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  1. IFMT


    Thanks for the interest Ed. The ea71 is the 1600cc. The only dimension I can find through internet part searching is the bore at 92 mm. Same as ea81. 1600cc has shorter stroke. I know the simple answer is to take the .040 off the heads but then I have to make another manifold. I saw that RAM sells manifold adapters. I want to keep my 2 barrel carb set up as I already have it as it works. I do have carb heat but with the stock manifold I can't say I've ever needed it. Another thing with the carb heat and the stock manifold is that I can't tell any difference with it on or off. Not like an aviation engine where the RPM drops with carb heat applied. Might help the HP with dense cold air. What is the size of the 'bigger' valves. The engine I want to rebuild will need a complete going through. I see it was opened up before and whoever did this was sloppy. Pistons switched left and right and wrong washers under nuts on heads. I'm a licensed heady duty mechanic. I know that doesn't mean much but I do understand attention to detail and building this things absolutely right. I'm going to order a set of the 71 pistons and try it. Where is the extra groove on the cam. This engine is hydraulic lifter.  Cheers.

  2. Av8r3400


     

    Guess the 912 might be about the same as 582 if it only has head cooling.  Thanks.

     

     

    Kitfox uses the same belly radiator for both.

     

    My friend who used to have the Suby powered Kitfox used a VW radiator (I think), mounted as a scoop on the belly.

     

    Here is a similar setup on a Rans S7 under construction.

     

    Rad3.jpg

  3. EDMO


    I CANT FIND the posts where we were talking about using EA-71 pistons in an EA-81 to raise the compression.  So, What is the 71?  Is that the 1600cc, with same bore but shorter stroke - where the 81 is about 1800cc?

    I looked in my Chilton Subaru book tonight and here is what I found on the EA-81, but no other piston dimensions were given - just clearances.

    1980-84

    Turbo charged = 7.7 compression ratio, 95 hp, at 4800 rpm

    2 barrel carb = 8.7 ratio, 72-73 hp at 4800 rpm

    1985-87

    2 barrel carb = 9.5 ratio, 82 hp at 4866 rpm

    MPFI            = 9.0 ratio, 94 hp at 5200 rpm

    SPFI            = 9.5 ratio, 90 hp at 5600 rpm

    Turbo           = 7.7 ratio, 111 hp at 4800 rpm

         Now, the question is:  Other than the Turbo, did they change pistons to change compression, or did they do something else.  I don't have a clue!

    I was told that milling the heads .040 would raise the compression from 8.7 up to 9.1 on the early models. 

    And that the automatic trans had bigger valves and hydraulic lifters instead of solid - and that the cams will not interchange - the hydraulic cam has an extra groove around it for identity - and no adjustment on rockers.

    but you could have the heads machined to take the bigger valves with the solid lifters.

    NOTE:  These hp ratings are for the original engines in cars - for planes, the hp is rated higher.

    Hope this info is usefull to someone.

    EDMO

  4. EDMO


    Thanks for the info.

    Better check the fins and tubes on these - I have read that heater cores don't cool the water as much as a radiator the same size.

    A/C evaporators from Chevy - not Ford tho - were used as cheek rads by some conversions, and they are supposed to work well.

    Since the EA-81 is 1800cc - more than 3 times the volume as a 582, I don't think they will interchange - they might be an added cooling for a belly rad on the Soob.

    Appreciate the thought.

    EDMO

    Guess the 912 might be about the same as 582 if it only has head cooling.  Thanks.

  5. allonsye


    Ed -

     

    I've a source for these:

     

    NIB Aluminum Spectra Premium 94553 Heater Core Without A/C 1973-86 Chevy Truck

     

    They're 6.5 x 8". Light as a feather. $15 each -- 1/2 what the auto parts stores charge. Ping me and I'll send you their email addy.

     

    Combined, they're dimensionally same cooling area as the spendy vertical, reduction drive mounted  Rotax radiators and enormously cheaper.

     

    I've been vexed with coming up with a solid way of mounting them that is not affected with engine movement and vibration.  The PO's on mine installation was copper and the brackets all cracked, mounted off the eng mount and the reduction drive.

     

    Anyways, I think an installation solution is to glass-in receiving pockets or brackets behind the cowl inlets that these will slide into with sealing baffles. A "Y" connection above the gear box, off the fwd eng mounts to support the weight of the lines and coolant and create parallel simultaneously flow to both radiators.

     

    Much cheaper solution than the $400 kitfox belly setup (including the radiator cowl) and would look better.

     

    On the other hand though, since you're cooling a Subie, I don't know if it'll be enough cooling for you. I thinking in terms of a 582. Have you looked at the UL912 setups to mimic that?

  6. marshawk


    Hi Ed , its a Rotec TB! -40  ,they are out of Austraila and it was around $650.00, it wasn't cheep but seems to be working well and I didn't have much room under the cowl.I didnt fly it with a regular carb so not sure of the performance differences but it got lots of good reviews

  7. IFMT


    The kitfox 3 leaf is 1 1/4 wide versus the 1 1/2 avid. You will need to bend a shim to wrap around the kitfox spring to make it work. The geometry will be off on the avid so your wheel will not track neutral. I bought one and tried it but I wasn't satisfied with the result. Went down to the local machine shop and got a heavy duty one bent. Used the old avid single spring as a backer for it. I have a lot of extra weight on the tail to counter my soob engine. Have not had trouble since.

  8. EDMO


    when you take .040 off of heads, you insert a washer under the rocker supports to maintain pushrod length - I will have to go back and read about making intake fit.   There was a used Soob dealer and repair place in Anchorage, and I could go there in their scrap bin and get parts for about what the aluminum was worth - or free.   Got a place like that near you?

    I read about making your own fiberglass intake and saving lots of weight.......There is a lighter alternator, and starter too.

    EDMO

  9. herman pahls


    I would like a stiffer tailwheel spring than the 2 leaf by 1-1/4 wide I currently have that will not raise the tail and lose angle of incidence.

    Kitfox offers a 3 leaf for their newer higher gross weight Models.

    What are you Avid flyers using and where do you source them?

    Thanks Herman

     

     

  10. IFMT


    Same bore. Wrist pin position is different. I don't have an ea71 piston to compare. Hoping somebody has actually done it. Talked to Delta cam to get the 250 cam grind and the tech said I could shave .020 on the heads and the intake would still fit. Just thinking if the piston switch works it may be a better way to go.

  11. Av8r3400


    Automotive (or motorcycle) engines run at a tiny fraction of their maximum output for the majority of the time in an automotive application.

     

    In an aircraft, the engine is operating at a very high percentage of it's maximum output, most of the time.

  12. C5Engineer


    Flew a 1.4 today after a run, tq, run tq, fly the pattern tq cycle. This motor seems a lot more powerful than my old one. Overall I am happy with it and can't wait to try it out when hot and heavy where a couple hundred rpm make a world of difference.

  13. EDMO


    First I have heard of this - have you checked the books for bore and stroke comparisons?  I've heard of using VW pistons, and oversize too, but no personal knowledge - I have a Soob specs book if you need it looked up.

    EDMO

    what size and kind of TBI is that?  Cost? I have thought of trying one of the cheaper ones if I have any trouble with my Holly, which may never happen.

    EDMO

  14. EDMO


    I was thinking - that gets me into trouble sometimes - that if they cooled an 1800cc motor on a bike in stop n go traffic, then they should cool a plane on the ground or in air. :huh:  Even if mounted farther back in cowl, if you have ducting to them?  I agree on the more cores, the better cooling.  Do they make a 4 core?

    I will have to check my VW Rabbit rad - it is probably 2 or 3 core?

    EDMO

  15. IFMT


    Any of you soob guys know anything about ea71 pistons in ea81 to up compression? I read that this will work and no shaving the heads. The intake manifold will still fit right. Finally getting around to refreshing a spare ea81 I have. Thanks.