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 2368435 for flyrotary@lancaironline.net; Thu, 04 Oct 2007 11:28:11 -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-omta02.mail.rr.com with SMTP id <20071004152730.XNLI3965.cdptpa-omta02.mail.rr.com@edward2> for ; Thu, 4 Oct 2007 15:27:30 +0000 Message-ID: <006301c8069b$1b6bdb50$2402a8c0@edward2> From: "Ed Anderson" To: "Rotary motors in aircraft" References: Subject: Re: [FlyRotary] Re: Problem? [FlyRotary] Re: Coolant Water Pressure Date: Thu, 4 Oct 2007 11:27:42 -0400 MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_0060_01C80679.9419D6F0" 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_0060_01C80679.9419D6F0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Sorry, thanks Bill. I recall now. Also you are correct, got distracted = and did not finish. But back to your situation. First, to get a bit more specific. At 2200 rpm and a modest 14.7:1 Air Fuel Ratio and 14" Hg manifold = pressure and with 2/3 of the waste heat going to the radiators for = rejection, you engine would be producing approx 26 HP. Previously, I neglected to account for your reduced throttle setting = (near idle) and was using WOT parameters. But, now with manifold = pressure around 14" Hg the power out put would be close to 26 HP, it = could be a bit less. But, in any case, that would mean you need to = reject only around 750 BTU/Min through your radiator to keep your temps = within limits. =20 You indicate you have an approx. 80F delta T across your radiator core = with the coolant temp at 210F. A large delta T is one indication of = slow air flow as each unit of air is carrying more heat. You have a = fan which apparently has the spec to draw 970 CFI across the 11" dia of = the Fan. Lets assume that was the flow through the entire core. Then = that would give you 970*.0765 =3D 74 lbm/min of air mass with the Fan = alone. =20 Q =3D 75 * .25 * 80 =3D 1500 BTU/Min just due to the flow resulting from = your fan -- the prop blast would likely help that figure. So if I am not completely off in left field, it would appear that with = 760 CI core, you should easily be cooling at 2200 rpm. However, unless = your temp readings are way-off, its pretty clear that you are not. = Possible things that come to mind. 1. Coolant flow being impeded. Possible causes: (a), Hole in bottom of thermostat housing not plugged and no thermostat = you DID plug the 1/2" hole in bottle of the thermostat housing, did you = not? (I presume the Renesis has it as the older 13Bs all did) - if you = do not plug this hole and are NOT using a Mazda (must be Mazda RX-7) = thermostat then you could be losing 20% of your cooling effectiveness = (particularly at lower rpm). (b). Pump belt slipping- but I think the Renesis uses a serpentine belt = so that is not likely - besides, if it were you would probably hear and = smell it. (c). Double pass radiator causing a 33% drop in flow rate - could be, = but still hard to believe it would not cool at 2200 rpm with 720 CI even = it this postulation were true. But, if the hole in the bottom of the = thermostat is not plugged AND the pump is facing more back pressure due = to the double pass, the combination could result in a larger than 30% = decrease in coolant flow. (d). Air trapped in block - already discussed this one 2. Air flow being impeded. Possible causes: (a) Insufficient air inlet/outlet (b) Flow Separation in the ducts=20 3. Sensor readings in error. Do you have any other indications of overheating, pinging of the = block after shut down, smoking block, etc. If I were to make a WAG, I would still say it is trapped air. The = reason is you have enough core, you have a Fan (which I don't and many = do not) which should make ground cooling at 2200 rpm a breeze (no pun = intended). So unless the coolant is not flowing as we expect, that is = the only other thing I can think of is trapped air. Regarding your question about running without a cap. In fact, I do just = that when I am trying to get air out, however, my cap is on the suction = side of the pump and is on a header tank. So not as likely to get any = thing pushed out. You cap is apparently on the pressure side of the = pump? So the pump could push some coolant out - particularly if there is any = obstruction/restriction, in fact given that you have a double pass = radiator with its resistance, I think it likely that even low rpm = operation would result in coolant being pushed out the radiator cap hole = - unless it is on the suction side of the pump. Do you have any photos of your installation you could post?? Ed =20 ----- Original Message -----=20 From: Bill Bradburry=20 To: Rotary motors in aircraft=20 Sent: Thursday, October 04, 2007 10:03 AM Subject: [FlyRotary] Re: Problem? [FlyRotary] Re: Coolant Water = Pressure Yep, Ed. I have your original prop.a Performance Prop 76 X 88. Tractor = configuration.It is a Lancair Legacy. The air going through the radiator after the fan is picking up 80*, = which seems like a lot to me..This is measured after the fan and may not = be representative of the rest of the core. But prop blast should be = supplying the balance of the core with at least some air.. I was running at 2100-2200 rpm during this test which I failed to = mention. If you look at your calculations you were doing before you = were distracted by the prop question, I think you were about to arrive = at the conclusion that it should be cooling.?? My coolant is a 50/50 antifreeze mix. I mention this because of the = next question. Back in my car repair days, you could tell if the thermostat was = sticking by removing the radiator cap and watching to see if the water = started to flow as the engine heated up. I don't have a thermostat, so = can I remove the radiator cap and start the engine to determine flow, or = will the high flow pump shoot antifreeze all over my plane? =20 I am interested in your completed calculations to see what you = determine my cooling results should be. =20 Without the folks on this list, only really gifted people like you and = Tracy could ever hope to "get er done". =20 Thanks, Bill B =20 -------------------------------------------------------------------------= ----- From: Rotary motors in aircraft [mailto:flyrotary@lancaironline.net] = On Behalf Of Ed Anderson Sent: Wednesday, October 03, 2007 7:19 PM To: Rotary motors in aircraft Subject: [FlyRotary] Re: Problem? [FlyRotary] Re: Coolant Water = Pressure =20 Grass? what grass? {:>) =20 Yes, it sounds like the air should rise to the top of your slanted = radiator. However, My experience has been that unless I run the engine = up to around 5000 rpm for about 15-30 seconds (does not have to be long) = that I do not have much success getting air out of the block. It seems = to take that velocity of coolant flow to drag the water out of the = block. =20 You have over 700 cubic inches of core, so that should be plenty for = cooling a two rotor. =20 =20 A multi pass radiator (two pass in your case) can require more coolant = pump flow as indicated by this extract from a pretty respected name in = racing/cooling circles: =20 Double pass Double pass radiators require 16x more pressure to flow = the same volume of coolant through them, as compared to a single pass = radiator. Triple pass radiators require 64x more pressure to maintain = the same volume. Automotive water pumps are a centrifugal design, not = positive displacement, so with a double pass radiator, the pressure is = doubled and flow is reduced by approximately 33%. Modern radiator = designs, using wide/thin cross sections tubes, seldom benefit from = multiple pass configurations. The decrease in flow caused by multiple = passes offsets any benefits of a high-flow water pump. =20 =20 Again, these are just back of the envelope calculations based on a = great deal of assumption about your parameters. My gut feel is that 700 = cubic inches should have no problem cooling your installation at those = power settings even being a double pass radiator. So I would look else = where. =20 You indicate you have an approx. 80F delta T across your radiator = core with the coolant temp a 210F. You have a fan which apparently has = the spec to draw 970 CFI across the 11" dia of the Fan. Lets assume = that was the flow through the entire core. Then that would give you = 970*.0765 =3D 74 lbm/min of air mass. =20 Q =3D 75 * .25 * 80 =3D 1500 BTU/Min just due to the flow resulting = from your fan - it would seem that plus whatever flow you are getting = from your prop - Prop??. =20 =20 Hey, this dumb question just occurred to me - I assume you are = running with a prop?? in a tractor configuration. I lose track of who = has what. =20 =20 Ed =20 =20 =20 =20 =20 =20 =20 ----- Original Message -----=20 From: Bill Bradburry=20 To: Rotary motors in aircraft=20 Sent: Wednesday, October 03, 2007 5:12 PM Subject: [FlyRotary] Re: Problem? [FlyRotary] Re: Coolant Water = Pressure =20 I have an aluminum double pass radiator with the finned core size of = about 18.25 X 18.25 X 2.25. It is behind the engine and leaning = rearward at the top at about a 30-35* angle. The water from the engine = enters on the left lower and crosses the bottom half of the radiator to = the right side then rises and goes back across the top of the radiator = and exits the top left side and returns to the engine. My radiator cap is at the top right corner of the radiator at the = point where the water starts its second pass through the top half. My = pressure port is just below the radiator cap. The pressure sending unit = is in a "T" with the hose which goes to the =BC" port at the top of the = rear iron connected to the other side of the "T". I thought that this = hose could have some effect on the pressure, but I am not certain why it = would. =20 Any air in the system should either rise to the top of the radiator, = or if it was trapped in the block, it could come through the hose to the = radiator. All air should be found therefore? Under the radiator cap. I = have never found any air there. =20 I think I found out a little something about the fuel system today. = I only put a few gallons in the right tank and have been checking for = leaks and running the engine on this fuel. I wanted to run it down to = the "non-usable" level and then do the same thing with the left tank. = So I have been really low on fuel. My pressure has been holding, but I = thought that I could hear bubbles from time to time going through the = lines. =20 Anyway, before, I could get a good start by setting the mixture at = about 4 PM oclock and it would fire up in a couple of blades. Today, I = tried hitting the primer button a couple of times and it would start and = immediately die. I finally had to set the cold start on and leave it on = just to get the engine to run! Finally after it warmed up, it ran with = the mixture set at 12 oclock, but it was not steady. As my fuel ran = out, the pressure dropped finally to about 28 lbs and the engine started = its death rattle. I shut it off at that time. =20 The temperature had risen to 210* the ambient temp was 87-88* and = the air after the radiator was 168* This is with my radiator fan = running. (11" and 970 CFM) probably about 10-12 minutes of running the = engine . My oil temp was only 160* and the air temp after the oil cooler was = 145* , I think that this would gone higher if I ran longer, because the = oil in the pan was up to 170-180* or so. The pan holds 5 qts, 8 qts in = the system. Water pressure was up to 22-23 lbs and oil pressure was 70 lbs. =20 All my temp probes are within a degree or so of one another and with = a mercury thermometer in the hangar when reading ambient temp and the = engine is cold. I think they are all correct. =20 I have the air/fuel ratio setup that comes with the EM-2, but it = doesn't work till the O2 sensor gets to about 800* or so, no help on = trying to figure out starting ratio. =20 The timing brings up a good point. I got the Renesis out of a = wrecked car with 1800 miles on it, so the timing is set to the factory = setting for the Renesis. I have never checked it. Does anyone know = what the factory setting would be for the Renesis?? =20 Staging is a good point, but I think that you are correct about = having enough fuel to run a low speeds and not enough to run faster. I = was running out of fuel and probably didn't have enough to rip it. =20 You really have good insights when you are helping folks.. You are = pretty right on with your advice. =20 Thanks, Bill B (Must mow yard.Must mow yard..) -------------------------------------------------------------------------= --- From: Rotary motors in aircraft [mailto:flyrotary@lancaironline.net] = On Behalf Of Ed Anderson Sent: Wednesday, October 03, 2007 12:53 PM To: Rotary motors in aircraft Subject: [FlyRotary] Re: Problem? [FlyRotary] Re: Coolant Water = Pressure =20 Yes, too hot for that rpm, I agree. =20 Assuming you followed the good suggestions offered by Al, Lynn and = others regarding getting all the air out of the block - really = important! I almost cooked engines two times because of excess air in = the coolant system. Here is something that may quickly tell you = something about the air you may have in the system. =20 I can't recall what type of radiator set up you have, but with the = Two GM cores I use which are mounted vertically, you can touch the side = tank of the radiator and determine if there is air in the system. In my = case, if I do a complete drain and refill of the system, on the first = run up the core's tanks will be hot approx 2/3 of the way up and then = they are much cooler - indicating that the remaining 1/3 of my core is = filled with air. It generally takes me 3 runups reaching 5000 rpm = before I can touch the core tanks and find them hot all the way from = top to bottom. So depending on your radiator set up that might be = something you can quickly check. =20 If the mixture is too lean, you can get a backfire out the intake, = too rich and its generally the exhaust - where unburned fuel cooks off. = So that and black smoke would indicate to me too rich a mixture. I = presume you do not have an Air/Fuel ratio indicator - strongly recommend = you get one, that tells you right away whether you are running rich or = lean. Even a cheap one can be a tremendous help in finding out whether = too rich or too lean. =20 One thing you may want to check is your ignition timing. If using = Tracy's EC2 you need to set the static timing around 35 Deg BTDC. The = EC2 backs off 10 deg from that (25Deb BTDC) as its default starting = point for ignition timing. So if you set the static timing to say 25 = Deg then the EC2 would be having the engine operate at a 25 - 10 deg =3D = 15 Deg BTDC which is pretty retarded timing for the rotary. OR if you = set it too far advanced then the timing might be too advanced. So just recheck it when you get the chance. =20 Another possibility is your injection system might not be staging = properly. IF that were the case, the engine might work fine below the = staging point but not above it. Could possibly be a sticking secondary = injector (if too rich or lean). But, that is a bit down the likely = list. Something impeding the fuel flow might provide sufficient fuel = and low rpm but not sufficient to run at high rpm. =20 Hope some of this helps =20 Ed =20 Ed Anderson Rv-6A N494BW Rotary Powered Matthews, NC eanderson@carolina.rr.com http://www.andersonee.com http://members.cox.net/rogersda/rotary/configs.htm#N494BW http://www.dmack.net/mazda/index.html =20 =20 =20 =20 =20 =20 ----- Original Message -----=20 From: Bill Bradburry=20 To: Rotary motors in aircraft=20 Sent: Wednesday, October 03, 2007 11:23 AM Subject: [FlyRotary] Re: Problem? [FlyRotary] Re: Coolant Water = Pressure =20 Ed, this is at about 2000 rpm. Like a fast idle. I am getting = all kinds of fuel cut like stoppages if I try to run the engine faster. = I haven't seen more than about 3700 rpm, but I just started it and have = not tried to tune anything. I figure I will have to run longer to get = it tuned and the cooling is holding that back. =20 Speaking of that, you guys were talking a while back about the = effects you see when the engine is too lean, or too rich. Talking about = backfires, etc and what each effect represents. I have forgotten what = means what.senior days, not moments! Do any of you remember how that went? I am having some problems = getting started and am not certain if I am too rich or too lean. I am = getting backfires out the exhaust at times and smoke from the exhaust at = that time. (black) I ran the batteries down yesterday trying to get started due to = this. When I originally started the engine, I flooded it. I am trying = to prevent this now and am concerned that I may not be using enough = mixture. =20 Bill B =20 -------------------------------------------------------------------------= - From: Rotary motors in aircraft = [mailto:flyrotary@lancaironline.net] On Behalf Of Ed Anderson Sent: Wednesday, October 03, 2007 10:05 AM To: Rotary motors in aircraft Subject: [FlyRotary] Problem? [FlyRotary] Re: Coolant Water = Pressure =20 Bill,=20 =20 You indicate you get overheating after 10-15 minutes run time. I = may have missed it, but is this at idle, max throttle or what. Also = what is your OAT. If at idle or low power then, yes what you are seeing = is not what it should be. On the other hand, if at WOT or high power = settings, then 10-15 minutes run time would be indication of a great = cooling capacity. I can not run my engine more than a minute or two at = WOT on a 80F day without temps getting into the 200F range. But, that = is at 5800-6000 rpm. At idle, the temps stabilize and I can idle all = day with safe temps. =20 My coolant system runs with no air cushion and yes, I get a = hydraulic "lock" pressure reading of as high as 25 psi immediately upon = engine start up. After a 30 - 60 seconds of running the pressure drops = down to zero and then after a few minutes running builds back up as the = coolant warms up to operating temperatures. =20 =20 Plenty of suggestion have been made about what to check - all = good. =20 =20 Good luck. =20 Ed =20 Ed Anderson Rv-6A N494BW Rotary Powered Matthews, NC eanderson@carolina.rr.com http://www.andersonee.com http://members.cox.net/rogersda/rotary/configs.htm#N494BW http://www.dmack.net/mazda/index.html ----- Original Message -----=20 From: Al Wick=20 To: Rotary motors in aircraft=20 Sent: Wednesday, October 03, 2007 9:30 AM Subject: [FlyRotary] Re: Coolant Water Pressure =20 Bill, the definitive test is the one I described below. Really = encourage you to do it as described. Resist assumptions. Convert your = ideas to measurements. =20 -al wick ----- Original Message -----=20 From: Bill Bradburry=20 To: Rotary motors in aircraft=20 Sent: Wednesday, October 03, 2007 6:08 AM Subject: [FlyRotary] Re: Coolant Water Pressure =20 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*?? =20 Thanks for the suggestions of where to look, guys. =20 Bill B =20 ---------------------------------------------------------------------- From: Rotary motors in aircraft = [mailto:flyrotary@lancaironline.net] On Behalf Of Al p Wick Sent: Tuesday, October 02, 2007 7:49 PM To: Rotary motors in aircraft Subject: [FlyRotary] Re: Coolant Water Pressure =20 Your coolant reservoir should be above engine.=20 =20 1) If it is, remove two cups of air from the reservoir. Then = repeat your test.=20 2) If you now see pressure rise above 22 psi within 5 minutes = of cold start, you clearly have compression gases leaking into cooling = system or bad gage. =20 3) Air in the block is 10 times more significant than any = other cooling factor. Make darn sure you don't have any. It causes local = boiling, high temps, strange behavior. =20 Operating with two cups of air under cap is an important = safety and diagnosis advantage. Everyone should do it. With that two = cups, you only see 22 psi if you have a genuine problem. You only see 0 = psi if you have genuine problem. The pressure is then a very fast and = reliable indicator of system integrity. So two cups of air has no = negative effect on system efficiency, just a substantial improvement in = safety. Only time it could be a negative would be if your reservoir was = way too small, way too low, or flowed way too much coolant. =20 Since you describe high temps AND pressure, I suspect you have = temperature problem. =20 I deliberately overheated my engine many times so that I was = intimate with pressure and temperature patterns. Then tested various = concepts. Don't recommend you do the same. =20 -al wick =20 =20 On Tue, 2 Oct 2007 12:38:55 -0400 "Bill Bradburry" = writes: I just recently got my Renesis started again after finishing = my cowl. I seem to be getting very high coolant pressures. I can only = run the engine about 10-15 minutes before hitting the redline at 210*. = My water pressure is at 27 Lbs at that time. I only have a 22 Lb = radiator cap, so I assume that I am blowing into the recovery tank, but = I have not confirmed that. My oil temp has never exceeded about 165*. = It might have gone higher if I could have run longer??? =20 This whole water pressure thing has me a little baffled. = Since this is a closed system and the only way pressure can build is due = to the expansion of the coolant after heating???, I am confused by some = comments that have been made from time to time. I remember something = that Tracy said about his pressure would build for a time, then go to = zero. It seems to me that the pressure should correlate to the temp = pretty closely since it is a closed system??=20 =20 Can someone enlighten me a little on the science of this = pressure? It seems to me that there could be some pressure build up on = the positive side of the pump, but it would go negative on the suction = side, so the net effect of the pump should be close to zero?? =20 Also, my Renesis had only 1800 miles on it when I bought it, = so I did not have to tear it down. As a result, I am somewhat in the = dark as to how the water flows through the system. Could someone help = me with that? I had to remove the thermostat tower for height clearance = , so I made an adapter plate that takes water from the top outlet of the = pump and sends it to the radiator (double pass), then from the radiator, = it returns to the lower inlet of the pump. =20 Thanks, Bill B =20 -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_0060_01C80679.9419D6F0 Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable
Sorry, thanks Bill. I recall now.  Also you = are=20 correct, got distracted and did not finish.
 
But back to your situation.  First, to get = a bit more=20 specific.
 
At  2200 rpm and a modest 14.7:1 Air Fuel = Ratio and=20 14" Hg manifold pressure and with 2/3 of the waste heat going to the = radiators=20 for rejection, you engine would be producing approx 26 HP.
 
  Previously, I neglected to account for = your reduced=20 throttle setting (near idle) and was using WOT parameters.  But, = now with=20 manifold pressure around 14" Hg the power out put would be close to 26 = HP,=20  it could be a bit less.  But, in any case, that would mean = you need=20 to reject only around 750 BTU/Min through your radiator to keep your = temps=20 within limits. 
 

 You indicate you = have an=20 approx. 80F delta T across your radiator core with the coolant temp at=20 210F.  A large delta T is one indication of slow air flow as each = unit of=20 air is carrying more heat.   You have a fan which apparently = has the=20 spec to draw 970 CFI across the 11" dia of the Fan.  Lets assume = that was=20 the flow through the entire core.  Then that would give you = 970*.0765 =3D 74=20 lbm/min of air mass with the Fan alone.

 

Q =3D 75 * .25 * 80 =3D = 1500 BTU/Min=20 just due to the flow resulting from your fan -- the prop blast=20 would likely help that figure.

 

So if I am not completely = off in=20 left field, it would appear that with 760 CI core, you should easily be = cooling=20 at 2200 rpm.   However, unless your temp readings are = way-off,=20 its pretty clear that you are not.  Possible things that come = to=20 mind.

 

1.  Coolant flow = being=20 impeded.  Possible causes:

 

(a), Hole in bottom of = thermostat=20 housing not plugged and no thermostat   you DID = plug the 1/2"=20 hole in bottle of the thermostat housing, did you not? (I presume = the=20 Renesis has it as the older 13Bs all did) - if you do not plug this hole = and are=20 NOT using a Mazda (must be Mazda RX-7) thermostat then you could be = losing 20%=20 of your cooling effectiveness (particularly at lower = rpm).

 

(b).  Pump belt = slipping- but I=20 think the Renesis uses a serpentine belt so that is not likely = - besides,=20 if it were you would probably hear and smell it.

 

(c).  Double pass = radiator=20 causing a 33% drop in flow rate - could be, but still hard to = believe it=20 would not cool at 2200 rpm with 720 CI even it this postulation = were=20 true.  But, if the hole in the bottom of the thermostat is not = plugged AND=20 the pump is facing more back pressure due to the double pass,  the=20 combination could result in a larger than 30% decrease in coolant=20 flow.

 

(d).  Air trapped in = block -=20 already discussed this one

 

2.  Air flow being=20 impeded.  Possible causes:

(a) Insufficient air=20 inlet/outlet

(b) Flow Separation in the = ducts=20

 

3.  Sensor readings = in=20 error.

 

     = Do you have=20 any other indications of overheating, pinging of the block after shut = down,=20 smoking block, etc.

 

 

If I were to make a WAG, I = would=20 still say it is trapped air.  The reason is you have enough core, = you have=20 a Fan (which I don't and many do not) which should make ground cooling = at 2200=20 rpm a breeze (no pun intended).   So unless the coolant = is not=20 flowing as we expect, that is the only other thing I can think of is = trapped=20 air.

 

Regarding your question = about=20 running without a cap.  In fact, I do just that when I am trying to = get air=20 out, however, my cap is on the suction side of the pump and is on a = header=20 tank.  So not as likely to get any thing pushed out.  You cap = is=20 apparently on the pressure side of the pump?

So the pump could push = some coolant=20 out  - particularly if there is any obstruction/restriction, in = fact given=20 that you have a double pass radiator with its resistance, I think it = likely that=20 even low rpm operation would result in coolant being pushed out the = radiator cap=20 hole - unless it is on the suction side of the pump.

 

Do you have any photos of = your=20 installation you could post??

 

Ed

 

 

----- Original Message -----
From:=20 Bill=20 Bradburry
Sent: Thursday, October 04, = 2007 10:03=20 AM
Subject: [FlyRotary] Re: = Problem?=20 [FlyRotary] Re: Coolant Water Pressure

Yep,=20 Ed.

I have your = original=20 prop=85a Performance Prop 76 X 88. Tractor configuration=85It is a = Lancair=20 Legacy.

The air = going through=20 the radiator after the fan is picking up 80*, which seems like a lot = to=20 me=85.This is measured after the fan and may not be representative of = the rest=20 of the core. But prop blast should be supplying the balance of the = core with=20 at least some air=85.

I was = running at=20 2100-2200 rpm during this test which I failed to mention.  If you = look at=20 your calculations you were doing before you were distracted by the = prop=20 question, I think you were about to arrive at the conclusion that it = should be=20 cooling=85??

My coolant = is a 50/50=20 antifreeze mix.  I mention this because of the next=20 question.

Back in my = car repair=20 days, you could tell if the thermostat was sticking by removing the = radiator=20 cap and watching to see if the water started to flow as the engine = heated=20 up.  I don=92t have a thermostat, so can I remove the radiator = cap and=20 start the engine to determine flow, or will the high flow pump shoot=20 antifreeze all over my plane?

 

I am = interested in=20 your completed calculations to see what you determine my cooling = results=20 should be.

 

Without the = folks on=20 this list, only really gifted people like you and Tracy could = ever hope to=20 =93get er done=94.

 

Thanks,

Bill=20 B

 

From:=20 Rotary motors in aircraft = [mailto:flyrotary@lancaironline.net] On=20 Behalf Of Ed Anderson
Sent: Wednesday, October 03, = 2007 7:19=20 PM
To: = Rotary motors in aircraft
Subject: [FlyRotary] Re: = Problem?=20 [FlyRotary] Re: Coolant Water = Pressure

 

Grass?  what grass? = {:>)

 

Yes, it sounds like the = air should=20 rise to the top of your slanted radiator.  However, My experience = has=20 been that unless I run the engine up to around 5000 rpm for about=20 15-30 seconds (does not have to be long) that I do not have much = success=20 getting air out of the block.  It seems to take that velocity of = coolant=20 flow to drag the water out of the = block.

 

You have over 700 cubic = inches of=20 core, so that should be plenty for cooling a two rotor. =20

 

A multi pass radiator = (two pass in=20 your case) can require more coolant pump flow as indicated by this = extract=20 from a pretty respected name in racing/cooling=20 circles:

 

   = Double = pass=20 Double = pass=20 radiators require 16x more pressure to flow the same volume of coolant = through=20 them, as compared to a single pass radiator. Triple pass radiators = require 64x=20 more pressure to maintain the same volume. Automotive water pumps are = a=20 centrifugal design, not positive displacement,=20 so with a = double pass=20 radiator, the pressure is doubled and flow is reduced by approximately = 33%.=20 Modern radiator designs, using wide/thin cross sections tubes, seldom = benefit=20 from multiple pass configurations. The = decrease in=20 flow caused by multiple passes offsets any benefits of a high-flow = water=20 pump.

 

 

Again, these are just = back of the=20 envelope calculations based on a great deal of assumption about your=20 parameters.  My gut feel is that 700 cubic inches should have no = problem=20 cooling your installation at those power settings even being a double = pass=20 radiator.  So I would look else = where.

 

 You indicate you = have an=20 approx. 80F delta T across your radiator core with the coolant temp a=20 210F.  You have a fan which apparently has the spec to draw 970 = CFI=20 across the 11" dia of the Fan.  Lets assume that was the flow = through the=20 entire core.  Then that would give you 970*.0765 =3D 74 lbm/min = of air=20 mass.

 

Q =3D 75 * .25 * 80 =3D = 1500 BTU/Min=20 just due to the flow resulting from your fan - it would seem that plus = whatever flow you are getting from your prop - Prop??. =20

 

Hey, this  dumb = question just=20 occurred to me  -  I assume you are running with a prop?? in = a=20 tractor configuration.  I lose track of who has=20 what.

 

 

Ed

 

 

 

 

 

 

 

----- Original Message = -----=20

From: Bill=20 Bradburry

To: Rotary motors in = aircraft=20

Sent:=20 Wednesday, October 03, 2007 5:12 = PM

Subject:=20 [FlyRotary] Re: Problem? [FlyRotary] Re: Coolant Water=20 Pressure

 

I have an = aluminum=20 double pass radiator with the finned core size of about 18.25 X = 18.25 X=20 2.25.  It is behind the engine and leaning rearward at the top = at about=20 a 30-35* angle.  The water from the engine enters on the left = lower and=20 crosses the bottom half of the radiator to the right side then rises = and=20 goes back across the top of the radiator and exits the top left side = and=20 returns to the engine.

My = radiator cap is=20 at the top right corner of the radiator at the point where the water = starts=20 its second pass through the top half.  My pressure port is just = below=20 the radiator cap.  The pressure sending unit is in a =93T=94 = with the hose=20 which goes to the =BC=94 port at the top of the rear iron connected = to the other=20 side of the =93T=94.  I thought that this hose could have some = effect on=20 the pressure, but I am not certain why it=20 would.

 

Any air = in the=20 system should either rise to the top of the radiator, or if it was = trapped=20 in the block, it could come through the hose to the radiator.  = All air=20 should be found therefore? Under the radiator cap.  I have = never found=20 any air there.

 

I think I = found out=20 a little something about the fuel system today.  I only put a = few=20 gallons in the right tank and have been checking for leaks and = running the=20 engine on this fuel.  I wanted to run it down to the = =93non-usable=94 level=20 and then do the same thing with the left tank.  So I have been = really=20 low on fuel.  My pressure has been holding, but I thought that = I could=20 hear bubbles from time to time going through the=20 lines.

 

Anyway, = before, I=20 could get a good start by setting the mixture at about 4 PM oclock = and it=20 would fire up in a couple of blades.  Today, I tried hitting = the primer=20 button a couple of times and it would start and immediately = die.  I=20 finally had to set the cold start on and leave it on just to get the = engine=20 to run!  Finally after it warmed up, it ran with the mixture = set at 12=20 oclock, but it was not steady.  As my fuel ran out, the = pressure=20 dropped finally to about 28 lbs and the engine started its death=20 rattle.  I shut it off at that = time.

 

The = temperature had=20 risen to 210* the ambient temp was 87-88* and the air after the = radiator was=20 168*  This is with my radiator fan running.  (11=94 and = 970 CFM)=20 probably about 10-12 minutes of running the=20 engine

.

My oil = temp was=20 only 160* and the air temp after the oil cooler was 145* , I think = that this=20 would gone higher if I ran longer, because the oil in the pan was up = to=20 170-180* or so.  The pan holds 5 qts, 8 qts in the=20 system.

Water = pressure was=20 up to 22-23 lbs and oil pressure was 70 = lbs.

 

All my = temp probes=20 are within a degree or so of one another and with a mercury = thermometer in=20 the hangar when reading ambient temp and the engine is cold.  I = think=20 they are all correct.

 

I have = the air/fuel=20 ratio setup that comes with the EM-2, but it doesn=92t work till the = O2 sensor=20 gets to about 800* or so, no help on trying to figure out starting=20 ratio.

 

The = timing brings=20 up a good point.  I got the Renesis out of a wrecked car with = 1800=20 miles on it, so the timing is set to the factory setting for the=20 Renesis.  I have never checked it.  Does anyone know what = the=20 factory setting would be for the = Renesis??

 

Staging = is a good=20 point, but I think that you are correct about having enough fuel to = run a=20 low speeds and not enough to run faster.  I was running out of = fuel and=20 probably didn=92t have enough to rip = it.

 

You = really have=20 good insights when you are helping folks.. You are pretty right on = with your=20 advice.

 

Thanks,

Bill = B  (Must=20 mow yard=85Must mow yard..)

From:=20 Rotary motors in = aircraft=20 [mailto:flyrotary@lancaironline.net] On=20 Behalf Of Ed Anderson
Sent: Wednesday, October 03, = 2007 12:53=20 PM
To: = Rotary motors in aircraft
Subject: [FlyRotary] Re: = Problem?=20 [FlyRotary] Re: Coolant Water = Pressure

 

Yes, too hot for that = rpm, I=20 agree.

 

Assuming  you = followed the=20 good suggestions offered by Al, Lynn and others regarding getting = all the=20 air out of the block - really important!  I almost cooked = engines two=20 times because of excess air in the coolant system.  Here is = something=20 that  may quickly tell you something about the air you may have = in the=20 system.

 

  I can't recall = what type=20 of radiator set up you have, but with the Two GM cores I use = which are=20 mounted vertically, you can touch the side tank of the radiator = and=20 determine if there is air in the system.  In my case, = if I do=20 a complete drain and refill of the system, on the first run up the = core's=20 tanks  will be hot approx 2/3 of the way up and then they are = much=20 cooler - indicating that the remaining 1/3 of my core is filled with = air.  It generally takes me 3 runups reaching 5000 rpm = before I=20 can touch  the core tanks and find them hot all the way = from top=20 to bottom.  So depending on your radiator set up that might be=20 something you can quickly check.

 

If the mixture is too = lean, you=20 can get a backfire out the intake, too rich and its generally the = exhaust -=20 where unburned fuel cooks off.  So that and black smoke would = indicate=20 to me  too rich a mixture.  I presume you do not have an = Air/Fuel=20 ratio indicator - strongly recommend you get one, that tells you = right away=20 whether you are running rich or lean.  Even a cheap one can be = a=20 tremendous help in finding out whether too rich or too=20 lean.

 

One thing you may want = to check=20 is your ignition timing.  If using Tracy's EC2 you need to set the = static=20 timing around 35 Deg BTDC.  The EC2 backs off 10 deg from that = (25Deb=20 BTDC) as its default starting point for ignition timing.  So if = you set=20 the static timing to say 25 Deg then the EC2 would be having the = engine=20 operate at a 25 - 10 deg =3D 15 Deg BTDC which is pretty retarded = timing for=20 the  rotary.  OR if you set it too far advanced then the = timing=20 might be too advanced.

So just recheck it = when you get=20 the chance.

 

Another possibility is = your=20 injection system might not be staging properly. IF that were = the case,=20 the engine might work fine below the staging point but not above = it. =20 Could possibly be a sticking secondary injector (if too rich or=20 lean).   But, that is a bit down the likely list.  = Something=20 impeding the fuel flow might provide sufficient fuel and low rpm but = not=20 sufficient to run at high rpm.

 

Hope some of this=20 helps

 

Ed

 

Ed Anderson
Rv-6A = N494BW=20 Rotary Powered
Matthews, NC
eanderson@carolina.rr.comhttp://www.andersonee.com
http:/= /members.cox.net/rogersda/rotary/configs.htm#N494BW
http://www.dmack.net/mazda= /index.html

 

 

 

 

 

 

----- Original = Message -----=20

From: Bill=20 Bradburry

To: Rotary motors in = aircraft=20

Sent:=20 Wednesday, October 03, 2007 11:23 = AM

Subject:=20 [FlyRotary] Re: Problem? [FlyRotary] Re: Coolant Water=20 Pressure

 

Ed, = this is at=20 about 2000 rpm.  Like a fast idle.  I am getting all = kinds of=20 fuel cut like stoppages if I try to run the engine faster.  I = haven=92t=20 seen more than about 3700 rpm, but I just started it and have not = tried to=20 tune anything.  I figure I will have to run longer to get it = tuned=20 and the cooling is holding that back.

 

Speaking of that,=20 you guys were talking a while back about the effects you see when = the=20 engine is too lean, or too rich.  Talking about backfires, = etc and=20 what each effect represents.  I have forgotten what means = what=85senior=20 days, not moments!

Do any = of you=20 remember how that went?  I am having some problems getting = started=20 and am not certain if I am too rich or too lean.  I am = getting=20 backfires out the exhaust at times and smoke from the exhaust at = that=20 time. (black)

I ran = the=20 batteries down yesterday trying to get started due to this.  = When I=20 originally started the engine, I flooded it.  I am trying to = prevent=20 this now and am concerned that I may not be using enough=20 mixture.

 

Bill=20 B

 

From:=20 Rotary motors in = aircraft=20 [mailto:flyrotary@lancaironline.net] On=20 Behalf Of Ed Anderson
Sent: Wednesday, October = 03, 2007=20 10:05 AM
To:=20 Rotary motors in=20 aircraft
Subject: [FlyRotary] = Problem?=20 [FlyRotary] Re: Coolant Water = Pressure

 

Bill,=20

 

You indicate you get = overheating after 10-15 minutes run time.  I may have missed = it, but=20 is this at idle, max throttle or what.  Also what is your = OAT. =20 If at idle or low power then, yes what you are seeing is not what = it=20 should be.  On the other hand, if at WOT or high power = settings, then=20 10-15 minutes run time would be indication of a great cooling=20 capacity.  I can not run my engine more than a minute or two = at WOT=20 on a 80F day without temps getting into the 200F range.  But, = that is=20 at 5800-6000 rpm.  At idle, the temps stabilize and I can = idle all=20 day with safe temps.

 

My coolant system = runs with no=20 air cushion and yes, I get a hydraulic "lock" pressure reading of = as high=20 as 25 psi immediately upon engine start up.  After a 30 - 60 = seconds=20 of running the pressure  drops down to zero and then = after a few=20 minutes running builds back up as the coolant warms up to = operating=20 temperatures. 

 

Plenty of suggestion = have been=20 made about what to check - all good. =20

 

Good=20 luck.

 

Ed

 

Ed Anderson
Rv-6A = N494BW=20 Rotary Powered
Matthews, NC
eanderson@carolina.rr.comhttp://www.andersonee.com
http:/= /members.cox.net/rogersda/rotary/configs.htm#N494BW
http://www.dmack.net/mazda= /index.html

----- Original = Message -----=20

From: Al = Wick=20

To: Rotary motors in = aircraft=20

Sent:=20 Wednesday, October 03, 2007 9:30 = AM

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

 

Bill, the = definitive test is=20 the one I described below. Really encourage you to do it as = described.=20 Resist assumptions. Convert your ideas to=20 measurements.

 

-al=20 wick

----- Original = Message=20 -----

From:=20 Bill Bradburry=20

Sent:=20 Wednesday, October 03, 2007 6:08 = AM

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

 

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

 

From:=20 Rotary motors in = aircraft=20 [mailto:flyrotary@lancaironline.net] On Behalf Of Al p=20 Wick
Sent: = Tuesday,=20 October 02, 2007 7:49 PM
To: Rotary motors in = aircraft
Subject: [FlyRotary] = Re: Coolant=20 Water Pressure

 

Your coolant reservoir should be = above engine.=20

 

1) If it is, remove two cups of air = from the=20 reservoir. Then repeat your test. =

2) If you now see pressure rise = above 22=20 psi within 5 minutes of cold start, you clearly have = compression gases=20 leaking into cooling system or bad=20 gage.

 

3) Air in the block is 10 times more = significant than any other cooling factor. Make darn sure you = don't=20 have any. It causes local boiling, high temps, strange=20 behavior.

 

Operating with two cups of air under = cap is an=20 important safety and diagnosis advantage. Everyone should do = it. With=20 that two cups, you only see 22 psi if you have a genuine = problem. You=20 only see 0 psi if you have genuine problem. The pressure is = then a=20 very fast and reliable indicator of system integrity. So two = cups of=20 air has no negative effect on system efficiency, just a = substantial=20 improvement in safety. Only time it could be a negative would = be if=20 your reservoir was way too small, way too low, or flowed way = too much=20 coolant.

 

Since you describe high temps AND = pressure, I=20 suspect you have temperature=20 problem.

 

I deliberately overheated my engine = many times=20 so that I was intimate with pressure and temperature patterns. = Then tested various concepts. Don't recommend you do the=20 same.

 

-al = wick

 

 

On Tue, 2 Oct 2007 12:38:55 -0400 = "Bill=20 Bradburry" <bbradburry@bellsouth.net>= =20 writes:

I just = recently got my=20 Renesis started again after finishing my cowl.  I seem = to be=20 getting very high coolant pressures.  I can only run = the engine=20 about 10-15 minutes before hitting the redline at = 210*.  My=20 water pressure is at 27 Lbs at that time.  I only have = a 22 Lb=20 radiator cap, so I assume that I am blowing into the = recovery tank,=20 but I have not confirmed that.  My oil temp has never = exceeded=20 about 165*.  It might have gone higher if I could have = run=20 longer???

 

This whole = water=20 pressure thing has me a little baffled.  Since this is = a closed=20 system and the only way pressure can build is due to the = expansion=20 of the coolant after heating???, I am confused by some = comments that=20 have been made from time to time.  I remember something = that=20 Tracy said about his = pressure would=20 build for a time, then go to zero.  It seems to me that = the=20 pressure should correlate to the temp pretty closely since = it is a=20 closed system??

 

Can someone = enlighten me=20 a little on the science of this pressure?  It seems to = me that=20 there could be some pressure build up on the positive side = of the=20 pump, but it would go negative on the suction side, so the = net=20 effect of the pump should be close to=20 zero??

 

Also, my = Renesis had=20 only 1800 miles on it when I bought it, so I did not have to = tear it=20 down.  As a result, I am somewhat in the dark as to how = the=20 water flows through the system.  Could someone help me = with=20 that?  I had to remove the thermostat tower for height=20 clearance , so I made an adapter plate that takes water from = the top=20 outlet of the pump and sends it to the radiator (double = pass), then=20 from the radiator, it returns to the lower inlet of the=20 pump.

 

Thanks,

Bill=20 B

 


-al wick
Cozy IV powered by = Turbo=20 Subaru 3.0R with variable valve lift and cam timing. =
Artificial=20 intelligence in cockpit, N9032U 240+ hours from Portland, = Oregon
Glass panel = design, Subaru=20 install, Prop construct, Risk assessment=20 = info:
http://www.maddyhome.com/canardpages/pages/alwick/index.html

-Al Wick
Cozy IV powered by Turbo = Subaru 3.0R=20 with variable valve lift and cam timing.
Artificial = intelligence in=20 cockpit, N9032U 240+ hours from Portland, Oregon
Glass panel = design, Subaru=20 install, Prop construct, Risk assessment info:
htt= p://www.maddyhome.com/canardpages/pages/alwick/index.html<= /SPAN>

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