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What is the benefit of engines with interference design? Seems to me that having a non-interference is more ideal in the "just in case" scenario. IE - why build an engine that can potentially destroy itself if the TB breaks when you can design one that won't?

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What is the benefit of engines with interference design? Seems to me that having a non-interference is more ideal in the "just in case" scenario. IE - why build an engine that can potentially destroy itself if the TB breaks when you can design one that won't?

 

 

Well its not planned that way. In order to get higher compression, more valves per cylinder, and cleaner emissions, you have no choice but to have an interfernce engine. There are fewer and fewer interfernce engines, and i think all 4 cylinders are now, and maybe all v-6's.

 

nipper

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IE - why build an engine that can potentially destroy itself if the TB breaks when you can design one that won't?
another way to put what nipper said as an overview - it's market driven. you have probably even played a part in dictating the market based on prior purchases of goods. if not, then you are a minority but are subject to mass market based product offerings.

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another way to put what nipper said as an overview - it's market driven. you have probably even played a part in dictating the market based on prior purchases of goods. if not, then you are a minority but are subject to mass market based product offerings.

 

so its all HIS fault :banana:

 

 

nipper

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another way to put what nipper said as an overview - it's market driven. you have probably even played a part in dictating the market based on prior purchases of goods. if not, then you are a minority but are subject to mass market based product offerings.

 

I agree with Gary here...most consumers are not going to be comparing whether the respective cars they are considering purchasing are interference or non interference design. Even many of those who recognize the difference may plan to trade the car in prior to the TBelt change interval, so it's "the next guy's problem." I have seen cars with timing chains touted as lower maintainance compared to timing belt equipped cars.

 

With the EJ22, one could make the argument that the modest HP gains of the Phase 2 redesign barely justify the loss of the bullet proof, non interference design of the Phase 1.

 

Nathan

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Well americans want cheap cars with lots of power, and thats the tradeoff. Tming chains are noisey, heavy and expensive, belts are cheap and light and quiet.

 

Every year we want more HP that most of us will never use, just for bragging rights. So there has to be more vlaves and more compression in a tight little space.

 

Then throw in emissions and bingo. Only so much you can do in a little space, and it all has to be timed properly.

 

BTW this is not a new thing, interfernce engines have been around since the 60's.

 

There is a return coming back around to chains, but thats more because of emissions then anythng else (since they are going to tighten up again).

 

nipper

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I think the HP increase between phase 1 and 2 was about 7

 

I like the bulletproof engine myself - easier to deal with if the belt breaks because of benign neglect

 

BTW - Interference engines have been around even longer than that - Mercedes diesel engines are interference in the OM-621 - break a timing CHAIN and it's bye bye CAM TOWERS (since the valves are straight up and down, not much chance of damage, but the pistons hitting the valves will snap off the cam towers right at the base - yeah, don't ask how I know...plus it's fun putting the timing back in - crank to cam gear to mechanical injector pump)

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In The HP wars, they dont care if its 1 hp more, its still 1 hp more then the previous year.

 

nipper

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so its all HIS fault :banana:
hey, i put it nicely! it is my fault too, that's why i know something on the subject.
In The HP wars, they dont care if its 1 hp more, its still 1 hp more then the previous year
exactly...fits what i said perfectly. it's about marketing, not true performance.

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Well americans want cheap cars with lots of power, and thats the tradeoff. Tming chains are noisey, heavy and expensive, belts are cheap and light and quiet.

 

nipper

 

I don't care too much about power (I must be a non typical "American") but I think I'm going to look for an H6 in the next Outback, just for the reliability. I don't like worrying about when my timing belt is going to break, and I generally change them early. They both have 60k - 80k on them now. 2000 OBW 2.5's...

 

Let's face it, if it was horsepower I was after, I wouldn't be driving a 2000 Outback.

 

2X2KOB

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...

Let's face it, if it was horsepower I was after, I wouldn't be driving a 2000 Outback.

 

2X2KOB

 

Well...DUH! (same attitude HERE :lol: ) BUT mine is non-interference so I can go 100,000, fearlessly :)

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BUT mine is non-interference so I can go 100,000, fearlessly :)

 

You set your goals way to low.

 

Mine IS interference and has already been 235,000, and I expect to get at least another 100k out of it. :headbang:

(the engine/car, not the timing belt)

 

 

*knock on wood*

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You set your goals way to low.

 

Mine IS interference and has already been 235,000, and I expect to get at least another 100k out of it. :headbang:

 

 

*knock on wood*

 

 

How often do you change the timing belt?

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For me, ('97 2.5 DOHC) I think the dealer recommended interval is every 106k miles or every 106 months. My aunt was the previous owner. She put the first 195k on it, and had all maintenance, oil changes and all, done by the dealer on schedule. Only exception was when the timing belt was replaced when the head gasket went at about 80k, so I still have a while to go before worrying about it again.

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Have about 20k on the belt (got the service records with the car when I bought it) So planning to go 80 more or until about 230k or so. I'll probably order the kit and keep it in reserve until I need it. (BTW - 105k is your "California Required" interval but if 1k makes all that much difference, they have a miracle in statistics)

 

Think I might try 4oz of the grill cleaner terpene in the sump as a running engine flush before the next oil change. And I'm considering a trans flush as well - sis said it made hers run so much better

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You think your crankcase is dirty? Why would it be? I wouldn't put weird stuff in my oil. I use Mobil 1 though, so crud doesn't build up.

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NOW, the SVX EG33 is technically valve-valve interference since it is a DOHC engine, but the EG33 was the only Subaru engine to have one cam gear-driven off the other. So unless your cams got out of sync with each other, which is a HIGHLY-unlikely scenario, it is basically a non-interference engine.
AFAIK, the SVX would never run into a interference problem period.

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The terpene is "orange oil" and is about the strongest natural anionic detergent you can find. It's why your hands can come so clean after peeling a really "oily" orange. The stuff is so powerful that it will lift off burnt on grease off a bar-b-q grill.

 

Previous owner had a motor flush done with one of the "butyl cellosolve" and petroleum distillate flush stuff - I think from the service description, anyway. I want to finish the job and baseline my oil changes. The vehicle is about 1500 miles into this cycle and the oil is a bit dark, so I suspect a residual of the flush is just floating up some more "stuff" (done at about 140k). I might just change the oil and see what happens from there.

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The refrence was made that if you change your tb at 100K your ok, but that unless your mechanic is a idiot or is greedy and charges you for parts they did'nt change. I had a conversations with a customer who had their belt done and one of the new idler failed about 5k into the belt changed and trashed the engine. Lesson learned don't buy cheap parts!!

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