Hi Everyone,
Just wondering if it is worth having my next engine machined to accept a sand seal. The engine will be used in a road racing application.
Thanks for your input.
Sand Seal for Road Racing
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Piledriver
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Re: Sand Seal for Road Racing
If you plan on running any level of case vacuum, its essential.
Addendum to Newtons first law:
zero vehicles on jackstands, square gets a fresh 090 and 1911, cabby gets a blower.
EZ3.6 Vanagon after that.(mounted, needs everything finished) then Creamsicle.
zero vehicles on jackstands, square gets a fresh 090 and 1911, cabby gets a blower.
EZ3.6 Vanagon after that.(mounted, needs everything finished) then Creamsicle.
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VW&MGman
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- Joined: Wed Feb 27, 2008 6:12 pm
Re: Sand Seal for Road Racing
Hi Piledriver,
what do you mean by that?
what do you mean by that?
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Piledriver
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Re: Sand Seal for Road Racing
If you run any level of vacuum in the case it will suck dirt into the engine without a crank seal.VW&MGman wrote:Hi Piledriver,
what do you mean by that?
Running a slight crank case vacuum is a very good idea, and is quite doable.
Some negative pressure helps keep the oil in the case, no oil leaks will also greatly help getting through tech.
If you are NOT running case vacuum, it will puke oil out the gap around the crank at high rpm, and then you need a sand seal anyway.
There is no real need for ACVW engines to leak like sieves.
Addendum to Newtons first law:
zero vehicles on jackstands, square gets a fresh 090 and 1911, cabby gets a blower.
EZ3.6 Vanagon after that.(mounted, needs everything finished) then Creamsicle.
zero vehicles on jackstands, square gets a fresh 090 and 1911, cabby gets a blower.
EZ3.6 Vanagon after that.(mounted, needs everything finished) then Creamsicle.
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FJCamper
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- Posts: 2913
- Joined: Wed Nov 14, 2007 2:19 pm
Re: Sand Seal for Road Racing
Hi VW&MGman,
VW deliberately did not seal the case behind the fan pulley. It was designed to suck in air around the crank, and help equalize case pressure, which as you know blows out valve cover gaskets or sucks them in, depending on where the high and low pressure areas are most powerful. Actually, the pressure and then partial vacuum sort of rotates around inside the case and gets blown from side to side by connecting rod and piston movement.
The case is supposed to evacuate pressure via the generator tower breather tube, but that is not enough for racing. The crank pressure gets too high and starts to blow oil out around the crank behind the pulley.
Porsche knew this early on and soon dropped the VW-style 2-piece case and developed the three-piece 356 case, which had a pulley oil seal. We call pulley seals "sand seals" because they were really necessary for the dune buggy guys.
We run pulley seals on our racing engines, and as much crankcase ventilation as we can devise. A nice side effect of the dry sump is it tends to also suck out crank pressure.
Case venting is a subject and science all its own.
FJC
VW deliberately did not seal the case behind the fan pulley. It was designed to suck in air around the crank, and help equalize case pressure, which as you know blows out valve cover gaskets or sucks them in, depending on where the high and low pressure areas are most powerful. Actually, the pressure and then partial vacuum sort of rotates around inside the case and gets blown from side to side by connecting rod and piston movement.
The case is supposed to evacuate pressure via the generator tower breather tube, but that is not enough for racing. The crank pressure gets too high and starts to blow oil out around the crank behind the pulley.
Porsche knew this early on and soon dropped the VW-style 2-piece case and developed the three-piece 356 case, which had a pulley oil seal. We call pulley seals "sand seals" because they were really necessary for the dune buggy guys.
We run pulley seals on our racing engines, and as much crankcase ventilation as we can devise. A nice side effect of the dry sump is it tends to also suck out crank pressure.
Case venting is a subject and science all its own.
FJC
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Ol'fogasaurus
- Posts: 17881
- Joined: Mon Nov 13, 2006 10:17 pm
Re: Sand Seal for Road Racing
Very well put FJ and 'Pile.
Lee
Lee