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Old 10-23-2020, 09:27 AM   #76
BeastianSTI
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Quote:
Originally Posted by rtv900 View Post
^ok
you said you don't understand why diesels were brought up.
I said it was clearly stated. People keep repeating how vacuum is critical, so I asked how do diesels do this then since they have no vacuum.
Nobody can ever answer that legitimately.
My point was vacuum obviously isn't that critical or it wouldn't work in the other half of all ICE's on the planet.
I thought that was very clear.
Just to ask some questions on that front...

1. Diesel piston rings and pistons aren't identical to petrol engines, right? IIRC they use a two-ring design and are likely of higher quality.

2. As someone else mentioned, Diesel engines usually have an air pump to provide some degree of vacuum in the engine, right?

Not saying you're wrong here, but there are other differences we'd need to consider in order to rule out any sort of vacuum as being necessary, in my view
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Old 10-27-2020, 02:17 PM   #77
Homemade WRX
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1.) Diesel rings are different but they also typically run higher CR and boost pressure.

2.) A diesel with a vacuum pump isn't using that pump to create vacuum in the crankcase.

3.) Comparing breaking in a performance gas engine and a diesel is comical to me.

4.) Delta P across the rings is delta P across the rings. Using engine braking does actually invert the direction of the delta P that helps seal the rings.

I've done break-ins on 11, 13, 16L semi diesels, OEM gas, and then gas race engines. All are different for their own reasons.

If you think we send a truck engine out needing 1000 miles to break-in while not pulling a trailer, you're high. Same goes for one of the IMSA, WEC, or NASCAR engines.
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Old 10-27-2020, 04:20 PM   #78
rtv900
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1) sure, but the fundamentals are the same
2) right, the vacuum pump is for accessories, not the engine, that would serve no purpose
3) noone is suggesting the actual procedure would be the same for some monster diesel vs a little high revving gas. The context was solely about vacuum being required to get a ring seal.
4) ok, revert or not, is it critical? Seems like it isn't

I bet the fundamentals of those different break in were kind of the same though, fundamentally right?
Like you consider the engine you have, you choose an output level to keep good cylinder pressure, you choose an rpm range that the engine operates well within, you consider the oiling system, etc
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Old 11-03-2020, 04:51 PM   #79
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More or less, yeah. I'm a firm believer that engineering does a lot of idiot proofing to some respect.

I'm a believer of if it is a performance engine, break in the cam, do a quick oil change, drive it around a while or slap it on the dyno to get it all hop, bothered, shaken down, and make sure nothing is wrong. Then start diving into it.

On my current 2.1 build, I start beating it after about 200 miles. I had a lot of shaking down outside of the engine.
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