Don Terrill’s Speed-Talk

We have a wet sump road race customer who spent $1000 on a custom windage tray and crank scraper from one of the nationally known builders, plus another $500 for installation. Evidently he expected some quantifiable magic, but the dyno showed no horsepower increase.

We didn't promise any horsepower, but agreed on a road race engine with an hour of hard pulls, a windage tray/scraper should help keep the oil around the pickup.

Other than the Ishihara-Johnson site, where can we send him to read up on what to reasonably expect from a windage tray and crank scraper? Any links on here to increases on the dyno?

I didn't dyno my engine this time. Kicking myself for not doing it. I used the I-J crank scraper system. The Teflon one.

Our very own Kevin Johnson is the on to talk to. I still have my notes from our several conversations before I bought a crank scraper. I damn sure didn't pay that kind of money for the I-J scrapers but I'd be hard pressed to believe what your customer has is any better or nicer that what I have.

Popcorn at the ready.

Typically a dedicated scraper will return about 2-3% at peak rpm (NA) even when used with an existing windage tray. OEMs call windage trays all sorts of things and sometimes they have multiple trays.

A factory team with a relatively modern engine designed with full CAD contacted me and I modified both the existing tray and created a dedicated scraper. The return was over 3.5% at 7500 rpms on the dyno. Dynos do not represent quite accurately what can happen on the track.

For the same reason, it is important to know what the particular racing use is because many factory trays are designed for multi- or general purpose use.

In extremely competitive classes like FF 1600 (Kent engine), increases of even a single hp are coveted because over 50 years of developments for the platform have occurred. Most people are trying to save their engine from self destructing due to various oiling issues rather than looking for incremental power increases from scrapers.

Understated British experiences CA 1960.

Triumph used a screen on its straight six. Porsche did so as well with the 928 and experimented with differing mesh sizes too. The crown of the mesh can be oriented to act as a simple directional or expanded metal screen.

It is important to remember that the bulk of the oil-air mix can cause the sump level to flood screened areas. This should be planned for.

A good road race wet sump pan is the most difficult type to design. Many of the most important features required to control the oil in a road race environment will not contribute to any hp gains on a stationary dyno. I have extensive experience in this field. The real proof of how good an oiling system works is the lifespan of the bearings in a FAST car with an aggressive driver. Slow cars can get away with less than ideal systems.

Just give the car to the press corps and access to a skidpan and track. You might even get some useful information on restraint systems and crumple zones.

All kidding aside, driving technique is super important. Some drivers just have a natural ability to drive machines at their limit and not destroy them. Others not so much.

Whether it’s a large displacement V8 or small displacement I4 matters a lot. The pan volume matters a lot, too.

I’m convinced that with a big V8 and huge pan, scrapers and windage screens do nothing (positive) to power when measured on a dyno. However, with a shallow oil pan and road-racing conditions, they can be very beneficial. My opinion.

When I first started I received a litany of remarks like it works on big V8 engines and not on small inline engines or vice versa -- insert your configuration here: ___________

Over the years I have corresponded with or spoken to numerous racers active since the early 1960s who have used scrapers on big V8 engines. Good grief, Mopar engineers incorporate a scraper type window on the modern Hemi tray.

I think you could probably find one of the old hemi engines driving an air raid siren and fit it with a huge pan and see no benefit whatsoever.

With a big cross plane V8, I believe that gas flows in the ceankncase are way more important than oil flows. Anything that goes in the crankcase and oil pan should be mostly about managing gas flows, if you are dealing with a big V8 with atmospheric pressure in the crankcase.

I agree that gas flow is extremely important. Oil problems can exacerbate flow problems and vice versa.

I was contacted by several race teams running the Coyote where gas flow and oiling problems were trapping the oil in the head at high rpm and emptying the pan. A modified tray and scraper solved that problem.

Likewise, a manufacturer, which shall go nameless, designed a pan and tray for a different engine that did not take gas flow into account, raising the oil temperature by 10 degrees F every lap and prompting a withdrawal at 7 laps.

With respect to the 928, I think some people might remember a dry sump pan that did not take gas flow into account and emptied and trapped the full reservoir of oil in the crankcase in a matter of seconds.

This thread is just one example of many that prove speedtalk.com is worthy of saving.

I have not seen enough verifiable power differences on an engine with a standard factory pan and windage trays compared to the same engine with a really good windage and scraper system. However I have seen on the dyno an engine under loads with a really bad oil pan and windage control really mess with pressures, oiling, and bearings! Being competitive on a track means running well and consistent, not grenading the engine and hopefully a place on the podium at the end of the race. A good oil control system will help get you there, a bad one will result in some bad DNF's.

Mercedes presented a paper at an SAE convention in Detroit, Michigan about 44 years ago that gave some very valuable information about churning of oil and the power losses. The first chart below is for a truck diesel engine tilted at up to 30 degrees in various directions. Note that up to 8% power loss is readily observed with these fairly modest static measurements. The last chart is a warning to people that try adding a quart to address oiling issues. Be very careful. I am sure that readers here have examined Mercedes V8 oil sumps and noted the floor ribs that act as both scrapers and oil guides. Ford, Porsche and Nissan also use this particular expression of technology.