Crossover or minivan; which is more spacious and comfy?

The 2008 Nissan XTrail. PHOTO | FILE |

What you need to know:

  • With cars so similar these days, it depends on a make’s features.

Hi Baraza, 

I have a family of four and I’m looking for a good car. My two priorities are space and comfort. I’m torn between crossovers (X-Trail, CRV, Murano, RAV4) and minivans (Honda Stream, Stepwagon, Honda Odyssey). Checking online (always the best source of sane, reasoned arguments), there are a lot of impassioned arguments for each.

Some say crossovers are just minivans in disguise and are no more than ego-boosters, but others praise their off-road capability and performance. 
As for minivans, their advocates say they cannot be matched when it comes to comfort.
They are also quite spacious and more fuel-efficient than crossovers. The main argument against them seems to be that “they are not cool”. I don’t think we’ll go off-roading but we plan to travel quite a lot. Which type of car would you recommend? I’m leaning towards a minivan, especially a Honda.

Hello,

Crossovers are less disguised minivans and more hatchbacks or compact wagons in high-heeled shoes; but then again, in this era of platform sharing, CAD designs and corporate faces, the lines are getting seriously blurred between segments.

I wouldn’t call them ego boosters as much as I would fashionable trends-du-jour that are blindly followed by a middle class defined by their desire for a sense of belonging and sameness, a middle class that, lately, cannot seem to get enough of these things. With the exception of oversized American pickups, crossovers are the most profitable class of car a manufacturer can make.

Minivans are roomy, true, and offer increased practicality such as sliding doors that come in handy when ensconced in tight parking spots.

Whether or not they are more comfortable it to be decided on a case by case basis because a car like a Mercedes-Benz GLE is a crossover and more comfortable than most minivans, but again the Toyota Alphard is one of those same minivans and is luxurious like you can’t believe.

The minivans might seem “uncool” because they portray the image of a family man who has resigned himself to breeding rugrats and has long since forgotten the joys in some of the finer things in life, such as a two-door sports car.

This mindset doesn’t really apply here in Kenya, where our tastes are strange and our priorities skewed. This explains the popularity of the Voxy and its ilk.

If you won’t off road and you do a lot of road trips, then the minivan is for you, image be damned. Hondas are not half bad, particularly the Odyssey, and at least you will shed the “Kenya uniform” blight that afflicts those who shop for Toyotas.

How come the New Holland TD80 has more horsepower than YTO X704 tractor?

*****

Hi JM,

I have been an ardent reader of your column for some time now and I get lots of info on how you break down issues and lots of kicks on how you dispense off irrelevant ones.

I do not know in which column mine falls but since it has to do with engines it might be right up your alley, so here goes: In the recent past we acquired a YTO X704 tractor, a real bargain, from the Orient and on close comparison with other tractors in its class I think the Chinese are on to something here, or taking us for a ride. Without diverting onto the qualities and durability of Chinese machinery and with the above engine specifications, kindly delve into how a smaller displacement engine of a New Holland TD80 gives more horsepower than that of a YTO X704 Engine, both naturally aspirated 4x4 drive.

My Google-fu did not clearly fill me in since it just differentiated engine and draw bar horsepower, a standard for measuring tractor power in the tractor world. Note that on the farm, the one with more horsepower calls the shots. Feel free to throw in some algebra, calculation,s etc, just to spice it up a bit.

The engine specs for the two are:

YTO X704 tractor:

Displacement (L) - 4.4

Bore x stroke (mm) - 105x125

Rated power (Kw)/Hp at 2400 rpm - 51.5/70 Max. torque (N.m)/speed (r/min) - 237

New Holland TD80 tractor:

Displacement (L) Capacity - 3.9

Bore x stroke (mm - 104 x 115

Rated power (Kw)/Hp at 2500 rpm - 58.8 / 80 Max. torque (N.m)/speed (r/min) - 298

Hi Allan,

I see we are in yet another engineering class. Now, besides the capacity, which is the most obvious factor in determining engine outputs, several other considerations come into play; split not so evenly between physical and mechanical constants such as bore to stroke ratio and other fringe-scientific observations such as “how well the engine is developed”.

Not to be discriminatory or racist in any way, but New Holland is one of the biggest and longest lived tractor names out there. The Chinese.... not so much. It is easy to tell who will have a better made tractor between the two and that sort of half answers your question.

A more thoughtful answer would incorporate deeper details and these are those details:

1. From the information you gave, both engines are “undersquare” (stroke > bore), meaning they are both good for torque, but there is what we call the stroke ratio value, determined from dividing the bore figure by the stroke figure. Undersquare engines have stroke ratios below 1:1. So now,
The YTO X 704 has a stroke ratio of 0.84:1 while the New Holland TD80 has a stroke ratio of 0.96:1. These two numbers carry some significance.

While some engines are undersquare, some, like the Chinese, are more undersquare than others (the New Holland) and despite the inherent torque advantages of an undersquare engine, it is not without its drawbacks. The lengthy stroke increases engine friction due to the longer distance covered by the piston.

There is higher peak piston acceleration, again due to the fact that the piston has to cover a longer distance at a given rpm compared to square or oversquare engines, but increased piston speeds do not necessarily equate to increased engine speed. Also, the comparatively narrow heads (as occasioned by a narrow bore) make porting and valving less efficient: one can’t install bigger ports or numerous valves for easier breathing.

We can see from an engineering point of view that the “undersquareness” of the Chinese engine already puts it at a slight disadvantage; but a closer look at those numbers indicates the cylinder dimensions of the two engines are not very different. There is about half a litre between them, with the Chinese getting the fatter end of the displacement stick. So why then is the Chinese equipment outdone despite its bigger engine? That big engine is its own undoing.

For one, undersquare engines are not particularly revvy as pointed out, which is why the live in tractors and other slow-turning engines; and to make power you need revs, plenty of them.

Seeing how the torque is already getting shortchanged by intra-cylinder frictional losses; and now you can’t rev the nuts out of the engine, things are looking pretty bleak. The bigger the engine, the more the frictional losses and the heavier the parts that will try and resist rotation by reason of sheer mass alone.

Disadvantage: China.

Now these are just the inherent engineering aspects that affect the torque an engine develops and are a skeleton framework of what to consider in engine design before diving in. Like the exhausts we discussed last week, it all comes down to a fine balance of a myriad of little considerations and how well they work together. I’m not saying bigger engines make less power but there reaches a point where an increase in capacity will not do much for the power figure bottom line; if anything it might send the graph in the opposite direction.

The exact torque figure an engine will put out depends on numerous other factors, such as the lengths of the intake and exhaust runners, the compression ratio, brake mean effective pressure, valve number, design and timing; cam profiles and generally the degree of technology that has gone into the engine.

These are what separate the performance parameters of engines of the same size; or the reason why you may find a smaller engine making better numbers than a larger one.

Having developed a certain amount of torque, the power an engine makes is then determined by how high that engine can rev while carrying that torque. Your New Holland engine develops more torque and carries that torque to higher revs (2500rpm vs the 704’s 2400), which is why it has more power.

*Addendum: how high an engine can rev is in itself yet another topic, where physical design and material science come into play.

I want to change my Toyota from automatic to manual

*****

Hello,

I’m looking for advice on changing an AE91 Sprinter with a 5A-FE engine from its original auto transmission to manual simply because I prefer to drive a manual car. Is it too much work? What’s the procedure?

Buying a factory manual car is out of the question since I like everything else about the car.

Reyaad

Hello Reyaad,

The conversion from an auto to a manual is a fairly simple one on paper, especially for the AE91 Toyota Sprinter, though I initially disagreed about trading in for a manual instead of doing the swap. But then I gave it some thought and realised that model is a bit long in the tooth and shopping for a clean example might not be as immediately successful as it would have been a decade ago, if at all. These cars are slowly disappearing from our roads and the few left either lean towards the shabby side or are simply not for sale.

Anyway, the conversion process: you need the replacement gearbox at hand, as well as its flywheel, clutch pack, pressure plate, clutch and brake pedal assemblies (the brake pedal in most automatics is uncomfortably wide if you opt to introduce a third pedal into the footwell) along with their master and slave cylinders, wiring harness for the manual box where applicable and whatever other little knick-knacks that will be necessary for the conversion to be a success. These might vary from car to car, which is why I won’t delve into a comprehensive breakdown, but a trustworthy mechanic should be able to walk you through the requisite shopping list before work starts.

The truncated process list involves removing the driver’s seat, exchanging the fat, original, automatic-only brake pedal for a skinnier, manual-specific one and drilling holes into the forward bulkhead to accommodate the new pedal and master cylinder.

The next big step is removing the gearbox, having disconnected anything and everything that needs disconnecting: cables, linkages, wires and driveshafts.

Once the transmission is out, remove the torque converter and flywheel assembly and replace them with their manual transmission equivalents (flywheel and clutch pack). Sling the manual transmission into position and fasten it in place, taking note of torque specs when tightening bolts. From here attach the clutch slave cylinder and lines. Then attach the gear lever from inside the car, replace or reattach what you had disconnected but didn’t discard, then, most importantly, bridge the wires that go to the automatic transmission’s selector box, otherwise the car won’t start. An alternative to bridging the wires is to have an aftermarket ECU since the car will only refuse to start on its stock ECU.

Drive off into the sunset, rowing your own gears to your heart’s content.

*Disclaimer: it is one thing to read the theoretical version of this exercise; it is quite another actually doing it. Certain parts of the process can be really tiresome or frustrating, especially if you are dealing with a small, packed or crowded engine bay.

This entire guide was distilled and highly summarsed from the same procedure performed on a Toyota Starlet GT with a 4E-FTE engine. For optimum results, I strongly advise you to leave the job to a professional who knows what he is doing, because much as it sounds fairly straightforward, it is a difficult job.

After changing my Nissan’s gearbox, its performance has gone down

Hi Baraza,

I recently changed the gearbox of my Nissan Sunny B15 Super saloon. Thereafter, I noticed that whenever I accelerated, I couldn’t surpass the 80km/hr mark. The vehicle also doesn’t pick well on the hill until I press on the acceleration pedal to the end. My mech had advised that I need to check the throttle sensor and fuel pump. What could be the problem? I love this car and am not about to give up on it yet.

Braion.

Hi Braion,

You do not specify whether the vehicle is manual or automatic, or even if you changed from one version to the other like the man with the Sprinter above intends to. Now that you instead specify flagging performance when going uphill, I’d suggest you start by checking the load sensor of the engine, which determines when the engine is working hardest (such as when going uphill) and sends signals to the ECU to open the taps a little wider, adjusting the air-fuel ratios for better performance.

A faulty load sensor means the ECU can’t tell if the engine is straining and will not make the necessary adjustments - hence the poor performance.

A transmission-related diagnosis would be to check the torque converter stator to see if it is malfunctioning. The stator assembly is the “torque multiplier” in the transmission, so if it is not working as it should, engine torque is not multiplied and the car, therefore, underperforms.