Has anyone dyno'd their engine out of the car and in it. Not in theory, or 15-20%, but real life numbers? If so, what were they?

 

Quite often the engine dyno will not have all the accessories hooked up and some use an electric water pump. So things will be even more skewed in favor of the engine dyno.

So one would need to know the particulars of the engine dyno to calculate the drive train losses. That would be one reason the percentages would vary somewhat.

 

Dynos are so inaccurate that it doesn't really matter. Dynos are only good for relative purposes such as tuning.

 

An engine dyno will also have a completely different exhaust system, and an unlimited supply of cold air.

 

so no real life numbers?

 

What is it you're trying to figure out?

 

I think he's try to figure out how much parasitic loss difference would result between a dyno run on an engine dyno followed by another run on a chassis dyno. The answer isn't very clear cut. A lot of things can affect the parasitic loss factor. There isn't a specific parasitic loss percentage other than the 10-35% generalization you'll usually get. I'm with ME Leigh on this one. The dynos good for tuning and maybe general numbers but not much else.

 

I was going to try testing that but when I thought about it, it wouldn't be accurate. Just like as stated above, no accessories, different headers and exhaust, no intake. We've got an engine dyno here at teh shop and where I work part time we have a chassis dyno so I may do the comparison anyway but it wont make a difference. Dynos are for tuning. Not to mention every dyno is different, so is every operator and their procedures.