Return-Path: Received: from imo-m06.mx.aol.com ([64.12.136.161] verified) by logan.com (CommuniGate Pro SMTP 4.1.8) with ESMTP id 2840009 for flyrotary@lancaironline.net; Sat, 06 Dec 2003 11:36:41 -0500 Received: from Lehanover@aol.com by imo-m06.mx.aol.com (mail_out_v36_r1.1.) id q.c6.25cd7d0f (25711) for ; Sat, 6 Dec 2003 11:36:36 -0500 (EST) From: Lehanover@aol.com Message-ID: Date: Sat, 6 Dec 2003 11:36:36 EST Subject: Re: [FlyRotary] Re: Expansion Chambers To: flyrotary@lancaironline.net MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="-----------------------------1070728596" X-Mailer: 9.0 for Windows sub 5101 -------------------------------1070728596 Content-Type: text/plain; charset="ISO-8859-1" Content-Transfer-Encoding: quoted-printable In a message dated 12/6/2003 10:13:45 AM Eastern Standard Time,=20 eanderson@carolina.rr.com writes: The coolant will typically only build to 16-18 PSI, due to expansion up to=20 200=B0F. However, if the engine does overheat due to external factors, the=20 pressure inside the cooling system could reach as high as 28 PSI. Once the r= adiator=20 cap has opened and vented coolant, the engine will not cool down until it ha= s=20 been turned off. The radiator cap is basically a "safety valve", so always u= se=20 the highest pressure radiator cap that the radiator will tolerate. If you ar= e=20 unsure of the pressure rating for your radiator, check with the manufacturer= =20 for the maximum recommended operating pressure. I don't quite understand their statement about the engine not cooling down=20 after venting until you turn it off. I would think that reducing power and=20 therefore heat into the coolant would cause the problem to subside - assumin= g you=20 have any coolant remaining {:>), perhaps their statement "..and Vented=20 Coolant" means ALL the coolant. With the pressure cap in the system between the radiator and the recovery=20 bottle, any coolant that gets by the cap and into the bottle cannot be recov= ered=20 until the engine has cooled to ambient, or close to it. Only then will the=20 system pressure drop below ambient and coolant in the bottle will be at ambi= ent,=20 and thus at a higher pressure, so it replaces the coolant lost by the system= .=20 Not all of it, but close, because it takes some pressure to open the return=20 valve in the cap. The make up bottle has a level marked on it so you can fil= l=20 with coolant to that point. Notice also there are marks for cold and hot=20 coolant. About a quart apart on the bottle. This is so there is no chance th= at a=20 system cooling down will ingest air from an empty recovery bottle. The water pump is mounted very high on the engine, and a big dose of air=20 will prevent the pump from circulating coolant, with tragic result. Notice t= hat=20 in the "car" system, that coolant is full into the cap well on the radiator.= =20 When the system heats up, it is in hydraulic lock and builds pressure up to=20= the=20 relief setting on the cap. Only then does the cap begin to bleed off coolant= =20 to maintain the rated pressure. The cap well on the radiator is not the very= =20 best way to remove air from a rotary engine. If you take the time to run thr= ough=20 several heat cycles after you have the system open, then you will get most o= f=20 it out.=20 The early Rotary powered cars had a plastic bottle on the firewall, and that= =20 bottle had the pressure cap on it. There was a cap on the radiator used for=20 filling it but had no pressure element. Mazda was not alone in this practice= .=20 The advantage here was that the engine didn't have to cool all the way down=20= to=20 recover coolant from the recovery bottle. Small volume changes from changes=20= in=20 heat load would cause fluid exchange from the pressurized bottle to the top=20= of=20 the radiator. Coolant entered the bottle from the bottom, so a slug of air=20 forced out of the radiator would pop to the top of the recovery bottle and w= hen=20 power (and heat) was reduced in the engine it would recover only water from=20 the bottle. This, because the pressure in the bottle would be (for a few seconds) higher= =20 than the coolant system pressure. I keep my pressure bottle about 1/2 full.=20= I=20 have added a Shrader valve so I can pressurize the system before I start the= =20 engine. Both systems work well, and most people use the "car" system. Becaus= e=20 they are not aware that there is a (in my mind) a better system. And there i= s=20 little to fear from using the car system. The advantages of the old Mazda system are: it will return all of the coolan= t=20 in the bottle to the engine in case of a leak. You get nothing back from the= =20 "car" system until the plane is on the ground and cold. This system is much=20 better at removing air from an operating system. The weights are about the s= ame=20 for both. You can still find them in the junk yards but you can make one if=20 you want. You can mount either system anywhere. They don't need to be higher= =20 than anything to work. The car system is just a little less well off when mo= unted=20 low but not a problem, but it is open to ambient. The Mazda bottle can be=20 mounted anywhere so long as it is upright. And "anywhere" can be a real hand= y=20 location. Lynn E. Hanover =20 -------------------------------1070728596 Content-Type: text/html; charset="ISO-8859-1" Content-Transfer-Encoding: quoted-printable
In a message dated 12/6/2003 10:13:45 AM Eastern Standard Time, eanders= on@carolina.rr.com writes:
The coolant will typically only build to 16-1= 8 PSI, due to expansion up to 200=B0F. However, if the engine does overheat=20= due to external factors, the pressure inside the cooling system could reach=20= as high as 28 PSI. Once the radiator cap has opened and vented coolant, the=20= engine will not cool down until it has been turned off. The radiator cap is=20= basically a "safety valve", so always use=20= the highest pressure radiator cap that the radiator will tolerate. If you are unsure of the pressure rating for your radiator, chec= k with the manufacturer for the maximum recommended operating pressure.
 
I don't quite understand their statement about the engine not= cooling down after venting until you turn it off.  I would think=20= that reducing power and therefore heat into the coolant would cause the prob= lem to subside - assuming you have any coolant remaining {:>), perhaps th= eir statement "..and Vented Coolant" means ALL the coolant.
With the pressure cap in the system between the radiator and the r= ecovery bottle, any coolant that gets by the cap and into the bottle cannot=20= be recovered until the engine has cooled to ambient, or close to it. Only th= en will the system pressure drop below ambient and coolant in the bottl= e will be at ambient, and thus at a higher pressure, so it replaces the cool= ant lost by the system. Not all of it, but close, because it takes some pres= sure to open the return valve in the cap. The make up bottle has a level mar= ked on it so you can fill with coolant to that point. Notice also there are=20= marks for cold and hot coolant. About a quart apart on the bottle. This is s= o there is no chance that a system cooling down will ingest air from an empt= y recovery bottle.
 
 The water pump is mounted very high on the engine, and a big dose= of air will prevent the pump from circulating coolant, with tragic result.=20= Notice that in the "car" system, that coolant is full into the cap well on t= he radiator. When the system heats up, it is in hydraulic lock and builds pr= essure up to the relief setting on the cap. Only then does the cap begin to=20= bleed off coolant to maintain the rated pressure. The cap well on the radiat= or is not the very best way to remove air from a rotary engine. If you take=20= the time to run through several heat cycles after you have the system open,=20= then you will get most of it out.
 
The early Rotary powered cars had a plastic bottle on the firewall, and= that bottle had the pressure cap on it. There was a cap on the radiator use= d for filling it but had no pressure element. Mazda was not alone in this pr= actice. The advantage here was that the engine didn't have to cool all the w= ay down to recover coolant from the recovery bottle. Small volume changes fr= om changes in heat load would cause fluid exchange from the pressurized bott= le to the top of the radiator. Coolant entered the bottle from the bottom, s= o a slug of air forced out of the radiator would pop to the top of the recov= ery bottle and when power (and heat) was reduced in the engine it would reco= ver only water from the bottle.
This, because the pressure in the bottle would be (for a few seconds) h= igher than the coolant system pressure. I keep my pressure bottle about 1/2=20= full. I have added a Shrader valve so I can pressurize the system before I s= tart the engine. Both systems work well, and most people use the "car" syste= m. Because they are not aware that there is a (in my mind) a better system.=20= And there is little to fear from using the car system.
 
The advantages of the old Mazda system are: it will return all of the c= oolant in the bottle to the engine in case of a leak. You get nothing back f= rom the "car" system until the plane is on the ground and cold. This system=20= is much better at removing air from an operating system. The weights are abo= ut the same for both. You can still find them in the junk yards but you can=20= make one if you want. You can mount either system anywhere. They don't need=20= to be higher than anything to work. The car system is just a little less wel= l off when mounted low but not a problem, but it is open to ambient. The Maz= da bottle can be mounted anywhere so long as it is upright. And "anywhere" c= an be a real handy location.
 
Lynn E. Hanover      
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