Here’s the latest reader question, along with my reply!
Alex asks: I’ve been looking at the Nissan https://www.engine-specs.net/nissan/hr12ddr.html 3 cylinder engine as a potential diesel conversion candidate. Here are some of the questions I need answered before making a commitment to purchasing a quantity of them for modification.
1. Will the 84mm stroke allow these engines to rev to 7500rpm if the cetane is sufficiently high and if so, what is that cetane number?
2. Will the all aluminum engine be sufficiently durable for 2 bar of boost if the engine bolts are up to spec?
3. As a general rule with turbo diesel, should my exhaust “trim” value move more OR less exhaust than if I were using pump gas given all else being equal.
I’m patient. I don’t care how long it takes to answer as long as the information is reliable. Thanks in advance for your replies.
My reply: This is a little beyond my orbit, so to speak – but I do have some general thoughts:
First, from what I have read, converting an engine that was designed to burn gas using spark ignition to a diesel compression ignition engine is not a good idea because the block and crank and other critical hard parts were not designed for the much higher compression/pressure experienced inside a diesel engine. Diesel blocks, cranks, heads – and so on – are usually specifically designed for that role and built of stronger stuff.
Second, I have never heard of a diesel engine that revs to 7,500 RPM. That is very high RPM for a gas engine.
On aluminum: Some new automotive diesels are made of aluminum and I assume the engineers have done their work. I myself would prefer cast iron – because I prefer a conservative approach, which is usually the more reliable and durable one when it comes to engines!
Hoping some of the engineers reading this will add their 50 cents…
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