charles28 138 Report post Posted September 5, 2009 Hi guys, As my engine is about to have a rebuild, I was wondering if the compression might be too high? My headgasket blew between 2 Cylinders, I think this could have been from Detonation. There is 2 possible ETA blocks that my car could have, one being 11-1 and the other 10-1, standard compression on a 325i was only 8.8-1 for facelift model. On ebay I have seen cometic headgaskets listed, these are triple layer stainless steal headgaskets available in differn't thicknesses, anyone thing something like this is necessary for my car? The Current 731 head was fitted to the engine in 2006 (by a previous owner) in my mind 3 years isn't very long for a headgasket to last considering the car had only done 5000 Miles in this 3 years. My guess is that its had detonation issues, once I check the number on the block I can confirm which compression ratio I have. Another question, should I get an ECU chip designed for the 2.7 Conversion? there are a few available over seas, also locally Autopassion can re-map the ecu, but at a cost of over $1300, however this option allows for the most power output, as its custom for the car. I assuming dyno tuning is part of it. Quote Share this post Link to post Share on other sites
Guest FrantiC Report post Posted September 6, 2009 11:1 isn't that bad.. If it is tuned right it should be fine. The pre 87 ETA blocks were 11:1, 87+ were 10.2:1 CR. I have not heard of anyone ever having issues running 11:1 CR, Are you using bigger injectors ? Motronic 1.3? Euro I's were either 9.4:1 or 9.7:1 CR, The U.S ones were 8.8:1 CR.. If you wanted to drop compression, get the 885 head instead of a steel headgasket. I have a 10:2CR ETA bottem end with the 885 head the compression is dropped to 9.5:1 CR, But have just recently added a 0.120" Cometic MLS headgasket furthur dropping compression to the 8.7/8.8CR range so it's more boost friendly. 885 head is far superior anyways with bigger valves, intake and exhaust ports etc.. Adding a multi layer steel headgasket would do the exact same as changing to the 885 head except you would still have the smaller valves... I was running a 885 head on a 10:2 ETA bottem end and 17.5lb injectors from an m50 325i with full motronic 1.3 and 164 ECU. Never had any issues at all was really quick too.. Quote Share this post Link to post Share on other sites
BM WORLD 1286 Report post Posted September 6, 2009 read this . click on the photo http://s145.photobucket.com/albums/r222/br...nt=P1040678.jpg http://s145.photobucket.com/albums/r222/br...nt=P1040679.jpg Quote Share this post Link to post Share on other sites
Deano 1 Report post Posted October 8, 2009 Hi guys, As my engine is about to have a rebuild, I was wondering if the compression might be too high? My headgasket blew between 2 Cylinders, I think this could have been from Detonation. There is 2 possible ETA blocks that my car could have, one being 11-1 and the other 10-1, standard compression on a 325i was only 8.8-1 for facelift model. On ebay I have seen cometic headgaskets listed, these are triple layer stainless steal headgaskets available in differn't thicknesses, anyone thing something like this is necessary for my car? The Current 731 head was fitted to the engine in 2006 (by a previous owner) in my mind 3 years isn't very long for a headgasket to last considering the car had only done 5000 Miles in this 3 years. My guess is that its had detonation issues, once I check the number on the block I can confirm which compression ratio I have. Another question, should I get an ECU chip designed for the 2.7 Conversion? there are a few available over seas, also locally Autopassion can re-map the ecu, but at a cost of over $1300, however this option allows for the most power output, as its custom for the car. I assuming dyno tuning is part of it. Hi Charles..did you buy that muffler of me about a month ago?Anyway my 2.7 is 11:1 with 885 head, 19lb injectors and M30 AFM. Will not run on 95 only 98 and I went to great lengths to get an eprom written for 2.7L to make it run without "pinging" It has 210 psi compression so with a 731 it will be higher and it will have to dyno tuned. I may be able to help with a correctly mapped for 2.7L eprom for your ECU if need be. Best bet is to use the 885 head, get it dyno tuned and hope for up to 120kW at the rears. Quote Share this post Link to post Share on other sites
charles28 138 Report post Posted October 9, 2009 Hi Charles..did you buy that muffler of me about a month ago? Anyway my 2.7 is 11:1 with 885 head, 19lb injectors and M30 AFM. Will not run on 95 only 98 and I went to great lengths to get an eprom written for 2.7L to make it run without "pinging" It has 210 psi compression so with a 731 it will be higher and it will have to dyno tuned. I may be able to help with a correctly mapped for 2.7L eprom for your ECU if need be. Best bet is to use the 885 head, get it dyno tuned and hope for up to 120kW at the rears. Yes, I purchased that exhaust from you. thanks for that I don't need to worry about the 2.7 engine for now as I went with the option of a factory 325i engine for that car. but will slowly strip down the 2.7 and see what it needs repair wise, i wouldn't mind having that engine in the 320i. I still havn't got that exhaust put on yet, but should be on next week, I have a spare 325i intake manifold, but need a 325i throttlebody for it eventually. I need to double check the block numbers on my eta block, its possible its not the 11-1 compression model. if it turned out to be the lower compression one then I can use the 731 head from my 320i engine, although it would be nice if the 731 head currently fitted to the eta block wasn't stuffed as its already port matched to that 325i intake manifold. Quote Share this post Link to post Share on other sites
