dek1581 Posted March 21, 2015 Share Posted March 21, 2015 looking to repower mack c85 from gas 707 to diesel (most likely maxidyne). could I utilize original air intake slots on side of cab or do I have to pipe and cap through engine cover? if not, what is the reason? Quote Link to comment https://www.bigmacktrucks.com/topic/39345-why-are-there-different-air-intakes-diesel-vs-gas/ Share on other sites More sharing options...
j hancock Posted March 21, 2015 Share Posted March 21, 2015 Maybe.It is a function of the volume of air needed for the engine. I would probably try it with the original setup and see how it performs. Quote JimIt doesn't cost anything to pay attention. Link to comment https://www.bigmacktrucks.com/topic/39345-why-are-there-different-air-intakes-diesel-vs-gas/#findComment-283388 Share on other sites More sharing options...
fxfymn Posted March 21, 2015 Share Posted March 21, 2015 I would check out an existing diesel powered C model to see how Mack did it. My guess is that the air filter is so much larger for the diesel that it will not fit inside the dog box. Quote Money, sex, and fire; everybody thinks everyone else is getting more than they are! Link to comment https://www.bigmacktrucks.com/topic/39345-why-are-there-different-air-intakes-diesel-vs-gas/#findComment-283397 Share on other sites More sharing options...
1958 F.W.D. Posted March 21, 2015 Share Posted March 21, 2015 Diesel engines like to have cooler air coming in. Most fire apparatus that have gasoline powered engines back then used the air that was drawn in from inside the engine box. Hot air. Gasoline engines didn't really care that much. Diesel engines like the cooler air, drawn from the exterior of the engine box, and yes, they also require a lot more air. The physics of air movement did tend to restrict (to a certain extent) the air going into a diesel when the intake was inside the engine box.We had a 1978 Hahn with a 671T Detroit (shut up you morons, I was 6 years old when it was delivered and I had nothing to do with it........) that had a square Farr intake/filter on the inside of the engine box. Later in life we switched it out to an exterior-mounted and much larger cannister-type intake/filter. She ran a hell of a lot better after that. 1 Quote TWO STROKES ARE FOR GARDEN TOOLS Link to comment https://www.bigmacktrucks.com/topic/39345-why-are-there-different-air-intakes-diesel-vs-gas/#findComment-283401 Share on other sites More sharing options...
bulldogboy Posted March 28, 2015 Share Posted March 28, 2015 Many years ago, Nashua, NH had a 1959 Mack "C-85F" with a "707" gas engine re-powered with a Mack diesel (283 hp). The work was done by McDevitt Mack in Manchester, NH. The new air intake was mounted horizontally on top of the engine cowl. The joke was that the Mack engine had jet assist. bulldogboy Quote Link to comment https://www.bigmacktrucks.com/topic/39345-why-are-there-different-air-intakes-diesel-vs-gas/#findComment-284439 Share on other sites More sharing options...
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