Gents,
Some hard data. Hooked up a vacuum/pressure gauge and did some runs around my "test loop."

1) Is there blowby in a rotary? (I thought yes). Hooked up gauge between nipple on filler neck and PCV valve which is in turn connected to the plenum. All other crankcase taps were capped. In theory under boosted conditions the crankcase should build pressure if there is blowby and would then be vented to the plenum when you lift and there is vacuum - the PCV opening. Sure enough as soon as I boosted, the crankcase pressurized and the car smoked like crazy - nowhere for turbo oil return, or eshaft bearing oil to go but into the engine and be burnt. Lift throttle and see plenum vacuum and the crankcase pressure would slowly bleed off though the PCV valve.

2) Is it entirely oil slosh or is there crankcase pressure pushing oil into the catch can? Capped PCV valve and hooked up gauge between filler neck nipple (on my cap) and the catch can (vented to atmosphere). Duh...with catch can vented to atmosphere there should be no pressure to speak of. And the gauge showed this. Virtually no vacuum and no pressure (about 1/2 psi tops)in the filler neck regardless of boost or no boost when vented to the catch can.

This answers the question somewhat that will oil drain back into the oil pan from the catch can using just gravity? If there is no crankcase pressure then there there should be no reason it shouldn't drain.

3) Can the PCV valve be used as a check valve between catch can drain and oil pan? Not really. I hooked up a funnel and filled it with oil and even when open the PCV valve would only drip oil under gravity induced flow :-(

So the question now is twofold - how to drain the oil back into the pan and where to find a suitable check valve. One thing I noticed was the location of the dipstick...just below catch can drain nipple. Hmmm. Need to find a *GOOD* check valve though as it essentailly comes from the same location as the filler neck so oil surge would be of similar concern.

Any thoughts please share.

For Gene,
The existing OE metal Xover tube is too high for the catch can drain. But what I had though about was actually moving the catch can to the pax side of the car and running the vent line from the filler neck over the top of the engine to the catch can. This would make rigging a drain to the turbo return line much easier.

FWIW,
Crispy

PS Brad I WILL be in touch ASAP!!!

Crispy, thanks for the REAL data and taking the time to get it! I was thinking about the dipstick tube the other night as well. Seems you could easily remove the dipstick and make a fitting to attach the can to?

Just be really trick and braze a fitting into the dipstick tube. the amount of oil flowing through shouldn't be impeded by the relatively small diameter dipstick wire.

<glad I don't need this setup. My original Jaz setup works perfectly>

Thanks for the data Crispy!

Gene

Crispy,

FWIW, the new Crispy Cap didn't really prevent the catch bottle from filling up with oil @ Putnam Park (recent Sept 19 PCA event). 15-minute sessions tops before the bottle was completely full (running regular road tires and pads). Putnam Park is probably the only track that fills the catch can in 15 minutes. The track is short and fast with 8 right-handers and 2 left-handers www.putnampark.com. All the right-handers are high-G loaded turns. Other tracks like Mid Ohio, IRP, and Road America don't fill the catch bottle until after multiple sessions. So perhaps Brad's not running any short fast tracks...we know it CAN'T be because Brad's not running fast enough LOL :) I guess I can avoid the full-catch-can problem by avoiding Putnam Park, and running only big "technical" tracks like IRP and Mid Ohio?

I'm ignorant. Can someone explain what a "dry sump" oil system is versus the conventional oil system?

Gene if we drain the oil back into the primary turbo inlet, wouldn't we be oiling the intake tract again, which is the whole reason Crispy concocted the catch can in the first place ("catch can 22" LOL :) ) ?

The upshot with Crispy's Catch Can @ Putnam Park is after a full lapping weekend, I will have changed my oil with 4 quarts of Mobil 15W50 LOL...have fun, and do maintenance all in the same weekend :)

Seriously, the major benefit with Crispy's Catch Cap/Can is that the intake tract is dry (relatively speaking). The Efini Y-pipe to the IC is dry. There is some oil after the IC, but that could be residual oil from BEFORE I re-installed PaulyDee's version of the Crispy Catch Can (with recently updated "Crispy Cap"). The GReddy FMIC 2-row is a huge IC core with plenty of volume in those end tanks to hold residual oil!

The downsides? 15-minute sessions at Putnam Park ONLY; Mid Ohio, IRP, Road America aren't really major issues for the Crispy Catch Can/Can setup.

Can the Crispy Catch Can/Cap be improved? Probably--and I await the new & improved version...hopefully only minor modifications will be required...

Keep those great ideas flowing!

Dry sumps are common in all racing motors. Rather than the oil pooling into a pan in the bottom of the engine where the oil pump sucks it out, the oil is held in a seperately mounted tank. That's where "dry sump" comes from; there's no oil pan! Without the pan a flat cover is used to seal the bottom of the motor. The oil pump is typically an external unit that is belt driven off the engine (Mazda has a version with external plumbing but the pump still inside the front cover; very neat). This external pump not only pushes oil through the system, it also actively scavenges (sucks) oil out of the motor at the same time. Many times the pump will also have more than one pump circuit. For instance in a piston motor the crankshaft journals and the valves could have their own feeds without having to share the same oiling circuit. This maintains absolutely the best oiling throughout the entire engine.

Dry sumps offer some real advantages in race applications:

The engine can be mounted lower since there is no pan.

In a piston motor the crank no longer has to splash through the oil in the pan. This puts less drag (windage)on the crank.

It is nearly impossible to starve the pump of oil.

Oil temps are slightly lower since the oil is not stored inside the hot motor.

You can make the oil capacity as big as you want as the oil tank can be mounted anywhere.

Cool, thanks, DamonB. FWIW, I think the BMW M5 has a dry sump?...

That's a first......:rolleyes:


Damon's description is 100% correct. Most Production and GT based SCCA cars run dry sump and it is an extremely expensive conversion (Approaching 5K with pump, front cover, reservoir and lines/fittings.)

I have yet to see a street third gen with this system implemented. Anyone daring enough to be the first?
:)

MOST racing dry sump systems run more than 1 pump - Usually there is a HIGH PRESSURE engine (belt or gear) driven pump that shoves the pressurized oil into the engine and to all the moving parts, up to 3 or 4 SCAVANGE Pumps (usually electric) that suck the oil out of the crank case and/or cam galleries etc, and pump it back to a big Tank (Group C cars used tanks as large as 20L for Le Mans), some systems also add a feed pump to pump the oil from the tank to the pressure pump (common for acrobatic aircraft that need to pull lots of both positive & negative G)

Dry sump sounds like the way to go. Too much money. Guess us ignorant folk will retire from the sport in deference to the real SCCA racers here. I'll just stick some Toyo RA-1s on steel wheels with plastichrome spinners (afterall the poll has spoken!), yeeah...I can "pretend" to be a racer.

In short all we (I unless anyone can do it first) have to do is figure out a way to plumb the drain line back to the pan :)

Manny,
I feel for ya. This past weekend I could run 4 laps tops before filling the can....a few long hard right handers.
I've run clockwise tracks with not a drop. And counterclockwise track like Summit Point Main and will catch only half a can after an entire day.
FWIW,
Crispy

A few frosty beers and some sleep deprivation have inspired me... a few absurd solutions... starting with the most absurd...

1) Extend your oil filler neck way up high so it sticks out of the hood like some kind of smoke stack. Who knows, it could become the next big street racer fashion rage.

2) Could you custom fabricate some type of filler neck the bends way over toward the center of the engine? Would that help keep it from creeping up on high g turns?

3) Have the catch can drain to the windshield washer fluid reservoir? It would hold a lot of oil and you could live without it. Or you could replace it with a mini one like Crispy made.

-John

I like draining the catch bottle oil back in the dipstick opening idea...we can "T" into the dipstick opening with a really good fitting. This would allow the oil to drain from the catch bottle back into the oil pan?

Right then - time for another idea from me!!

Why not use an oil level sensor to check when the oil gets to a certain level (1/3?). Then plumb in a small filter, pump, and valve.

When it activates the level sensor, the valve opens, and the pump activates.

This way you should be able to tap it into the sump without fear of oil from the sump being blown up into the catch-can. This (in my eyes anyway) seems alot simpler than extending the filler-neck or any of the other methods.



I'm on a roll, I've got another idea!!

Why not remove the sump cover, and connect hoses to all the oil in/outs on the engine, then simply connect them to a remote resevoir. It's nowhere near as good as a dry sump setup, but it should give the benifit of cooler oil, and being able to mount the engine lower.

http://reganrotaryracing.tripod.com/catch.htm note that the new swivel fitting rubs the inside of the hood...

Manny,

Please read my post again :)

Thanks,

Gene

I guess I'm not following. You want the catch can oil drain tube to eventually route to the turbo oil drain tube (which is not the primary turbo inlet)? Help me understand. I'm ignorant, remember?

Manny,
You are correct. Turbo oil drain tube NOT the turbo air intake pipe/elbow.
Crispy

I must correct a misconception. Crispy, who is a good friend, did not come up with the Williams-Sonoma mod. It was developed by our <track> friend, John Eppley. John found the baster, fitted it to his track car's (which is very similar to mine) Jaz catch can (which I found initially and was marketed by Pauly Dee's old shop). Anyway, the baster mod should be called the Eppley-Williams-Sonoma mod.. or short version, the Eppley Baster mod.

FWIW, Eppley and I both find the Jaz-Baster mod combo COMPLETELY cures our track slosh problems. We run at CW and CCW tracks, some high speed and some 'technical'. (Hey, Manny, if you go fast enough they are ALL technical). This year alone I have run Texas World, Watkins Glen, Mosport, Mont Tremblant, Barber Motorsports Park and VIR full. Trust me, if you don't slosh at Mont Tremblant or Barber, you don't have a problem.

I'm lost now too. What is the "baster" mod?

It's shown on Crispy's site at the bottom http://reganrotaryracing.tripod.com/catch.htm

Basically you cut a Williams-Sonoma stainless steel baster 3.75" from the tip and epoxy it into your oil filler cap. This creates a longer path for the oil to slosh out the filler tube. This is the mod John Eppley developed to augment the Jaz catch can breather mod.

Alright that makes perfect sense. It is the same as the other mod (sorry I can't remember the original person) where tubing is stuck throught the stock nipples with the same idea.