[Diy_efi] Venturi effect crankcase breather

[Adam Wade]

--- arnie <arnie_ at charter.net> wrote:

> I'd like to know how improving the top ring seal
> adversly affects engine longevity.

It doesn't.  Suggest you re-read my previous replies
for clarification.

> Sure, it is gonna be more pronounced at high rpms,
> at WOT there is very little vacuum generated,

Very little vacuum generated where?

> so improving vacuum via outside source is designed
> to benefit WOT specifically.

You've now completely lost me.  The crankcase was held
at a constant depression in all testing.

> At part throttle, the engine generates it's own
> vacuum.

Not in the crankcase, it doesn't.  I believe you're
thinking of the intake runner.

> Tenth of a hp?  :)  Expense of teardown?  Don't see
> how.

Care to elaborate?

> What evidence is there of longevity compromise?

Several engines were run to ring seal failure, as I
understand it.

> My point was it (the second ring) seals well
> enuf to cause pressure to build below the top ring.

Again, there is pressure everywhere, it's just a
matter of how much.  You haven't shown anything that
indicates that thre is enough pressure between the
rings to cause any issues.

>> Which compromise do you wish to make?

> Again, don't see the compromise.

I suggest you get out your basic engineering
handbooks.  There isn't a signle part of a motor
vehicle that is not the intersection of a variety of
compromises.

>> For my street bike, I have no interest in
rebuilding
>> the whole top end every 2000 miles, so I don't run
>> drag racing levels of crankcase pressure.

> Am I missing something.  Reduction of second ring
> sealing, with larger end gaps, has been done by oem
> auto mfrs. for a decade, as I noted earlier.  I'd
> say closer to 200,000 than 2000.

So you decided to change the conversation from
producing a depression in the crankcase over to second
ring gap.  Next time, please let the rest of us know.

=====
| Adam Wade                       1990 Kwak Zephyr 550 (Daphne) |
| "It was like an emergency ward after a great catastrophe; it  |
|   didn't matter what race or class the victims belonged to.   |
|  They were all given the same miracle drug, which was coffee. |
|   The catastrophe in this case, of course, was that the sun   |
|     had come up again."                    -Kurt Vonnegut     |

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