Ibreakstuff Posted March 5, 2015 Share Posted March 5, 2015 (edited) Just looking for some confirmation based on a recent epiphany. We know there are 3 "generations" of MPFI heads, but I am looking for how many molds there were and if each/any have subtle changes. I have found at least 8 different casting numbers and the molds seem to vary slightly. In my possession are MPFI heads with castings numbers TK4 TK6 TK7 TK9 TK10. And recently some EDM heads were posted with pictures showing TK8 (Thanks Drischnie). I know that TK3 and TK5 exist also, just from my stash of pictures. I should note also that most of my heads are from turbo cars, I would be interested to see some heads from NA mpfi EA's (XT4's in the states). The only actual differences between the head revisions seems to be the casting material and the quality of the cast itself. I think it is a myth that Subaru beefed up the bridge between valves and my calipers can't measure any differences. The TK9 heads seem to be the best quality castings imho and I have found a few of them without cracks over the years. I will avoid TK10 heads in the future. What my research has found: TK3 EA82 No lines (gen1) ? TK4 EA82 Underlined (gen2) USDM dot high above stamp TK5 EA82 Underlined (gen2) ? TK6 EA82 Underlined (gen2) USDM line above stamp TK7 EA82 Underlined (gen2) USDM dot just above stamp between E and A TK8* EA82 Underlined (gen2) EDM (thanks Karhu for posting) TK8* EA82 Box (gen3) EDM (thanks Drischnie for posting) TK9 EA82 Box (gen3) USDM smooth/worn casting lines but tight aluminum grains TK10 EA82 Underlined (gen?) USDM both examples I have sharp casting lines but are porous and brittle Notes/etc: -I ordered them by casting numbers, but I am not sure this would be the order they were molded chronologically. TK10 being underlined (often referred to as gen2) is what makes me question this. -The casting number can actually be viewed on the top of the head externally, it will say JAPAN #. The number will match the TK# stamp inside. -The combustion chamber shape appears to be the same on every head except the TK8 head posted by drischnie. This mold intrigues me. -Above the EA82 stamp are 2 numbers, these appear to be the date of the casting. Just month and day, not year unfortunately. I could be wrong and this could just be batch numbers, but the top number is lower than 12 and the second is lower than 31 (that I have found)Any input? Comments?edit: -Added second TK8 EDM head Edited March 8, 2015 by Ibreakstuff Quote Link to comment Share on other sites More sharing options...
Ibreakstuff Posted March 5, 2015 Author Share Posted March 5, 2015 TK9: TK8: *note the combustion chamber shape Quote Link to comment Share on other sites More sharing options...
Loyale 2.7 Turbo Posted March 5, 2015 Share Posted March 5, 2015 One small question: Are you Sure that all those are MPFi? None are for the SPFi / Carb Setup? Kind Regards. Quote Link to comment Share on other sites More sharing options...
Ibreakstuff Posted March 5, 2015 Author Share Posted March 5, 2015 One small question: Are you Sure that all those are MPFi? None are for the SPFi / Carb Setup? Kind Regards. 100% positive. All of the heads I own came from turbo cars, RX's mostly. I have 9 heads sitting in the dining room (my wife hates me), all are dual intake heads. I can take pictures of each if you desire. 1 Quote Link to comment Share on other sites More sharing options...
Loyale 2.7 Turbo Posted March 5, 2015 Share Posted March 5, 2015 100% positive... OK, thank you for your Kind Answer. ... All of the heads I own came from turbo cars, RX's mostly... all are dual intake heads... You're a Lucky guy ... Those are Rare / Scarce now. People in need for replacements will pay good money for them. ... I have 9 heads sitting in the dining room (my wife hates me)... I understand that Feeling... Also My Wife & Daughter doesn't want to see my Automotive stuff around our home... ...I can take pictures of each if you desire. That is not needed for me, I believe you. However sharing pictures of them Side by Side, pointing their Differences, is a good idea, in my own humble opinion. The Non-USDM Turbo EA82's makes a little more Hp because of the less restricted Pollution / Fuel consumption controls & legal regulations, and thus might explain the difference on the Combustion Chamber, found on the European Specs EA82T Heads, compared to the US Specs ones. Kind Regards. Quote Link to comment Share on other sites More sharing options...
Loyale 2.7 Turbo Posted March 5, 2015 Share Posted March 5, 2015 (edited) I can see that the TK9 heads has an almost Flat, combustion chamber that seems to be less deeply "Carved" on the Head, while the TK8 heads has the combustion chamber, "Carved" Deeper on the Heads, also they're Not Flat, they goes even Deeper between the intake and the exhaust valves. Even if the Shape of the Piston's Heads are the same used on both Heads, there will be certain change of Compression between the engines featuring the TK8 and the TK9 heads; I bet that different pistons were used on the Different heads as well. The Logic says that 9 shall be "newer" than 8, and the lack of that deep "V" shape between the intake & exhaust valves on the TK9 head, might be intended as a reinforcement, to avoid the usual Cracks that the EA82 engine's heads tend to have, after certain use / overheatings. Kind Regards. Edited March 5, 2015 by Loyale 2.7 Turbo Quote Link to comment Share on other sites More sharing options...
Ibreakstuff Posted March 5, 2015 Author Share Posted March 5, 2015 OK, thank you for your Kind Answer. You're a Lucky guy ... Those are Rare / Scarce now. People in need for replacements will pay good money for them. I understand that Feeling... Also My Wife & Daughter doesn't want to see my Automotive stuff around our home... That is not needed for me, I believe you. However sharing pictures of them Side by Side, pointing their Differences, is a good idea, in my own humble opinion. The Non-USDM Turbo EA82's makes a little more Hp because of the less restricted Pollution / Fuel consumption controls & legal regulations, and thus might explain the difference on the Combustion Chamber, found on the European Specs EA82T Heads, compared to the US Specs ones. Kind Regards. My wife only allows one room of the house to have car parts, nothing with smelly transmission fluid either. I traded some closet space for that clause in the contract LOL. I had to have a place to measure/blueprint parts at a normalized temperature, the garage temps swing wildly. With the heads, I'll make an effort to lay them out later and take pictures later today. Most are super dirty, I still have a lot of cleaning to do. Regarding the Euro spec cars, I thought that it was just the computer (EGT vs O2 controlled), and cat free exhaust that opened up the extra power. That TK8 head is the only one I have ever seen with that chamber shape, I sent her a offer on them.. if nothing else to document and cc the chamber volume for comparison. I appreciate the kind words Jeszek 1 Quote Link to comment Share on other sites More sharing options...
Ibreakstuff Posted March 5, 2015 Author Share Posted March 5, 2015 I can see that the TK9 heads has an almost Flat, combustion chamber that seems to be less deeply "Carved" on the Head, while the TK8 heads has the combustion chamber, "Carved" Deeper on the Heads, also they're Not Flat, they goes even Deeper between the intake and the exhaust valves. Even if the Shape of the Piston's Heads are the same used on both Heads, there will be certain change of Compression between the engines featuring the TK8 and the TK9 heads; I bet that different pistons were used on the Different heads as well. The Logic says that 9 shall be "newer" than 8, and the lack of that deep "V" shape between the intake & exhaust valves on the TK9 head, might be intended as a reinforcement, to avoid the usual Cracks that does heads tend to have, after certain use / overheatings. Kind Regards. I came to similar conclusions, it would be interesting to compare the actual changes in chamber volume and how that would effect the compression ratio (lower in the TK8 head). The one flaw to the theory is that the even older molds have the same flat shape as the TK9 head. Over the years on the USMB, it has been quoted that Subaru made changes to the bridge area in the heads. But I see nothing to indicate that they did, at least between gen2 and gen3, other than the casting quality. I know the pressure and temp of the casting will have an effect on ductility and some of these are definitely better castings than others. This is hard to show in a picture too. 1 Quote Link to comment Share on other sites More sharing options...
Ibreakstuff Posted March 5, 2015 Author Share Posted March 5, 2015 This was an enigma to me, surprised no one else has pointed it out over the years. There is only one thread that points out the casting numbers and its on ausubaru. Quote Link to comment Share on other sites More sharing options...
Loyale 2.7 Turbo Posted March 5, 2015 Share Posted March 5, 2015 ...I appreciate the kind words Jeszek You're welcome my friend, I only try to help. My wife only allows one room of the house to have car parts ... the garage temps swing wildly... In my case, I traded closet space also, but only for New parts that I store, usually NOS Subaru Parts; and certain valuable tools, such like the OBD II Scanner. Thanks God our Caribbean climate is very templated and doesn't swing, because I store the Rest on a Big Plastic storage Box, at the open garage whose roof doesnt cover the sides (I planted a -now Huge- Pine tree). ... I know the pressure and temp of the casting will have an effect on ductility and some of these are definitely better castings than others. This is hard to show in a picture too... Yes, I've notice a casting improvement on other engines, from the weight they have, there shall be more material put under more pressure, to make stronger parts, so you can measure the different weights of the Heads. ... it would be interesting to compare the actual changes in chamber volume and how that would effect the compression ratio ... ... I sent her a offer on them.. if nothing else to document and cc the chamber volume for comparison... That would be Awesome! ... Regarding the Euro spec cars, I thought that it was just the computer (EGT vs O2 controlled), and cat free exhaust that opened up the extra power... That might help a little, the LADM (Latin American Domestic Market) Specs Subarus from that vintage, came without both catalytic converters as well. ... There is only one thread that points out the casting numbers and its on ausubaru. That thread @ AUSubaru is this: ~► http://www.ausubaru.com/forum/showthread.php?t=15800 There is also, another thread there, where a guy even cut the heads in half to make a dissection and study the total size / amount of material between valves, water jackets, etc... and document the differences between heads. ~► http://www.ausubaru.com/forum/showthread.php?t=15810 Kind Regards. Quote Link to comment Share on other sites More sharing options...
ccrinc Posted March 5, 2015 Share Posted March 5, 2015 In the USA, the only real difference that I know of is a change NOT between the valves, but in the exhaust ports. Comparing the 3 gens here, it is very easy to see how Subaru beefed up the metal in that area because that is where they failed most often. Quote Link to comment Share on other sites More sharing options...
jono Posted March 5, 2015 Share Posted March 5, 2015 aha, I thought Drischnies heads were different in the combustion area and thought that was the GEN3 difference, but obviously not from the sounds of this thread. They look like decompression to me, maybe std flat top pistons were used with these heads the TK8 of Deutchland ? There is another quirk between some markets and part of the power increase thought to be - the throttle position sensor angles of action differ if you read the factory manuals of the 85,86 series you may find what i thought I found - a few degrees difference in the on off switching degrees within the TPS ?? Quote Link to comment Share on other sites More sharing options...
drischnie Posted March 6, 2015 Share Posted March 6, 2015 (edited) in Europe we had three Versions of the EA82T models. without catalysator: 136PS and 196nm with catalysator: 131Ps and 192nm with 3-way-catalysator: 120PS and 183nm If thats help, here the standard part numbers of the EA82T EDM Models over the years: right side: 11039AA640 11039AA641 11039AA642 11039AA644 11039AA711 left side: 11063AA481 11063AA153 11063AA191 11063AA192 11063AA193 11063AA453 all other head-part numbers were for the EDM EA82 NA Models, MPFI and Carb In the USA for example,the EA82T head numbers for the right side are these: 11039AA010 11039AA011 11039AA012 11039AA013 11039AA780 these numbers are the Same numbers on the JDM EA82T Models. Edited March 6, 2015 by drischnie Quote Link to comment Share on other sites More sharing options...
Karhu Posted March 6, 2015 Share Posted March 6, 2015 just looked one of my engines, EA82T in -89 Leone Touring Wagon, with "underlined EA82" heads, and they says "8 JAPAN" on top of the heads. EDM model of course. I can check sometimes my other engines with mpfi/turbo heads, if it helps with this, i have examples from all three generations in XTs and Leones. Quote Link to comment Share on other sites More sharing options...
Ibreakstuff Posted March 7, 2015 Author Share Posted March 7, 2015 just looked one of my engines, EA82T in -89 Leone Touring Wagon, with "underlined EA82" heads, and they says "8 JAPAN" on top of the heads. EDM model of course. I can check sometimes my other engines with mpfi/turbo heads, if it helps with this, i have examples from all three generations in XTs and Leones. Odd, so it seems that TK8 head can come both in underline and boxed EA82 then? Are you sure it didn't say "6 JAPAN"? Any idea what the combustion chamber looks like? Quote Link to comment Share on other sites More sharing options...
Karhu Posted March 7, 2015 Share Posted March 7, 2015 (edited) Are you sure it didn't say "6 JAPAN"? Any idea what the combustion chamber looks like? Absolutely sure that´s 8: I´m going to resealing that engine, and i will take some photos of combustion chambers when heads are taken off. You see there is some coolant in wrong place. I think intake manifold gaskets are gone, but there was some other oil/coolant leaks so i took engine up. I am interested of those different head designs, because i've planned to build "high performance EA82T" with using best parts from its era. So, in future, I intend to disassemble three engines: MPFI N/A, Turbo with "spider" intake and one other turbo with Gen3 heads. In this connection, i would compare those EDM heads and share results here. Edited March 7, 2015 by Karhu Quote Link to comment Share on other sites More sharing options...
Ibreakstuff Posted March 8, 2015 Author Share Posted March 8, 2015 Thanks for confirmation Karhu. So it would appear there are 2 different TK8 EDM heads, one underlined (gen2) and one boxed (gen3).I ended up coughing up the dough for Drischnie's heads, when they arrive I'll put some valves in and CC the combustion chamber. Then we can compare it to the USDM spec heads (which I think are around 39cc in the heads). I have a piece of plexi with a hole drilled for that. 1 Quote Link to comment Share on other sites More sharing options...
Loyale 2.7 Turbo Posted March 8, 2015 Share Posted March 8, 2015 ... I ended up coughing up the dough for Drischnie's heads, when they arrive I'll put some valves in and CC the combustion chamber... Awesome! ... Keep us Updated. Kind Regards. Quote Link to comment Share on other sites More sharing options...
Caboobaroo Posted March 8, 2015 Share Posted March 8, 2015 I have a MPFI XT engine at work that is NA. Will try and get you the desired numbers tomorrow. Quote Link to comment Share on other sites More sharing options...
Karhu Posted March 20, 2015 Share Posted March 20, 2015 (edited) My other -88 EA82T wagon with EA82 heads, says "2 JAPAN". This is what i can see with flashlight, top of the driver's side head only. EDM. Edited March 20, 2015 by Karhu Quote Link to comment Share on other sites More sharing options...
-tombba- Posted May 13, 2015 Share Posted May 13, 2015 Heres some more EDM heads: TK 6 not underlined. Taken from turbo engine: https://www.dropbox.com/s/rpvpyq2l263ucaw/2015-05-13%2019.57.47.jpg?dl=0 TK 5 underlined. Taken from NA MPFI engine: https://www.dropbox.com/s/uul1qb941fwxkp7/2015-05-13%2020.00.05.jpg?dl=0 I also have a set of gen 3 heads that I have to check what casting mark do they have in them. But that will take a while Quote Link to comment Share on other sites More sharing options...
jono Posted May 13, 2015 Share Posted May 13, 2015 100% positive. All of the heads I own came from turbo cars, RX's mostly. I have 9 heads sitting in the dining room (my wife hates me), all are dual intake heads. I can take pictures of each if you desire. yeah , but we love ya ! 1 Quote Link to comment Share on other sites More sharing options...
jono Posted May 14, 2015 Share Posted May 14, 2015 these differences have me thinking....wouldn't you think that the Japanese would keep the best, most efficient, up-to-date with development heads for their own market? I wonder if EDM use standard flat top or not so dished pistons given the extension of space in the roof of the EDM head ? Quote Link to comment Share on other sites More sharing options...
drischnie Posted May 15, 2015 Share Posted May 15, 2015 i hope Ibreakstuff will write soon here. he bought my new EDM heads. Quote Link to comment Share on other sites More sharing options...
scoobiedubie Posted May 16, 2015 Share Posted May 16, 2015 (edited) Just looking for some confirmation based on a recent epiphany. We know there are 3 "generations" of MPFI heads, but I am looking for how many molds there were and if each/any have subtle changes. I have found at least 8 different casting numbers and the molds seem to vary slightly. In my possession are MPFI heads with castings numbers TK4 TK6 TK7 TK9 TK10. And recently some EDM heads were posted with pictures showing TK8 (Thanks Drischnie). I know that TK3 and TK5 exist also, just from my stash of pictures. I should note also that most of my heads are from turbo cars, I would be interested to see some heads from NA mpfi EA's (XT4's in the states). The only actual differences between the head revisions seems to be the casting material and the quality of the cast itself. I think it is a myth that Subaru beefed up the bridge between valves and my calipers can't measure any differences. The TK9 heads seem to be the best quality castings imho and I have found a few of them without cracks over the years. I will avoid TK10 heads in the future. What my research has found: TK3 EA82 No lines (gen1) ? TK4 EA82 Underlined (gen2) USDM dot high above stamp TK5 EA82 Underlined (gen2) ? TK6 EA82 Underlined (gen2) USDM line above stamp TK7 EA82 Underlined (gen2) USDM dot just above stamp between E and A TK7 EA82 Box (gen 3) TK8* EA82 Underlined (gen2) EDM (thanks Karhu for posting) TK8* EA82 Box (gen3) EDM (thanks Drischnie for posting) TK9 EA82 Box (gen3) USDM smooth/worn casting lines but tight aluminum grains TK10 EA82 Underlined (gen?) USDM both examples I have sharp casting lines but are porous and brittle Notes/etc: -I ordered them by casting numbers, but I am not sure this would be the order they were molded chronologically. TK10 being underlined (often referred to as gen2) is what makes me question this. -The casting number can actually be viewed on the top of the head externally, it will say JAPAN #. The number will match the TK# stamp inside. -The combustion chamber shape appears to be the same on every head except the TK8 head posted by drischnie. This mold intrigues me. -Above the EA82 stamp are 2 numbers, these appear to be the date of the casting. Just month and day, not year unfortunately. I could be wrong and this could just be batch numbers, but the top number is lower than 12 and the second is lower than 31 (that I have found) Any input? Comments? edit: -Added second TK8 EDM head Add a TK7 Gen 3 to this list. I have it sitting right in front of me. Edited May 16, 2015 by scoobiedubie Quote Link to comment Share on other sites More sharing options...
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