CBU from 100% gas vs Ethanol in GDI application

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I've gotta a GDI engine and have access to 100% gasoline (93 octane), just wondering if it MIGHT prevent carbon in an engine known for some really bad buildup
 
now I'm no scientist/engineer/mechanic, but to my understanding, the FUEL isn't the problem with DI carbon buildup, it's where the fuel is delivered.
with port, or even tbi, the fuel "washes" the backside of the valves.

if it's really bad, you'd be better off figuring out how to add a single injector after the throttle body...

you'll notice some manufacturers, while never acknowledging there was a carbon problem, have redesigned the next generation of those engines with both port and direct injection...
 
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At least two large ones have said that the combined systems are for part throttle cylinder filling issues, evidently some issues with this with DI.

It should also be noted that many many DI owners never have any significant issues from some makes and models. I am not certain this is all engineering expertise but it may be a driver thing.

No one could use a single injector at the throttle body unless they completely redesign the intake to avoid cylinder to cylinder distribution issues.
 
Mazda Skyactv engines seems to have solved the issue by designing a nice oil vapor separator in the PCV system. Mazda also found that running the intake valves at a higher temperature helped. My old Mazda CX7 with DI was doing great when I sold it at ~ 80,000 miles with their "OLD" PCV system. Ed
 
Originally Posted By: SteveSRT8
At least two large ones have said that the combined systems are for part throttle cylinder filling issues, evidently some issues with this with DI.

It should also be noted that many many DI owners never have any significant issues from some makes and models. I am not certain this is all engineering expertise but it may be a driver thing.

No one could use a single injector at the throttle body unless they completely redesign the intake to avoid cylinder to cylinder distribution issues.


Huh? Throttle body injection was huge in the 90's...and you can still buy throttle body injection kits for use on SBC's today. I think it would be quite simple to integrate a single injector in these DI systems for part throttle operation and reduced carbon build up.
 
Originally Posted By: DriveHard
Originally Posted By: SteveSRT8
At least two large ones have said that the combined systems are for part throttle cylinder filling issues, evidently some issues with this with DI.

It should also be noted that many many DI owners never have any significant issues from some makes and models. I am not certain this is all engineering expertise but it may be a driver thing.

No one could use a single injector at the throttle body unless they completely redesign the intake to avoid cylinder to cylinder distribution issues.


Huh? Throttle body injection was huge in the 90's...and you can still buy throttle body injection kits for use on SBC's today. I think it would be quite simple to integrate a single injector in these DI systems for part throttle operation and reduced carbon build up.


Ever since port injection the manifolds are designed for air only. If you examine most manifolds that move fuel and air (carburetor/TB) they are heated and radically different than modern ones for FI. So you cannot just mount an injector behind the TB without redoing the manifold design first.
 
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Originally Posted By: Eddie
Mazda Skyactv engines seems to have solved the issue by designing a nice oil vapor separator in the PCV system. Mazda also found that running the intake valves at a higher temperature helped. My old Mazda CX7 with DI was doing great when I sold it at ~ 80,000 miles with their "OLD" PCV system. Ed


yep, some mfgrs obviously have it figured out. I still think driving style plays a huge part as well, evidenced by the advice to drive them at high rpm for a period to clean the intake valves. Some of us do that every time we drive them!
 
Originally Posted By: Speak2Mountain
I've gotta a GDI engine and have access to 100% gasoline (93 octane), just wondering if it MIGHT prevent carbon in an engine known for some really bad buildup


Doubt it will make a lick of difference bud.
 
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