FB25 engine into a SG9 forester

lefty

lefty

Forum Member
Joined
Jul 11, 2008
Messages
900
Location
Perth Australia
Car Year
MY05
Car Model
Forester
Transmission
XT lux manual
https://www.facebook.com/pages/Rising-Sun-Subaru/186267344729378

So for ppl thinking about doing a new Subaru FA/FB swap into a older Subaru body this may answer your questions. A customer of ours has done a $1800 FB25 engine into a SG9 forester. Next job is fitting the newer wrx/legacy cable 6sp into older shell....and also working on fa20 into older shell and in 4wd and red set ups.
This foz atm is getting 7.5lt per 100km.

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Gidday Lefty

That's interesting; very interesting.

Is the 7.5L/100 Kms overall? City driving? Open road driving?

My MY06 currently returns around 10 to 12.5L/100 Kms when used for short trips around the suburbs (to the shops and the like). If I'm doing longer trips around town, it is more towards the lower of these two figures.

On the open road, it returns around 7.3L/100 Kms. That's with two adults on board plus a moderate amount of gear, air-con running, on cruise control at 100-110 Km/h.

I expect that if I were prepared to take from one light to the next to almost reach the speed limit, my around town economy would be far better.

I guess that you can see what I'm driving at. These things are very much dependent on the individual and how they drive their car, and where, and when.

It is certainly a viable option for people who want the benefits of the EJ-253 in their car, but wouldn't it be easier (and cheaper ... ) to retro-fit an EJ-253 to a series I SG?
I don't know the answer, I am just posing the question.
 
Ratbag, the same amount of work is involved in all engine conversions.
There is the physical swap qhich is fairly straight forward. Then the xonputer and wiring.

Lefty, who did the wiring cut down? Was the standard harness and ECU (fb25) used?

What gearbox was used? Where was the conversion done? Where was the engine sourced from?

This might be a swap I'll consider next in the foz. After a year or so I'll be sick of the EJ251. The biggest issue I have with my engine swap is the rubbish fuel economy. Doesnt get any better than 500km to a tank, ever!
 
Gidday Taza

taza said:
Ratbag, the same amount of work is involved in all engine conversions.
There is the physical swap qhich is fairly straight forward. Then the xonputer and wiring.
Click to expand...

I understand that, mate. That's always been the case, even in the case of dinosaur engines.

This might be a swap I'll consider next in the foz. After a year or so I'll be sick of the EJ251. The biggest issue I have with my engine swap is the rubbish fuel economy. Doesnt get any better than 500km to a tank, ever!
Click to expand...

If you get rid of the big tyres, the big lift and the SF gearing, you would get far better economy, just as I would (around town) if I went a lot easier on my right foot ... :iconwink:. That's the point I was making. The 2.5L donks can give heaps of performance, but it takes a fair whack of fuel to shift a 1.5 tonne car around at speed. That's why I get such good economy on the open road (I drive very steadily on the open road - mostly); and such ordinary economy around town, where I am a bit of a lead foot :lildevil:. Maybe make that "a lot of a lead foot" ... :iconwink: :rotfl:.

However, I think that the serious changes made to the cams, valves and inlet systems in the EJ-253 (vs the EJ-251), do help achieve better performance, better torque and better fuel economy overall.

The proof of this (if any were needed) is that I get better economy around town towing my fully loaded trailer than I do without it! Maybe, just maybe, that's because I don't drive Roo2 like a racing car when towing the trailer ... :lol:.

The FB engine worries me more than a little for a number of reasons, and I am glad that both our cars have the EJ engine. Also happier with the 4EAT Sportshift auto in our SH than any of the various CVTs.
 
I run standard size wheels and tyres on the foz, the lift kit wouldnt have much effect on the car. However my gearing is shocking. At my hwy cruising speed its doing 3400rpm.

However 95% of my driving is city and stop/go traffic. Im very lead footed around town and average 11-11.5 l per 100km at all times.
The only real long distance towing this motor has done I averaged 12l per 100km, but that was driving into head winds, a/c on and sitting on 110kmhr.
Which I think is reasonable for the size of the car.

The worst ive had was the other weekend when I was offroad with the subie boys and used 16l per 100km. The engine was at 100% load for hours on end with the a/c on in mega soft sand and going flat out in low range the whole time.
 
G'day again Taz

taza said:
I run standard size wheels and tyres on the foz, the lift kit wouldnt have much effect on the car. However my gearing is shocking. At my hwy cruising speed its doing 3400rpm.
Click to expand...

That gearing will absolutely kill your fuel economy. That's worse than my old Impreza by a lot. Roo2 is doing around 2630 rpm at 100 kmh (38 kmh/1000 revs in fifth/HR) even in fifth/LR it is only doing about 3150 rpm at 100 kmh.

However 95% of my driving is city and stop/go traffic. Im very lead footed around town and average 11-11.5 l per 100km at all times.
The only real long distance towing this motor has done I averaged 12l per 100km, but that was driving into head winds, a/c on and sitting on 110kmhr.
Which I think is reasonable for the size of the car.
Click to expand...

I routinely get over 500 km before I fill up with round town driving. There is usually between 5-9 litres in the tank when I fill. That is, if I were to run it dry, I would get 550-570 kms on a tank around town. On the open road, I think it's the most economical car I have owned since my Morris Mini 850; and it's not far behind the Mini ...

The Mini would get around 40 mpg. Roo2 will get around 38.7 mpg. Both cruising on the open road at the speed limit. Number 1 Colt wasn't far behind, but it was only very rarely driven at anything like the speed limit on the open road ... 1H55m from North Terrace in Adelaide to Bordertown - 284 kms ...
The worst ive had was the other weekend when I was offroad with the subie boys and used 16l per 100km. The engine was at 100% load for hours on end with the a/c on in mega soft sand and going flat out in low range the whole time.
Click to expand...

Yeah; not good.
My mate's Statesman gets worse than that around town ...
 
Yeah the gearing needs work, that is in the pipeline.
I feel that a 5th gear that'll do 2800rpm at 110kmhr would be adequate without laboring the engine too much.
I average 470km to a tank when the light xomes on. Id have around 10l still in the tank at that point.

I am not worried with my offroad fuel economy, im prepared for it. Id rather have plenry of power rather than less power and good economy.
I qonder if the lift kit plays much effect on the areo dynamics and economy of the foz.
 
sorry I don't have any details as it's not my car. It just popped up on my fakebook feed
 
That looks almost like a factory fit Lefty. I'd go the FB series too, only because you'd assume Subaru has learned something about engine design over the years. I'd assume the FB engine would be more economical than the EJ - assuming everything else being equal - as all manufacturers have been concentrating on that with new designs.

Interesting comment Ratbag about the gearing in yours. If you look at the gear and diff ratios the X/XS manuals have taller overall gearing in 5th compared with my XT which has a WRX box with some different ratios in lower gears. Mine indicates 2500rpm at an indicated 100km/h (real 93km/h) and 2700rpm at a real 100km/h (according to my Garmin)
 
guzzla said:
That looks almost like a factory fit Lefty. I'd go the FB series too, only because you'd assume Subaru has learned something about engine design over the years. I'd assume the FB engine would be more economical than the EJ - assuming everything else being equal - as all manufacturers have been concentrating on that with new designs.
Click to expand...

I'm not so certain that the FB engine is a better engine than the last of the EJ engines. It may well be in some respects, but there are other things that lead me to the view that I'd rather an engine that's the last model after 25 years of design and development than one that's the first in a new design ...

Interesting comment Ratbag about the gearing in yours. If you look at the gear and diff ratios the X/XS manuals have taller overall gearing in 5th compared with my XT which has a WRX box with some different ratios in lower gears. Mine indicates 2500rpm at an indicated 100km/h (real 93km/h) and 2700rpm at a real 100km/h (according to my Garmin)
Click to expand...

While the overall FD ratios are slightly different, the overall ratio is 0.780 x 4.111 = 3.206:1 for the X/XS, and 0.738 x 4.444 = 3.278:1 for the XT. Hardly worth mentioning, really.

The real difference is that the X/XS have low range. This makes creeping and crawling easier, specially with higher torque at lower revs than the XT has.

Off the mark performance is another thing altogether. The XT will leave the N/A cars behind by a very considerable margin 0-100 kmh - around 3 seconds faster ... Now that's not inconsiderable ... :poke: :lol: :rotfl:.

It would be interesting to compare the two cars 0-50 or 0-60 kmh though ...

As always, it's horses for courses ... :cool:.
 
That looks awesome lefty :quitar::quitar:
I want one too :ebiggrin: :biggrin: :ebiggrin:

Regards
Mr Turbo
 
Ratbag said:
It would be interesting to compare the two cars 0-50 or 0-60 kmh though ...
Click to expand...
Actually the XT is truly electrifying at that. It leaps off the line and must be one of the great traffic light specials around. Never rev the guts out of it just a few extra and good use of the clutch and it almost leaps across the intersection. And all without wheelspin which stuffs every FWD car that tries it. They have a reputation of doing it easier than an equivalent model WRX (stock for stock) because of the lower gearing. And with the reflashed tune in mine putting out 370Nm of torque at the wheels from 3000rpm to 3800rpm it makes passengers scream if I submit them to that sort of thing. SWMBO abuses me every time lol

My brother with the 03 Forester X says every time after he has driven it how he can't understand how anyone could keep their license it's so easy to do. I've never had a ticket in the last 25 years.....
 
^ That's hardly surprising.

The EJ-251 has about the same maximum torque as the EJ-253, but its usable torque occurs over a considerably narrower rev range - starting higher and finishing lower.

Perhaps a more appropriate performance comparison would be comparing cars using the N/A EJ-253 with those using the turbo "EJ-253" (i.e. the DOHC EJ-255)?
 
The main improvements in the fb series engines are from using light weight internals. This gives a decent economy boost while power remains pretty much the same as previous.

Just a question on the cost. Where you say $1800 for the conversion was it 1800 for the engine, 1800 for install labour or 1800 for the whole lot?
 
^ Problem is with how they made some of the internals lighter, David.

AFAIK, they made the piston skirts shorter. This reduces the weight, but increases the tendency of the pistons to rub against the cylinder wall while they try to go up and down the bore sideways. This was corrected (maybe ... ) by offsetting the big end on the crank pin by 0.5° (IIRC), thereby introducing a loss of efficiency by introducing an angle into a relationship that should be as straight as possible ...

Subaru have had to coat the short piston skirts with molybdenum to reduce the friction caused by the pistons not going straight up and down the bore and rubbing against the cylinder walls. This is a retro-fit in quite a number of engines returning under warranty with horrendous oil burning problems.

Apparently, Subaru consider 1L/1,000 miles to be "normal" oil consumption. I haven't had an engine that used this amount of oil for about 40+ years! The Impreza used next to none (not measurable) between oil changes that were 12,000 to 20,000 kms apart. Roo2 used no measurable amount of oil in 8,000 kms and 24 months. This is what I regard as "normal" oil consumption ...

Anyone know how many piston rings the EJ-253 and the FB have? I suspect that another weight saving measure in the FB engine might have been achieved by reducing the number of rings from four to three, chucking the second oil control ring ... This, along with recommending the use of 0W-20 oil in the FB engine, might just account for some serious complaints of hugely excessive oil burning by FB engined Foresters.

This is also the recommended weight oil for the EJ-253 engines. Is anyone using oil as light as this? Has anyone else even realised that this is the oil recommended by Subaru for the MY06 EJ-253 engines (and for our MY10 SH that also has an EJ-253 donk in it)?

I sure as heck would not even entertain using engine oil as light as this in Oz. I use Shell Helix Ultra fully synthetic 5W-40 in both. It is good for about -40° to +50°C ambient. 0W-20 is no better for low temperatures, and maxxes out at +40°C ambient. Fat lot of good for Australia!

One can buy a flaming lot of fuel for the price of a complete engine rebuild ...

So, no, I am not a fan of the FB engine at this time.
 
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