X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Received: from cdptpa-omtalb.mail.rr.com ([75.180.132.120] verified) by logan.com (CommuniGate Pro SMTP 5.1.12) with ESMTP id 2384213 for flyrotary@lancaironline.net; Fri, 12 Oct 2007 20:38:47 -0400 Received-SPF: pass receiver=logan.com; client-ip=75.180.132.120; envelope-from=eanderson@carolina.rr.com Received: from edward2 ([24.74.103.61]) by cdptpa-omta01.mail.rr.com with SMTP id <20071013003808.JDQL6760.cdptpa-omta01.mail.rr.com@edward2> for ; Sat, 13 Oct 2007 00:38:08 +0000 Message-ID: <000f01c80d31$665404c0$2402a8c0@edward2> From: "Ed Anderson" To: "Rotary motors in aircraft" References: Subject: Re: [FlyRotary] Re: FW: [FlyRotary] Re: Coolant Water Pressure Date: Fri, 12 Oct 2007 20:38:39 -0400 MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_000C_01C80D0F.DF0DE740" X-Priority: 3 X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook Express 6.00.2900.3138 X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2900.3138 This is a multi-part message in MIME format. ------=_NextPart_000_000C_01C80D0F.DF0DE740 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Perhaps for an "normal" automotive use, the cavitation rpm was not seen = as critical as it would be as normal use of an Rx-7. Apparently just = buzzin the engine to 8000 rpm in the auto could be tolerated for brief = periods. But, naturally in aircraft operation, we might run at = 6500-7000 rpm for hours - would like be a bit more critical. But, as I mentioned, that data out of the Racing Beat technical catalog = (1992) might well be dated. I feel fairly confident that the Renesis = must be able to cope with much higher rpm as Tracy has had his up to = 7500 rpm (don't know for how long), but without any ill effects. Ed ----- Original Message -----=20 From: Al Wick=20 To: Rotary motors in aircraft=20 Sent: Friday, October 12, 2007 5:49 PM Subject: [FlyRotary] Re: FW: [FlyRotary] Re: Coolant Water Pressure That's quite the surprise. Japanese engineers are expert at making = sure the design has extra safety margin. Even back in the 70's. Although = they are much better at it now. I can't imagine they are rpm sensitive = 33 years later.=20 I have heard of a lot of guys adding flow restrictions on pump inlet, = not aware they are increasing pressure drop. Particularly true with fuel = systems.=20 -al wick ----- Original Message -----=20 From: Ed Anderson=20 To: Rotary motors in aircraft=20 Sent: Friday, October 12, 2007 2:14 PM Subject: [FlyRotary] Re: FW: [FlyRotary] Re: Coolant Water Pressure Hi Al, Racing Beat's Rotary Tech catalog specifies that for 1974 and later = pumps using stock main and water pulley, that engine rpm above 6300 rpm = would cause the stock water pump to cavitate. . This is of course with = OEM size hoses. That cavitation beings gradually and becomes worst as = rpm and temperature increases and if full throttle operation is = maintained under those conditions "...the engine will not last long." Now that information is somewhat dated (my catalog is dated 1992). = I strongly suspect that, the Renesis for example would be able to = handle a higher sustained rpm. And perhaps the later 13B's as well, I = just have not seen any information more recent on the topic. =20 I fly with a main pulley sized for 20% less water pump rpm and my = alternator has a 20% reduction as well. So my top engine rpm (sustained) = around 6500 rpm hopefully keeps me out of the bubble zone. Ed =20 ----- Original Message -----=20 From: Al Wick=20 To: Rotary motors in aircraft=20 Sent: Friday, October 12, 2007 4:29 PM Subject: [FlyRotary] Re: FW: [FlyRotary] Re: Coolant Water = Pressure Where does the fear of pump cavitation come from? Is that = speculative or have some guys inadvertently choked off the pump inlet = with small diam hose instead of OEM size? -al wick ----- Original Message -----=20 From: Al Gietzen=20 To: Rotary motors in aircraft=20 Sent: Friday, October 12, 2007 11:31 AM Subject: [FlyRotary] FW: [FlyRotary] Re: Coolant Water Pressure This was rejected because of the photo files being too large, so = I'll send one of the pics separately. Al Subject: RE: [FlyRotary] Re: Coolant Water Pressure Bill; Here is the setup I use. On the first photo, the filler neck is = on the left, and connects to the line going to the inlet side of the = pump. The two small lines (3/16") coming into the side are air bleed = lines going from the high points of my two radiators (note that the = pressure at the filler neck will be near the lowest in the system.) The = 'overflow' from the filler cap goes to the bottom of the accumulator = bottle on the right (made from a discarded fire extinguisher). The accumulator bottle overflow goes over board, but coolant = only goes out here once on first heatup. When cold, there is only about = 3 - 4" coolant in the bottom of that bottle, so there is air in there = that compresses as things heat up. Coolant forced out of the filler = neck on heat up is draw back in on cooldown. The idea is that whenever the engine is running, there is = positive pressure on the system - at the pump inlet; reducing the chance = of pump cavitation at high RPM. And positive pressure is maintained at = altitude even when throttling back and the coolant temp is decreasing. Originally I had a 23# cap on the filler neck, and 15# on the = accumulator bottle. I later reversed the two to lower system pressure = on initial heatup (as soon as the engine heats up at all the pressure = goes to filler cap pressure), but it still gives me the sum of the two = caps under any extreme condition to protect against boiling. Keep in = mind that the caps are 'differential pressure' so at altitude the max = absolute pressure in the accumulator bottle is reduced by the reduction = in the ambient. Al -----Original Message----- From: Rotary motors in aircraft = [mailto:flyrotary@lancaironline.net] On Behalf Of Bill Bradburry Sent: Thursday, October 11, 2007 8:49 AM To: Rotary motors in aircraft Subject: [FlyRotary] Re: Coolant Water Pressure Lynn, I don't know what we would do without you. I have several questions. =20 Where can I get a good accumulator tank? =20 I was thinking of making one out of a used fire extinguisher = and was also looking at one from Moroso that looks like a flat canteen. = The one from Moroso has an inlet on the bottom and one on the top side = as well as one for the pop off of the radiator cap. Due to space = constraints, I will probably try and make one. I need something about 3" = diameter and maybe 12" or so long. Will I need the inlet on the top = side? If so, where does it plumb to? I suppose I will still need an overflow tank from the pop off of = the radiator cap? After talking with Tracy yesterday, I tried to see if the = engine would stabilize temp somewhere below 230* at 2600 rpm. No joy! = I suspect that I will need to increase air flow to get this to happen. = I will try an leaf blower on the cowl today. My pressure stabilized at 22 lbs (cap in constant blow off = relief) but the temp would not hold. If I had this same condition with = the system you described, what would prevent the air from blowing off = and then water from the accumulator? It seems to me that no matter what system you have, the pressure = has to stabilize below the pressure rating of the radiator cap, else you = will be losing first air, then water???? Bill B ------------------------------------------------------------------------ From: Rotary motors in aircraft = [mailto:flyrotary@lancaironline.net] On Behalf Of Lehanover@aol.com Sent: Wednesday, October 03, 2007 10:28 AM To: Rotary motors in aircraft Subject: [FlyRotary] Re: Coolant Water Pressure In a message dated 10/3/2007 9:08:53 A.M. Eastern Daylight Time, = bbradburry@bellsouth.net writes: I think that I would see air under the radiator cap if I had a = compression gas leak? I never see any air.=20 To check a piston engine for head gasket leaks, you would put = the cylinder at TDC and pressurize the cylinder to about 150 lbs with = compressed air and check the radiator for air bubbles.How do you check a = rotary? I will check the pressure sender against a mechanical gage. =20 There is obviously a heating problem, but I think the pressure = is higher than it should be until just ready to boil. I shut the engine = off at 210*, and at 22+ lbs, the boiling point should be well above = 250*?? Thanks for the suggestions of where to look, guys. Bill B It is extremely difficult to remove all of the air from a rotary = engines cooling system. It is also extremely important. If air is under = the pressure cap in a static situation, it will remix with other coolant = when the engine is at speed. The coolant moves very quickly through the = system. The coolant volume appears to increase slightly because much of = the air is reintroduced into the water. This coolant then becomes a poor = conductor of heat. You need the anti foaming agent in Antifreeze. Just a = bit, perhaps 10%. The system with the relief cap right on the radiator = or filler point, starts to offload coolant as soon as the engine is = started. It is in hydraulic lock, and has a small volume. The actual = boiling point calculated for this coolant makes no difference at all. = The cap opens a bit when the trip pressure is attained, the pressure = drops to 22 PSI or whatever for your cap, and a bit more heating trips = the cap again. It is exactly the same as most cars. So, at first in each heat cycle, there may be no correlation = between coolant temperature, and the actual amount of coolant dumped by = the cap. This is only true closer to a constant operating temperature. = And then pressure may be alarmingly unstable with power changes. The = accumulator system makes pressure rock solid.=20 Make the pressure cap into a filler cap, sealing only the top = lip of the radiator or filling port. Connect only a bleed hose and run = it to the bottom of a recovery bottle, and put the pressure relief cap = on that bottle. Keep the bottle about 1/3 full. Note after several heat = cycles, the amount of water you need to add to keep that bottle 1/3 full = is reduced each time. Once all of the air is out of the cooling system, = no more coolant need be added to the bottle.=20 Heating and cooling of the system, makes sweeping changes in = coolant volume. The air cushion in the bottle acts as an accumulator = (used in thousands of aircraft) to maintain a constant pressure and = coolant supply. Race cars use a Rolairtrol or spin bottle in the hose from the = top of the engine to the radiator. Water enters the bottle at about half = height on a tangent and adds a spinning motion. Water leaves through a = center hole at the bottom.=20 Trapped air pops to the top of the bottle and that is plumbed to = the bottom of the accumulator as above.=20 You used to get the plans for this thing when you buy a Cosworth = race engine. Does Cosworth know something you don't?=20 Anyway, after about three heat cycles (operating temperature and = back to room temperature) the coolant system will be solid coolant with = all of the air removed. It will not be hydraulically locked against the = cap. It will have the relief cap pressure, and will hold that for as = long as the engine is hot.=20 I have a Shrader valve installed in my accumulator tank, and = before I start the engine I charge that bottle with compressed air until = the cap relieves at 22 PSI. Now I know it has pressure, and I know it = has 22 PSI. This was the stock system on all Mazda cars in the 70s. I didn't = invent it.=20 It is unlikely that you have leaking compression seals, unless = there is coolant blowing out of your makeup tank, or coolant is running = out of your exhaust system after shutdown.=20 My recovery bottle is mounted where the passenger foot well = would have been. Even with the bottom of the engine. So long as the hose = ID is less than 1/4" and the hose enters the bottle on the bottom of the = coolant supply, it matters not at all where that bottle is located. = There is a money back guarantee with this system.=20 Lynn E. Hanover=20 ------------------------------------------------------------------------ See what's new at AOL.com and Make AOL Your Homepage. ------------------------------------------------------------------------ -- Homepage: http://www.flyrotary.com/ Archive and UnSub: = http://mail.lancaironline.net:81/lists/flyrotary/List.html -Al Wick Cozy IV powered by Turbo Subaru 3.0R with variable valve lift and = cam timing.=20 Artificial intelligence in cockpit, N9032U 240+ hours from = Portland, Oregon Glass panel design, Subaru install, Prop construct, Risk = assessment info: http://www.maddyhome.com/canardpages/pages/alwick/index.html -Al Wick Cozy IV powered by Turbo Subaru 3.0R with variable valve lift and cam = timing.=20 Artificial intelligence in cockpit, N9032U 240+ hours from Portland, = Oregon Glass panel design, Subaru install, Prop construct, Risk assessment = info: http://www.maddyhome.com/canardpages/pages/alwick/index.html ------=_NextPart_000_000C_01C80D0F.DF0DE740 Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable
Perhaps for an "normal" automotive use, the = cavitation rpm=20 was not seen as critical as it would be  as normal use=20 of  an Rx-7.  Apparently just buzzin the engine to 8000 = rpm in=20 the auto could be tolerated for brief periods.  But, naturally in = aircraft=20 operation, we might run at 6500-7000 rpm for hours - would like be a bit = more=20 critical.
 
But, as I mentioned, that data out of the Racing = Beat=20 technical catalog (1992) might well be dated.  I feel fairly = confident that=20 the Renesis must be able to cope with much higher rpm as Tracy has had = his up to=20 7500 rpm (don't know for how long), but without any ill = effects.
 
Ed
----- Original Message -----
From:=20 Al Wick =
Sent: Friday, October 12, 2007 = 5:49=20 PM
Subject: [FlyRotary] Re: FW: = [FlyRotary]=20 Re: Coolant Water Pressure

That's quite the surprise. Japanese = engineers are=20 expert at making sure the design has extra safety margin. Even back in = the=20 70's. Although they are much better at it now. I can't imagine they = are rpm=20 sensitive 33 years later.
 
I have heard of a lot of guys adding = flow=20 restrictions on pump inlet, not aware they are increasing pressure = drop.=20 Particularly true with fuel systems.
 
-al wick
----- Original Message -----
From:=20 Ed Anderson
To: Rotary motors in = aircraft=20
Sent: Friday, October 12, = 2007 2:14=20 PM
Subject: [FlyRotary] Re: FW:=20 [FlyRotary] Re: Coolant Water Pressure

Hi Al,
 
Racing Beat's Rotary Tech catalog specifies = that for=20 1974 and later pumps using stock main and water pulley, that=20  engine rpm above 6300 rpm would cause the stock water pump to=20 cavitate.  .  This is of course with OEM size hoses.  = That=20 cavitation beings gradually and becomes worst as rpm and temperature = increases and if full throttle operation is maintained under those=20 conditions "...the engine will not last long."
 
Now that information is somewhat = dated (my=20 catalog is dated 1992).  I strongly suspect  that, = the=20 Renesis for example would be able to handle a higher sustained = rpm. =20 And perhaps the later 13B's as well, I just have not seen any = information=20 more recent on the topic. 
 
I fly with a main pulley sized for 20% less = water pump=20 rpm and my alternator has a 20% reduction as well. So my top = engine=20 rpm (sustained) around 6500 rpm hopefully keeps me out of the = bubble=20 zone.
 
Ed 
 
 
 
----- Original Message -----
From:=20 Al = Wick
To: Rotary motors in = aircraft=20
Sent: Friday, October 12, = 2007 4:29=20 PM
Subject: [FlyRotary] Re: = FW:=20 [FlyRotary] Re: Coolant Water Pressure

Where does the fear of pump = cavitation come=20 from? Is that speculative or have some guys inadvertently choked = off the=20 pump inlet with small diam hose instead of OEM size?
 
 
 
-al wick
----- Original Message ----- =
From:=20 Al=20 Gietzen
To: Rotary motors in = aircraft=20
Sent: Friday, October 12, = 2007=20 11:31 AM
Subject: [FlyRotary] FW:=20 [FlyRotary] Re: Coolant Water Pressure

This was rejected = because=20 of the photo files being too large, so I=92ll send one of the = pics=20 separately.

Al

Subject:=20 RE: [FlyRotary] Re: Coolant Water Pressure

 

Bill;

 

Here is the=20 setup I use. On the first photo, the filler neck is on the left, = and=20 connects to the line going to the inlet side of the pump. =  The two=20 small lines (3/16=94) coming into the side are air bleed lines = going from=20 the high points of my two radiators (note that the pressure at = the=20 filler neck will be near the lowest in the system.)  The = =91overflow=92=20 from the filler cap goes to the bottom of the accumulator bottle = on the=20 right (made from a discarded fire = extinguisher).

 

The = accumulator bottle overflow goes over board, but coolant only = goes out=20 here once on first heatup.  When cold, there is only about = 3 =96 4=94=20 coolant in the bottom of that bottle, so there is air in there = that=20 compresses as things heat up.  Coolant forced out of the = filler=20 neck on heat up is draw back in on cooldown.

 

The = idea is=20 that whenever the engine is running, there is positive pressure = on the=20 system =96 at the pump inlet; reducing the chance of pump = cavitation at=20 high RPM.  And positive pressure is maintained at altitude = even=20 when throttling back and the coolant temp is=20 decreasing.

 

Originally I=20 had a 23# cap on the filler neck, and 15# on the accumulator=20 bottle.  I later reversed the two to lower system pressure = on=20 initial heatup (as soon as the engine heats up at all the = pressure goes=20 to filler cap pressure), but it still gives me the sum of the = two caps=20 under any extreme condition to protect against boiling.  = Keep in=20 mind that the caps are =91differential pressure=92 so at = altitude the max=20 absolute pressure in the accumulator bottle is reduced by the = reduction=20 in the ambient.

 

Al

 

-----Original=20 Message-----
From:=20 Rotary motors in aircraft [mailto:flyrotary@lancaironline.net] = On Behalf Of Bill=20 Bradburry
Sent:=20 Thursday, October = 11,=20 2007 = 8:49 = AM
To: Rotary motors in=20 aircraft
Subject:=20 [FlyRotary] Re: Coolant Water Pressure

 

Lynn, I = don=92t know=20 what we would do without you.

I = have several=20 questions. 

Where = can I get=20 a good accumulator tank? 

I was = thinking=20 of making one out of a used fire extinguisher  and was also = looking=20 at one from Moroso that looks like a flat canteen.  The one = from=20 Moroso has an inlet on the bottom and one on the top side as = well as one=20 for the pop off of the radiator cap.  Due to space = constraints, I=20 will probably try and make one. I need something about 3=94 = diameter and=20 maybe 12=94 or so long.   Will I need the inlet on the = top=20 side?  If so, where does it plumb to?

I = suppose I=20 will still need an overflow tank from the pop off of the = radiator=20 cap?

After = talking=20  with Tracy = yesterday, I=20 tried to see if the engine would stabilize temp somewhere below = 230* at=20 2600 rpm.  No joy!  I suspect that I will need to = increase air=20 flow to get this to happen.  I will try an leaf blower on = the cowl=20 today.

My = pressure=20 stabilized at 22 lbs (cap in constant blow off relief) but the = temp=20 would not hold.  If I had this same condition with the = system you=20 described, what would prevent the air from blowing off and then = water=20 from the accumulator?

It = seems to me=20 that no matter what system you have, the pressure has to = stabilize below=20 the pressure rating of the radiator cap, else you will be losing = first=20 air, then water????

 

Bill=20 B

 

From:=20 Rotary motors in aircraft [mailto:flyrotary@lancaironline.net] = On Behalf Of=20 Lehanover@aol.com
Sent: Wednesday, = October 03,=20 2007 = 10:28 = AM
To: Rotary motors in=20 aircraft
Subject:=20 [FlyRotary] Re: Coolant Water Pressure

 

In a = message=20 dated 10/3/2007=20 9:08:53=20 A.M. = Eastern=20 Daylight Time, bbradburry@bellsouth.net = writes:

I = think that=20 I would see air under the radiator cap if I had a compression = gas=20 leak?  I never see any air.

To = check a=20 piston engine for head gasket leaks, you would put the = cylinder at TDC=20 and pressurize the cylinder to about 150 lbs with compressed = air and=20 check the radiator for air bubbles=85How do you check a=20 rotary?

I = will check=20 the pressure sender against a mechanical gage. =20

There is=20 obviously a heating problem, but I think the pressure is = higher than=20 it should be until just ready to boil.  I shut the engine = off at=20 210*, and at 22+ lbs, the boiling point should be well above=20 250*??

 

Thanks for=20 the suggestions of where to look, guys=85

 

Bill=20 B

It = is=20 extremely difficult to remove all of the air from a rotary = engines=20 cooling system. It is also extremely important. If air is under = the=20 pressure cap in a static situation, it will remix with other = coolant=20 when the engine is at speed. The coolant moves very quickly = through the=20 system. The coolant volume appears to increase slightly because = much of=20 the air is reintroduced into the water. This coolant then = becomes a poor=20 conductor of heat. You need the anti foaming agent in = Antifreeze. Just a=20 bit, perhaps 10%. The system with the relief cap right on the = radiator=20 or filler point, starts to offload coolant as soon as the engine = is=20 started. It is in hydraulic lock, and has a small volume. The = actual=20 boiling point calculated for this coolant makes no difference at = all.=20 The cap opens a bit when the trip pressure is attained, the = pressure=20 drops to 22 PSI or whatever for your cap, and a bit more heating = trips=20 the cap again. It is exactly the same as most=20 cars.

So, = at first=20 in each heat cycle, there may be no correlation between coolant=20 temperature, and the actual amount of coolant dumped by the cap. = This is=20 only true closer to a constant operating temperature. And then = pressure=20 may be alarmingly unstable with power changes. The accumulator = system=20 makes pressure rock solid. 

 

 

Make = the=20 pressure cap into a filler cap, sealing only the top lip of the = radiator=20 or filling port. Connect only a  bleed hose and run it = to the=20 bottom of a recovery bottle, and put the pressure relief cap on = that=20 bottle. Keep the bottle about 1/3 full. Note after several heat = cycles,=20 the amount of water you need to add to keep that bottle 1/3 full = is=20 reduced each time. Once all of the air is out of the cooling = system, no=20 more coolant need be added to the bottle. =

 

Heating and=20 cooling of the system, makes sweeping changes in coolant volume. = The air=20 cushion in the bottle acts as an accumulator (used in thousands = of=20 aircraft) to maintain a constant pressure and coolant=20 supply.

 

Race = cars use=20 a Rolairtrol or spin bottle in the hose from the top of the = engine to=20 the radiator. Water enters the bottle at about half height on a = tangent=20 and adds a spinning motion. Water leaves through a center hole = at the=20 bottom.

Trapped air=20 pops to the top of the bottle and that is plumbed to the bottom = of the=20 accumulator as above.

You = used to=20 get the plans for this thing when you buy a Cosworth race = engine. Does=20 Cosworth know something you don't? 

 

Anyway, after=20 about three heat cycles (operating temperature and back to room=20 temperature) the coolant system will be solid coolant with all = of the=20 air removed. It will not be hydraulically locked against the=20 cap.

It = will have=20 the relief cap pressure, and will hold that for as long as the = engine is=20 hot.

 

I = have a=20 Shrader valve installed in my accumulator tank, and before I = start the=20 engine I charge that bottle with compressed air until the cap = relieves=20 at 22 PSI. Now I know it has pressure, and I know it has 22=20 PSI.

 

This = was the=20 stock system on all Mazda cars in the 70s. I didn't invent it.=20

 

It = is unlikely=20 that you have leaking compression seals, unless there is coolant = blowing=20 out of your makeup tank, or coolant is running out of your = exhaust=20 system after shutdown.

 

My = recovery=20 bottle is mounted where the passenger foot well would have been. = Even=20 with the bottom of the engine. So long as the hose ID is less = than 1/4"=20 and the hose enters the bottle on the bottom of the coolant = supply, it=20 matters not at all where that bottle is located. There is a = money back=20 guarantee with this system. 

 

Lynn = E.=20 Hanover 

 

See = what's new=20 at AOL.com and Make AOL Your = Homepage.

--
Homepage:  = http://www.flyrotary.com/
Archive and=20 UnSub:  =20 = http://mail.lancaironline.net:81/lists/flyrotary/List.html
-Al Wick
Cozy IV powered by Turbo Subaru 3.0R with = variable valve=20 lift and cam timing.
Artificial intelligence in cockpit, = N9032U 240+=20 hours from Portland, Oregon
Glass panel design, Subaru install, = Prop=20 construct, Risk assessment info:
htt= p://www.maddyhome.com/canardpages/pages/alwick/index.html
-Al Wick
Cozy IV powered by Turbo Subaru 3.0R with variable = valve lift=20 and cam timing.
Artificial intelligence in cockpit, N9032U 240+ = hours from=20 Portland, Oregon
Glass panel design, Subaru install, Prop = construct, Risk=20 assessment info:
htt= p://www.maddyhome.com/canardpages/pages/alwick/index.html
------=_NextPart_000_000C_01C80D0F.DF0DE740--