough for me to go up and down the dual carriageway outside a few times before coming back, and then downloading the log to the laptop.  This highlighted two things – firstly that the mixture wasn’t too far off, and secondly the person who had chosen the values of the lookup table’s columns had made things difficult for me as some odd numbers had been picked.  I decided to change this to make it easier to do in future, which meant an hour or two adapting the contents of the old table to the new values; let’s just say I know a LOT more about Excel than I used to, and also if I wasn’t as good at working with files and making macros I’d probably still be entering the 560 new values needed for the car to run!

With the new settings in, the engine ran well, and was starting to free up; before it wouldn’t tick over and now it was happily ticking over too fast.  A 20-minute drive saw nothing untoward (although it is quite a rattly beast), and with a rev limit of 4000 and throttle limit of “about half” there was lots of data in the right area to work with.  Because of the way it works, it’s very quick for the computer to then come up with new fuelling figures (you tell it what you want to see and what you already have, and it works out the values for you), so although I’ve not changed anything since that long run, I’m sure that the new table will improve matters greatly.

At the moment the car looks like one of those pictures you see of a new model being tested as there are cables from under the bonnet going into the passenger compartment, and when it’s running the passenger seat is full of meters, cables and laptop.  I’m back to work this week, so I’ll have less time to do much on the car, but it should hopefully have a few runs in the evenings and see the low-speed and low-throttle running sorted out and as it should be.  Once the engine is a bit freer (with a few more miles on it, say 2-300) then I can give it some more revs and more throttle and fix those areas too.  And see if it goes better than the last one!

This morning it was time to see if everything worked OK, but first there was a list of things to fix before taking the car out – a new thermostat housing was needed as the old one leaked, re-filling the gearbox oil, replacing a few bolts and nuts here and there, but in about an hour the list was checked off and all was ready to go. Nothing else to do after running it up to check there were no leaks but to go to the Post Office and tax the beast (handy, being 1st September), and then take it up the road.

It starts fine, and sounds sweet, but the mapping is completely wrong now – it really doesn’t run well at all, compared with the pussycat that it was before.  This isn’t unexpected as the cylinder head is completely different to the previous one, having had far more work done to it (still within the rules, of course), but I wasn’t expecting it to be this far out – it’s so far out that it makes it very difficult to drive, particularly as the engine is brand new so I can’t rev the hell out of it.  However, a trip up and down the road went OK, and nothing fell off, broke or burst into flames.

Another thing struck me as I drove it – the diff is nowhere near as vicious as I expected – you can feel that it’s working, but it’s not hard work to drive, so that’s a relief.  However, I need to put a few hundred miles on the engine before I’d risk putting it on the dyno to get the full-throttle fuelling sorted out, so it’ll either mean spending a long time with Paul, the laptop and the wideband O2 meter sorting things out step by step, or to get an extra bit of hardware that will log all the fuelling as I go, and allow much more accurate and quick alteration of the fuel mapping.  The downside is that no-one in the UK seems to have any stock of them, so I’m a bit stuck…. I’m trying to get it ASAP, but it’s looking bad.  Typical!

So, this morning started with an engine and gearbox ready to go into the car.  Had a late start as my assistant (OK, my Mum!) was busy until around 10, but by then the engine was on the sling and in position; the only help needed is to get everything lined up to get the engine mount by the water pump in place – I’ve tried it single-handed and it is possible but not straightforward.  Handily the sling was perfectly balanced, so it worked without any grief at all – 10 minutes later the exhaust was connected (as I’d left it in place) and the engine and box were in place.

The rest of the day was just a case of bolt everything back in place.  I didn’t want to hurry as there plan was to spend the day getting it in and running, which shouldn’t need to be hurried.  There were  a few fasteners that needed replacing here and there, so the traditional trip to Allfix to buy bolts was had at lunchtime, and then everything else got bolted up.  Just needed to fit the driveshafts and it’d be nearly ready to run.

Except this is the first time I’d fitted driveshafts into the gearbox with the new diff.  If you’ve never fitted them before, they’re held in place with a circlip that goes inside the gearbox, and fitting is usually just a case of putting them in position and knocking them into place.  But the new diff doesn’t have a chamfer on it, which meant the shafts just would not go in place.  I’d tried for ages, and cut myself a few times getting them in and out.  In the end, I found the problem – the circlip was dropping and dropping too far for it to go into place.  I needed to keep them in place as they went in, and thought how to do it; putting some grease in the groove stopped it moving, and they went in reasonably easily – in fact this is a tip I’d use again and again, I’m sure on a properly chamfered diff it would then be a piece of cake.

The last thing to take care of was to put all the liquids into the engine – oil, gearbox oil and water.  This went OK, and there were no leaks, which was good.  I disconnected the ECU (so that it wouldn’t fire up) and then turned the key, the idea being to build some oil pressure before attempting to start it.  This took a few goes to do, but that’s to be expected with a totally dry engine, and it got pressure pretty quickly.

Time then, to see if it would fire.  I connected the ECU and switched on, not turning it over, just to see if it was holding fuel.  It wasn’t – a pipe from the fuel rail to the pressure regulator was leaking like hell, so that was replaced.  Checked pressure again, and it seemed OK.

Time for the S or B moment.  Turned the key.

It fired up, nearly instantly.  And this is despite not having the throttle sensor connected as I can’t find the cable.  Kept blipping the throttle, and it sounded fine.  The gearbox sounded a bit noisy, but it’s splash-lubricated and it was in neutral – only having the gearbox actually turning lubricates it.  Smiled a fair bit, and then turned off, and walked round to admire my handiwork, only to find a pool of petrol!  The return pipe to the tank was leaking as well, so that needed to be dressed, and I waited a while for the heady smell of Super Unleaded to subside, which thankfully it did fairly quickly.

I connected up the gear linkage so I could put it in gear, and then started it again.  All seemed well, so I checked the gears.

First.  Second.  Third.  Fourth.  Fifth wasn’t there.

Tried again.  Nothing.  Reverse? No problem!  Fifth?  No chance.

Disaster.  Despite having checked it when built, I’d clearly made a mistake.  I tried them all again, all OK aside from Fifth, which just didn’t seem to be there; it’s not that the lever was stiff, it just wouldn’t go anywhere near where it should do.  Gutted, it’d mean hours of work to remove it all, and then to find out what was wrong.

Usually when things go wrong, I get depressed, have a moment of dispair and then make a plan and get on with it.  This time it was no different, really, but before doing so I decided to check out exactly what was happening before ripping it all out.  The only things that had changed was the tightening of the detent plug (which makes the gears ‘latch’ in place) and the reverse light switch; both of these also allow viewing of the selector mechanism to a limited extent, so I got Mum to change gears while I looked at the internals.

And fifth went in.  No problem.

Every time.  Until I put the detent in again, and then it went.  I then did the detent with the gearbox in neutral, and it worked, and kept working.  Looks like it’ll be OK – at present the car is still on stands, and has no gearbox oil in, so I’ve not run it up since the ‘fix’, but I’ll do that before anything else; it may be OK.

There’s been one more development; I’ve spent some time on the phone to Richard from Motorsport News tonight, and he likes the idea of the blog and us trying to do not only Rally GB but Finland next year, so hopefully there will be people reading this next week who are new to the blog and will want to support us this year and maybe even next year too.

So, since finishing the build on the head there has been a considerable delay, and this has been because of parts supply issues.  The problem is simple – there aren’t many pattern parts such as bearings, etc., available for the Felicia’s engine, and getting stuff from main dealers is just a joke;  Skoda may well score highly in customer satisfaction for their cars, but the local agent’s parts service leaves a lot to be desired; if it wasn’t for sites such as vagcat.com it would have been impossible to even get prices for any of the parts from them, as it made it possible to look all the parts prices up before visiting; without this they’d not even be interested.  The prices were astronomical in some respects, and there was no delivery time guaranteed either – it was essentially “order them and see if any of it turns up”.  Hardly ideal when you need to get an engine rebuilt.

There are companies who specialise in older Skoda parts, and while I’ve got the parts I needed at a reasonable price, there were some issues with missing parts and damage to a bearing meaning that another week was wasted waiting for these parts to arrive, and typically these were parts that were necessary for even getting started with the engine, leading to a three-week delay before work could begin.

Building an engine is an odd thing; most people view it as a black art and something they’d never attempt, but in many respects engines are reasonably simple devices.  However, building one that will work well involves a LOT of time being spent making sure everything is done not only properly, but in a manner that is optimum; everything about the engine needs to be measured and checked; bearing clearances, piston ring gaps, weights of pistons and con rods, etc, and all of this takes time – hours and hours, in fact.  When it comes to things that need to be removed and replaced to measure (such as the thrust bearing clearance), then it can take an hour or two just to get this spot on.

The Skoda engine is a little different to many engines in that it contains “wet” liners – the ‘tubes’ the pistons run in are not a part of the engine block (unlike on many), but are a separate component, having up and downsides, the biggest of which is needing to be ‘shimmed’ to be the right height relative to the top of the block, and this takes a while fitting, measuring, refitting, etc., and making sure each one is right as well as the difference between each one.  Once they’re done, the crank can be fitted, and then the rings (which need to be fitted carefully and not broken, as they are quite fragile), and then the conrods fitted to the pistons, and the pistons into the engine itself.  All of this took a few hours, and left it looking like this:

Which is finally starting to look like an engine, rather than a kit.

Next up is timing of the camshaft – this is another area where attention to detail is crucial.  Without turning this into a lecture, the camshaft controls the opening and closing of the valves that let air into and out of the engine.  The timing of this is one of the most fundamental things controlling the characteristics of the engine, and not only do you need a particular camshaft (this one has a longer duration and more lift than a standard camshaft), but the timing of it in relation to the crank is very important.  There are timing marks and keys in parts of the engine, but they have a range of inaccuracy, and checking the timing of the new timing chaing it was about 2.5 degrees out, which doesn’t sound like a lot, but it’d make a difference.  To adjust this means making up an “offset key” which is a piece of metal with the top offset to the bottom, to rotate the sprocket in relation to the cam.  Sounds simple.  Took 2 hours to make.

Next was fitting the head, and here an error occurred; The head had 1.6mm removed from it to increase the compression, and therefore 1.6mm would need to be taken out of the rocker adjustment to account for this.  I forgot, and bent a few pushrods when doing it up.  Fortunately no damage was done (I removed the head to check this), and I had some spares already, so it only cost a head gasket and an hour or so.  Once it was all fitted up properly, I set the clearances properly, and turned it over, and it sounds fine, all opening up and closing OK.

After this there was the oil pump and front cover to fit, which was straightforward, and then the sump.  Once the (temporary) rocker cover went on, it looked done, except the flywheel and clutch were still needing to be fitted – this can’t be done with the engine on the stand, so some awkward lifting and use of blocks was needed, but it all went OK.

Then it was time for some final work on the gearbox, which I’d mostly done several weeks ago.  However, I looked at the list of torques for each part of the gearbox and suddenly wondered if I’d done the crownwheel bolts (that bolt to the diff) to torque properly.  I spent 10 minutes wondering if I had or not (I know I did originally, but then it was removed while I sorted out the clearance problems on the casing), and then thought there’s only one way to find out, and that was to take the gearbox apart and know for sure – the consequences of a bolt coming loose wouldn’t bear thinking about.  It took an hour to dismantle and rebuild, which isn’t too bad, and as it turns out…. I had done them up.  Better safe than sorry!  The final assembly was done after cleaning the end casing as the rest looked so good it would be a pity to spare half an hour and have it look like an old shed!

The final bit to do was mate the engine and the gearbox, which never goes that smoothly as getting the gearbox shaft to engage with the clutch plate always takes a bit of fiddling, but it went OK.

So, after about a week of work, and about £1500, here’s the engine and gearbox, post-Sunseeker disaster:

Today the weather isn’t so great, and I’m obviously working in the drive, so the fitting can wait until tomorrow.

The head is the part of the engine that everyone seems to know everything about – the kind of thing that people would say “back in the day” that you’d need to get a “Stage 3 Porting Job” or similar. Not that anyone had any idea what that actually meant, and in many cases what would be a good idea either!  I’ve seen some horrendously badly-done “porting” jobs in my time, looking like they’ve been done with an angle grinder, or some kind of garden machinery.  The idea is to get more air into the engine, and that doesn’t just mean “make the holes as big as possible”, there’s a LOT more to it than that.

However, as with just about everything else on the engine, there are limits, and once more they’re prescribed by the FIA.  Many of the things that a “normal” tuner would do aren’t allowed – valve and port entry sizes have to be kept as per the paperwork, which does allow for some minimal changes to be made, but they’re exactly that – minimal.  In a case like this, every little helps (hopefully), and the head I have has been prepared to an excellent standard, and within the letter of the rules, which is a good thing.

As you can see, it’s a nice bit of work, but there are things to be done to it; the first of which is to check the compression ratio.  This is how much the air and fuel that goes into the engine is compressed, and the volume in the cylinder head is the main way of changing this; I’ve had the head machined to increase this, BUT need to check it, and to do that the valves need to be refilled, and then the cylinder head placed on a flat surface and the volume measured by putting liquid in from a burette.  The volume I was looking for was 24.6cm³, giving a compression ratio of 11.5:1, which will mean two things – firstly an increase of about 8% power with no other changes, and secondly that we’ll need to run it on good quality fuel!  However, this means fitting the valves to it, otherwise (obviously) you can’t fill the chamber up!  So, in they all went…

… and measurement found that it was spot on – precisely 24.6cm³, so that calculation was perfect.  Great.

Next up, fitting the manifold;  this might sound like a “bolt it on, Darren” instruction, but there is a small amount of play in the holes, meaning that alignment can be an issue, and in addition the ports in the head don’t line up exactly with the ports in the manifold; in addition the ports in the manifold are actually slightly smaller than they are allowed to be, so opening them up slightly to align them should pay benefits; again it’s only a small thing, but every little helps; I’m hoping for 100bhp from the engine, which is a 20% increase over the old one, and with the restrictions that running to International spec place on us, it will not be easy….

Today was the 2009 running of Fat Albert Stages, which is based at Keevil Airfield in Wiltshire. This is a good event for two reasons – firstly, it’s a very well-run event and features a good combination of high-speed sections (which are on the main runway area, long straights with some chicanes and so on) and a section which is extremely tight and technical and makes demands on car and crew. The second reason is that it’s only 55 miles away, so it can all be done in a day. But this does mean getting up at about 5 to manage this, and then there’s an hour’s drive to get there (although for some reason TomTom said it would take 1:45, which was a bit strange). Got there dead on time at 6:45, and found that Mike had left my pass with the Marshal there, as agreed.

It’s always a bit weird turning up to an event to navigate with or drive with someone you’ve never met before – you have no idea really how things are going to go on a number of levels. Fortunately I needn’t have worried about this – I found Mike easily enough (in the queue for scrutineering) and checked everything out – the car seemed fine, and luckily I fitted in the seat OK, and we got to know each other while waiting for the car to be scrutineered, which it passed without problem. It was then just back to the service area to check if the intercom adapter I’d made up (Mike’s intercom is a different make and each uses different connections) worked, which it did, and then wait around for the start times to be posted.

Events like this have a wide range of cars entered, from things such as the Furzelands’ WRC Subaru, right down to the lowest-budget rally cars you could imagine, and everything in between. On the first few events I was amazed at the diversity of machinery that was present, but after a while you get to accept that people decide to run all sorts of different cars, for all sorts of different reasons, and looking at a results sheet doesn’t really tell the tale; a single cc-based class can have a madly-tuned hothouse flower competing with a totally standard road-spec car, but that’s the nature of the beast. But it’s not often you get to see something like this:

An Aston Martin. There were varying opinions from people I spoke to throughout the day, some saying that they “don’t belong” in rallying, others who loved it. I can’t see the problem, and it certainly looked and sounded different to the usual cars, and that’s saying something.

Anyway, the stages. Mike hadn’t been rallying much for the last few years, and this was his third event this year, and he was happy just to go out and get back into it, plus sitting in with someone new it will always take some time to work together, so a “fair” pace was what he was after to start out with, and we managed that – there were no real dramas at any point, although it became clear that Mike is no stranger to the handbrake, and damn good at it too – he really got the car launched sideways in places where needs be, and made it look smooth and fast from where I was. The braking areas needed to be honed down, for sure, but for the most part it went well; the car is only a standard 1600 engine with twin 40s on, so it’s not a high-powered screamer, but it went well enough, touching nearly 100 on the longest straight.

Stage 2 was a repeat of stage 1, and we went a bit quicker. There was a corner which was a long 45 degree one which tightened towards the end, and the first time round the car felt a bit light on the way in; I thought it felt a bit too quick on the entry. And half way through it turns out I was right – the back stepped out, and we were going sideways. We were doing about 70 when this happened, and typically we drifted into the line of cones; it was interesting seeing them come sideways at the car, and we then hit one which had a wooden sign in it, with a sizeable bang, and came to a halt. It took a few seconds to get the car going again, and by this time the next car was coming along at quite a pace. We’d moved the cones that showed where the stage was, and as a result they ended up coming quite close to us, and we were facing them at this point. Fortunately nothing untoward happened, and with them out the way we could get going, which Mike did quickly. Despite having spun and taken time to get the car running again, we managed to go one second quicker; I’d think we lost about 15 or so with the spin, so that wasn’t all bad. Unlike the side of the car:

Stages 3 and 4 were slightly altered runs of 1 & 2, and they went well; different lines and speeds were tried on various corners, and it was coming along quite nicely; paring down braking points until they were pretty much there and trying to get back up to speed on “the corner of woe”, and everywhere else trying to keep it neat and tidy. We caught a slower car in one place and he very kindly moved out of the way (car 91), so thanks for that, and in general it went well; it was sunny now and getting a bit hot in the car by the end of the stage, but all good fun.

Stages 5 & 6 featured another change to the layout again, and they went well too; the car was behaving itself well, and the second run was quicker than the first. There was a fun moment where the car that had witnessed and passed our spin on stage 2 span in front of us (there’s a bump mid-corner), so I guess they knew how we felt; Mike had thought I’d been a bit too cautious about the speed over that bump but given what happened there it looks like I was right!

Then it was lunchtime, with a break while the stage layout is changed (they are run in the reverse direction in the afternoon), but the break became a lot longer when a glider had to perform an (apparently emergency) landing on the airfield, leading to a 40 minute or so delay. Once we got going, it was good fun; the reversed layout had a few surprises (one of the sections was new, and wasn’t really clear on the map so the first time through was a bit interesting at speed), but seemed to be a lot quicker; there was a downhill straight where the car was topping 100 before a hard braking area and a chicane for a handbrake turn, and a few times this was taken right on the limit with the front of the car just starting to push before gripping and turning us round.

Stage 9 was a small modification again, and I made a right mess of it; I looked at the wrong corner, called it and then took us through a plastic barrier. Mike and I both thought someone had dragged it into the way, but they hadn’t; he deftly spun the car round and we carried on for the rest of the stage, with the calls being punctuated by apologies by me. Dammit! Fortunately no damage was done to the car by this small off, and Mike was quite happy with the outcome, saying it had been a laugh anyway! Stage 10, the last of the day was a re-run of 9, and we got it right throughout, and it went well pretty much everywhere.

All in all, a fun day, with good stages and organisation, fun with a new crew and nothing serious going wrong. Not a bad way to spend a Saturday, and we’d finished 45th out of 90 starters, with 52 classified.

Well, I say swapping roles, it’s not entirely that.  I’ve got myself a seat tomorrow on Fat Albert Stages navigating for Mike Dunning in his 1600 Peugeot 205.  I’ve done Fat Albert a couple of times before, and it’s a great event; the weather is supposed to be good tomorrow as well, which is a bonus, as is, of course, being able to turn up, pay some money and then not have to worry all day if the car breaks as for once I won’t be paying for any repairs.  I’ve got all the maps all ready to go, and Google Earth makes a very handy tool when wanting to work out distances as the maps aren’t to scale.  I’ll take my camera and let you all know how it goes.

The bottom end of the engine is the un-heralded part of the engine – whenever people talk about tuning, it’s all heads and cams and manifolds. The bottom end does the unglamorous job of turning the explosion inside the cylinders into usable power, and it does this with a few simple (but precise and important) components. The main parts are the pistons, connecting rods, crankshaft and flywheel. Most of these need to be to the correct (near original) spec, again as defined by the FiA, and this means for most cars that they are modified original production parts. The engine I have has previously been built to a high standard, with a lightened flywheel (within the specs on the papers, again everything has tightly defined limits), and what looked to be slightly reworked standard connecting rods and pistons.

Once I’d dismantled it all, I found that the crank wasn’t badly worn at all, so a simple regrind will take care of this; it’s already been left at Magnum to have the work done. Separating the pistons from the con rods needed to be done even if the pistons are to be re-used; the reason for this is to weigh each part individually (as left together it’s possible that a heavy piston may have been with a light con-rod, leading to balance issues which wouldn’t be noticeable weighing the entire assembly all in one). It was nice to see that my first impressions of the engine (taken when I needed to swap the bearings before Rally GB 08) were right – each part had been balanced to within a gram, and close inspection of the rods saw nothing untoward at all. The pistons have some wear on them, so I’m trying to source some replacements (standard, as the current ones are standard and look absolutely fine, despite being taken to 7500 for over a year in my hands and no doubt plenty of time before), but the Skoda parts specialist I usually use is ill at the moment, so that may hold things up for a few days.

If you’re not familiar with the technicalities of motorsport, it’s easy to think that you can “tune” your car any way you like – most rally cars you see seem to have a ‘full on’ engine and the owners have spent a considerable amount of time and money on getting them to the point where they are. For many local and national events, this may be true.

However, for International motorsport the FiA decided that car specifications need to stick to a tightly-defined set of rules, and parts must be largely original or ‘performance’ ones which have been supplied by the manufacturer at some point (it’s more complex than this in reality). When you’re a works team with a large budget, this is no problem – parts supply is no problem. But a few years down the road some of the parts needed to be legal become very rare and therefore expensive. And as technology improves, older cars get left behind with a fixed specification that cannot be changed. And that’s one of the main issues with running the Felicia; the engine which is in the car was old technology even when the car was introduced in 1995, dating back to the mid-1980s (and its heritage goes back a LONG way before then), so it’s relatively unsophisticated (a good thing) and low powered (not a good thing). This would be fine if you had carte blanche to modify the engine as you see fit, but alas this isn’t the case if you wish to compete internationally; major components that you would normally change when tuning the car (such as the inlet manifold) have to be the ones specified in the car’s papers.

Which leaves me with very few truly performance options. So, I need to make the best of what I can use, which in this case is the standard manifold setups that Skoda used and homologated (i.e. had inspected by the FiA). I ran the car with an MPi manifold (standard, from the later cars) last year, and it ran fairly well, but certainly wasn’t quick. And now it’s time to go faster, so all options need to be checked. But checking this is difficult without specialist tools, and it’s expensive to get others who have them to do this checking for you as every possible permutation needs to be tested!

Handily, the internet is full of lots of people with crazy/stupid/brilliant ideas, and one of them is a guy called David Vizard, who I would describe as an old-school tuning guru. His name is synonymous for many with car tuning, and he’s written many books on the subject. I’ll cut to the chase; he outlined a way of measuring the amount of resistance to airflow that components present, for about £20 or so. So I headed off to B&Q, bought the things I needed and then built it. Essentially, you attach your cylinder head to a vacuum cleaner, and measure how much pressure drop there is – the more drop, the more resistance there is.

Here you can see the box (with black pipe to connect to the hoover at the bottom), and the cylinder head, manifold and inlet. The clear pipe goes from a spark plug to a manometer…

which shows how much pressure change there is – the more reading on here, the more the flow is restricted into the head.

While this is in no means an accurate, calibrated flow bench, it did show up something very interesting; I have two cylinder heads, and both of them showed no difference when just the bare heads were tested – I was disappointed as one is a very nice job, and the other is near standard. But as soon as the manifold went on, things changed dramatically – the ‘nice’ head showed far less of a loss when putting the manifold on; I can only attribute this to the ports on that head needing to be fed the air the way the manifold does it, as any other changes (such as adding the inlet duct) made the same difference on both setups.

The next step is to make the setup read more accurately; as you can imagine it’s rather course (although the info it has provided has been invaluable), and a piece of equipment to do this accurately is quite expensive (around £400, minimum), so my options are limited at the moment. Just thought I’d share my top quality piece of engineering with the world.

Doing any kind of a job can give you pleasure, but doing one really well is definitely a step above that, and this time round I was hoping that the gearbox would be as good as it’s realistically possible to be. To that end, lots of new parts have been bought, so it has new bearings throughout, new seals, and as already seen the cases are looking nearly new, they’re that clean. Even new bolts have been bought at great expense (well, £4.50).

However, building one of these gearboxes isn’t just a ‘put it back together’ job, and the reason for that is simple – the diff and the gearkit are different sizes to the original parts, meaning that the gearbox has to be carefully ‘shimmed’ to get all the clearances right, and in addition some parts of the casing need to be ground away to provide room for the new internals – in this case there is a bit of grinding needed for the diff to fit in place – the cases will go together without, but it won’t turn. So that took an hour or so to sort out, and the same for the gearbox where 4th gear is a LOT bigger than standard. Once all that was done, it was just a case of measuring what size shims were needed, and fortunately due to my previous habit of destroying standard gearboxes, I had all the right bits. Before the cases went together, this is what it looked like:

The rest was just bolt together stuff, no problems really. Gearboxes are odd things – they’re an essential part of a car (and even more so in a tuned car), and in theory they are quite simple. But they seem to be (particularly ‘performance’ ones) a massive source of grief for many people with all sorts of horror stories of failures – including my own. But you never know 100% until it’s in the car, so here’s hoping that all is well…