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regardless of the scale of the engine, the mean piston speed at maximum rated engine revs will be somewhere in the 20 m/s range That's commonly said (especially in textbooks), and it's reasonable for car engines, but it doesn't seem to hold up if you calculate rated mean piston speed for a wider variety of engines.  Examples: MPS...

Hi, It is load type Dynocom dyno with 24' roller but that doesn't matter now. If we assume about 15% tranny and tyre losses, that makes 445hp at the crank! How about that number at 6250rpm and 1,6 bar gauge boost? I just need some math here, is that power level possible "on paper" at least? Regards!

1.6 bar gauge boost = 2.6 bar absolute manifold pressure near sea level. That amount of power is plausible from that size of engine with that much boost. Detonation control at such high boost pressure and with a compression ratio in a normal range is, of course, quite another matter, even with very good intercooling, but that's not the question that was asked.

The larger the cylinder the more difficult it is to control detonation. And why in the days of the recip aircraft engines cylinder size was optimized and to increase power more of them were added.  

ivymike , your post is very interesting. I think an additional factors that should be included when comparing mean piston speed across diverse applications is the ratio between nominal operating rpm (e.g. cruising rpm for automotive applications), and peak rpm. I suspect that passenger cars and motorcycles will exhibit the highest ratio between nominal and peak rpm, with commercial vehicles in the middle, and stationary powergen applications...

388hp on an 86mm squared 4 cylinder at 6250 rpm comes out to be right around 28 bar of BMEP. More than reasonable for an absolute pressure of 2.6 bar in my opinion. To put it in perspective that'd be just over 10bar at atmospheric pressure, which is actually relativly mild tune. Ofcourse you lose some in pushing the turbo and heating of the charge but I consider it plausible. My question is why is he only running 18m/s of piston speed on...

I found the problem... I had a turbo failure yesterday so I spent the better part of to day pulling all of the turbo stuff off and putting my old 4-1 header and N/T exhaust back on .While I was at it I welded an egt bung on.So after it all was back together, I took a test drive and egts under the same circumstances temps were 1100-1150*f So I guess the turbo/manifold combination was to restrictive ...so that combined with the failure means...

Wow, someone who actually wants their RWHP number to be lower than the dyno measured. Personally, I find the arguements about the "RWHP" numbers from a dyno completely useless. Recently, I saw someone post that changing their wheels lowered the "RWHP" by 12hp and that he could really feel the 12hp loss on the street. The sad part is that he had no clue that the "RWHP" due to inertia will change depending on the...

I'm with Somptinguy ( and probably of the same era). My buddy and I used to add a bit of Castrol "R" to our XT500 four stroke singles just for that special aroma. Can't guarantee it ran better - but sure smelled good...

My company has begun manufacturing sod roll installation equipment.  Mainly these units are in the landscaping industries to install large rolls of sod on residential or commercial properties.  They are power by Kubota D902 diesel or a Kohler Command 27 Gas Engine.  My question is where on the CARB website would I find the requirement for the engines and any other requirements that our...