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EA71 Pistons

EA71 Piston Engine

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62 replies to this topic

#1 Twitch de la Brat

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Posted 31 May 2013 - 01:10 AM

Looking for new/nearly new EA71 pistons for a high comp EA81 build.

And finding these little buggers is proving to difficult. Not more than I anticipated, but still tough.

I can get ring sets all day long, but the pistons themselves are tougher finds.

I'd go to a wrecking yard and get some, but with as much strain as they'll be under, I don't want to toss something in there that may have issues.

Because pulling this motor back apart may not be an option for some time.

And it'll be dealing with me trying to tune it and figure out what octane it'll take it to prevent ping...

Anyway, anyone got any to sell? I've got cash and am willing to deal.

 

Twitch

 

PS: OEM Part number is 380050100 if anyone was wondering


Edited by Twitch de la Brat, 31 May 2013 - 01:11 AM.


#2 NorthWet

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Posted 31 May 2013 - 01:25 AM

Not answering your request, but...

 

Have you considered EA82 SPFI or MPFI pistons?



#3 Twitch de la Brat

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Posted 31 May 2013 - 08:38 AM

I have, and after taking with someone who's done multiple builds, the SPFI/MPFI pistons just don't make as much power as the flat top EA71's.
And I'd hate to get mostly through this and half-rump roast the pistons.
Plus finding new/low mileage SPFI pistons is proving almost as difficult as EA71's.

Twitch

#4 ivans imports

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Posted 31 May 2013 - 09:41 AM

dont use them weak between the ring lands use loyale ea82 pistons have a thin ring on top lands the ea71 has thick uper ring that makes piston crack between the ring lands



#5 Twitch de la Brat

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Posted 31 May 2013 - 03:15 PM

What circumstances make them crack?
Like, what shape were the engines that had the cracked pistons?
Thanks for the input, but I need to know what makes them crack, like normal use, or severe abuse. Because if the pistons last 50k, that's good enough for me.

Twitch

#6 ivans imports

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Posted 01 June 2013 - 10:03 AM

any one i pushed over 6500 rpms even new ea71 piston have seen broken cant take the rpms. I whould never use a thick  uper ring piston



#7 Twitch de la Brat

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Posted 01 June 2013 - 10:54 AM

Ok. That's actually not a big deal in my case because I'm running a torque cam in it and will rarely see anything above 5000-5500.
And I don't think I've ever pushed my stock motor that high...
Thanks for your input though :)
I'll do some research on piston design and why they fail to give me a better potential for endurance.

Twitch

#8 NorthWet

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Posted 01 June 2013 - 11:38 AM

IIRC, the usual cause of top land failures is a loose fit between the ring and the groove wall that causes the ring to pound on the lands as the piston reverses travel.  Anything that causes the groove to wear (mileage, damage while cleaning the groove, extra ring mass from a thick ring) will aggravate/accelerate the issue.  The distance between the top ring and the piston crown is also a factor.

 

My apologies for being the first one to open this distraction from your post.



#9 turbosubarubrat

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Posted 01 June 2013 - 11:59 AM

the first link first result is the best deal at $140 with pisons and rings or by pistons $50 apiece and have to buy rings

http://www.ebay.com/...cat=0&_from=R40

http://www.ebay.com/...2&_skc=50&rt=nc



#10 Crazyeights

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Posted 01 June 2013 - 05:21 PM

the first link first result is the best deal at $140 with pisons and rings or by pistons $50 apiece and have to buy rings

http://www.ebay.com/...cat=0&_from=R40

http://www.ebay.com/...2&_skc=50&rt=nc

I have done 2 EA engines with the ebay "thompson-engine" piston and ring sets and they work well.


Edited by Crazyeights, 01 June 2013 - 05:22 PM.


#11 Twitch de la Brat

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Posted 01 June 2013 - 08:45 PM

The only problem is I'm looking for EA71 pistons.
I have EA81 pistons that are just fine. I can re-ring them no problem.
I was looking for higher compression EA71 pistons.
They actually are approx .020" taller than EA81 pistons if I remember reading the thread right.
And that's perfect for me.
Because that'll leave me with about .020-030" between the head and the piston crown. :grin:

Twitch

#12 NorthWet

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Posted 01 June 2013 - 09:31 PM

On that second eBay link,  the 10th item claims to be for 78-80 brats.



#13 bonvo

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Posted 02 June 2013 - 02:20 AM

i have pistons but there in a short block currently



#14 LeoneTurbo

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Posted 02 June 2013 - 02:26 AM

EUDM EA81 and EA71 engines use the same pistons (ie. EUDM EA81 has higher compression ratio than USDM EA81). I've never seen EA71 (or therefore EA81) pistons fail because of high rpm's. The EA71S engine with twin carbs spins easily to 7k rpm reliably.



#15 ivans imports

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Posted 04 June 2013 - 09:08 AM

I whould plane the block down to increase the comp ratio before i whould change pistons with a good ea82 / late ea81 pistons it whould rev to 7000rpms all day. We had a ea71 in a buggy ran it to death it shatered all 4 pistons of the rods and still turned over and crank was ok pistons just came apart thiss one saw 8000rpm + for hours never jumped a push rod or bent a valve just broke pistons



#16 Twitch de la Brat

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Posted 04 June 2013 - 07:02 PM

I'm already shaving the block ;) :grin:
Its losing a total of .030 off each side.
And being able to run an EA71 for 8000 rpm for hours is good enough for me to run it in my high comp motor. This thing won't be seeing nearly that kind of abuse. It'll be my DD/Honda eater. Most of the time it'll be humming along at 2-3k, sometimes pushing up to 4 on the freeway. Its all about torque here man.
And it seems EA71 pistons hold up just fine to torque applications. But I'll be finding out soon if I will be buying EA71 or EA82 pistons. It all depends on availability now.

Twitch

#17 ivans imports

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Posted 05 June 2013 - 09:24 AM

Also the ea71 pistons have a sloted oil ring oil feed grove the ea82 has a drilled oil ring feed holes thiss makes the pistons way stronger as they break on the sloted oil ring grove 94 ea82 flat tops best for strength with drilled oil feed holes



#18 Twitch de la Brat

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Posted 05 June 2013 - 01:52 PM

Ok, show me where the EA82 spfi pistons make as much power as the EA71's. From those who have used both in high performance builds, high revving to torque monsters.
And that potential for cracking is why I'm going with brand new/barely used. This engine will have an oil cooler, a high flow radiator, 2 cooling fans, and a mechanical temp gauge on both the oil and the cooling system. Overheating shouldn't be a problem on this engine, so heat fractures in the pistons should be minimal.

Twitch

#19 ivans imports

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Posted 06 June 2013 - 09:40 AM

Its not about how mutch power you make its about how reliable it makes it whats the actual comp diference ? have seen the ea82 pull 8500 rpms no broken pistons the spi ones are very strong. I have a 80 ea71 with ea82 carb this engine is strong but was alway afraid of breaking the pistons have been siting on this engine for years. Will drag it out and put ea82 spi pistons in it and rebiuld her and let you know how it runs in my old brat will see what it can take. Whats the highest rpms that anyone has seen a ea71 rev to ?



#20 junk250

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Posted 07 June 2013 - 12:24 AM

Rock Auto has Beck-Arnley EA-71 pistons with rings for 27.79 each.

 

I searched 1979 dl / engine / piston.

 

Hope this might help !


Edited by junk250, 07 June 2013 - 12:28 AM.


#21 Twitch de la Brat

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Posted 07 June 2013 - 09:17 PM

Rock Auto has Beck-Arnley EA-71 pistons with rings for 27.79 each.
 
I searched 1979 dl / engine / piston.
 
Hope this might help !


I already looked. There's only 3 available >_<

I'm worried about power. As I already said it won't be revving high.
I'm talking about sheer power. I looked at the EA82 pistons, and after talking with someone who's built a couple of these motors said the EA71's build more power.

Twitch

#22 junk250

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Posted 08 June 2013 - 12:24 AM

I'm not up on performace Subarus , but I was a VW BUG mechanic back in the day and built a bunch of BUG engines(mostly stock).

 

Its amazing how similar VW and Subaru engines are, you have 1100, 1200, 1300, 1400, 1500, 1600, 1800 ect., and almost any combination of  parts might fit.

 

With the VW, the 71' on 1600 thin stud block was supposed to be best, then you had many combinations of crank, heads, pistons, cams that could be used in a build.

 

I had a 56' 40 horse 1200 BUG that would cruise at 70 mph all day long.

 

The OHV boxer is a neat motor.


Edited by junk250, 08 June 2013 - 12:39 AM.


#23 Crazyeights

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Posted 15 June 2013 - 11:36 PM

I have a HP EA81 going together now.  I have sets of EA71, EA81, and EA82 SPFI pistons available.  I'll install one of each type of piston (without any rings) to see what the measurements are at TDC. I'll also try and post a photo of the different types.


Edited by Crazyeights, 16 June 2013 - 11:52 AM.


#24 Twitch de la Brat

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Posted 17 June 2013 - 12:39 AM

Thank you Crazyeights. That will help immensely.

 

Twitch



#25 Tsuru

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Posted 17 June 2013 - 10:54 PM

yay! Scientific factual information!

I am lurking on this one out of sheer morbid fascination!







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