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Engine Specific Info and Questions => IDI Engine => Topic started by: Dan19030 on November 30, 2008, 02:13:20 am
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Hi guys. I have a slightly ambitious project I am about to start. A mk3 polo track car with a 1.9 AAZ. I have a polo ready to go and aso have a caddy with a 1.9 N/A engine. If I was to rebuild the N/A engine (it's knocking) could I just simply bolt a turbo to it? I understand that the compression ratios are the same so will I have to just work out a way to control boost pressure and up the fueling. Or am I just dreaming?
Cheers, Dan
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you're not dreaming, Do it and keep us informed on how it's going. You will need a IP for a turbo. and an intercooler if you want to extract some real power.
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The reason I ask is I have a couple of merc cdi turbos and intercoolers and it would be a lot cheaper to use parts I already have. Not sure what turbos they are or what pressures they put out, just feeling the ground before I dig a really big hole and jump down it. How would I control the boost presure? obviously the N/A engine doesn't have a transducer to control it. and also the pump won't have a boost pressure connection to adjust fueling. Should I just adjust the pump for max boost as this is where it will mostly run?
What is an IP?
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IP=Injection Pump
The IP is where all power comes from in a mechanically timed IDI (In-Direct Injection) Diesel. The LDA or boost aneroid (that spaceship looking thing on top of turbocharged diesels IP) can be thought of as not allowing full fueling until boost is sufficient or as to reduce fueling as boost is decreased. Whether you look at it one way or the other the whole point is to allow max fueling when conditions are right and to prevent melting holes in your pistons when conditions aren't. If you set the N/A (Naturally Aspirated=no turbocharger) for max fuel at max boost conditions when you are 'off' boost or before your turbo spools up you will be dumping way too much fuel into the cylinders and could potentially melt them or your turbo from high EGT's (Exhaust Gas Temps). Don't know if you had any of the old Caterpillar diesels in England that didn't have a boost aneroid but when they would climb a hill and downshift they would belch out a huge cloud of black smoke and black smoke=unburnt fuel=high EGTs.
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Thanks for clearing that. I understand now and have a few options to ponder over. I am kind of new to playing with diesels really always been a bit of a petrol head, but quickly being converted thanks to my 1.9td vento. Thanks again guys. I will keep you informed of the project.