Direct injection

[Dfeeds]

I do not see the connection.

I'll keep it simple. Carbon build up happens regardless if you're PI or DI. The difference is, with port injection, the fuel comes in contact with the top of the valves and cleans them. With direct injection, the fuel is sprayed directly into the combustion chamber so it's not coming in contact with the valves and cleaning them. The mustang has both PI and DI injectors so it's not anymore of an issue than any other car.

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[WildHorse]

It's fairly well established that one point of compression is good for a 3-4% bump with all else the same....

Its called diminishing returns .

 

[Shadow277]

Nah, the catch can craze spans all makes, models, and engine technologies.

I don't dishagree. After rebuilding my K24Z7, the shop recommended a catch can because I was STILL burning 2.5 quarts of oil over 280 miles.

 

[Shadow277]

I'll keep it simple. Carbon build up happens regardless if you're PI or DI. The difference is, with port injection, the fuel comes in contact with the top of the valves and cleans them. With direct injection, the fuel is sprayed directly into the combustion chamber so it's not coming in contact with the valves and cleaning them. The mustang has both PI and DI injectors so it's not anymore of an issue than any other car.

So it's unburnt gasses being reintroduced into the motor causing carbon deposits?

 

[FruityJudy]

All this concern over carbon buildup and noone running meth....

 

[Kermut]

Nah, the catch can craze spans all makes, models, and engine technologies.

Im debating a catch can for my new Mach. It seems like a pretty low-effort endeavor, so even if it had minimal gains, it would be worth it?

 

[engineermike]

Im debating a catch can for my new Mach. It seems like a pretty low-effort endeavor, so even if it had minimal gains, it would be worth it?

I’ve never bought one and probably never will. I believe it’s snake oil.

 

[engineermike]

All this concern over carbon buildup and noone running meth....

I don’t think valve coking will be an issue so I wouldn’t do it for that reason. I wouldn’t do it at all because you can’t stop the pcm from cutting fuel when it decides to reduce torque. You’re setting it up for a super lean condition.

 

[Vlad Soare]

I’ve never bought one and probably never will. I believe it’s snake oil.

I've seen what it catches. Just imagining all that oil entering the intake manifold and smearing everything in its path makes me cringe.
I'll give you that it probably wouldn't cause any actual issues, at least not for a long time, but still, why not keep your engine clean if it's so easy and cheap to do?

Actually it does, sort of. Ford gets EGR from cam timing at cruise.

How does it work?

 

[ice445]

I've seen what it catches. Just imagining all that oil entering the intake manifold and smearing everything in its path makes me cringe.
I'll give you that it probably wouldn't cause any actual issues, at least not for a long time, but still, why not keep your engine clean if it's so easy and cheap to do?


How does it work?

Because it doesn't keep it clean. The catch can is only catching some of the oil, not all the vapors. To me it's like a bandaid on a gunshot wound, sure it makes you feel better but it's not doing anything notable. The intake manifold has a large surface area and an immense cooling effect to condense the rest of those vapors. Luckily on our engine it's pretty easy to remove the intake manifold and clean it.

 

[Vlad Soare]

I don't know. I've unplugged the hose that goes from the catch can to the intake, and it looked clean and dry to me.
So, even though the can theoretically doesn't catch all the oil, it sure seems like it catches an awful lot of it. Not being able to catch everything is no reason to give up. Catching 99% is still much, much better than catching 0%. Actually, even catching 40% would be much better than zero - it means you'd get in 100k miles the amount of gunk that others would get after 60k miles. So, it if's cheap and easy, why not?

 

[ice445]

I don't know. I've unplugged the hose that goes from the catch can to the intake, and it looked clean and dry to me.
So, even though the can theoretically doesn't catch all the oil, it sure seems like it catches an awful lot of it. Not being able to catch everything is no reason to give up. Catching 99% is still much, much better than catching 0%. Actually, even catching 40% would be much better than zero - it means you'd get in 100k miles the amount of gunk that others would get after 60k miles. So, it if's cheap and easy, why not?

Because the amount of physical gunk possible is a constant, there's only so much surface area for oil to accumulate on since fuel is washing the hot bits pretty much constantly. The minimal residue/coking effect in something like a composite intake manifold upstream of the combustion chamber doesn't allow for infinite accumulation from what I've seen, so even if you're stopping 80% of the blowby, eventually that 20% will create the same amount of gunk as someone who never cared to stop any of it.

With that said I don't really disagree with your logic. In my case, I had a catch can for a while and it caught oil, yeah. But I realized I didn't care to constantly empty it. And in my case the can's line was leaking onto my timing cover, and I could clearly see oil buildup in the outlet line telling me that it's just a losing battle. I'd rather skip having to mess with it and just leave it factory and burn all that blow by. So in my opinion it just doesn't do enough to make it worth it to me personally. But if it is to you then great.

 

[mangosmoothie]

I had an OCC on my Mazdaspeed3 (DI only) and it caught mostly moisture in winter.. Then I had to worry about it freezing... which it did a few times... oops.

The couple oz I collected in the summer spread over the few thousand miles seems like it wouldn't matter much.

The main reason I installed an OCC in the first place was because it was a vented can. I was worried more about venting excess crankcase pressure after going big turbo.

I don't think I need a vented can with the 8 or so lb of boost I'm running, and the PI washes the valves. So I'm not worried about it on this car.

 

[bankyf]

Oil vapor=loss of octane. How much of an affect it actually has and how much a catch can will help is certainly arguable, but any is too much and anything that can reduce it(catch can) at minimal expense and effort is worth it to me.

 

[andrewtac]

I’ve never bought one and probably never will. I believe it’s snake oil.

Follow just about everything else you write on here, so is this true in all cases? In my case as I have turned up the boost (now I see 17-18 in the high rpms) my catch can gets oil and e85 in it. Not a ton but some, and more so when i am running it hard. If i drive normal, it stays empty. With the Paxton and probably 12 or under I don't think I ever had any in it. I vent off both valve covers. I bought the catch can more out of convenience as it was easier than trying to plumb back in as I am running filter on the blower (or open). Suppose I could route back in, wouldn't it be more beneficial to keep the oil/e85 mixture (and maybe some h20/meth from when I spray) out of the blower or intake path? I think I had less than $100 in the can and hoses (Amazon special).

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