I'm thinking the root cause is reversion: poor scavenging and exhaust gasses going past the intake valve. If the engine is VVT, valve timing can be all sorts wrong.
Looking for a high Noack oil, if this makes any sense here.
- Thread starter Nayov
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I'm thinking the root cause is reversion: poor scavenging and exhaust gasses going past the intake valve. If the engine is VVT, valve timing can be all sorts wrong.
This is like becoming an alcoholic on the off chance it might reduce the formation of kidney stones
I did actually have a DR tell me to drink a six pack and jump off the third stair up.
I find a lot of water and a ride on the Harley usually moves them right along....
Not fun.I did actually have a DR tell me to drink a six pack and jump off the third stair up.
I find a lot of water and a ride on the Harley usually moves them right along....
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I was going to add this point about reversion, thanks for bringing it up. Us old hot rodders that ran a tight lobe separation angle (108°) know all about the rumpity-rump and why its making a ragged idle.
But I would venture that with vvti you would want no overlap near idle to off idle, and, maybe a late exhaust closing for some EGR where signaled by the K sensor, especially in the LSPI range. I have not read any white papers on vvti programming with D.I so who knows what 'they' are doing or why. I know keeping oxides of nitrogen in line appears to have adversely affected fuel mileage in many implementations. VW seems to have their 1.4T Di motor well tuned for torque and fuel mileage. Are they still cheating ?
- or are they just smarter than the average bear?
Can you refer me to the article that discusses Noack and intake valve contamination? Thanks, Jetronic. ED
It's on here somewhere in one of the GDI threads I'm sure. I don't keep tabs anymore. it was a study that rerouted the pcv so it wouldn't get burned by the engine and the test engine showed the same buildup as with regular PCV system
DI engines should be less sensitive to valve overlap, so go for your 106 LSA and smooth idle. You read it here first.I was going to add this point about reversion, thanks for bringing it up. Us old hot rodders that ran a tight lobe separation angle (108°) know all about the rumpity-rump and why its making a ragged idle.
But I would venture that with vvti you would want no overlap near idle to off idle, and, maybe a late exhaust closing for some EGR where signaled by the K sensor, especially in the LSPI range. I have not read any white papers on vvti programming with D.I so who knows what 'they' are doing or why. I know keeping oxides of nitrogen in line appears to have adversely affected fuel mileage in many implementations. VW seems to have their 1.4T Di motor well tuned for torque and fuel mileage. Are they still cheating ?
- or are they just smarter than the average bear?
I've also seen info where the PCV gasses enter the intake manifold had a bearing on which intake valves had the most deposits. The intake valves closest to where the PCV gasses enter the intake had the most deposits. Like said earlier, if there was only fresh air and zero PCV gasses entering the intake on a DI engine, there wouldn't be anything to deposit on the valves. I highly doubt valve overlap on the exhaust stroke has much to do with intake valves getting deposits on them ... not many 4 banger commuters idle like a highly modified 1960s muscle car with a crazy cam. Exhaust valves that get all the exhaust gas flow don't have crud built up on them like some intake valves do.
With NOACK once the lighter fractions are evaporated or distilled you wont have a high NOACK lubricant anymore. So for say a typical 5W30 It would be just fresh oil for a time. Do a NOACK test. Then repeat it on same sample.
Pre-burn it off to make it low Noack like Project Farm does with coffee pots and hot plates.
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Pre-oxidized for that Starbucks-style touch.Pre-burn it off to make it low Noack like Project Farm does with coffee pots and hot plates.
Cuts down on intake valve deposits.
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