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Difference in diesel engines? Rich 2-9-17  
As I look at different bus conversions, I see different engine types like, 8v71, 8v92, etc.

I think these are 8 cylinder, but not sure what the number following the first part is. Can someone break this down fur me?

Thanks, Rich
Re: Difference in diesel engines? Zane 2-12-17  
Hi Rich, not an expert like Bubba the Bus Tech, but you're right, the first number is the number of valves or cylinders, and the second is the diameter of the cylinder.

So, 8v71 would indicate an 8-valve, 71mm diameter cylinder.

It's been a long time since I reviewed this, but I think that's correct.

The difference in size then would indicate a different overall power output, the 8v92 obviously being larger.


Re: Difference in diesel engines? Bubba The Bus Tech 2-13-17  
8V71 Means a V8 71 cubic inches per cylinder Also known as a 71 series engine

The 92 Series Engines are based on the 71 Series. Differences are the 92 series engines make considerably more power due to the turbo and make better fuel economy by around 10%. The 6v92 makes about 10% more power than the 8v71 The 8v92 about 40%

The down side is the 92 has a "Wet Sleeve" construction and tends to not like sitting. To counteract this they require careful cooling system care. There are test kits to track this.

After a 3 decades running Detroit Power the 92 series rarely runs until overhaul with out a serious internal failure while the 71 usually does.

I personally would take an 8v71 over the 92 series for RV use as they are simpler and cheaper to fix and less prone to failure,

Last notes: These engines should not be idled, Target a 3 minute warm up or until air pressure is up, three minute cool down and shut it off. (If its over hot three minutes after it cools off on the gauge)
Run the correct 40 weight diesel oil. 30 weight if under freezing. Not 15w40 unless nothing else is available.
How to drive a two stroke diesel: Rev it out all the time, Two strokes do not like to be under 1,500 rpm at full throttle.
If you are overheating climbing a hill go down 1 gear and hold the engine at max governed rpm.
They make best power just before the governor limits them at usually 2,250 rpm they often are set at 2,050 for fuel mileage and 2,350 rpm for power.
The same engine in a fire truck can rev to 2,650 rpm but expect a 100,000 mile engine life. Take a 318 hp engine to about 350 hp.
The 92 series engine must be run at more than 1,500 rpm while under heavy load, they tend to over fuel and tear themselves up otherwise.
Most truckers and bus drivers in the day ran on the governor 100% of the time, primitive cruse control ; )
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