excessive oil "blow by" solutions?
 

For lack of a better term, when I road race, or AX my FC I push almost a quart into the overflow tank, leaving me about a quart low. Too much oil pressure? I think my pressure is around 65-80 at WOT hot(Mobil1 5w30). I've seen that most FDs do this, but I am pushing out alot of oil. I am running 1.3-1.6 bar of boost on the track(yes, ~ 20psi, ~480rwhp). Any thoughts on a solution? maybe some sort of oil recirculation system. Anyway, all constructive input is appreciated. Thanks, Carl

Carl,

We have diesel generators here at work with oil seperators in the crankcase vent lines. They have a small line at the botom that drains into the oil pan. Would there be a problem running a small hose from your catch tank to your oil pan?

Carl this was a good old thread on the subject, https://www.rx7club.com/showthread.p...=oil+catch+can

Carl, I share your pain. After filling my quart sized catch can, my road race car proceeded to blow even more oil all over the exhaust. I looked back, saw the cloud of blue and thought the motor was done. My (at the track) fix was to re-plumb the vent line into the bottom of the catch can so the oil could drain back. It appeared to work quite well. My long term solution will likely involve a larger catch can mounted right over the vent line with a breather installed in the top. I'll also run the filler neck line into the catch can.

Hope this helps,
-Trent

The Racing Beat oil pan baffle helps quite a bit. (we're talking the 2nd gen motor here right?)

Thanks for the input, not sure if I have the RB baffle, I do not think so, as I do not see an extra gasket/metal edge. I will add that ASAP anyway, thanks for the reminder. As far as the return to the pan, I do not see why not, that was the direction I was headede, but rather than suggest it, I wanted to see if someone was using it already. I do not like the idea of a quart plus low on the track. So i would go braided, and use a bulkhead fitting I would think. I would not trust a simply tapped hole in the pan. What other locations if any might be better/safer than the pan? Car is great so far, I can run 20 psi on the road course with O'k temps. I am going to continue to work on lowering my temps though.
Josh, what WOT oil pressures are you running, any downside you can think of to the setup, such as difficulty maintaining oil pressure(should be unconnected, just asking) etc? Thabnks, Carl

The blow by is caused by making a right hand turn when under boost and has nothing to do with oil pressure. The oil pan does not see the same psi as the oil circulating through the engine.
What happens is the oil is collected on the left side of the pan and when under boost, the 'crankase' is pressurized and needs an outlet. Unfortunately for us, the only way out is up the filler neck and/or the turbo oil return line. The oil is literally pushed out the way it was originally poured into the engine or in the latter case, the oil is burned up by the turbo as seen through the exhaust.

I used to go through a quart or so also until I added an oil pan baffle plate and a larger breather line. I used to run a -6an size line out of the top of my oil filler cap but found that was not enough venting. I would still blow out my dipstick tube (HUGE mess) and the exhaust would smoke during track time from the turbo oil return not draining properly. I switched to a -10an size line out of the top of my oil filler cap to a quart sized catch can with a breather. My catch catch can is hardly half full now. For easy draining, I installed a quick drain fitting with a hose to the bottom of the catch can that I just screw in to drain. quick, easy, no mess.

Ideally, that oil would return to the oil pan but I would like someone to try and weld a bung (or bulkhead fitting as Carl mentioned) onto the right side (exhaust side) of the oil pan to ventilate the crankcase during right handers without pushing oil up the filler neck and into the catch can essentially eliminating the problem. The air will take the path of least resistance.

Another method is to run a vacuum pump which are available.

FWIW, I am only vented off the rear iron. I am thinking of running a loop directly to the turbo drain, but I need to make sure I do not preesurize the drain line, and create a oil starvation problem for my turbo bearings, thought?

This will eventually kill your turbo bearing. :eek:

run with about 3.5 quarts instead of 4.5

Won't make any difference in operating temps if you have good coolers and ducting.

With all due respect, reducing oil capacity by ~23% is a bad idea, especially considering that the car is not designed to oil at ~1.3Gs in the first place. As far as temps, it would not have a big effect, but any is too much IMHO. Th right thing to do is solve the problem, the car will expel oil until it is easily 1 quart below "low", at which point you are in danger of cooking your motor. Thanks for the input, I will be trying some things at the track in Sept., I will post my results. Carl

hey carl,
good luck ontrack tomorrow.

i too read that long/interesting thread on blowby and concluded the only solution is to vent both sides of the pan. as Dave suggests.

howard coleman

Hey it works for me :D I also change my oil every 2k track miles. Call me crazy but the car runs on the track like a daily driver does on the street hehe :)

I'm also not running with the same power or tire size as you but you just said it yourself. The car is not designed to efficiently oil the motor at 1.3gs so if you throw the extra quart up the neck and into your overflow you're just wasting it and making a mess. If the car is running at normal temps with the current setup run a quart low because it won't make a difference and you won't have the mess.

Temps are 220 oil 210 water after 20 minutes at 20 psi...

If you're getting those temps in 85 plus degree weather you're doing fine especially considering those boost levels. That said I wouldn't expect to get much life out of the engine making that kind of constant power.

Last month it was 100 degrees out and my water and oil temps didn't go higher than 190. However if I was running 20lbs of boost I suspect my temps would of been through the roof LOL. My manifold was cracked and the boost was limited to 9 or 10 psi.

Update, I made some modifications to my air box, and the nose. Temps are 210 oil, and 200 water@ 20 psi. ACT is trying to make a clutch for me, the Spec Stage III clutch lasted one day LOL... RX7Store said their 500hp FD uses that clutch, I guess one of us is not making as much torque as the other. I will be the test mule for a new RX7 Clutch from ACT. Hopefully, it can handle the ~500+ FWTQ I am throwing at it. I am spinning 180*(temp) 13" goodyear slicks coming off the turns. I was able to hang with a ~700hp/620tq GT40 replica today(til my clutch died), some crazy stuff. Sweepers, that were ~80mph in my MKIV Supra on R compounds, are ~95+ in the RX :D.

I think you may need a clutch with more than one disc at this point. :bigthumb:

I may(go Exedy/ACT double), ACT is going to make a sprung hub 6 puck disc, and a "double X" PP for my car. I know something else will likely break, but that's the price you pay. Right now I am so strapped money wise, that if I get a sponsor, I need to try and make it work. I am confidebt ACT can make a clutch to hold my modest torque(compared to Supras /vipers etc). I was almost as quick through the corners as a Lotus Exige Sport(1428lbs/230hp) that was on Yokohama slicks made just for that car. Carl

Carl, where were you testing at?

Water injection does magical things that is all i can say about this guys track car :)

Well, where is the oil going Carl? my car was pissing out oil but couldnt figure where? Looked like around the oil filter @ highloads.. or am i completely talking about the wrong thing here?
:)

Can you post up some pics of your enginebay/car :)

please..

Also, have you tried running some more boost on the track? we ran 25psi for about 5 minute's constantlyaround the track and it was fine on the standard motor.

Mind you this was @ WOT all the time , not pussy driving :)>>>> but you have circuit slicks.. damn that must feel super duper fast with that power.

After many attempts we solved the problem from catch can fill up in one heat to less than 1/4 quart per several heats with the following (JAZ catch can to the left of the IC [looking from inside]):

1. one breather line from top oil filler cap
2. one breather line from old secondary turbo (now single) up and around the engine to the same catch can

With this we never had any more oil messes but the catch can always collected some oil, workable. Worked great for both left and right corners etc. and running high boost. Our engine worked very well anyway.

Now after an engine rebuild and keeping the same catch can breather setup we do not collect any oil whatsoever at the catch can.

Therefore, we have concluded that if the engine is breathed properly then oil and blow-by etc are due to the engine condition itself. Sad but true.

Thunderhill, no times, just working on debugging.It was a NASA event, 500+hp 914 700HP+GT40, 600hp+ corvette, 550hp Audi S4, all on slicks, that was a very fast group. I'd say ~15 cars in the group, 7 sessions for 179.00. I was really pleased with my temps, I think I can run a full session at 20 psi now without problems. Tighen I'll add water injection, and reliability will only get better. I am going to have to go to the high end hose clamps, those billet hinged pieces, the T bolts are not getting it done, maybe two T polts, and longer custom couplers with a double bead. T bolts hold O'k until you get them very hot, and oily, then, even T bolts slip. I am going to make some 4" couplers, this blowing hoses off is getting old... carl

Id just like to add, you should get a twin aftermarket oil cooler setup , it seems your oil temps are getting abit high for my likes IMHO.

http://www.northwestnissans.com/test...jpn05a-112.jpg

Seems to me as long as both sides of the pan are vented we'd all be fine. No matter how big a breather or catch can we use if only one side is vented oil will always be pushed out. As soon as the oil begins to slosh up the filler neck the pressure in the sump will actually continue to drive the oil up the neck and keep pushing it out rather than letting it slosh back into the pan.

If both sides of the pan are vented one side will always be uncovered and so the pressure can take the path of least resistance, venting without having to push oil ahead of it.

It made a big difference for me by adding a TII Turbo's oil fill neck (I have a 3rd gen) and made a small adapter to angle the neck towards the center of the car. I also used the unused oil drain from going single with both lines going to either side of a Jaz catch can. I only have the one event at VIR with this setup but I only had one session where I picked up any oil at all and it was a small amount. Granted it wasn't my best weekend but it seemed successful. The cap doesn't have much room between the alt and UIM but it's enough...

Here's some pics that may help. I don't know if it's applicable to your setup but I thought it may help someone...

http://www.geocities.com/gqmracerx7/OilTube01.jpg

http://www.geocities.com/gqmracerx7/OilTube02.jpg

http://www.geocities.com/gqmracerx7/OilTube03.jpg