tjbell said:
I'm 50/50 on catch cans, I see both sides of the argument. I have personally never run one, but this is indeed cool if it works, because brand name catch cans are stupid expensive for what they do.
As a guy that spent some time as an engineer in the auto industry my take on the issue is also 50/50. It’s sad that PCV systems cannot be designed and engineered better by the OEMs. It’s been a problem for almost 4 decades now and direct injection compounds the issue for intake valves. A catch can is a band aid on a gushing wound in my opinion. It can help but it still doesn’t fix the problem. It probably does help keep some gunk off intake valves in some cases.
I have one on my turbo Miata, for a few reasons. The PCV valve doesn’t completely block positive manifold pressure, so it acts like a boost leak and pressurizes the crankcase. Plus the PCV system doesn’t suck out crankcase vapors when there’s positive pressure in the IM. Therefore, the PCV is completely disconnected. Also with an aftermarket ECU you tune your fuel map based on the assumption of air in the manifold. Oil isn’t air, and it could affect your air/fuel ratio as calculated by speed/density method.
I think for a non-boosted car running a stock ECU with a safe tune, it probably isn’t necessary. I can’t think of any way that it would hurt anything though.
In reply to ShinnyGroove :
OEM turbos often use a check valve inline with the PCV so the crankcase is never pressurized. Brake boosters work the same. You can use a brake booster check valve and it helps a lot. I did this when running 25 psi of boost myself.
In reply to edizzle89 :
I'm interested to see how much fluid you'll find in it. And also how you'll be using the car.
I don't have aftermarket catch cans on my street cars but I have one between the PCV and the intake on all of my race cars. There are a few fast, high-G left handers at my local tracks, and the cars would start blowing blue smoke at the exit of these turns after 15-20 mins of high-rpm running. If I didn't start short shifting, the car would start misfiring within a few laps. Eventually broke down and installed a cheap catch can off of ebay. No more smoking or missing coming out of left handers after that was done.
I have a quick update on how the catch can is doing. It's been 2 weeks since the install and it looks like it's caught some oily condensation which is about what I would expect this time of year. But it seems to be doing a decent enough job for $10 and it's that much less crap going into my intake manifold.
Looks like it works great and has plenty of capacity!
Im going to have to try this on the neons. They're notorious for sucking lots of oil through the pcv and smoking on the dohc engines
F'sho. I'll build one like this instead of : https://www.summitracing.com/parts/mor-85600 ($145.00)
And thanks edizzle89!
edizzle89 said:
I have a quick update on how the catch can is doing. It's been 2 weeks since the install and it looks like it's caught some oily condensation which is about what I would expect this time of year. But it seems to be doing a decent enough job for $10 and it's that much less crap going into my intake manifold.
I wonder if it keeping that chocolate milk from mixing back in with your oil makes any difference to the integrity of your oil and and longevity of your engine. For $10 I don't really see a down-side.
noddaz
SuperDork
9/28/19 12:08 p.m.
In reply to edizzle89 :
It has now been 8 months since your install. Can we get an update?
noddaz
Yes. Bump again. 4-year Update??
SkinnyG (Forum Supporter) said:
Yes. Bump again. 4-year Update??
Didn't expect to see this pop back up haha. Unfortunately I sold the car about 2-ish years ago. But in that time it did continue to catch similar milky oil like pictured above, although less milky in the summer months (as to be expected). It would get to ~1/2 way about every month or 2 so somewhat regular draining was needed. I will say the design of the 'catch' part that you remove to drain was significantly more robust on the Lowes (Kobalt brand) separator compared to this harbor freight piece, the Lowes unit screwed on were the harbor freight one had a lock table you'd pull down and twist to drop. I did have to replace the o-ring on the bowl since it didn't seem to be designed to be regularly removed and installed. The bowl also had some wiggle to it which I wasnt a fan of, the Lowes part kept everything held tight.
I know this isn't a side by side test of these cheap air/water separators compared to the 'legit' expensive catch cans but they aren't a complicated part with a bunch of complex intricate workings. Air goes in, hits a filter, vapors are grabbed and collected, clean air goes out. In my book, for the cost, I'd run a separator every time. Although I'd probably stick with the more quality Lowes, Home Depot, etc vs. going with harbor freight again.
Excellent feedback, thanks for the update!
