13b NA, mix of s5/s6 parts. It's 4.5 weekends old now. Really likes to spit oil, has always been a problem since built (not by me). Spends all its time between 7k-9k RPM. I upgraded to a 5/8" vent tube off the fill neck, still spit up 18-20oz of oil in 35 min race. I have a catch can for my catch can, it's ridiculous.

It's been suggested side seals aren't doing their job. Any opinions here on why it spits so much?

 

An oil pan baffle will help this. Also what is the vent on the center housing hooked to? An oil separator tank with a drainback might help this too. Do you have the stock oilpan or a racing piece?

 

I too would suspect the side seals. That is quite a bit of oil for an n/a engine to be puking up.

A baffle may help some but venting the other side of the engine will eliminate the problem all together, regardless of the side seals. Tap a fitting into the front cover on the right side below the the mop. The pressure in the oil pan has to go somewhere and if oil is blocking its path, then the puking will begin.

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https://www.rx7club.com/showthread.p...t+cover&page=5

 

Mine used to do the same thing. I would fill the 1 quart catch can in a 20 minute race. What we did was get a TII filler neck and run 1 vent tube off the top, about 1 inch below the bottom of the filler cap with 1/2" line and loop it back down to a lower vent tube just below the bottom 90 degree bend. Off the middle of the loop, we run a 1/2 line off to the catch can. I am trying to use the 2 openings as a sorta oil/ air separator that has a drain back and the 2-90 degree bends as a type of baffle.

It must work as we have reduced the puking to less than 1 cup in a 3 hour race. We run a baffle plate in a stock pan as well. It is interesting as the puking initially only reared its head during sustained high speed/rpm, high g load corners to the right. As we developed more cornering capability the problem got worse until we came up with this solution.

Eric

 

Pretty typical of these cars, especially when you start turbocharging them. That is why venting the other side of the engine completely eliminates the problem. Glad you were able to figure something else out that helped and is certainly easier to do than tapping into the front cover, but I don't think it would work as well with turbo cars, but in the case of the OP, it sounds like a good solution.

 

mine was spitting oil when i went single, we created a tap in the filler neck with into a breather tank that loops back into the secondary return? in the oil pan. my oil pressure doesnt move from 60.


soo it goes Oil filler neck-->> Breather Tank--->> Oil Pan = win

 

Just to be clear, those loop systems solve the messy problem but the engine is still puking oil, it now just drains back into the engine. Venting the other side of the engine eliminates the puking of oil from the engine altogether.
There are obvious advantages to the latter.

 

Actually, mine solved the oil puking and hasnt pushed any oil out. There isnt a oil pressure issue anymore. It literally doesnt move off 60psi. there is no oil in the breather tank. This totally resolved all the oil pressure issues.

 

Good ideas and solutions, thank you.

In answer to a few questions, it's a modified stock pan with an ISC baffle plate. Also run a 3qt Accusump. Never had this problem before on the last motor (also with ISC baffle and Accusump), only this new motor. Vent on center housing by fill neck runs to vented catch can.

Why is it puking? Side seals? Any other possible reason?

If side seals are the case, I am going to pull it and have a new motor built. Don't want to spend a few grand but will if necessary. This one has never made the power it is supposed to, and if it is the side seals, that might explain part of the reason HP is crappy and help me justify writing this motor off as a turd.

 

In my car it was puking oil from the oil pressure created from the GT40R. During load it would start building pressure in the oil pan, and pushing it out the filler neck.

 

I think the rub is an N/A motor should not be doing this. There is nothing that should pressurize the pan that much. I would second that your engine seems to have an oil seal issue.

I have also seen a "other side vent" solve these issues on turbo cars. (Damian & GooRoo) But again, the N/A cars shouldn't really have this problem unless you are running silly power and tires (high Gs).

 

Exactly. The only way you're pressurizing the pan this much with an NA engine is if compression is pushing into the pan past the side seals.

We've built plenty of similar engines that might lose a minuscule amount of oil in a session, usually none. And no special breather is needed. If you need a huge breather or complicated venting on this engine you've got too much crankcase pressure and you're just back to having a sick engine.

 

Im sorry can someone please post a link to "venting the other side of the engine?" Im curious about this. Also na car, smokes from oil breather and the other fc just puked oil from the oil breather, never happened before on this car.

 

https://www.rx7club.com/race-car-tec...5/#post5014991