I get a lot of hire cars for work and I had a Duster for a week last year. It was by far the worst hire car I have ever had. Build quality was very poor, bits of the car were falling off and it only had 60 miles on the clock. It was also unrefined and unpleasant to drive. Both the 05-13 and 2013 onwards Octavia are a much nicer car. I would strongly recommend a test drive first.

That’s fantastic. Thought it was going to be a supermono based on all your mods!

I race with my brother too except we’re in endurance so closer to supersport regs.

Porter_Jamie, what bike was all the development for? Sounds like an interesting piece of kit.

Kaiser, you’re assuming a linear relationship between air flow through the carb and the amount of fuel delivered. I have limited experience of tuning carbs but I’m fairly certain this isn’t the case.

When we fitted a full exhaust system to a carbed CBR600 it took many hours of dyno work and plug chops to tweak the fuelling and it was still a compromise. It makes fuel injection tuning seem a doddle!

You’d be better off buying a decent book on exhaust/carburettor tuning if you really want to understand it. The relationship between exhaust back pressures and flow velocities etc are fairly complicated stuff. I would love to have the time to understand it better too.

I very much doubt average speeds point to point are much better.

Made a big difference to my lap times at Snetterton. Not quite point to point but does that count?

Coffeeking, I’ve never seen a bike with an air flow meter. Everything I’ve seen has always been speed density/throttle position based.

Vinnyeh, the standard fuelling on the standard exhaust was very good, there were no big gains to be had anywhere.

The new exhaust made more power than the standard exhaust from 6000RPM right through to 16500RPM

I doubt a modern 600/1000/V-twin etc would gain more then 1-2bhp from an exhaust change

My 2007 GSX-R1000 gained 8BHP by removing the cat and changing the end can.
My 2010 R6 gained 15BHP by changing the entire exhaust system and air filter.

There are still big gains to be had on modern bikes with exhaust changes, although the restriction is not normally in the end can.

It does still apply to fuel injected bikes. Most modern bikes only run closed loop control of the fuelling in a very small band to meet emissions criteria. BMW are the only bikes I’ve seen that run closed loop more extensively.

The rest of the time they are running open loop and will require modifications to the fuelling to account for any changes to the exhaust.

Why do people think they can ad-lib their exhaust flow better than the manufacturer with millions of pounds spent on research?

My bike went from 109BHP to 124BHP on the same dyno after fitting an exhaust made by a man in a shed in Essex. It needed significant changes to the fuelling too.

It was a rescue dog when we got it aged around 2-3 years old. Unsure of its past and this may have had some bearing on it’s behaviour but it was just too much of a risk to keep.

Strangely it was completely fine around the rest of the family but took a serious dislike to me.

My parents had one several years back when I lived at home. We had the dog for about 5 months then one day without any provocation it attacked me. Took it to various dog trainers, had it castrated but it still kept trying to have a chunk out of me.

They are very strong and I was lucky to get away without serious injury.
We gave it to an EBT rescue centre in the end a told them about its behaviour. I was glad to see the back of the horrible little bugger.

Andy, I bought a BWM 328i Sport after the Impreza and i preferred everything about it. It was great fun in the winter! My brother has just bought a 2002 E46 330i Sport for £4200 and it’s a great car, well worth a look.

I owned an Impreza STI for 2 years. It was fun to begin with but you soon realise the handling isn’t great and the fuel economy is terrible. It would average between 7 and 18mpg and only ever got above 20mpg by driving off boost everywhere.

They’re quite robust and servicing is actually very cheap compared to anything with similar performance though.

Try and get a long test drive in one before deciding. You might be impressed for the first 20 mins but once this wears off you may find you can’t put up with the cheap interior and other short-comings. They’re a bit of a one trick pony.

20W 6V available here:

http://www.sjscycles.co.uk/mr11-twin-pin-fitting-light-bulb-unit-20-watt-gh235-for-blt-prod4361/

An upgrade to LED does sound tempting though!

Make sure you get the right voltage bulb though. My passubio (XC) was 6V and it seems 12V is much more common.

I got a bulb from Maplin for under £3 for my passubio.

The beam wasn’t quite as nice but it does the job.

Supply and return flow meters are what we use at work for large diesel engines. It’s considered to be more accurate than using the calculations from the injector signals.

The pipes are probably fitted to the wrong outlet. Just swap them over.

The Disappearance of Alice Creed?

Lazybike, you are absolutely right and it’s something I completely forgot to mention. The ring claims many lives a year, some by accidents outside of your control (e.g. oil on track from a car in front) others due to people just getting carried away and exceeding their limits. Anybody going should look at the death rates and remind themselves that a hefty bill is not the worst outcome.

I like to drive the laps at a fair pace e.g. sub 9 minutes but don’t push anywhere near as hard as I would on a short circuit in the UK, maybe only 80% pace. That spare 20% can then hopefully be used if either I make a mistake or someone else around me does. Most accidents I’ve seen have been from people trying to drive at 100%.

Bazzer, the closed track days would be a good option for yourself as you’ve got plenty of track experience. The pace is generally much higher but the driving standards are higher too.
For me it’s different from a day at Anglesey. At the ring I’m not looking to push 100% and just try to find a nice flow. The elevation changes are something that you just don’t get at Anglesey and it really adds to the experience. The corner speeds are also higher than most UK tracks and the lack of run off and barriers gives you a much hightened sensation of speed even compared to somewhere fast like Silverstone.

One of the more serious crashes I’ve seen at the ring, the driver survived:

Impreza’s do attract the chavs, I can’t deny that. It got lots of attention at the ring though, seems they’re not common in Germany.

Another good thing about the ring is the cars you’ll see, some very interesting motors will be there and best of all being driven hard, even the classics.

Bazzer, it’s not like driving on the road! When it’s really busy it can be a bit frustrating getting caught up in the traffic, but I’ve also had laps without seeing another car. You just have to chill out if it’s busy and not take it too seriously. If you’ve had plenty of time on track I don’t think you’d find it hard to learn.
It does makes the UK tracks feel a little bit tame afterwards, although I suspect Spa may do this also.

Hora, I agree there will always be a risk of somebody else doing something daft but I’ve never had a problem there. My insurance exlcuded the ring (except for 3rd party) and I go prepared for the fact that the worst may happen and it may cost me money. To not go because something might happen is a bit too over-cautious for me.

p.s. I don’t own a baseball cap or live with my parents!

Have you been Hora? Anybody acting like an idiot is generally given a hard time by both the staff and public.

It is an amazing track, well worth a visit. Do your homework first though. I learnt the track on Gran Turismo and found it a big help, although it doesn’t prepare you fully so build the pace steadily.

Be aware that the general rule is if you break it you pay for it and as previously said most insurance companies have exclusions for the ring. Hire companies are reported to have spotters at the ring to check that their cars are not being used there.

Oh, and don’t forget your petrol money. I spent over £500 in 2 days just on fuel on the last trip!

Tinas, the most important thing is to test ride a few yourself and form your own opinion. I had a GSXR600 and thought the midrange was fine although I did end up caning it everywhere as the top end was even better!

I also thought that the SV650 was dreadful and still do. It seems that some people like twins and some like fours. Neither opinion is wrong, just buy whatever floats your boat and enjoy it.

I was out on my motorbike yesterday and witnessed some very poor and dangerous riding by other bikers. A lot of the bikers I saw had no understanding of road positioning and visibility.

I went home in the end because I didn't want to be caught up in somebody elses accident.

Have you shopped around for insurance? I bought a GSX-R 600 as my first bike at the age of 24 and insured it for under £300.

I was loaned a SV650 while mine was in for a service once and couldn't wait to give it back.

5'11" on an 18" frame with 90mm stem and inline post. I've tried a 16" and I'm definitely better off on an 18".

Sounds like a knackered battery.

If it's already been turned over there's not much point putting oil down the bores. Jump start it or new battery.

Gingerblokes advice is worth following.

There is a difference. Below the boost threshold the turbo will not spool however long you wait. Above the threshold the time between opening the throttle and the turbo generating boost pressue is the lag time.

If the engine produces enough torque below the boost threshold then the car will accelerate slowly until it reaches the boost threshold, the turbo will then spool and the car will accelerate faster. All the FQ400 example shows is an engine that doesn't have much torque below the boost threshold and a reasonably high boost threshold.

The FQ400 example is not turbo lag either, it's due to the engine being below the boost threshold and being unable to spool the turbo.

Exactly Rob! It's about choosing a car to suit your needs.

My family told me I should have bought a diesel when I bought the BMW and I explained with figures why they were wrong and they just don't get it. The same people also say how nice my car is to drive!

I am comparing like for like though. Take the VW passat as an example, some of the engine options available are 2.0 Petrol, 2.0T Petrol, 3.2 Petrol and 2.0TDI. So the car is the same only the engine is different.

The 3.0 Petrol I refer to is a BMW 330 4 door saloon, I don't see this as a sports car. For the same price and same age I could have an Audi A4 2.0TDI, a car that I consider to be in the same class.

If I did huge mileage I may consider a Diesel but in my opinion the only plus point they have is fuel economy. I prefer everything else about the petrol engine.

You seem to be contradicting yourself so I wont say any more.

However, I will play top trumps:

Mercedes 6.0 V12 Turbo – 1000Nm. Petrol rules!

I'm off home now. I reckon I can get the 11 miles home with 23 gear changes. In the diesel I think it would take 37.

The graphs are wheel torque/total reduction versus engine speed. If you re-scaled the graphs so that all the cars were in a gear ratio that allowed them to travel at the same speed at max rpm the 3.0 petrol has more wheel torque than the 2.0TDI through the whole rev range as does the 2.0T VAG petrol. The 2.0 VAG petrol has more wheel torque only at low and high engine rpms.

What I'm trying to say is that I have to change gear less in my petrol car than I do in the diesels I drive.

Whilst a diesel engine has a higher peak torque, the gearbox has to have higher gear ratios due to the lower engine speeds. This results in less torque at the wheels which is what actually accelerates the car. A petrol car has higher wheel torque than a diesel at low rpm and high rpm.

The diesel only has greater wheel torque in the mid range. To me this feels like a narrow power band and hence more gearbox stirring.

I could well be wrong about the limiter, my experience with turbo diesels is based on much larger engines.

Do you have any figures for these modded engines, e.g. dyno charts? I suspect removing the spring will slow down the decrease of torque but it will still be decreasing. Do the diesels that rev to 5500rpm still use the standard turbo? I'm really interested to see how much torque they're producing at those revs.

The problem with 70mph at 4000rpm in a diesel compared to 6000rpm in a petrol is that at 1500rpm in my petrol I have 84% of peak torque available, yet in the diesel you are now at 1000rpm. In the Audi 2.0TDI I drive for work, this means one of 2 things either change down or wait and wait for the turbo to spool then get a big lump of torque. I prefer my car.

My 3.0 petrol engine returns between 30-35mpg. I happily pay for the extra fuel not to drive a diesel.

So the limiter starts to kick in at 4000rpm yet the engine continues to rev to 4500. That's nearly 15% of the rev range. This is not caused by a limiter, but due to turbo constraints. Volkswagen have chosen a turbo that spools early but cannot flow enough air at above 4000rpm, and rightly so.

A petrol turbo will have lag, all turbos have lag. This means that you cannot get instant power. The lack of power below 1500rpm is not due to lag, but due to being below the turbo spool point. Lag and spool are different.

I can see an argument for Turbo Diesels, they provide acceptable performance with good economy. However, I would still spend my money on a larger capacity petrol engine with far better throttle response than either a turbo diesel or turbo petrol. If I were to do more miles I may consider a diesel, but I find petrol engines both more relaxing and more enjoyable to drive.

Molgrips, that graph shows the TDI's power falling off sharply before the red-line not increasing all the way.

Or you could buy mine for £1295 with all the toys already on it. Cost me about £4.5k to build, used it for a year then went to play in Australia.

DH Bike For Sale

This was some advice I was given from a bike riding paramedic who sees the leathers crash tested by humans:

Top Quality at affordable prices = Scott, Wulf, Swift and if they are still around in the UK Furygan. Clover and IXS.

OK = HG, Frank Thomas is getting better along with Carrera, Texport, Spyke, Arlen Ness.

Total rubbish = Alpinestars (they should be banned ) Dainese, MJK.

Good quality but expensive = BKS, Crowtree, RS Taichi, Nankai, Kushitani.

I bought a Wulf 2-piece and am very impressed with it and my Spyke 1-piece has been down the road twice and has survived. Fit is paramount, so try before you buy.