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2003silverado's avatar
2003silverado
Explorer II
Feb 10, 2015

Non Tow vehicle question for diesel gearheads

One of my zero turn lawn mowers has a 31hp turbo diesel engine. The turbo charger apparently grenaded itself (according to a local diesel tech) and in the process it seems to have sent shrapnel into one of the cylinders because it also has a cracked piston. I am in the process of replacing the bad piston.

Here is my question...The same model of mower (and other brands of mowers) is available with the identical engine less the turbo charger with a horsepower rating of 27, not the 31 mine is rated for. The model numbers of the engines are the same except for a T as the last digit-DM-950d(t)- the T designates the turbo charger. What I would like to do is rebuild the engine but not put a new $1500 turbo on it and just live with the 27 hp of the naturally aspirated one. If I were to loop the oil and coolant lines past the turbo, and reroute the air intake and exhaust, is that all I would have to do to make this a non turbo engine? Or is there more to it like turning the injection pump down to inject less fuel?

Thanks for your non towing advice.
  • The engine is a 3-cylinder Daihatsu but most likely branded as a Briggs & Stratton Vanguard.

  • What year and brand of diesel? Most would not be the same.
    Vanguard has free parts books online so you could look up the injector pump or head or whatever for both turbo and non turbo and see if they are the same.
  • I will try to find out what the compression ratio is for both engines.

    As for over fueling...If it's not blowing black smoke is that a pretty good indication that it is not over fueling? And if it is can I just turn the IP down to the point its not?

    Thanks again.
  • Compression is usually the same in diesels but the problem will be the fueling portion. It may still fuel as if it had the turbo and you might get a lot of black smoke and high EGT.
  • Does the non-turbo have the same compression ratio as the turbo engine? Often when a manufacturer adds a turbo they reduce the compression ratio to keep cylinder pressures in check. If they did this, and I don't know that they did, and you don't install a turbo you will have quite a bit less than 27 HP.