[ANSWERED] DI Impact on Valves
09-02-2015, 12:19 PM
#121
Burning Brakes
I'm just posting in here to say that I installed a catch can this past weekend and it must be doing something right.
I can visually see a change.
How so?
Well since I have owned my Vette my outer two exhaust tips have always had black carbon on them that I have to clean off every week.
I installed my catch can this Sunday and washed my car. Made sure my exhaust tips were squeaky clean.
Been driving my Vette this week in stop and go traffic and also been hammering it hard at WOT when I get the chance.
My exhaust tips? SQUEAKY CLEAN just the same as when I washed them Saturday.
That catch can is doing something!!
I plan on checking to see what is in it this weekend.
I can visually see a change.
How so?
Well since I have owned my Vette my outer two exhaust tips have always had black carbon on them that I have to clean off every week.
I installed my catch can this Sunday and washed my car. Made sure my exhaust tips were squeaky clean.
Been driving my Vette this week in stop and go traffic and also been hammering it hard at WOT when I get the chance.
My exhaust tips? SQUEAKY CLEAN just the same as when I washed them Saturday.
That catch can is doing something!!
I plan on checking to see what is in it this weekend.
09-02-2015, 01:21 PM
#122
Race Director
I'm just posting in here to say that I installed a catch can this past weekend and it must be doing something right.
I can visually see a change.
How so?
Well since I have owned my Vette my outer two exhaust tips have always had black carbon on them that I have to clean off every week.
I installed my catch can this Sunday and washed my car. Made sure my exhaust tips were squeaky clean.
Been driving my Vette this week in stop and go traffic and also been hammering it hard at WOT when I get the chance.
My exhaust tips? SQUEAKY CLEAN just the same as when I washed them Saturday.
That catch can is doing something!!
I plan on checking to see what is in it this weekend.
I can visually see a change.
How so?
Well since I have owned my Vette my outer two exhaust tips have always had black carbon on them that I have to clean off every week.
I installed my catch can this Sunday and washed my car. Made sure my exhaust tips were squeaky clean.
Been driving my Vette this week in stop and go traffic and also been hammering it hard at WOT when I get the chance.
My exhaust tips? SQUEAKY CLEAN just the same as when I washed them Saturday.
That catch can is doing something!!
I plan on checking to see what is in it this weekend.
09-08-2015, 05:59 PM
#123
Burning Brakes
Why not go old school? Old days they ran crankcase gasses up to the intake through a tank with steel wool. The oil and junk would cool and condense the oil and it would fall back into the crank case and the air to the intake was nearly junk free? Why can't a more advanced system like that be used to clean the PVC gasses?
Good call on that. The Elite Engineering cap has steel wool in it too. I have it here on the top of my cars Dry Sump tank. It does that exact same thing you mention before routing back to the intake.
09-09-2015, 05:07 PM
#124
Burning Brakes
Here is how much oil my catch can caught after 300 miles.
Whether it is catching all of it or not, it is catching something! Better here than in my intake and on my valves.
Whether it is catching all of it or not, it is catching something! Better here than in my intake and on my valves.
09-09-2015, 10:45 PM
#125
Burning Brakes
Looks a lot like mine
LS engines need one, as the title of my Catch Can thread mentions-
(https://www.corvetteforum.com/forums...h-can-pic.html)
Last edited by dmoneychris; 09-09-2015 at 10:47 PM.
12-29-2015, 11:04 PM
#126
Burning Brakes
These carbon deposits on the valve stems and valve face are part of the combustion process. This is the case with all internal combustion engines that have intake and exhaust valves. It also happens on all 2 stroke engines and shows up in the exhaust ports.
These deposits can be cleaned off by blasting with walnut shells or scrubbing on rebuilds. They will re-cur within several thousand miles of running. The DI engines accumulate deposits are a somewhat higher rate than port injected engines. They both reach the same point after many miles.
All engines that I have rebuilt over the past 20 years have the carbon accumulation on the valve stems, faces, ports and combustion chambers. The piston tops have the same carbon surface.
You clean them off during a rebuild or a walnut blasting process and they soon return, maybe within 500 miles.
Chemicals can only clean some of the deposits. Repeated dyno tests at initial, 50 hrs later and 100 hrs later showed no reduction in hp or torque levels due to these deposits.
A catch can might reduce the carbon accumulation rate, but will not eliminate it.
These deposits can be cleaned off by blasting with walnut shells or scrubbing on rebuilds. They will re-cur within several thousand miles of running. The DI engines accumulate deposits are a somewhat higher rate than port injected engines. They both reach the same point after many miles.
All engines that I have rebuilt over the past 20 years have the carbon accumulation on the valve stems, faces, ports and combustion chambers. The piston tops have the same carbon surface.
You clean them off during a rebuild or a walnut blasting process and they soon return, maybe within 500 miles.
Chemicals can only clean some of the deposits. Repeated dyno tests at initial, 50 hrs later and 100 hrs later showed no reduction in hp or torque levels due to these deposits.
A catch can might reduce the carbon accumulation rate, but will not eliminate it.
12-30-2015, 11:50 AM
#127
Advanced
I'm on Car & Driver's e-mail list. On their December 11th mailing they had a Hennesse dyno comparison of a new 2016 Camaro SS vs. a 2014 C7 Stingray. Chevrolet markets the Camaro as having 455 hp compared to the C7's 460. The dyno results showed that the Camaro produced 21 more horsepower than did the C7. There was very little commentary concerning the test. The first question, however, that came to my mind was how many miles were on the C7 and could have the mileage and resultant 21 less hp had something to do intake valve coking?
BMW suggests that their DI engines have their intake valves cleaned at 50,000 miles. They have a specifically designed tool or part that fits directly to the intake ports that allows compressed air and walnut shells be pressure injected to clean the intake valves and another connection for a shop vac to exhaust the shells and carbon deposits. The charge is around $500 for 4 cylinder cars. If the customer opts out of the "recommendation", BMW feels that they will return somewhere between 75 and 90K miles with performance issues! I do not think this procedure is covered in the owner's manual. This information is from our local BMW dealer. I've seen this exact valve cleaning process performed on a You Tube video.
BMW suggests that their DI engines have their intake valves cleaned at 50,000 miles. They have a specifically designed tool or part that fits directly to the intake ports that allows compressed air and walnut shells be pressure injected to clean the intake valves and another connection for a shop vac to exhaust the shells and carbon deposits. The charge is around $500 for 4 cylinder cars. If the customer opts out of the "recommendation", BMW feels that they will return somewhere between 75 and 90K miles with performance issues! I do not think this procedure is covered in the owner's manual. This information is from our local BMW dealer. I've seen this exact valve cleaning process performed on a You Tube video.
12-30-2015, 08:46 PM
#128
I'm on Car & Driver's e-mail list. On their December 11th mailing they had a Hennesse dyno comparison of a new 2016 Camaro SS vs. a 2014 C7 Stingray. Chevrolet markets the Camaro as having 455 hp compared to the C7's 460. The dyno results showed that the Camaro produced 21 more horsepower than did the C7. There was very little commentary concerning the test. The first question, however, that came to my mind was how many miles were on the C7 and could have the mileage and resultant 21 less hp had something to do intake valve coking?
BMW suggests that their DI engines have their intake valves cleaned at 50,000 miles. They have a specifically designed tool or part that fits directly to the intake ports that allows compressed air and walnut shells be pressure injected to clean the intake valves and another connection for a shop vac to exhaust the shells and carbon deposits. The charge is around $500 for 4 cylinder cars. If the customer opts out of the "recommendation", BMW feels that they will return somewhere between 75 and 90K miles with performance issues! I do not think this procedure is covered in the owner's manual. This information is from our local BMW dealer. I've seen this exact valve cleaning process performed on a You Tube video.
BMW suggests that their DI engines have their intake valves cleaned at 50,000 miles. They have a specifically designed tool or part that fits directly to the intake ports that allows compressed air and walnut shells be pressure injected to clean the intake valves and another connection for a shop vac to exhaust the shells and carbon deposits. The charge is around $500 for 4 cylinder cars. If the customer opts out of the "recommendation", BMW feels that they will return somewhere between 75 and 90K miles with performance issues! I do not think this procedure is covered in the owner's manual. This information is from our local BMW dealer. I've seen this exact valve cleaning process performed on a You Tube video.
Although the special headers that the Camaro comes with probably help too.
01-07-2016, 08:32 PM
#130
Safety Car
How many miles on the 2014 C7? How tired was that engine?
Frankly, it was an idiotic comparison. The only thing that would be remotely meaningful would be to break in two brand new cars and test them back to back. Even then, sample to sample variation could make the test meaningless if they got a really good sample of one of the cars and a less than average sample of the other.
Frankly, it was an idiotic comparison. The only thing that would be remotely meaningful would be to break in two brand new cars and test them back to back. Even then, sample to sample variation could make the test meaningless if they got a really good sample of one of the cars and a less than average sample of the other.
01-18-2016, 05:09 PM
#131
Melting Slicks
Member Since: Feb 2009
Location: Dallas Georgia
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2020 Corvette of the Year Finalist (track prepared)
C3 of Year Winner (track prepared) 2019
How many miles on the 2014 C7? How tired was that engine?
Frankly, it was an idiotic comparison. The only thing that would be remotely meaningful would be to break in two brand new cars and test them back to back. Even then, sample to sample variation could make the test meaningless if they got a really good sample of one of the cars and a less than average sample of the other.
Frankly, it was an idiotic comparison. The only thing that would be remotely meaningful would be to break in two brand new cars and test them back to back. Even then, sample to sample variation could make the test meaningless if they got a really good sample of one of the cars and a less than average sample of the other.
03-11-2016, 07:44 AM
#132
Burning Brakes
03-11-2016, 12:49 PM
#133
Race Director
How should a technician educate customers on the nature of the GDI system and guide them in taking the right steps to avoid buildup of carbon deposits?
Albert: I would highly recommend that technicians share their knowledge with customers that bring in GDI-equipped vehicles for service. Technicians can advise them to follow the manufacturer's schedule for service, and take a few proactive measures to have their vehicle inspected between services. GDI is a great technology and if serviced properly is nothing to be intimidated by, as a consumer or as a technician. In fact, techs can help their customers enjoy driving a GDI-equipped vehicle.
All the techs I have dealt with are more like "Don't bother me, I'm beating the book, no time to talk."
