What do you think about a crank scraper for FE?

[bgd73]

I thought they used them on v or flat engines. I remember I had a corsica that had one, threw a rod coasting down a hill. I blamed the baffle.

given the inline is a parasitic loss just to look at, it is probably another backwards to keep the baffle out. Baffling to gain a bit more at the bottom of a cylinder it never touches? keep heat? who knows. there is physics of straight up and down, everything around it must be a yoyo as well.

[Frank Lee]

Baffling is right!

[Kevin Johnson]

Originally Posted by ConnClark

Typically these things are only effective under hard acceleration, and if thats the case your fuel economy is out the window anyway. They provide no benefit under cruising conditions. I suppose they might have some benefit if you go up very steep hills a lot but thats it.

Hi,

I make the scrapers referenced. There is a lot of misinformation out there.

For example, in ConnClark's engine, Mercedes engineering includes five crank scrapers in the floor of the pan.

In my Mercedes diesel (300 SDL), I often cruise at 3000 RPM. That is well within the effective range of a scraper at cruising conditions.

[Kevin Johnson]

Originally Posted by ATaylorRacing

Or, you can run 1/2 qt low on your oil to keep the crank counter wts from splashing into the oil. I do this on the cars I race and they are a tiny bit quicker AND helps eliminate oil foaming.

Not too many people have taken the time to actually measure how much oil is in the pan of a G10 or G13 engine. If you do, you will find that the running oil level is just beneath the windage tray which also acts as a slosh baffle.

Running a drag or road racing car definitely requires you to look at the oil level and sometimes you need to reduce it.

[Kevin Johnson]

Originally Posted by Red

The 4.0 doesn't spin high enough for a scraper to be any help. Plus the main brace girdle more or less does the same thing. Not sure if yours had that or that was part of the 00-02 updates

See the comments on the straight six Mercedes diesel. The AMC straight six is an old design. Similar basic block architecture as the Mopar slant six.

It is worth noting that Toyota and BMW completely re-engineered their straight four and straight six blocks to include much greater windage control.

A lot of people think that because their engines do not have a particular part in them it is because the part does not do anything. With OEMs it is usually a case of dollars.

Here is a good example:

The 1995 Dodge Neon 2.0 had an OEM windage tray AND crank scraper designed for it. At the last minute, the windage tray was removed and placed in the performance catalog but the crank scraper was retained. The following year, the crank scraper was removed. Jumping back about 30-35 years, Chrysler engineered a windage tray with crank scraper louvers for the slant six. It was left out of the production engines but was included in the aftermarket performance catalog.

[Kevin Johnson]

Originally Posted by ConnClark

Actually its not there to prevent drops from hitting the crank. Its there to keep oil sloshing up from the pan from hitting the crank. Preventing drops from hitting the crank is futile because the drops come from the main and rod bearings. Some of this leakage is necessary to splatter some oil on the cylinder walls to provide lubrication to the rings.

A windage tray is present to help protect the sump oil and shield the rotating assembly from splashing or migrating oil. This is a difficult set of tasks that are often diametrically opposed in implementation. The more you shield the sump the more you create a second sump that embodies that which you are trying to avoid. Some engines have three layers of trays (see, for example, the RB26DETT).


At low rpms the scraper does physically remove adhering oil but at higher rpms, oil is actively entrained in a cloud by the pressure differential around the rotating assembly. The scraper disrupts the pressure differential and this releases oil until a different equilibrium is reached.

If you increase the efficiency of your cooling system (oil on the underside of pistons that is applied and removed quickly) you can more safely run the engines on leaner mixes and/or higher compression. You may enter into issues about FE for a given octane level and fuel cost but that will give you something to chew apart at leisure.

If you want to do this cheaply then look at the NA Honda B-series engines. Their four cylinder engines have a total of twenty oil squirters directed at the base of the piston for cooling. Sixteen of those (twelve for a G10) can be easily added to the rods.

[Kevin Johnson]

Another comment.

One thing that pops into my head is the sort of narrow idea of FE presented here. I actually use a three cylinder Metro with a scraper to pick up engine blocks, tow trailers and pick up sheet steel. I use the engine through the full range of rpms that it was designed for. I keep up with traffic on the expressway too.

In the past, I owned (amongst numerous other vehicles) a slant six equipped Valiant that I used to tow fully laden trailers over the Sierras -- so, doing a steady 4000 rpm for hundreds of miles uphill and downhill. Currently, I drive the Metro and the diesel Mercedes.

I think that I am hypermiling when I use the Metro in lieu of the 10mpg Grand Wagoneer that sits in my driveway as well -- getting roughly a 400% increase in mileage.