Hybrid taxis

Posted on March 30th, 2014 in Hybrid Power,testing,Toyota by Julian Edgar

I recently spent some days in Darwin teaching people in government how to write clearly. It’s a long time since I’ve been in Darwin, and the growth and increasing affluence of the city was plain to see.

But the thing that fascinated me more than anything else in Darwin was the proliferation of Toyota hybrid taxis. The Prius, Prius V and Camry hybrid just dominate the taxi fleet.

Watching the few non-hybrid taxis sit there in ranks, waiting for customers with the car engines running to keep the air-conditioned cabins cool, it struck me how Toyota hybrids have a clear fuel economy advantage in these conditions.

And what’s that? Well, they can have the air con compressors and cabin fans operating with the engine switched off – until the HV battery gets low in charge, anyway.

One Prius taxi I went in had a dash displayed fuel economy of 7.5 litres/100km (horrendous for a Prius) but with the car being driven abysmally, and with all that time stopped with the air on, that was probably a pretty good figure compared with a conventional drivetrain.

(Yes the HV juice that runs the air con still needs to come from the petrol, but an engine is less efficient at idle than when driving the car, so overall, the fuel economy would benefit with the hybrid approach. Not to mention the battery juice achieved through braking regen.)

When I was in Germany a few months ago, there were many Prius taxis in the ranks – oftentimes, as many of the hybrid Toyotas as there were Mercedes and Volkswagens. I don’t think that fuel economy in those cool German cities would be a stellar advantage to the hybrids over diesels, so that brings up another taxi advantage. The Prius driveline is basically bulletproof – the engine, power split converter and electronics give extraordinarily little trouble. (That’s not just lucky – Toyota went to enormous pains to ensure that hybrids wouldn’t get a bad reputation through poor reliability.)

Taxi operators are among the hardest economic heads operating vehicles – they will use a car only if there is an overall economic benefit. So compared with other manufacturers, the taxi purchase / maintenance cost equation must be highly competitive for the Prius.

Wouldn’t it be funny if one of the greatest advances in car technology in the last 80 years – hybrids – ended up entering the mainstream through the back door of taxi use?

Bloody brackets….

Posted on March 18th, 2014 in Hybrid Power,Materials,tools by Julian Edgar

I hate making brackets that hold things driven by belts.

The last, most horrible job that I performed in this area was installing a supercharger on a Toyota Prius. I wanted to get the little blower mounted in a position where it could be driven by a longer version of the standard serpentine belt. This required painstakingly accurate building of a heavy duty and rigid bracket. The only place to put the bracket was where the engine mount sat – so the new bracket also became a new engine mount.

In itself that wasn’t so difficult, but getting the pulley mounted in exactly the right plane was just so time consuming.

However, in the end, the belt drive system (including a new idler pulley) worked perfectly – pity the supercharger was so noisy that it all had to come off again.

Right now I am building the bracket to place an alternator on a 2001 Honda Insight. (The Insight doesn’t normally use an alternator.) I don’t know if it’s just me, but this darn bracket is taking me forever.

The alternator is being located between the engine and the firewall, with access possible from both top and bottom. But the bolts on which the mount can ‘pick up’ are few and far between, meaning the bracket has to be a complex, odd shape.

Furthermore, it needs to provide the mounts for two idler pulleys. Why two? Well, they are needed so that firstly, there’s enough belt wrap around the crank pulley; and secondly, so that the belt misses the engine mount.

The resulting alternator bracket needs to be stiff, able to be installed (more difficult than it sounds when the fastening bolts for the bracket are on the side of the block, the end of the block, and under the block), and of course needs to be able to be built.

So how long is this taking me?

Including making a mount on which the alternator can sit temporarily as it’s juggled into the correct position, positioning the two idlers, clearing the torsional vibration damper on the driveshaft at full suspension bump, nestling the alternator as close as possible to the engine block, moving things around so an off-the-shelf belt will fit – and then cutting and welding 8mm plate, positioning the alternator drive pulley and the two idler pulleys in exactly the right plane, straightening bracket distortion after welding… well I’m still going on the bracket, and I reckon so far it’s taken me three full days.

I know I am a pretty slow worker, but three bloody days!

Anyway, the good news is that the top part of the bracket is now in position, the alloy engine mount has been milled to allow the plate to be sandwiched between the engine mount and the block without then causing a host of clearance problems, and as I write this, I am waiting for a belt that I think is the right size – better to have a belt on hand before I drill the hole for the second idler pulley….

Turning over a new leaf

Posted on March 14th, 2014 in Intercooling,tools,Turbocharging by Julian Edgar

Over the last few weeks I have been working on my little Honda Insight. I’ve been installing a turbo, water/air intercooler system and a new airbox, the latter fabricated from scratch.

It’s a complex job in that there’s not much space – especially when I am deliberating oversizing everything (but the turbo) to improve volumetric efficiency.

I am also doing things in a significantly different way to the approach I’ve used previously.

So what’s different then?

Specifically, I am being very careful that each newly-placed nut or bolt can be easily accessed by a tool. This means that instead of just looking at aspects like strength, weight and functionality, I am adding another criterion – can I get a spanner (easily) on that bolt?

It might seem a kinda obvious thing to do but I must admit I have never much done this in the past. In fact, I remember working on my little Daihatsu Handi turbo, way back around 20 years ago. The water/air intercooler I first installed on that car was so tight for space that the nuts had to be placed on bolts using long-handled, long-nose pliers. Yes, both long-nose and long-handled!

It was like performing surgery.

I got so jack of it that in the end I removed that intercooler heat exchanger and fitted another that sat on top of the engine rocker cover, in clear view – and with clear access.

The trickiest job so far on the Honda has also involved a water/air heat exchanger core, the one that sits on a fabricated steel frame bolted to the top of the gearbox, next to the engine.

The intercooler bolts to the frame via three rubber mounts. I need to (1) gain access to the frame’s mounts to bolt it to the gearbox, and then (2) gain access to both ends of the rubber feet, and (3) gain access to the bolts that hold little (extra) brackets to the intercooler core itself.

So far I am JUST successful: the rear bolts for the intercooler rubber mounts, positioned partly under the windscreen in the deeply indented firewall, can be accessed by using a short 12mm spanner – not a ratchet spanner as it looks may be needed, but a conventional spanner. The other fasteners are all easily accessible.

Another tricky job were the mounts for the airbox. A long cylindrical design mounted at an angle to the horizontal, it also sits on the gearbox. By manipulating the bracket design until it was all ‘just so’, I am able to access all three mounting bolts using a long extension on my small socket set.

Importantly, making a design that allowed access to these points was almost the first step in the process – I didn’t position the airbox solely for plumbing access to the turbo. Had I done this, the bolts holding the airbox in position would have been ‘blind’, and furthermore, would have needed tiny hands to even get to them.

And I have to say, positioning the fasteners for good access has made it so much easier to work on the car. That’s especially noticeable when some items, like the airbox, have been on and off perhaps 50 times while the intercooler water hoses have been routed and then fastened into place, and then the intercooler-to-throttle-body tube has been fabricated (twice!).

So for me no more the bad habits of the past: now everything I install has to be easy to work on, no matter how small the space into which it must fit.