Don Terrill’s Speed-Talk

Ah! but that's why many times correct type and shape screening for windage issues and oil control works so well, less opportunity for the oil ricochet you are discussing.

Newold1 wrote: ↑Mon Jan 08, 2018 3:59 pm Ah! but that's why many times correct type and shape screening for windage issues and oil control works so well, less opportunity for the oil ricochet you are discussing.

Do the best dry sump systems include windage screens or trays? Not by my understanding. They just minimize volume and isolate bays, but no screens or trays. This tells me that oil spray reflecting back to the crankshaft is a minor issue to power. Of course, this is highly speculative.

For me, windage trays belongs to wet sump systems and have one main purpose: preventing oil from surging from the sump into the rotating assembly in actual use. A good tray does that with minimum additional pumping losses.

In my opinion and working knowledge a GOOD windage tray or screen helps keep windage from whipping oil back up into the rotating assembly and also keeps oil drop and splash from bouncing back up into the rotating assembly. In a dry sump system the oil in the sump is being sucked out of the pan and hence the actual oil volume in the pan is way less (most stored in tank) and does not encounter the same effects of windage that oil in a wet sump experiences. That is why most all dry sump systems have compartments with suction at multiple points and no trays or screening. The oil in a dry sump system does not have a chance to stay at volume in the sump and does not get whipped around by any windage. That is why its referred to as a DRY sump.

Chrysler claimed their windage trays were good for 15 hp @ 6000 rpm.

Yes, most dry sump pans utilize a windage screen or baffled tray. Regardless of wet or dry, the design and positioning are crucial to performance. If you can lower the tray/screen away from the crankshaft and utilize a scraper you're heading in the right direction.

Geoff2 wrote: ↑Tue Jan 09, 2018 2:56 am Chrysler claimed their windage trays were good for 15 hp @ 6000 rpm.

When’s and where did they claim that? And under what operating conditions?

Reef wrote: ↑Tue Jan 09, 2018 4:41 am Yes, most dry sump pans utilize a windage screen or baffled tray. Regardless of wet or dry, the design and positioning are crucial to performance. If you can lower the tray/screen away from the crankshaft and utilize a scraper you're heading in the right direction.

High budget dry sump pans? What I’ve seen, they have sealed bays, suction port in each bay, minimum volume, and no windage tray. Some have a scraper like lip hangin over the ports, but higher the budget the smaller that scraper lip.

If you're losing horsepower with a windage tray, I suggest some serious A-B-A dyno testing, as well as a serious look at crankcase pressure (including "piston pumping") and how much oil is being cast off from various parts. You might consider viscosity as well. I consistently use the louvered-divided windage tray, combined with a wheelstand baffle under the oil pump, and a crankshaft scraper. We've seen gains when it is fitted correctly. But you can't have a large quantity of cast off oil that can't be passed through the tray, and you can't have a lot of crankcase pressure.

Alan Roehrich wrote: ↑Tue Jan 09, 2018 8:09 am If you're losing horsepower with a windage tray, I suggest some serious A-B-A dyno testing, as well as a serious look at crankcase pressure (including "piston pumping") and how much oil is being cast off from various parts. You might consider viscosity as well. I consistently use the louvered-divided windage tray, combined with a wheelstand baffle under the oil pump, and a crankshaft scraper. We've seen gains when it is fitted correctly. But you can't have a large quantity of cast off oil that can't be passed through the tray, and you can't have a lot of crankcase pressure.

Gains on the drag strip or track? Or gains on a stationary dyno? More stable oil pressure and in some cases more power in actual use makes sense to me, these devices reduce the damage done by surging oil. But where would the gains from a windage tray come from on a stationary dyno?

Alan Roehrich wrote: ↑Tue Jan 09, 2018 8:09 am ..... But you can't have a large quantity of cast off oil that can't be passed through the tray, .....

This is why I prefer a screen over a tray. I feel like it has less tendency to bounce the oil back up.

Exactly, that is the only windage trays I use are screen type and I do attempt to make sure they are shaped to enclose the rotating assembly at a good working distance.

I only use stripper type screening material which also make a big difference. In almost all cases you should not use conventional type screen for sump areas it does not handle oil as well as the stripper screening. I also always use a crank scraper to strip oil from the crankshaft counter weights and bottoms of rods.

Some I see using non ventilated or flat metal trays which I think is sometimes a mistake as it then just collects oil closer to the rotating assembly and becomes a billiard ball rail for oil ricochet. If you are going to use a solid metal tray I would pretty much all recommend one with louvers or shaped windows and some curvature mimicking the the rotating assembly. I have never had a serious oil control or windage issue with this type of set up on conventional wet sump oil pans with or without vacuum pump.

I haven't seen Kevin Johnson post here in a while but I'd be interested to hear his opinion on this topic.

Newold1 wrote: ↑Tue Jan 09, 2018 2:44 pmI also always use a crank scraper to strip oil from the crankshaft counter weights and bottoms of rods.

What do you mean by that?

Crankshaft scraper that looks like this. www.jegs.com/i/moroso/710/25830/10002/-1

Newold1 wrote: ↑Tue Jan 09, 2018 3:17 pm Crankshaft scraper that looks like this. www.jegs.com/i/moroso/710/25830/10002/-1

What oil would there be on the crankshaft counterweights at 6000 rpm to be stripped by a device like that?