Engine compatibility
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From: Gloucestershire
Engine compatibility
Hi
I have just joined the forum looking for some information.
My brother has a Legacy B4. It has suffered bottom end failure. The crank is a write off. As far as I am aware it has an EJ208 engine. I've suggested it will be easier and cheaper to source another engine.
Which engines can we actually use to replace the engine in his car? Does it have to be an EJ208 or can we use an Impreza engine? EJ208 engines seem to be more expensive.
Thanks
I have just joined the forum looking for some information.
My brother has a Legacy B4. It has suffered bottom end failure. The crank is a write off. As far as I am aware it has an EJ208 engine. I've suggested it will be easier and cheaper to source another engine.
Which engines can we actually use to replace the engine in his car? Does it have to be an EJ208 or can we use an Impreza engine? EJ208 engines seem to be more expensive.
Thanks
Last edited by jakeycrx; Feb 23, 2015 at 08:10 AM.
Scooby Regular
Joined: Dec 2012
Posts: 282
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From: England
An ej205 is close. But the impreza ej205 has lower compression pistons I think 8.5:1 compared to the ej206 and ej208 legacy which have 9:1. Crank and rods and crankcase are the same.
The heads are similar. inlet cams are the same. ej206 and ej208 have exhaust cams like the sti ej207 (non avcs type). The main problem with the heads is that the left bank (cylinders 2 and 4) head on the impreza ej205 does not have the drilling for the turbo oil feed for the primary turbo.
You could get away with the difference in compression ratio and cams with a remap. But you'll never get an oil feed to the primary turbo.
So the cheapest option for you would be to replace the crankshaft/bearings, oil pump, oil modine (if fitted - some ej206/8's don't have them) and thoroughly clean the sump of swarf.
If you do decide to use the impreza ej205. Then I would use it complete and convert to single turbo. I would do this anyway as the legacy primary turbo phase is so lame I'd rather actually have the lag.
Then you will need a load of other parts to convert to single turbo like headers, up pipe, turbo, downpipe, centre pipe, gearbox cradle, single turbo ecu. Wiring mod, remap.
Of course you could use your twin turbo heads on an ej205 bottom end (you'll still have wrong compression pistons though)
The heads are similar. inlet cams are the same. ej206 and ej208 have exhaust cams like the sti ej207 (non avcs type). The main problem with the heads is that the left bank (cylinders 2 and 4) head on the impreza ej205 does not have the drilling for the turbo oil feed for the primary turbo.
You could get away with the difference in compression ratio and cams with a remap. But you'll never get an oil feed to the primary turbo.
So the cheapest option for you would be to replace the crankshaft/bearings, oil pump, oil modine (if fitted - some ej206/8's don't have them) and thoroughly clean the sump of swarf.
If you do decide to use the impreza ej205. Then I would use it complete and convert to single turbo. I would do this anyway as the legacy primary turbo phase is so lame I'd rather actually have the lag.
Then you will need a load of other parts to convert to single turbo like headers, up pipe, turbo, downpipe, centre pipe, gearbox cradle, single turbo ecu. Wiring mod, remap.
Of course you could use your twin turbo heads on an ej205 bottom end (you'll still have wrong compression pistons though)
An ej205 is close. But the impreza ej205 has lower compression pistons I think 8.5:1 compared to the ej206 and ej208 legacy which have 9:1. Crank and rods and crankcase are the same. The heads are similar. inlet cams are the same. ej206 and ej208 have exhaust cams like the sti ej207 (non avcs type). The main problem with the heads is that the left bank (cylinders 2 and 4) head on the impreza ej205 does not have the drilling for the turbo oil feed for the primary turbo. You could get away with the difference in compression ratio and cams with a remap. But you'll never get an oil feed to the primary turbo. So the cheapest option for you would be to replace the crankshaft/bearings, oil pump, oil modine (if fitted - some ej206/8's don't have them) and thoroughly clean the sump of swarf. If you do decide to use the impreza ej205. Then I would use it complete and convert to single turbo. I would do this anyway as the legacy primary turbo phase is so lame I'd rather actually have the lag. Then you will need a load of other parts to convert to single turbo like headers, up pipe, turbo, downpipe, centre pipe, gearbox cradle, single turbo ecu. Wiring mod, remap. Of course you could use your twin turbo heads on an ej205 bottom end (you'll still have wrong compression pistons though)
Scooby Regular
Joined: Dec 2012
Posts: 282
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From: England
If you're using the twin turbo heads then maybe. But they use the thinnest gaskets already. I don't think you can buy thinner. They increase the compression ratio by almost completely removing the bowl in the piston.
To be honest, using an old ej205 and doing a half hatched rebuild will probably be a waste of time when the bottom end goes in that as well.
Better off rebuilding the engine that it came with or converting to single turbo properly.
To be honest, using an old ej205 and doing a half hatched rebuild will probably be a waste of time when the bottom end goes in that as well.
Better off rebuilding the engine that it came with or converting to single turbo properly.
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