need bb Posted March 15, 2014 Share Posted March 15, 2014 I am in the process of having my short block rebuilt due to high compression and leakdown in cylinders 2/4. I have decided to go with a 4032 pistons as I want the engine to last 100K miles and use no oil. I originally was going to go with Mahle 4032 99.75mm pistons but my engine builder won't use them due to multiple issues he had in the past. I have heard good things about the Wossner 4032 pistons but they only make a 99.50mm and 100mm and I don't want to bore my block to 100mm. If my cylinder walls are in good condition is there any chance I can use the Wosser 99.50mm? My backup plan is to go with the Cosworth 99.75mm pistons. They are about $400 more expensive, but this is still cheaper than new block halves at $1K. Link to comment Share on other sites More sharing options...
GTTuner Posted March 15, 2014 Share Posted March 15, 2014 I have the Woosners I honed the cylinders with a stone hone and dropped them right in. You can run just about stock piston to wall clearance with a 4032, this is why they are quieter. Call Woosner and get the recommended piston to wall clearance and measure it. I was on the tight side but I went for it. 80,000 miles later I use 1/4 quart every 3000 miles. They specialize in Porsche 911 pistons so they are familiar with boxer engines. Link to comment Share on other sites More sharing options...
need bb Posted March 16, 2014 Author Share Posted March 16, 2014 Thanks Paul. Everyone I have talked with say that the wear on the cylinder walls after 75K miles could make it difficult to do a drop in with the proper clearance. I was told that is why Manley now has a 99.55mm piston so I am surprised your clearances were on the tight side. Link to comment Share on other sites More sharing options...
GTTuner Posted March 17, 2014 Share Posted March 17, 2014 My cylinders had minimal wear @ 80K. Link to comment Share on other sites More sharing options...
Max Capacity Posted March 19, 2014 Share Posted March 19, 2014 With 154,000 miles, mine still had the crosshatch pattern in the walls. Use a good machine shop. 305,600miles 5/2012 ej257 short block, 8/2011 installed VF52 turbo, @20.8psi, 280whp, 300ftlbs. (SOLD). CHECK your oil, these cars use it. Engine Build - Click Here Link to comment Share on other sites More sharing options...
need bb Posted April 3, 2014 Author Share Posted April 3, 2014 A lot of engine builders I have talked with say that using a 99.50mm pistons on a used shortblock will yield clearances of around .004" which is too much for 4032. Paul do you know if you block had A or B cylinders? Just wondering if the Wossner's are slightly bigger than 99.50mm since you PW clearances where on the tight side. Thanks Link to comment Share on other sites More sharing options...
LivingTheLegacy Posted April 5, 2014 Share Posted April 5, 2014 I have the Woosners I honed the cylinders with a stone hone and dropped them right in. You can run just about stock piston to wall clearance with a 4032, this is why they are quieter. Call Woosner and get the recommended piston to wall clearance and measure it. I was on the tight side but I went for it. 80,000 miles later I use 1/4 quart every 3000 miles. They specialize in Porsche 911 pistons so they are familiar with boxer engines. Hey I'm in the process of rebuilding my block, I've got an STi crank, eagle rods, ACL bearings, just wondering how much whp you've made on the wossners pistons. Do you know the upper limit by chance? I'm stuck between going forged or the 4032 to reduce piston slap/ wear. Link to comment Share on other sites More sharing options...
need bb Posted April 10, 2014 Author Share Posted April 10, 2014 The shop tore down the engine and said the ptw clearance with the stock 99.50mm pistons was .0035". This would be fine for a 2016 piston but I think it is an issue for a 4032 piston. Thoughts? Link to comment Share on other sites More sharing options...
Max Capacity Posted April 10, 2014 Share Posted April 10, 2014 PM "Nrw" Neil may have good ideas on that. Whoes doing your machine work, they should know subaru's or find another shop. I know a good one in North central CT. see my click here link. 305,600miles 5/2012 ej257 short block, 8/2011 installed VF52 turbo, @20.8psi, 280whp, 300ftlbs. (SOLD). CHECK your oil, these cars use it. Engine Build - Click Here Link to comment Share on other sites More sharing options...
need bb Posted April 11, 2014 Author Share Posted April 11, 2014 The shop only does Subarus and does the machining in house. They build lots of Subaru engines. My case is rare as most customers go the 2618 route while I am going with tighter 4032 pistons. Link to comment Share on other sites More sharing options...
1-3-2-4 Posted March 12, 2016 Share Posted March 12, 2016 I have the Woosners I honed the cylinders with a stone hone and dropped them right in. You can run just about stock piston to wall clearance with a 4032, this is why they are quieter. Call Woosner and get the recommended piston to wall clearance and measure it. I was on the tight side but I went for it. 80,000 miles later I use 1/4 quart every 3000 miles. They specialize in Porsche 911 pistons so they are familiar with boxer engines. Which woosners work on the ej255? Link to comment Share on other sites More sharing options...
need bb Posted March 14, 2016 Author Share Posted March 14, 2016 http://www.builtej.com/Wossner-EJ25-4032-Forged-piston-set.html In the end I had the block slightly bored to 99.75 to achieve the proper PTW. Link to comment Share on other sites More sharing options...
1-3-2-4 Posted March 20, 2016 Share Posted March 20, 2016 yeah I think I'm going to go that way too.. but for that size I only see 2618 pistons and not 4032. Link to comment Share on other sites More sharing options...
fahr_side Posted March 20, 2016 Share Posted March 20, 2016 Unless you have very low miles on your block the bores will be oval and tapered to some extent that makes ring seal very hit or miss. The Manley drop-in items are really meant for new shortblocks. The 99.55mm size is meant for low mile blocks that had not suffered a ringland or head gasket failure, in which case the bore cleans up nicely. If you insist on using 4032 slugs you will have to deal with the sizes that are available, which is not many. Obligatory '[URL="http://legacygt.com/forums/showthread.php/2008-gh8-238668.html?t=238668"]build thread[/URL]' Increased capacity to 2.7 liters, still turbo, but no longer need spark plugs. Link to comment Share on other sites More sharing options...
1-3-2-4 Posted March 20, 2016 Share Posted March 20, 2016 I was shocked how the bores did not look bad at all when I took the pistons out Link to comment Share on other sites More sharing options...
fahr_side Posted March 20, 2016 Share Posted March 20, 2016 How they look to your untrained and naked eye means nothing. Mine still had plainly visible cross-hatching all around but were tapered and oval beyond service limits on #3, which was the cylinder with the leaks across the gasket and a cracked ring land. Measure the bores according to the FSM, with a micrometer. Obligatory '[URL="http://legacygt.com/forums/showthread.php/2008-gh8-238668.html?t=238668"]build thread[/URL]' Increased capacity to 2.7 liters, still turbo, but no longer need spark plugs. Link to comment Share on other sites More sharing options...
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