Direct injection

[engineermike]

I’m not saying there is zero advantage in all cases. I’ve just found the manufacturers usually grossly exaggerate the benefits using scare tactics and pictures of ugly fluids. There is *usually* no disadvantage to having one.

All the oems are pushing compression ratios and specific power up for fuel economy reasons. Knock is the limiting factor. I can’t help but wonder why the oems never pursued this. It could be designed maintenance-free if it were to drain back to the crankcase.

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[IPOGT]

I’m not saying there is zero advantage in all cases. I’ve just found the manufacturers usually grossly exaggerate the benefits using scare tactics and pictures of ugly fluids. There is *usually* no disadvantage to having one.

All the oems are pushing compression ratios and specific power up for fuel economy reasons. Knock is the limiting factor. I can’t help but wonder why the oems never pursued this. It could be designed maintenance-free if it were to drain back to the crankcase.

Because when a smart guy engineer ( like yourself ) thinks of this great stuff, marketing says we’d rather have stickers on the door panels and finance says it costs too much and no ones getting anything, or marketing wins because of the bar graph someone showed in a meeting indicating how many more units would sell.

 

[beetle6986]

I can’t help but wonder why the oems never pursued this. It could be designed maintenance-free if it were to drain back to the crankcase.

I agree completely!

I put a catch can on my 2016 supercharged GT. I noticed some oil running out of the throttle body when I upgraded to a new throttle body. Car only has 5,000 miles on it.

I don't have one on my Cobra, but never noticed any oil in the throttle body. I'm taking the blower off for a port. It will be interesting to see how the bottom side of the blower and intercooler look. That should give me an idea if I need one for that car also.

My 335 definitely needs a catch can. The carbon build up in the values is bad enough with the direct injection. My OEM intercooler had a decent amount of oil in it when I removed it.

As for DI. There are some advantages and disadvantages. I don't think DI has much to do with the bump in HP for the 2018s.
Keeps cylinders cooler
more efficient. Runs a bit leaner than PI.
carbon buildup if you dont also have port injection
Sometimes difficult to find mechanical pumps to flow enough fuel for e85 while still keeping pressures high enough.

 

[Roostfactor]

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?

By advancing exhaust cam timing. This closes the exhaust valve sooner so not all the exhaust is evacuated from the cylinder. EGR=exhaust gas recircluation so since there is a bit of exhaust left in the cylinders it's gets burned a second time.

 

[markmurfie]

By advancing exhaust cam timing. This closes the exhaust valve sooner so not all the exhaust is evacuated from the cylinder. EGR=exhaust gas recircluation so since there is a bit of exhaust left in the cylinders it's gets burned a second time.

I would have said the opposite, retarding the exhaust cam, closes the valve later. This allows the piston to pull in gases, not only from the intake, but the exhaust as well during the initial part of the intake stroke.

So that some of what it has already pushed out, gets pulled back in, therefore recirculating the exhaust gases.

 

[Vlad Soare]

By advancing exhaust cam timing. This closes the exhaust valve sooner so not all the exhaust is evacuated from the cylinder. EGR=exhaust gas recircluation so since there is a bit of exhaust left in the cylinders it's gets burned a second time.

Thanks. It makes sense.
This is good news. This should be much more reliable than a standard EGR system and should have none of its drawbacks.

I would have said the opposite, retarding the exhaust cam, closes the valve later. This allows the piston to pull in gases, not only from the intake, but the exhaust as well during the initial part of the intake stroke.

So that some of what it has already pushed out, gets pulled back in, therefore recirculating the exhaust gases.

While both ways might work from a technical standpoint, I think this one would be a bit harder to control. I mean, after the power stroke you know (almost) exactly how much gas there is in the cylinder and can calculate when to close the valve in order to keep just the right amount. Whereas if you leave both valves open you'll have to make sure that the piston sucks exactly the correct amount of air and gas through each valve, and that the exhaust gas doesn't pass into the inlet manifold through the open inlet valve instead of going into the cylinder (or the other way around, that some of the air/gas mixture won't get lost by flying through the open exhaust valve). I'm sure it can be done, but somehow it looks a bit more difficult to me than the other solution.

 

[Garfy]

That's fair, it is pretty loud. But at that point, why spend a premium on a 2018+ only to disable one of the better features of the new engine...might as well get a 2017.

So the cons are more money spent, less power, worse fuel economy for pros of a slightly quieter engine.

Either way, it's easy to do in a tune...just have a reputable tuner make changes to when the DI comes in.

Actually, I can barely hear the DI clicking as my stock exhaust is louder. It's not like the engine is as loud as a diesel so I don't know what the fuss is all about. I've heard about the "tick" problem but not sure what it is all about as I don't think the noise from my engine is annoying at all (or maybe my engine doesn't have the "tick" as loud as some other people have experienced).

 

[Garfy]

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

Although I've only seen them primarily on "performance" cars; can't find any for Camrys, Civics, Accords, etc.

 

[Vlad Soare]

That's probably because whoever has a Camry, Civic or Accord isn't actually interested in cars. Those are bought primarily by people who just need something to take them from A to B as cheaply as possible.

 

[Garfy]

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

If you ever pulled an intake manifold on a car with some decent mileage on it, you'd notice the oil dripping out of the manifold. It's messy and ugly and coats the inside of the intake runners. That's why I got a "catch can" for my car; though only the passenger side. I don't drive it hard enough that would collect oil on the driver side can if I had one. Every time I drain my JLT unit I'm glad that all that oil didn't make it into the intake runners.

 

[Garfy]

That's probably because whoever has a Camry, Civic or Accord isn't actually interested in cars. Those are bought primarily by people who just need something to take them from A to B as cheaply as possible.

Probably true (with the exception of the Type R or Type S guys).

 

[Vlad Soare]

Indeed, the Type R may be an exception. But then, they do make catch cans for it.

https://www.mishimoto.eu/honda-civic-type-r-baffled-oil-catch-can-pcv-side-2017.html

 

[Garfy]

I would have said the opposite, retarding the exhaust cam, closes the valve later. This allows the piston to pull in gases, not only from the intake, but the exhaust as well during the initial part of the intake stroke.

So that some of what it has already pushed out, gets pulled back in, therefore recirculating the exhaust gases.

I don't know about the VCT engines but in the old pushrod 2 valve engines there was a bit of overlap where both intake and exhaust valves were open when the piston was at TDC just prior to the intake stroke of the piston. The idea was that the exhaust flowing out would cause a scavenging effect that would help to draw in the intake charge before the exhaust valve closes and the piston continues downward in the intake stroke.

 

[markmurfie]

While both ways might work from a technical standpoint, I think this one would be a bit harder to control. I mean, after the power stroke you know (almost) exactly how much gas there is in the cylinder and can calculate when to close the valve in order to keep just the right amount. Whereas if you leave both valves open you'll have to make sure that the piston sucks exactly the correct amount of air and gas through each valve, and that the exhaust gas doesn't pass into the inlet manifold through the open inlet valve instead of going into the cylinder (or the other way around, that some of the air/gas mixture won't get lost by flying through the open exhaust valve). I'm sure it can be done, but somehow it looks a bit more difficult to me than the other solution.

I only look at what the cams actually do. Saying the extra range is for EGR or not IDK.

Ford has the exhaust cam:

at 0 (full advance) at idle

at 40-50 in the low RPM low load areas, near full or full retard at cruising conditions

and at WOT, low RPMs 0-10, mid RPM 22 max, then advancing with high RPM back toward 15. well advanced considering its full range.

I think most people into tuning these would say the exhaust cam only moves because of emissions. Power Is mostly about intake cam VCT, and packages with intake cams only, etc. Some others will say you can "fix" turbo kit back pressure issues with the exhaust cam VCT.

I don't just look at the IVO and EVC events overlapping at top dead center, I also look at the IVC starting the compression stroke and the EVO ending the power stroke and their role in things.

Your MAF sensor doesnt care if both valves are open, it will tell you what amount of air is flowing in through the intake side, and you match that with fuel, and thats all that matters.

 

[engineermike]

If you ever pulled an intake manifold on a car with some decent mileage on it, you'd notice the oil dripping out of the manifold. It's messy and ugly and coats the inside of the intake runners. That's why I got a "catch can" for my car; though only the passenger side. I don't drive it hard enough that would collect oil on the driver side can if I had one. Every time I drain my JLT unit I'm glad that all that oil didn't make it into the intake runners.

I've seen oil inside the intake, for sure. I just don't think it's hurting it as much as the catch can companies would have you believe. My car consumes less than a quart of oil in 10,000 miles, which means the gasoline/oil ratio is about 2000/1 or 0.04%. If I am somehow convinced that the anti-knock properties of a catch can will buy me something performance-wise, then I'll get one, but most of what I've seen so far is just qualitative "ugly pictures" and scare tactics.

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