Has anyone built a high power N/A Subaru Flat 4?
Discussion
Does anyone know of a high power, naturally aspirated Subaru flat 4 engine?
I really want to use a Subaru flat 4 in my next project, but it cannot be turbocharged, sadly...
Is there a high power 2.5 out there? something running high compression and lairy cams, maybe with throttle bodies?
Are there any stroker kits available to increase the capacity or can the block/ liners be bored?
I assume that a turbo engine bottom end with high compression pistons and some high lift/ overlap cams would work with TB's? But, if someone has done it before, I would be interested to knwo what power they made!
Any info is greatly appreciated!
I really want to use a Subaru flat 4 in my next project, but it cannot be turbocharged, sadly...
Is there a high power 2.5 out there? something running high compression and lairy cams, maybe with throttle bodies?
Are there any stroker kits available to increase the capacity or can the block/ liners be bored?
I assume that a turbo engine bottom end with high compression pistons and some high lift/ overlap cams would work with TB's? But, if someone has done it before, I would be interested to knwo what power they made!
Any info is greatly appreciated!
Turbo'd boxers have lower compression pistons and thicker head gaskets due to higher compressions acheived through turbo assistance. Use a high comp engine/pistons on a turbo setup and the only bang you're going to get is when the engine blows up.
Like Vixpy said no point using N/A for scooby performance, there are plenty of turbo'd engines about for not huge amounts of money.
Like Vixpy said no point using N/A for scooby performance, there are plenty of turbo'd engines about for not huge amounts of money.
Haven't heard of anyone doing it, I guess mainly because all of the motorsport Subaru have been involved with involves turbos.I'd say give it a shot just so we can see how it works out. Most 2.0 4cam Legacies are around the 150-160bhp mark as standard and rev to 7-7500 (my '90 limiter was at 7750), if as you say you use the bottom end from an STi which is good for 8k+ rpm and throw some high compression bits on top it could have potential.
Capacity-wise, I think the biggest I heard of from a 2.5 STi lump was out to 2.65, Could be wrong on that one though.
Edited by GravelBen on Friday 17th October 11:10
It is not for a Scooby...
It is for a project car and will be mated to a Porsche 'box...
The regs we need to meet dictate no forced induction - Sadly!
I was thinking that a strong STi bottom end with high comp. pistons and then larger overlap cams should be good for 7500 rpm plus and a well ported head should be good for over 100bhp/l so a 2.5 engine could be coaxed above 250bhp.
Ideally, I would have 300bhp...
It certainly sounds feasible!
It is for a project car and will be mated to a Porsche 'box...
The regs we need to meet dictate no forced induction - Sadly!
I was thinking that a strong STi bottom end with high comp. pistons and then larger overlap cams should be good for 7500 rpm plus and a well ported head should be good for over 100bhp/l so a 2.5 engine could be coaxed above 250bhp.
Ideally, I would have 300bhp...
It certainly sounds feasible!
I think if you're willing to spend big money you could very likely get a N/A 2.5boxer to produce 250-300bhp and get it revving to 8K/8.5K rpm no probs, but it would have to have lightened and forged everything as well as being pretty high compression, reasonably hot cams and a well ported, skimmed and gasflowed head with bigger valves, uprated valve springs, bigger injectors, throttle bodies, mapping, etc..etc...
Blimey that won't be cheap by any stretch bearing in mind that for a fraction of the cost you could have a turbo boxer with little done to it to net the same results. I hope you have deep pockets but more power to your greasy elbow and lots of good luck as i for one would love to see it done!!
Just think 300bhp and no lag at all!!! then when you're finished with it you can stick it in mine
Blimey that won't be cheap by any stretch bearing in mind that for a fraction of the cost you could have a turbo boxer with little done to it to net the same results. I hope you have deep pockets but more power to your greasy elbow and lots of good luck as i for one would love to see it done!!
Just think 300bhp and no lag at all!!! then when you're finished with it you can stick it in mine
Might be easier and cheaper to use a Porsche flat 6 and get 300bhp as standard
http://cgi.ebay.co.uk/PORSCHE-911-996-ENGINE-3-4_W...
http://cgi.ebay.co.uk/PORSCHE-911-996-ENGINE-3-4_W...
I already have one of those in the back of my car Mark! 
I need a very short engine, which can be used in a longitudinal installation, which is less than 3.0 litres in capacity... The Subaru would appear to suit that criteria and I am sure that if a 2.5 could be persuaded to rev towards 8k rpm then it would produce over 250bhp with the right cams and head porting...
But, yes, all points taken... It might be a bit on the expensive side to just 'try'!
I need a very short engine, which can be used in a longitudinal installation, which is less than 3.0 litres in capacity... The Subaru would appear to suit that criteria and I am sure that if a 2.5 could be persuaded to rev towards 8k rpm then it would produce over 250bhp with the right cams and head porting...
But, yes, all points taken... It might be a bit on the expensive side to just 'try'!
dom9 said:
I already have one of those in the back of my car Mark!
I need a very short engine, which can be used in a longitudinal installation, which is less than 3.0 litres in capacity... The Subaru would appear to suit that criteria and I am sure that if a 2.5 could be persuaded to rev towards 8k rpm then it would produce over 250bhp with the right cams and head porting...
But, yes, all points taken... It might be a bit on the expensive side to just 'try'!
Are you sticking it in the back of a racing Beetle, per chance?I need a very short engine, which can be used in a longitudinal installation, which is less than 3.0 litres in capacity... The Subaru would appear to suit that criteria and I am sure that if a 2.5 could be persuaded to rev towards 8k rpm then it would produce over 250bhp with the right cams and head porting...
But, yes, all points taken... It might be a bit on the expensive side to just 'try'!
Sounds like an interesting project - the main problem you'll come up against is the fact that every Subaru tuner has gone down the forced induction route - other than your basic exhausts and filters, everything will have to be custom-built.
markCSC said:
Might be easier and cheaper to use a Porsche flat 6 and get 300bhp as standard
http://cgi.ebay.co.uk/PORSCHE-911-996-ENGINE-3-4_W...
Would be a lot easier and cheaper to start with an engine that actually worked.http://cgi.ebay.co.uk/PORSCHE-911-996-ENGINE-3-4_W...
Might be worth you ringing Chy Wright at Pennine Subaru,very knowledgeable about all Subaru's. Contact details here http://www.jetkart.co.uk/contact.htm
Mentioned on another forum is that the EZ30 (Subaru flat 6) is only 20mm longer and the latest generation puts out 240bhp from Subaru.
Other than that you can get stroker kits/short blocks for the 2.5l Boxer 4, have a look at http://store.crawfordperformance.com/store/categor...
I would think 300bhp would be possible, but it is un-chartered territory for any Subaru tuner.
Other than that you can get stroker kits/short blocks for the 2.5l Boxer 4, have a look at http://store.crawfordperformance.com/store/categor...
I would think 300bhp would be possible, but it is un-chartered territory for any Subaru tuner.
Thanks chaps - Sorry I haven't replied, work has been a bit busy of late.
The EZ30 could be interesting, but i think i would have to get a tape measure out an dhave a look. Is it shorter than the Porsche flat 6 do you think? Truth be told, I had assumed that the Scooby F4 would be a fair bit shorter than the Porsche.
If the EZ30 puts out 240bhp N/A, then I assume that a few more ponies could be found from cams, compression, TB's and an exhaust - But I wonder if you can get them to rev? Anyone know if there are many tuning parts available, even if they are in Japan?
The EZ30 could be interesting, but i think i would have to get a tape measure out an dhave a look. Is it shorter than the Porsche flat 6 do you think? Truth be told, I had assumed that the Scooby F4 would be a fair bit shorter than the Porsche.
If the EZ30 puts out 240bhp N/A, then I assume that a few more ponies could be found from cams, compression, TB's and an exhaust - But I wonder if you can get them to rev? Anyone know if there are many tuning parts available, even if they are in Japan?
Sorry to say but any Scoob engine is best Turbo's
Even the H6 has been under the tuners knife!
http://www.supercars.net/cars/3278.html
Even the H6 has been under the tuners knife!
http://www.supercars.net/cars/3278.html
dom9 said:
I already have one of those in the back of my car Mark!
I need a very short engine, which can be used in a longitudinal installation, which is less than 3.0 litres in capacity... The Subaru would appear to suit that criteria and I am sure that if a 2.5 could be persuaded to rev towards 8k rpm then it would produce over 250bhp with the right cams and head porting...
But, yes, all points taken... It might be a bit on the expensive side to just 'try'!
If it needs to be compact and able to mount longitudinally have you thought about a rotary unit from Mazda something like a N/A 20B from a Cosmo, or one of the new 13 B-MSP from a RX8, The 13 B-MSP in 228bhp guise should be easy enough to tune to 250-260bhp and will weight less than a 2.5ltr F4.I need a very short engine, which can be used in a longitudinal installation, which is less than 3.0 litres in capacity... The Subaru would appear to suit that criteria and I am sure that if a 2.5 could be persuaded to rev towards 8k rpm then it would produce over 250bhp with the right cams and head porting...
But, yes, all points taken... It might be a bit on the expensive side to just 'try'!
Another thought is that I believe that the Subaru boxer is based on the Alfa boxer, so it might be worth having a word with these guys to see if they could help.
http://www.ahmotorsports.co.uk/index2.htm
http://www.ahmotorsports.co.uk/index2.htm
Might be worth having a look here
http://forums.nasioc.com/forums/forumdisplay.php?f...
The Septics didn't have the turbo version for some years so many of them tunned the N/A model
http://forums.nasioc.com/forums/forumdisplay.php?f...
The Septics didn't have the turbo version for some years so many of them tunned the N/A model
stevieb said:
Sorry to say but any Scoob engine is best Turbo's
Even the H6 has been under the tuners knife!
http://www.supercars.net/cars/3278.html
there was a Ozy hill climb car that did the same thing as this! think they where pushing more like 850bhp though! lolEven the H6 has been under the tuners knife!
http://www.supercars.net/cars/3278.html
dose anyone else know of this being done??
As for the 2.5's i have heard them being taken all the way out to 2.8ltr with new liners! with a nice BIG set of throttle bodeis, custom grind cams, head work, high comp. custom pistons, light weight rods and crank you should beable to see well over 300bhp.... 2.3 ford Duratecs are making 340bhp now....
also check the Ozy market. they are always building mad things so there might be more info over there.
CChris.
PS what chassis is the engine going in?? also how come you cant run the engine with the turbo??
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