Subaru develops horizontally opposed Turbo Diesel engine

The cutaway picture is interesting. I see...

4 valves per cylinder, separate exhaust and intake camshafts, possibly with roller followers, one timing chain, *massive* connecting rods, nearly full skirted pistons, gear driven injection pump, and a good sized turbo and intercooler

Like chains last forever? They may not have a defined service life but they do wear out and are more expensive initially and more expensive to replace.

Don't know why they went to chain except perhaps with higher compression the engine is 'interfering' and chain is less likely to snap resulting in severe engine damage..

I'm also not sure how they managed to find room for the turbo under the engine. If there is that much space why isn't the engine mounted lower instead to further lower the CoG, the oft claimed benefit of the boxer engine.

Now if only they would put a frame around the door glass I would get a Subaru. This surprising cheapness of design is unacceptable to me. I've owned cars with this poor design, but never again.

Surprisingly, there aren't many complaints about this issue here. Maybe Subaru frameless door windows are better in some way than others (?), or perhaps Subaru owners are more foregiving.

I don't know.

My '00 Impreza has so far not given me any problems whatesoever in this compartment.

M.J.

The Tribeca got frames and recent spy photos of what is assumed to be the '08 Impreza body has them.

Other than some legacies/outbacks having a wind noise issue that is fairly easy to correct, I don't recall too many issues with the frameless windows. People sometimes complain the motors are slow. And they still get superior crash test ratings as well as anecdotal stories of rollovers, etc. with minimal occupant injury.

Still, you might get your wish soon, looks like.

Carl

Now if only they would get rid of a frame around the door glass I would get a Tribeca :-)

....

You're talking apples Vs oranges. They are NOT the same kind of chains. Old V-8's have a wide chain called a silent chain and the typ timing chain use on modern OHC engine is a single width roller chain like on would find on some smaller motorcycles. These don't last an awful lot longer than a belt.

Son's Toyota chain was so bad when he changed it, it had almost worn a hole in the cast chain cover from all the slap. Think the motor had about 180-200k miles. It was so noisy it should have been changed a lot sooner. Also a lot harder to do than a belt as the chain has to run internal for oiling, and not external like a belt.

I bet the reason this new engine uses a chain is the same reason the H6 uses a chain, not room for the wider belt.

Mickey

A chain if designed correctly like on my previous Saabs will last the life of the engine or about 400,000 miles. Saabs roller chain, running in oil were like new when I sold my vehicles at 179 & 264,000 miles respectively. Subaru uses a roller chain on their top-of-the-line engine i.e. 6 engine. What else is there to say? Belts are quiter but, the hum of a roller chain is like music to me. The belts take less power, they say but, I'll give up one hp for not needing a $500 belt change on a young engine (105K miles).

You come to appreciate the frameless windows when you park in a very narrow garage. With the window left down, entry/exit from the car is much, much easier than maneuvering around the window frame.

On an earlier car (97 Plymouth Neon), I was having chronic trouble with the frameless window alignment. The service tech explained that the problem was closing the door by pushing on the glass. Once I stopped doing that, my glass alignment problems stopped. I just carried that lesson to my Forester, and have no problems with wind noise, leaks, etc.

Hi,

Agreed!

I noticed something when the announcement was made about Subie and Toyota cooperating on a "Yaris based" model for European sales that Toyota's gone back to a chain on the regular Yaris. Maybe mfrs are coming around?

I've NEVER been a fan of t-belts, though on a simple straight 4 like the first water-cooled VWs where one could change one in a half hour or less, I guess they were "acceptable." I've yet to have ANY trouble with a straight gear driven system (VW flat fours) or chain system (various engine designs.) I only had to be stranded by the side of the road w/ a broken t-belt ONCE to be "permanently scarred" and that was w/ a non-interference engine. And IMNSHO any engineer who designs an interference engine w/ a belt should be taken out in the town square and shot in public! (And I'm being nice: some I know have suggested hanging by certain delicate body parts...)

Maybe someone's heard our thoughts and that's why the diesel uses a chain?

Rick

Hi,

Sorry, my experience doesn't support that statement!

Don't know what Toyota your son owns, but if it was "noisy" for a long time, and he did nothing about it, the design's not at fault.

Then he's at a mileage that would represent 2, 3, or even 4 belt changes, depending on model. At maybe $500 apiece (considering most owners probably have a dealer do the work), we're talking $1000 to $2000 worth of "maintenance" costs. What did it cost to replace the chain? (For a parts only comparison: a new chain and sprockets for my Toy truck can be had for a little LESS than the two OEM belts for my ol' Subie. Add the belt idlers and tensioners, and I could buy another chain and sprocket set!) Folks taking their car to the mechanic/dealer will lose a day each time the belt's changed, so 2-4 days are lost. How many days did it take to replace the chain? One? And did the chain actually break at any time in that 180-200k miles, stranding him on the side of the road? I'll bet my quarter there are VERY FEW belts that get that far w/o breaking.

We won't even go into the ubiquitous leaking cam seals on belt driven engines...

All in all, my vote's for a chain!

Rick

So the chain went at 180-200k miles? Big deal. At that point I'd just buy a new car. The $1200 I saved on timing belt changes can go to down payment!!!! The saving are even greater on an engine that requires 60k belt changes.

Mickey wrote: