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Car Forum / BMW Cars / January 2008E23 Engine swaps
Just for fun, Has anyone ever swapped a '85 3.5 litre engine into a '84 732i. The original engine was overheated beyond belief and completely screwed. The 3.5 litre engine has now been installed, having removed the electronic automatic and reinstalled the old hydraulic automatic trans. All the ancient 732 engine electronics have also been fitted onto the newer 3.5litre engine. The ONLY problem so far is the MAF meter. The correct 3.5 litre maf does not work with this cars computer, it will not start. The 3.2 litre maf does work with it, but as expected, in default configuration runs lean. The maf has been opened and the pressure spring loosened so as to enrichen the mixture to the correct level. I however have a feeling that, there is going to be a flat spot in acceleration somewhere up near wide open throttle due to the fact that the maf will be wide open before the throttle body hits wide open throttle. Since the car is not licenced, i have only driven it around my street and not taken it up to full speed. With the open centre differential on the 732, there is great difficulty in not having wheel spin at take off. We will swap in the LSD shortly. any constructive input ? > Just for fun, > Has anyone ever swapped a '85 3.5 litre engine into a '84 732i. The > original engine was overheated beyond belief and completely screwed. > The 3.5 litre engine has now been installed, having removed the > electronic automatic and reinstalled the old hydraulic automatic trans. > All the ancient 732 engine electronics have also been fitted onto the > newer 3.5litre engine. > The ONLY problem so far is the MAF meter. > The correct 3.5 litre maf does not work with this cars computer, it will > not start. The 3.2 litre maf does work with it, but as expected, in [quoted text clipped - 4 lines] > that the maf will be wide open before the throttle body hits wide open > throttle. > Since the car is not licenced, i have only driven it around my street > and not taken it up to full speed. With the open centre differential on > the 732, there is great difficulty in not having wheel spin at take > off. We will swap in the LSD shortly. > any constructive input ? Was there a reason not to use the entire injection system from the new engine?  Signature*Santa's helpers are subordinate clauses* Dave Plowman dave@davenoise.co.uk London SW To e-mail, change noise into sound. | Was there a reason not to use the entire injection system from the new | engine? the 3.5 engine we have installed has retained its injector rail and fuel injectors. As for the rest of the system, it was not possible to use the more advanced 3.5 controls without changing the entire engine wiring harness and computer, and who knows what else in that big bunch of spaghetti behind the dash. there are huge differences, the donor car, being a 735 executive, had electronic idle control, emissions controls, a propper throttle plate position sensor, a fully electronicly controlled automatic transmission., etc The driveline and interior were removed from this car after it was wrecked in an accident. This car has late style ignition system. the 732 poverty pack model the engine has been transplanted into has, no idle control, it has just an old school idle air valve adjustment screw & and an electricly heated auxillery air valve. For the throttle, its just a throttle switch that tells the computer when the engine isnt idling. It has no emissions controls and also a hydraulic transmission with a good old fasioned throttle pressure cable that also acts as the kick down switch. This car has Early style ignition system. Its working remarkably well considering its now a mongrel hybrid mix of early and late model componentry. Its actually more responsive than the 735 executive ever was. > | Was there a reason not to use the entire injection system from the new > | engine? > the 3.5 engine we have installed has retained its injector rail and fuel > injectors. As for the rest of the system, it was not possible to use > the more advanced 3.5 controls without changing the entire engine > wiring harness and computer, and who knows what else in that big bunch > of spaghetti behind the dash. > there are huge differences, the donor car, being a 735 executive, had > electronic idle control, emissions controls, a propper throttle plate > position sensor, a fully electronicly controlled automatic > transmission., etc The driveline and interior were removed from this > car after it was wrecked in an accident. This car has late style > ignition system. > the 732 poverty pack model the engine has been transplanted into has, no > idle control, it has just an old school idle air valve adjustment screw [quoted text clipped - 3 lines] > with a good old fasioned throttle pressure cable that also acts as the > kick down switch. This car has Early style ignition system. > Its working remarkably well considering its now a mongrel hybrid mix of > early and late model componentry. Its actually more responsive than the > 735 executive ever was. Right - but they both use flapper AFMs? My guess would to be to get the correct one for that capacity of engine with the same management - if indeed there was one made. Altering the spring tension is a bit hit or miss - and if as you say it's for a smaller engine might be different in other ways. If a hot wire AFM ignore this. ;-) Signature*Stable Relationships Are For Horses. Dave Plowman dave@davenoise.co.uk London SW To e-mail, change noise into sound. I'll see how she goes when i take it for an italian tune up. I am however, almost loosing interest in this project. Apon running the car for a while, ive discovered coolant leaking into the drivers side footwell (RHD). I've also nicked one of the transmission cooler hoses when installing the engine. The fun continues. We are going to pull the dash out anyway, and we have a spare hvac box incase its the heater core thats leaking - which it probably is, since theres a new hot water valve installed, which works, but the air comming out the vents is always hot, and the windows are also steaming up! Are e23's notorious for being a tad troublesome in their old age these days? |
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