Torque curve for 2.5 L Forester donk?

[taza]

So if im understanding right because I have massive amounts of carbon build up its making the engine struggle more thus having a higher compression?


So if I stripped the top end of the motor, clean her out properly, replaced the seals and anything else that may look worn it should in theory be like new? I know its not as simple as that, theres alot of work involved but it would defernately be worth it.

I'm not looking for a racing car Bennie and after driving an Outback with the 2.5l engine I would be happy with the power and torque figures from that thus adding the supercharger.

Since the car is soo blocked up adding the SC in the enginess current state could quite possibly blow it to bits. So I will hold off on adding it and I really don't want to do that.

I really want to do it as cheap as possible since I will be at uni plus I won't be able to get away without a car for more than a week, but I guess in the city you have public transport unllie where I am now.
I also want to help assist someone do it so I can learn for myself. I can't just do it mself as I dont have the tools, time or knowledge.

Driving in the cars current state though wont kill it will it? I know theres the added pressure but it souldnt be enough to kill it.

 

[Ratbag]

Gidday NL

RB, I dont think he wants to swap in a new engine...he wants THIS engine running properly & with a supercharger.

Understood. And that's a good solution, too. Changing to a different engine is always a LOT more complex than it sounds in theory ... :iconwink:.

But Taza, I really think you need to get it running properly BEFORE you add extra stress. Subarino would have had his running perfectly before he did his, which is why its lasted. Its great you're getting others to help you & you will learn heaps from, plus its very kind of them for all the offers of help you've had.

What Bennie is suggesting is a full rebuild. I'm guessing you're not so keen on that just yet. So perhaps when you have the engine out doing the seals (do you mean valve guides?) you could clean the pistons as RB said...do some research 1st.

Also use their experience to check valve clearance & anything else that can be easily done.

Seeing as how the really painful bit is usually removing/refitting the engine, a full strip seems to be sensible when the engine is out ... .

RB, a supercharger has been done before on a stock EJ20 with exc results incl longevity...Subarino's "Hatchie", still going strong. By all accounts, VERY STRONG lol

No doubt. The Subaru (and VW) boxer donks are about as strong as they come for petrol engines. Keep the boost rational (under about 4 psi?) and using the electronic clutch system a la Jaguar back in the 1960s should be a good solution. An oil cooler might be a very good idea though ...

A SC also gives more benefits than a turbo in most respects, without the downside of constantly available boost. There is no 'turbo lag' with a supercharger, for instance.

As an interesting aside, in my Fox, the ECU automatically detects extra load on the engine, and automatically turns off the air-conditioner while this extra load remains. Good thinking!

 

[El_Freddo]

But Taza, I really think you need to get it running properly BEFORE you add extra stress. Subarino would have had his running perfectly before he did his, which is why its lasted. Its great you're getting others to help you & you will learn heaps from, plus its very kind of them for all the offers of help you've had.

What Bennie is suggesting is a full rebuild.

Yes I am. And if you talk to Subarino he'll tell you that he did a rebuild, but I'm uncertain if it was the whole hog or just bearings/rods as he drowned hatchie at one point. After this rebuild he decided it was a good time to have a crack at the SC14.

RB, a supercharger has been done before on a stock EJ20 with exc results incl longevity...Subarino's "Hatchie", still going strong. By all accounts, VERY STRONG lol

Hatchie has an EJ22, but it's pretty much the same anyway...

So if im understanding right because I have massive amounts of carbon build up its making the engine struggle more thus having a higher compression?

The higher compression comes from either carbon build up on the rings - which you can't do anything about with out pulling out the piston and to do this you might as well go a full rebuild - or the other thing that's happening is that the oil rings are shot and allowing oil past to the compression rings where the oil is acting as a liquid seal - thus giving you the high compression.

Or the high compression is a result of someone toying with cams or something else within the engine that you don't know about. But this is doubtful.

So if I stripped the top end of the motor, clean her out properly, replaced the seals and anything else that may look worn it should in theory be like new? I know its not as simple as that, theres alot of work involved but it would defernately be worth it.

It'd be worth checking out the bore and to see if there's a rim or edge at the top of the cylinder where the head bolts on. Basically if you run your finger up the cylinder with your finger nail at the top it should be smooth like the rest of the cylinder, if there's a lip this can indicate wear in the bore or carbon build up on the edge of the cylinder. You can get a tool that removes this rim - it helps you remove the piston when you do a rebuild, but is probably not really necessary to use at this stage.

I'm not looking for a racing car Bennie and after driving an Outback with the 2.5l engine I would be happy with the power and torque figures from that thus adding the supercharger.

But this is what the boy racer does - you're comparing chalk to cheese - the EJ20 is a smaller engine, it may be unhealthy and the EJ25 healthy, but the "boy racer" inside is longing for that extra power and torque. That's just how it goes... Hence the SC idea. The SC will be sweet anyway - especially when offroad.

Since the car is soo blocked up adding the SC in the enginess current state could quite possibly blow it to bits. So I will hold off on adding it and I really don't want to do that.

The engine isn't blocked up, it's probably just tired and worn out. Not having seen the engine to check it out we're on the other end going by your description.

To know your engine is going to go the distance on the SC you really want to get it as "fresh" as possible - rebuild or find a fresh engine in a known good condition - EJ25 or Ej20, it really wouldn't matter IMO, the EJ25 might be a little more work to get it right.

I really want to do it as cheap as possible since I will be at uni plus I won't be able to get away without a car for more than a week, but I guess in the city you have public transport unllie where I am now.
I also want to help assist someone do it so I can learn for myself. I can't just do it mself as I dont have the tools, time or knowledge.

Driving in the cars current state though wont kill it will it? I know theres the added pressure but it souldnt be enough to kill it.

I know your pain about being at uni and needing/wanting to get your car right. Been there many times before!

You won't kill your engine, just make sure the oil is kept up to it. Also do a thorough check for oil leaks under the engine to make sure you're not losing it that way. And if possible, hook up an oil pressure gauge to see what's going on when you drive. I can tell when my EJ's hot simply by looking at the oil pressure gauge as it drops off once the oil is hotter!

Cheers

Bennie

 

[El_Freddo]

Keep the boost rational (under about 4 psi?) and using the electronic clutch system a la Jaguar back in the 1960s should be a good solution. An oil cooler might be a very good idea though ...

Since Taza's basically following in the footsteps of Subarino, from memory his EJ22 is running 6psi. Raptor reckons the stock NA EJ's are good for 10psi with the SC...

I agree with the electronic clutch - that's the best part about them and would certainly be on my list if I did this mod. The oil cooler would be a good idea too. I'm considering one for Ruby Scoo to help keep things cooler in the slow hot stuff.

Cheers

Bennie

 

[taza]

Ok thanks guys, ive got some good info to work with.

I basically know wat needs to be done and now to start putting it to action next week. Too bad RSR has closed his workshop.

As ive read the EJ's are almost bullet proof when the regular maintenace is done but if not they are expensive buggers to fix. Still will be worth it in the long run and when this is done the engine will probably outlast the rest of the car. haha

 

[Ratbag]

I know your pain about being at uni and needing/wanting to get your car right. Been there many times before!

Ditto ... :sad: .

You won't kill your engine, just make sure the oil is kept up to it. Also do a thorough check for oil leaks under the engine to make sure you're not losing it that way. And if possible, hook up an oil pressure gauge to see what's going on when you drive. I can tell when my EJ's hot simply by looking at the oil pressure gauge as it drops off once the oil is hotter!

Cheers

Bennie

My 68 Landcruiser oil pressure used to drop to zero when I stopped. Fairly alarming in any modern vehicle, but that engine originally didn't even have an oil pump in it! 1927 Chev design, IIRC.

My Kimberley had a high capacity oil pump in it, but was pretty alarming when only 7~10 psi at 160 km/h in 47°C. Black Wednesday fires in the Adelaide Hills. I had to get home to rebuild my pump motor before the fires got to me. New rings sitting on the seat beside me! 1933 Moffat-Virtue engine that had the same bore as a Wolseley 24/80 - 3" (IIRC ... a LONG time ago ... ). It took me about 20 minutes to reassemble the motor and have it running.

It burned more oil than Taza's Fox!

BTW, I have a set of high quality gauges sitting in my garage that could go free to a good home for the price of the postage. No use to me ...

Smith's. Oil pressure, Voltmeter, Ammeter; with mounting bracket, IIRC.

I will try to find them and take some piccies of them.

 

[NachaLuva]

As ive read the EJ's are almost bullet proof when the regular maintenace is done but if not they are expensive buggers to fix. Still will be worth it in the long run and when this is done the engine will probably outlast the rest of the car. haha

This prob comes from its aircraft background where maintenance is always done religiously & reliability Is critical.

Yep it will Taza. With the motor going strong & the charger on it'll be hard to get you away from your Foz :biggrin:

 

[taza]

This prob comes from its aircraft background where maintenance is always done religiously & reliability Is critical.

Yep it will Taza. With the motor going strong & the charger on it'll be hard to get you away from your Foz :biggrin:

Yeah, maintenance is everything.

Its hard enough at the moment to get away. I would spend more time with the Foz over a month than what I would in my bed sleeping. lol

 

[Ratbag]

G'day again Bennie

Keep the boost rational (under about 4 psi?) and using the electronic clutch system a la Jaguar back in the 1960s should be a good solution. An oil cooler might be a very good idea though ...

Since Taza's basically following in the footsteps of Subarino, from memory his EJ22 is running 6psi. Raptor reckons the stock NA EJ's are good for 10psi with the SC...

Even 3 bearing MG-As can be run at 7 psi; and there was a Twin-cam 1600 MG-A that ran at 14 psi, IIRC.

All depends on how often you want to rebuild your engine!
Stress = (Increase in Stressor)^2.
Double the pressure; quadruple the stress.

((14.7 + 7)/14.7)^2 = 218% stress; or 118% increase in stress, whichever way one prefers to think about it.
((14.7 + 4)/14.7)^2 = 162% stress.
BIG difference in longevity ...

The 4 psi boost will give a 27% increase in torque and power at any given rpm.

AND, of course, almost all SCs in my youth were constant drive - no electro-magnetic clutch ...

I agree with the electronic clutch - that's the best part about them and would certainly be on my list if I did this mod. The oil cooler would be a good idea too. I'm considering one for Ruby Scoo to help keep things cooler in the slow hot stuff.

Cheers

Bennie

 

[Rally]

When an engine is obviously in a worn out condition, I don't believe half fixes are the best answer. It's all well and good putting new rings and pistons in, but what about the bottom end of the engine? If you have got to the stage where the top end is NFG, then the cost of doing the bottom end is well worth considering. Better to spend the money there than with the supercharger, as you may well have to spend the money on the bottom end plus the cost of things like head gaskets that you've just put on. Weigh up the costs of the engine build, the cost of the supercharger then consider selling what you have to weight up against getting a Forrie that comes with a 2.5 standard.

 

[taza]

When an engine is obviously in a worn out condition, I don't believe half fixes are the best answer. It's all well and good putting new rings and pistons in, but what about the bottom end of the engine? If you have got to the stage where the top end is NFG, then the cost of doing the bottom end is well worth considering. Better to spend the money there than with the supercharger, as you may well have to spend the money on the bottom end plus the cost of things like head gaskets that you've just put on. Weigh up the costs of the engine build, the cost of the supercharger then consider selling what you have to weight up against getting a Forrie that comes with a 2.5 standard.

As ive said Rally, I appreciate everyones advice. With a 2nd gen Foz you get crap gearing. 3.9 diffs with a horrible low range. I currently have gearing im happy with 4.11 diffs and 45% reduced low range compared to the 19%.

With the amount of money thats been poured into the car with new suspesion, clutches, mods and all the rest it wouldn't be both getting rid of it. Not to mention im starting uni in a few weeks and will have next to no income (or money from the government anytime soon) to even look at getting another one in the next 4 years or so.

Whats invloved in rebuilding the bottom half of the engine?

It still has relativley low km (170,000) so I wouldn't of thought there would be too much wrong. She is still reliable and a good strong motor, just needs some work. And when you go throgh 5-7Litres of oil in 5000km thats abit worrying, not to mention costly overtime.

But to find out what actually needs to be done you can't tell until the engine is on a bench and being looked at.

 

[Ratbag]

Gidday Rally

When an engine is obviously in a worn out condition, I don't believe half fixes are the best answer.

Never is. Whether cars or anything else. It's called "Throwing good money after bad" ....

It's all well and good putting new rings and pistons in, but what about the bottom end of the engine? If you have got to the stage where the top end is NFG, then the cost of doing the bottom end is well worth considering.

Better to spend the money there than with the supercharger, as you may well have to spend the money on the bottom end plus the cost of things like head gaskets that you've just put on.

Weigh up the costs of the engine build, the cost of the supercharger then consider selling what you have to weight up against getting a Forrie that comes with a 2.5 standard.

As a retired CPA, I cannot agree with you more.

However: "Costly thy habit as thy purse can buy", as the saying goes. We all have to live within our means, whatever they may be.

I was never going to spend a poultice of dough on a new car. Roo2 cost less than half the price of a similarly equipped 2012 XS 'equivalent', around 45%, to be more precise.

Those here who have seen Roo2 know that it is (used to be ... ) in "as new" condition. Even my old Impreza (here: Roo1 ) looked and drove almost like new, and it is 18 y.o. with 240,000 kms on the clock.

I chose the 2006 2.5L N/A Fox for a number of good reasons, not least of which is that it will probably outlast me ... But also because I could foresee expenses with Roo1 on a vehicle that really didn't suit what I wanted to do in it.

Hugely better torque and dual range were also high on my list of priorities, as were approach & departure angles and general ground clearance.

IMO, and for my uses, the 2006/07 XS is actually better than the more modern models.

What I am trying to say is that these decisions are usually fairly complex, and depend very much on the individual and their needs and wants ...

 

[Rally]

To do the bottom end you will need to split the block- no big deal. The crank would need machining most likely and you'd want new big end and main bearings. There are a number of US sites that sell genuine Subaru parts but if the crank has been machined you'd want to check to see you get the right size. While not part of the bottom end I would also suggest using head studs and nuts rather than head bolts- say 12mm or 13mm. This way you won't get the head gasket leaks these engines are known to get. You'd want to check out the pistons to see if there are any marks on them, but at that milege a re-bore would be needed and thus new pistons. New rings would go with the pistons.

What I am suggesting is to do a costing of the various options and see which comes out on top. These seem to be the options:

1) Add supercharger and hope engine does not die
2) Buy second hand engine and hope engine is in good condition. Compression check will assist but does not tell you about bearings
3) Rebuild top end of existing engine and add supercharger.
4)Rebuild whole engine and add/not add supercharger
5)Sell existing car and put engine money towards 2.5 litre Forrie.

 

[Barry]

I well remember the intro to my car mechanical bible - John Muir's "How to keep your VolKswagen alive, a guide for the compleat (sic) idiot."
As the 'guru' said: "Be kind to thy donkey, for it bares thee".

Time was, a novice like me could pull down and re-build an air cooled flat 4, but I wouldn't be game with a modern Subaru engine. Too damn many wires for one thing!

However, the principles remain the same:

• Research the parts spec you want for your new engine and what it will cost to do as a change over.
• Do what you need to do to keep your current donk going until you have the cash for the replacement, then have it done.

In the end, if everything else about the car is what you want and in good condition, then an engine replacement is just another 'parts change' when it is finally due.

 

[taza]

To do the bottom end you will need to split the block- no big deal. The crank would need machining most likely and you'd want new big end and main bearings. There are a number of US sites that sell genuine Subaru parts but if the crank has been machined you'd want to check to see you get the right size. While not part of the bottom end I would also suggest using head studs and nuts rather than head bolts- say 12mm or 13mm. This way you won't get the head gasket leaks these engines are known to get. You'd want to check out the pistons to see if there are any marks on them, but at that milege a re-bore would be needed and thus new pistons. New rings would go with the pistons.

What I am suggesting is to do a costing of the various options and see which comes out on top. These seem to be the options:

1) Add supercharger and hope engine does not die
2) Buy second hand engine and hope engine is in good condition. Compression check will assist but does not tell you about bearings
3) Rebuild top end of existing engine and add supercharger.
4)Rebuild whole engine and add/not add supercharger
5)Sell existing car and put engine money towards 2.5 litre Forrie.

Thanks, I think I will look into option 3 and 4. Check out prices and the likes. Option 4 could be worthwhile if option 3 is done since the engine would already beout and apart.
Im not getting another engine and I don't want to kill this one completely. Plus im not buying a new car so it leaves me with little options. But 3 and 4 would be suit my needs and are feasible for me.

By the way both superchargers came in the mail today, but they are in Geraldton and I don't live thier anymore Will make a trip down on thursday and pick them up.

 

[Ratbag]

G'day again Taz

Thanks, I think I will look into option 3 and 4. Check out prices and the likes. Option 4 could be worthwhile if option 3 is done since the engine would already beout and apart.
Im not getting another engine and I don't want to kill this one completely. Plus im not buying a new car so it leaves me with little options. But 3 and 4 would be suit my needs and are feasible for me.

By the way both superchargers came in the mail today, but they are in Geraldton and I don't live thier anymore Will make a trip down on thursday and pick them up.

Pick them up on your way through to Perth, maybe?

I reckon this has been a very valuable thread.

It seems that you have your head well and truly around the options, and what's involved with each decision. THAT is usually the biggest part of anything like this.

Personally, I would encourage option 4 as being cost effective (read "affordable" ... ); and least likely to lead to regrets not very far down the track. Once that donk is back in your car it is too late to discover that you REALLY should have gone the extra mile with the crankshaft, main bearings, re-bore etc. These will add significantly to the cost of repairs if they are necessary, but definitely need to be examined while you have the chance.

The SC can be fitted, or not, at your discretion later.
You are stuck with the decision if you put the donk back in your car only to find that still it doesn't work very well ...

All the best with it all, mate.

AND keep us posted on your progress and discoveries; as I am sure you will ... .

 

[taza]

It has been an informative thread RB for sure. Hopefully it will help someone who has gone through what I have (no service history???), I don't know.

Yeah I would be really pissed if I had done the top end and still had any issues at all. I will however look into the cost of doing the topend and what the additional cost of doing th bottom end would also be.
Now being currently unemployed money will be tight but it needs to be done, plus I want t help assist and learn. I don't want to pay a mechanic and especially when that could be $1200 in labour or more.

 

[Ratbag]

G'day again mate

It has been an informative thread RB for sure. Hopefully it will help someone who has gone through what I have (no service history???), I don't know.

Yeah I would be really pissed if I had done the top end and still had any issues at all. I will however look into the cost of doing the topend and what the additional cost of doing th bottom end would also be.
Now being currently unemployed money will be tight but it needs to be done, plus I want t help assist and learn. I don't want to pay a mechanic and especially when that could be $1200 in labour or more.

When I was young, cash was in short supply. I understand.

Best money I ever spent was for a "real" OEM workshop manual for each of my cars; and the tools to do the job, of course. Still have all of them ...

Reason I know what I know now is from doing exactly what you have been doing, and plan to continue to do. It helps even after you can no longer do it; or no longer wish to.

About 30 years ago I swore that I would never own a car again that I HAD to work on (a very long story ... ). Even though I continued to maintain my own cars until about 10 years ago, I left whatever big stuff had to be done to the experts. Lucky to have a terrific, competent, honest mechanic as we did for all that time.

Roo1 was serviced by Subaru for the first 200,000 kms.

The chap we now have (Ross) is the same sort of bloke as Geoff was.

IME, Subarus need to be serviced (relatively) regularly. Apart from that, they seem to be very light on the wallet for repairs and maintenance ... :biggrin:.

Unless they do something incredibly stupid, I will never again own anything else.

 

[Ratbag]

With a 2nd gen Foz you get crap gearing. 3.9 diffs with a horrible low range. I currently have gearing im happy with 4.11 diffs and 45% reduced low range compared to the 19%.

Trust me, the gearing on mine is nigh on perfect.

That goes for the LR as well.

Subaru have designed the MY06 so that you can tour in LR. The owner's manual says not to exceed 188 km/h in 5th LR ... towing a trailer ...

With the unreal torque figures at very low revs, the gearing in 1/2/3/4 LR is flaming near perfect - just IMHO, of course.

I can wax lyrical about the crappy gearing and lack of low-end torque in my Impeza; but not that of Roo2. I don't know if others who own the 2.5L Fox feel the same way, but I sure do.

 

[taza]

Trust me, the gearing on mine is nigh on perfect.

That goes for the LR as well.

Subaru have designed the MY06 so that you can tour in LR. The owner's manual says not to exceed 188 km/h in 5th LR ... towing a trailer ...

With the unreal torque figures at very low revs, the gearing in 1/2/3/4 LR is flaming near perfect - just IMHO, of course.

I can wax lyrical about the crappy gearing and lack of low-end torque in my Impeza; but not that of Roo2. I don't know if others who own the 2.5L Fox feel the same way, but I sure do.

Its abit different to driving on sand though. When going with my mate in his Outback you could smell his clutch abit due to not having the real low gearing in the soft stuff. I managed fine due to my gearing but holding your revs unless doing over 4000rpm is hard in the soft stuff for my 2.0l in its current state and wasn't too much better when it was running t its best. The 2.5 cetainly held better but taking off and finding the right gear to be in was hard with the OB.

Rock crawling is abit different. Gearing is important for both accents and decents, mines fine. Just needs some more low end torque below 2000rpm... burn't out the 1st clutch trying to get up a 1 foot vertical ledge from a stop.

I have a workshop manual and many tools for someone my age. Everything I know I have learnt myself and im proud of what I know but to pull an engine out and apart is just abit beond me. Im happy to learn though