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Guest Message by DevFuse

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approx size of boxer engines - pls help

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7 replies to this topic

#1 asherpat


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Posted 16 January 2006 - 06:16 PM


i am new to this forum. i am an amateur car designer. A project i am working-on now (as a hobby) is a sports car with a boxer engine. the limitations i have is to package the engine and gearbox in a very tight "box". therefore, I want to see if Subaru flat-four turbo or H-6 and its gearbox (no-need in front/rear diff, the design is rear wheel drive) can be packaged in a tight space.

Especially of importance is the height of such engines or their blocks.

I wud therefore appreciate greatly if someone can, even if approximately tell me the physical dimensions (also the weight, if possible) of Subaru's most powerful engines and gearbox (guess there are two, the H-4 Turbos and H-6). Easier still perhaps the question shud be: what is the minimal rectangular box that one can fit Subaru most powerful engines.

many tks for your help.

#2 zyewdall


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Posted 18 January 2006 - 02:38 PM

Don't have dimenions handy. Someone on here has to though. They are awfully small engines as far as height and length, but are pretty wide. Consider that the back of the engine is actually forward of the center of the front wheels on a subaru and you can see how short they are. Of course the H6 is going to be a little longer...

On the differential, the front diff on a subaru is in the transmission, so you can't take it out. But you can just put it in 4wd mode and not hook anything up to the front axle stubs. Offroaders do this all the time if they put in a divorced transfer case and nissan front diff.

Edit: that is is you have a fwd/4wd tranny from the EA cars (1989 and earlier). The EJ ones are AWD so you can't take the front axles out. But why not have an AWD sports car. Or you could use an EA tranny with an EJ engine with the KEP adaptor.

#3 mikie


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Posted 19 January 2006 - 01:29 AM

w = 830
h = 600
l = 710
l2 = 430

fresh off the tape measure for the EJ20 Quadcam, all in mm. Width is from outside edges of cam covers, hight is from bottom of sump to top of intake manifold/throttle body. Length 1 is from front pulley to firewall, length2 is from front pulley to back of motor, not including flywheel. Back edge of throttle body is pretty much parallel to the back of the block. The reason i measured to the firewall is pretty much all of this space is required for the turbo(s) and I/C in a factory setup. The motor fills all of the space in this box quite nicely, with its very sqauare cam covers, sump+exhaust config and large inlet manifold.

#4 asherpat


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Posted 19 January 2006 - 04:25 AM

Mikie, fantastic, many thanks.

In my "project" I planned that the height of the engine containing box must not be much higher than 500mm, and you measured 600mm height of the engine.

I wonder if you can assess whether the intake manifold/throttle assembly can be modified w/o too much problems to go "sideways" rather than up - to save height - or these are "hard" points, i.e., part of the main block casting, etc.?

Also, I am not very familiar with Subaru engines, is the EJ20 Quadcam the most powerful 4-cyl engine of Subaru, or has the same block (which is OK for my project, in such case). Can you also assess the weight of this engine with the gearbox and diff. Even very approximate is ok for me, i.e., is it 100 kilos, 200, 300, etc., or north of 500kg?

Thanks again!

#5 keltikrewser


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Posted 19 January 2006 - 10:22 PM

this site has lots of links with dimensions


goood luck!

#6 mikie


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Posted 20 January 2006 - 12:20 AM

THe inlet manifold is very compact and flat, you wont be able to do much there. the throttle body faces rearward. On the bottom of the engine the sump looks large but the exhaust also hangs down on each side, you will be very hard pressed to gain anything there either.

THe EJ20 quadcam turbo engine is that used in the Impreza WRX rally car, and its a powerful engine with aftermarket support. Its been around since 1989 and in various revisions to the present day. The only other engine worth considering is the 3l flat six non-turbo sub engine, i have no info on it. Its nice to drive, but not 'stimulating'.

Weight of the ej20dohc may be 120kg, manual box maybe 60 kg.

#7 asherpat


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Posted 20 January 2006 - 07:14 PM


many thanks mate, have a nice weekend.

#8 spyder550


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Posted 22 January 2006 - 03:20 PM

Hi Felix
Not sure what I can really tell you. Engine wise it would depend on how theoretical or practical your project is. Most of the flat 4,or 6 engines can be made lower if you are prepared to custom build ancillary components.

E.G for the Subaru you can buy shallower sumps from Australia and lose some height there (or maybe dry sump). If you were prepared to build a new inlet manifold you could probably use 4 small motorcyle throttle bodies instead of the Subaru manifold and lose some height. That would leave you the alternator as the highest point, but there is a motorsports trick to mount it above the gearbox and drive it from a pulley via the driveshaft outputs .

Porsche lumps normally have the aircooled fan housing making them tallish, though you can get horizontal fan conversion which are low. The current watercooled flat 6's in the Boxster may be ok as Porsche often fit dry sumps to their cars to be able to fit the engine lower.

Apart from that the Mazda rotary is VERY small, I looked at one and the block was about 13" in diameter and although the ancillaries are on top of the engine you can
realocate the alternator, and get side draught induction system which would reduce the height to less than 500mm. You can get remote electric water pumps too which would help.

May I suggest contacting http://www.kennedyeng.com they do nice little catalogue you can order, and it includes all sorts of engine dimension stuff.

Apart from car engine, perhaps a large tuned bike engine these are very small very light with integral gearboxes and will put out over 200bhp at times.

Remember anything is possible just depends what budget you have.


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