(034) Types Of Engine Drag

In this video I talk about the types of engine drag – the various ways your engine is robbing itself of power. But that’s OK, I also include several ways that internal drag can be negated. 

Types Of Engine Drag – Video Transcript

Hey everybody Matt Covert here again from howtobecomearacecardriver.com. Today on this video we’re going to talk about the types of engine drag. Yes we’re getting into a little bit of technology here. But that’s OK. I think these things add up to make incredible drivers. The more knowledge you have, the better it’s going to be. So let’s hop right on in and talk about the types of engine drag.

Let’s start with one that’s really basic. By the way these are all types of parasitic – parasitic – whoops. Parasitic drag. It just means that while things are happening they’re stealing power – available power that could be used to propel the car forward, OK? So what we want to do is alleviate parasitic drag. And these are all examples of that OK?

So let’s take a look at the first one. And I’m going to call it mechanical drag. That might be the official name, it might not be, that’s OK. Mechanical drag. This happens from parts – no I’m going to change that. This happens from metal to metal contact. And you have a lot of this inside the engine. We’re talking about piston rings on cylinder walls. We’re talking about lifters that drag across cam lobes. All that kind of stuff – all those little metal on metal resistance – I’ve also heard it called skin drag or surface drag. All those things that touch each other are really just types of parasitic drag robbing available engine power. OK? Not a whole lot you can do about these. You can get roller cams you can get those little tiny piston rings. You can reduce the surface areas that touch each other. But really you’re kind of stuff with it. There has to be some mechanical components moving around. There has to be engine bearings which touch on journals which touch on whatever. So metal on metal contact – not a whole lot you can do about that. So that one is there and we’re pretty much stuck with it to some degree. Alright? We’ll move on to the next one.

This one’s really interesting. And I’m going to call it inertia drag. And we’ve talked about polar moments of inertia before. And so you know that reducing somethings weight can allow it to turn faster or change directions. A polar moment is simply an objects tendency to rotate around itself, OK? In this case we’re talking about moving components that are always trying to change direction. So we’ve got pistons that go up and down. We’ve got pushrods that go up and down. Connecting rods that go up and down. So there’s all kind of things that are changing direction all the kind. Rockers. They kind of pivot back and forth. All that kind of stuff. OK.

And on the same note here we can talk about rotational inertia. If you have a really heavy crankshaft and you’re trying to accelerate it – you push the throttle. It has to kind of get out of its own way. If it’s really heavy it takes more power to get it to turn quicker than it does a lighter crankshaft. And that’s why it’s really not that difficult to get four or five hundred horsepower out of an engine that has very lightweight components because they have low polar moments of inertia. And the parts change direction very quickly. And that’s really important. If you have heavy components in an engine it just robs a ton a power. Because the engine’s power is just going to changing direction of all these parts. So lighter components are often very expensive but they always pay off with power. So you can fight this inertia drag if you’ve got the money. So let’s go ahead and talk about one last one real quick.

And it is viscous drag. And as you know an engine has to push all kinds of fluids around to operate properly. We’re talking about, in some cases, power steering fluid. Not necessary though. We’re talking about coolant, which it definitely needs. And engine oil, which is definitely needs. OK so we’re talking about the movement of fluid. There are things you can do to negate this. You’ve probably heard of dry sump oil systems. This is a really cool way to make power.

Imagine for a second that your car is driving through a puddle and all that fluid is just kind of jumping up and splashing on you and you can kind of feel the resistance when you drive into a big puddle. Well that’s what the crankshaft has to do inside the crankcase. There’s tons of oil in there. It’s rotating so fast it’s probably just a big oil cloud. And all that kind of splashy oil inside that crankcase is actually keeping the crank from moving as fast as it can. OK. In a dry sump it actually takes the oil away from the crankcase and pumps it through an external pump somewhere else. So everything gets lubricated properly but you don’t have to fight that oil. And by the way that crank resistance in there is called windage. And that’s something else you can kind of do to resistance viscous drag inside your motor. You see that on a lot of racecars. It’s pretty expensive to put in a dry sump but that is totally worth it.

So in my opinion lighter components and a dry sump probably yield the best horsepower gains if you have the money. Because that stuff all really expensive. Anyway, there types of drag. They’re all parasitic. Mechanical, inertia, and viscous. Do everything to fight them within your budget because you will have a lot more power and power is fun.

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