frecobos Posted January 31, 2008 Share Posted January 31, 2008 Hi all, I have a Buggy that has an small and powerful EA81 engine and it has a custom Turbo installed. I don't have the year, but based on the thread you have regadring the EA81 manufacturing year (thanks) it looks like it was manufactured around 1984. Now it needs new pistons and I was looking for parts online. I found some afterrmarket pistons made by BECK/ARNLEY Part # 0124968 But I not sure if that's the correct piston. Their Parts description says "1984 SUBARU BRAT GL TURBO 1.8L 1781cc H4 MFI Turbo (5)" Does any one knows if by H4 their refer to the EA81 Engine? and any idea on what the "(5)" means? Thanks for any help! Just trying to know if those will fit my engine. Quote Link to comment Share on other sites More sharing options...
TheSubaruJunkie Posted January 31, 2008 Share Posted January 31, 2008 The H4 reffers to the layout. Horizontal 4 cylinder. All Subarus are H4's, except the 6cyl which are of course H6's. The description you posted is for a EA81T (turbo EA81). Is your custom Motor Fuel injected or carburated?? Quote Link to comment Share on other sites More sharing options...
audio_file Posted January 31, 2008 Share Posted January 31, 2008 welcome to the USMB! in short, yes an ea81 is a "H4" design, as apposed to say a V6 or inline 4. the "5" has to do with your vin number, if it has that 5 in a particular place in the vin or not decides exactly which ea81 variation you have i, like everyone else here, will recommend that you use the search function at the top of the screen, there is much information to be found here, if you are willing to do some digging! good luck chris Quote Link to comment Share on other sites More sharing options...
frecobos Posted January 31, 2008 Author Share Posted January 31, 2008 The H4 reffers to the layout. Horizontal 4 cylinder. All Subarus are H4's, except the 6cyl which are of course H6's. The description you posted is for a EA81T (turbo EA81). Is your custom Motor Fuel injected or carburated?? Mine is carburated. Quote Link to comment Share on other sites More sharing options...
Durania Posted January 31, 2008 Share Posted January 31, 2008 You have any pictures of your setup? Quote Link to comment Share on other sites More sharing options...
TheSubaruJunkie Posted January 31, 2008 Share Posted January 31, 2008 Carburated EA81's and Turbo EA81's have different pistons. The Turbo pistons are dished to lower the compression ratio. Your EA81, with the carburator, is a non-turbo EA81 with some type of custom Turbo installed. If you install EA81T pistons, then you will take a hit in performance. However, if you do run with the turbo pistons, you can crank your turbo up a tad to compensate for the lower compression. Quote Link to comment Share on other sites More sharing options...
frecobos Posted January 31, 2008 Author Share Posted January 31, 2008 I have been reading your web site and it is a MUST HAVE for people having Subarus. Congratulations to all the experts... ok, here are the pictures: Quote Link to comment Share on other sites More sharing options...
Durania Posted January 31, 2008 Share Posted January 31, 2008 That is a pretty crazy rig, would love to hear what that would sound like. Quote Link to comment Share on other sites More sharing options...
mcbrat Posted January 31, 2008 Share Posted January 31, 2008 awesome.... that's the set-up I should have had when I was running my holley 600.... though shooting gas into a hot turbo is not without danger Quote Link to comment Share on other sites More sharing options...
frecobos Posted January 31, 2008 Author Share Posted January 31, 2008 That is a pretty crazy rig, would love to hear what that would sound like. Actually, I was racing against other buggys and I was very competitive, in some cases I had more power. I decided to open the engine because it started to smoke from the valve covers. Guess what it had piston 3 and 4 broken.... Once I'm done I'll take a video and post the link for you. Hope it works harder than before. Quote Link to comment Share on other sites More sharing options...
mcbrat Posted January 31, 2008 Share Posted January 31, 2008 Actually, I was racing against other buggys and I was very competitive, in some cases I had more power. I decided to open the engine because it started to smoke from the valve covers. Guess what it had piston 3 and 4 broken.... Once I'm done I'll take a video and post the link for you. Hope it works harder than before. yeah, it was probably going lean due to the turbo.... what carb do you have on there? you're gonna probalby want something that can push more fuel in, or even set-up a single injector to help out when it's on boost..... Quote Link to comment Share on other sites More sharing options...
frecobos Posted January 31, 2008 Author Share Posted January 31, 2008 Carburated EA81's and Turbo EA81's have different pistons. The Turbo pistons are dished to lower the compression ratio. Your EA81, with the carburator, is a non-turbo EA81 with some type of custom Turbo installed. If you install EA81T pistons, then you will take a hit in performance. However, if you do run with the turbo pistons, you can crank your turbo up a tad to compensate for the lower compression. Thanks for the info, I'm not a mechanic (but I like it). So to be in the safe side and not having to touch the turbo, I think I can buy non turbo pistons. Their description for it says: "1984 SUBARU BRAT GL Piston - BECK/ARNLEY Part # 0124968" Do you guys think that this pistons will fit my EA81 engine or do I need to take in count something else? Quote Link to comment Share on other sites More sharing options...
WoodsWagon Posted January 31, 2008 Share Posted January 31, 2008 Are you replacing just 2 or all 4? If you're doing all 4, using turbo pistons will probably lower your compression ratio, which is good for a turbo motor because the detonation that cracked your pistons is caused by boost+timing+lean mix+high comp. Lowering the compression a bit will lead to a more durable motor, though less off-boost power. Oh, and that big spring on the wastegate actuator may be leading to boost spikes. do you have a boost gauge on the engine that you can watch while driving? Sick buggy. I have acces to a similar frame, just missing a lot of parts. Quote Link to comment Share on other sites More sharing options...
frecobos Posted January 31, 2008 Author Share Posted January 31, 2008 yeah, it was probably going lean due to the turbo.... what carb do you have on there? you're gonna probalby want something that can push more fuel in, or even set-up a single injector to help out when it's on boost..... The carburator is a Holley 7448 2 Barrel When I bought this buggy it was smoking black smoke, So I changed the Main jets from 85 to 79 (on 78 I lost power). Can that probably be the problem?... I dont want to be doing this work every year :-\ Quote Link to comment Share on other sites More sharing options...
frecobos Posted January 31, 2008 Author Share Posted January 31, 2008 Are you replacing just 2 or all 4? If you're doing all 4, using turbo pistons will probably lower your compression ratio, which is good for a turbo motor because the detonation that cracked your pistons is caused by boost+timing+lean mix+high comp. Lowering the compression a bit will lead to a more durable motor, though less off-boost power. Oh, and that big spring on the wastegate actuator may be leading to boost spikes. do you have a boost gauge on the engine that you can watch while driving? Sick buggy. I have acces to a similar frame, just missing a lot of parts. I planning on replace all 4. The boost gauge gets up to 6 psi maximum. Quote Link to comment Share on other sites More sharing options...
Numbchux Posted February 1, 2008 Share Posted February 1, 2008 I found some afterrmarket pistons made by BECK/ARNLEY Part # 0124968 But I not sure if that's the correct piston. Their Parts description says "1984 SUBARU BRAT GL TURBO 1.8L 1781cc H4 MFI Turbo (5)" to answer your original question. all brat's have the EA81 engine (in the US, anyway...). so, yes, those are EA81 pistons. but, being for a turbo, they have a different shape to allow for a lower compression ratio. so they are interchangeable, but not the same. if you're looking to drop your CR, these are perfect. Quote Link to comment Share on other sites More sharing options...
GeneralDisorder Posted February 1, 2008 Share Posted February 1, 2008 Get some forged pistons from RAM. Obviously you need better than stockers if you are grenading them with that turbo setup. That thing is rough, and getting it tuned will be interesting. Best to have the added protection of the forged pistons. Beyond that, if you still want stock pistons, I would just get a used set from a board member or new ones from the dealer. As long as they aren't torn up badly, they need not be new. It's the rings that really matter..... And since I'm on the subject - get regular sintered iron rings - the chrome one's are no good for the EA81's as they take FOREVER to seat in. As in 20,000 miles or more. The EA81's almost never wear their bore's if properly maintained (you can still see cross-hatching after 200,000 miles) so they take forever and a day to seat the rings if they are chrome. You will also eat the liners out of the block with chrome rings and these blocks can't really be sleeved easily. GD Quote Link to comment Share on other sites More sharing options...
frecobos Posted February 1, 2008 Author Share Posted February 1, 2008 Since I'm changing pistons, engine is already open.... Having this setup, Would you guys recommend to install oversized pistons, lets say to 0,5? Quote Link to comment Share on other sites More sharing options...
GeneralDisorder Posted February 2, 2008 Share Posted February 2, 2008 Since I'm changing pistons, engine is already open.... Having this setup, Would you guys recommend to install oversized pistons, lets say to 0,5? NO. Boreing without a bore plate will result in the sleeves spinning in the block. Hone only, no oversize pistons. If you need oversize then you need a new block. GD Quote Link to comment Share on other sites More sharing options...
mykingcrab Posted February 3, 2008 Share Posted February 3, 2008 The carburator is a Holley 7448 2 BarrelWhen I bought this buggy it was smoking black smoke, So I changed the Main jets from 85 to 79 (on 78 I lost power). Can that probably be the problem?... I dont want to be doing this work every year :-\ Welcome to the club!! These are worth every penny great info http://www.marshallinstruments.com/air_fuel_gauge.cfm Nice buggy, nice old school set up. This turbo/carb set up (I believe) is called "draw thru". Quote Link to comment Share on other sites More sharing options...
mellow yellow Posted February 6, 2008 Share Posted February 6, 2008 Actually, I was racing against other buggys and I was very competitive, in some cases I had more power. I decided to open the engine because it started to smoke from the valve covers. Guess what it had piston 3 and 4 broken.... Once I'm done I'll take a video and post the link for you. Hope it works harder than before. Looks like you have a real fun toy there!! G. D. Is right you do want forged pistons, but even the best pistons and can only handle so much abuse ( being run lean) when you start adding boost you need to add fuel. Would like to know what fuel system your running, and can only assume from picture. When you rebuilt engine I would advise using a two stage fuel pump and pressure sensitive regulator. the Mallory electric is adjustable on the low side and runs up to 37 psi. on the high side along with a mallory boost sensitive pressure regulator that is vacum activated, using a return fuel line to your tank. P.S the set up I mentioned is expensive around $400 there are others that can be researched. Good luck and have fun... Quote Link to comment Share on other sites More sharing options...
mcbrat Posted February 6, 2008 Share Posted February 6, 2008 Looks like you have a real fun toy there!! G. D. Is right you do want forged pistons, but even the best pistons and can only handle so much abuse ( being run lean) when you start adding boost you need to add fuel. Would like to know what fuel system your running, and can only assume from picture. When you rebuilt engine I would advise using a two stage fuel pump and pressure sensitive regulator. the Mallory electric is adjustable on the low side and runs up to 37 psi. on the high side along with a mallory boost sensitive pressure regulator that is vacum activated, using a return fuel line to your tank. P.S the set up I mentioned is expensive around $400 there are others that can be researched. Good luck and have fun... he's just running the carb, so no injection at all... If keeping the carb set-up, I'd split the fuel line and add a surge tank, with a FI fuel pump, and a line to a single injector, mounted into the intake right before the stock intake manifold, then add a boost gauge and an adjustable pressure switch, that would turn on the injector when boosting.... and add a bung to the exhaust for a O2 sensor and a AFR gauge.... or just invest in lots of spare engines Quote Link to comment Share on other sites More sharing options...
frecobos Posted February 7, 2008 Author Share Posted February 7, 2008 he's just running the carb, so no injection at all... If keeping the carb set-up, I'd split the fuel line and add a surge tank, with a FI fuel pump, and a line to a single injector, mounted into the intake right before the stock intake manifold, then add a boost gauge and an adjustable pressure switch, that would turn on the injector when boosting....and add a bung to the exhaust for a O2 sensor and a AFR gauge.... or just invest in lots of spare engines This sounds interesting. I'm have not finished fixing the pistons stuff and I think I already have my next project in mind.... Or yet better, Install a Ej25 Engine. Quote Link to comment Share on other sites More sharing options...
TeamCF Posted February 7, 2008 Share Posted February 7, 2008 Nice buggy. Good luck with your piston search and welcome to the board. Quote Link to comment Share on other sites More sharing options...
kiwi subbie Posted February 8, 2008 Share Posted February 8, 2008 that looks sooo cool. i want 1:grin: Quote Link to comment Share on other sites More sharing options...
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