The Rodding Roundtable
Motorhead Message Central => Rodder's Roundtable => Topic started by: 48builder on October 26, 2004, 12:59:39 PM
I'm making so much progress, that I'm thinking about firing this thing up soon. Before I do, I need to get a radiator in it. Since I have a subframe, I'm not really limited to the stock size. I can go up to about 26" wide and similar height.
I have found a few that may work, including late-model DodgeVan and Durango.
Should I limit my search to copper or aluminum? I don't really care. I guess aluminum transfers heat better, and saves a little weight. The Durango is aluminum, while the van is copper. Both are 2-row, and about the same size. The Durango is more expensive, but still a heck of a lot cheaper than the Walker I have in my '39.
I welcome all comments and other ideas.
Copper actually transfers heat better, the reason all the late models have gone to aluminum, weight, they are much lighter.
I have used the Dodge Van radiators on several cars, seem to have no trouble cooling.
Hi, Walt!
I would choose the copper radiator over the aluminum version.
IMHO, the copper will outlast the aluminum, especially on a vehicle that may not see alot of use.
The aluminum radiators seem to be more prone to corrosion.
...my $.02
I have to take exception to the latter posts with all due respect. While there is nothing wrong with copper/brass/solder radiators, aluminum radiators are constructed from much larger tube sections meaning that they increase flow, have higher BTU transfer and are far more efficient than copper/brass/solder. Almost 50% comparing area to area. Most 1" dual tubed aluminum radiators will easily out cool a 5 row c/b/s conventional styles.
The reason most OEM manufacturers use them is that they are more efficient, which means they can use a smaller area profile, which follows lower hoodline designs. Yes, weight is an issue too, but mainly they are selected for their efficiency. Also, contrary to popular opinion, they are far more rigid, LESS prone to leaking and will take far more pressure than conventional styles due to thicker walls and welded construction.
While copper conducts heat better, the overall surface conduction of the larger aluminum tubes far outstrip the coppers shear performance. Also, solder is a terrible conductor of heat and copper radiators are floppy compared to aluminum ones.
There are some generic aluminum radiators around from Summit that are very good and cheap. Also, check out www.streetrodstuff.com/Products/157 for the custom made jobbies!
Stay away however from multi-pass radiator designs. These require much more pressure to move the flow.
QuoteStay away however from multi-pass radiator designs. These require much more pressure to move the flow.
I had the stock radiator re-cored in the 41 with a multi pass core.
It'll idle around the fairgrounds all day long in 95 degree heat, and barely hit 190.
It has a 7# cap on it.
Quote from: "moondisc"QuoteStay away however from multi-pass radiator designs. These require much more pressure to move the flow.
I had the stock radiator re-cored in the 41 with a multi pass core.
It'll idle around the fairgrounds all day long in 95 degree heat, and barely hit 190.
It has a 7# cap on it.
I believe ya! Nothing necessarily wrong with multi-passes, but the most efficient design for street applications and especially slow cruising and variable RPMs would be large-tubed, all aluminum, single-core designed cores. This is because double pass radiators require 8x more pressure to flow the same volume of coolant through them as compared to a single pass radiator....and triple pass radiators require 12x more pressure to maintain the same volume. Since automotive water pumps are a centrifugal design and not positive displacement in a double pass radiator the pressure is doubled and flow is reduced by approximately 33%. OEM or modern radiator designs, using wide cross sections tubes, seldom benefit from multiple pass configurations due to the decrease in flow caused by multiple passe design. With decrease in flow so goes the reduction in turbulence as well. These could easily offset any benefits of a high-flow water pump you may have added.
Simply put, the single-pass designs are superior for street use. This does not mean that the multi-pass will not suffice in certain applications. I threw the warning in my previous post because alot of the "universal" and/or "racing" radiators are multi-pass designs.
On the other hand, applications where the RPMs of the motor/water pump are constant and high (such as racing and certain hauling situations), multi-passes are as good or better in some cases depending on use.
Well Steve, you're the engine-er and I can't even spell it, but it seems to me the longer the coolant stays in the radiator the more heat it's going to transfer.
Take the thermostats out of a flathead, it flows more volume. And overheats.
BTW my 41 has a 7 blade Volare steel fan, no shroud, and a stock 350 Olds.
My bud has the same combo in his Olds with with a shroud and the biggest alium rad he could get in it, and it overheats after about 10 min at an idle.
Like I said, I ain't no engine-er, but I know what works! :lol:
Ok, when you talk about multi-pass aluminum radiators are you talking about the style that Griffin makes? I'm running a stock radiator w/o shroud on my woodie and am in the process of replacing it with aftermarket, want to get all of the input possible before $$$ walker vs. griffin vs. US Radiator etc. I will definitly be using a cooling components electric fan and shroud combo.
I had a US Radiator in my 37, and I wasn't at all happy with it.
It sprung leaks around the filler neck, top hose connection and top tank.
Quote from: "moondisc"I had a US Radiator in my 37, and I wasn't at all happy with it.
It sprung leaks around the filler neck, top hose connection and top tank.
What did you replace it with? or did you repair it? MH
QuoteWhat did you replace it with? or did you repair it? MH
I just kept fixing it. Over and over again.
Sold the car after that.
Check the link Steve posted above for PRC radiators.
Everyone that's used them said they're great, and their prices look good too.
Quote from: "moondisc"... it seems to me the longer the coolant stays in the radiator the more heat it's going to transfer.
------------------------------
I've heard this said many times over the years, but I have to ask, "What happens to the coolant in the engine while it is staying in the radiator longer?"
It seems to me the longer the coolant stays in the radiator, the coolant in the engine is getting hotter than if it were flowing faster.
Thinking about it another way, if the coolant picks up 30 degrees in the engine, the radiator only has to "lose" 30 degrees to the ambient air. .....If the coolant gains 80 degrees in the engine, the radiator must now be capable of losing 80 degrees to the ambient air.
Many OEM GM set-ups overdrive the water pump by as much as 28% of engine rpm to speed up the waterpump. ....If lower flow rates were the answer, I doubt the factory would do that.
I realize there are other factors which affect heat transfer, and this may be an over-simplification of the conditions. ...We may also be "splitting hairs," with little difference in results.
What IS important, is having a radiator capable of losing the heat produced in the engine. ...If the engine produces more heat than the radiator is capable of losing to the ambient air, then overheating WILL result.
As has been discussed many times, ignition timing, fuel mixtures, and airflow through the radiator have a great influence on operating temps, ...probably as much as (or more than) radiator type or material.
Also, size does matter! :lol:
What do I do. So HOTRODSRJ, by single tube do you mean 1 row? I ask beacuse one fo the radiators I am considering is from a 2000 Durango with V8, and it says it has 2 rows. Would I be better off with a 1998 version with 1 row? Both of them have larger surface area than the one from my '95 Z28 donor car.
And speaking of my Z28, the LT1 motor has an electric water pump, so I am assuming I would want to stick with an aluminum radiator because it may not be able to produce enough pressure for a copper unit?
Don't confuse "rows" or "tubes" with "passes". Large tubed, dual row aluminum radiators are the conventional and most efficient design.
Also, most of the Griffins that I have seen are single-pass design. I don't think they make multi-passes. So, Griffin has one of the best designs on the market, albeit expensive.
Also, on another front .....I have fought this "myth" for years in many differing forums. Simply put, the more flow the higher the efficiency of the cooling system. This is why high flow water pumps where invented and "overdrive" pulley systems.
Also, the explanation of the coolant sitting in the radiator while slowing the flow is exactly right on. The coolant in the engine is sitting trying to absorb heat as well. This is a closed-loop system. And as the coolant rises towards its corrected vapor point (boiling point at pressure XX) it loses it's ability to absorb heat. So, for example, it takes more volume of 185 degree water to remove the exacting same amount of BTUs than 165 degree water.
One of the most interesting "layman's" explanation of how "flow" effects cooling came from a Doctor that I designed a cooling system for his muscle car. When he inquired about the "science of flow" thing I gave the thermodynamics explanation of what happens. He says, "I should have know this....this is the very same way the human cooling system works?" Going on he states, "When the body needs to be cooled the lungs and skin both act like a radiator exchanging heat to air. The blood vessels open up to increase the flow and moreover the heart is like the water pump in that it will increase to move the blood (which is the coolant) at higher flow rates. The increase in flow is what turns up the efficiency of the system to cool as fast as you can. Your breathing frequency increases as well to also increase heat exchange at the lungs. Conversely, when you are in a cold atmosphere and the body is trying to keep warm it shuts down the blood flow by lowering heart rate and dialating blood vessels (which also lowers flow) and slows breathing." So, that's one of the best analogies that I have heard.
The other issue is increasing flow increases turbulence. But this is not always the case. I have heard about the flatheads and taking the thermostats out purportedly increasing the flow and having overheating problems. What happens is that the cause and effect and therefore the deduction is faulty. What happens is that by taking the thermostats out the flow stream becomes extremely laminar and non-mixing. The lack of the usual turbulence caused by the exit of the thermostat makes the efficiency of the system lower. Simply putting large hole reducers in place of the thermostat reintroduces turbulence and should cool better.
Ron Davis in Glendale, AZ makes a nice radiator. I'm very pleased with the construction of mine. Price was decent, too.
So it's the lack of turbulence, and not the fact that the coolant isn't staying in the radiator long enough to transfer the heat?
Quote from: "moondisc"So it's the lack of turbulence, and not the fact that the coolant isn't staying in the radiator long enough to transfer the heat?
Yep.....slower the flow the lower the BTU transfer both in the radiator and block.
Have you ever went swimming in a large river where the top of the river when you dove in was nice and warm, yet only a few feet down it was cold as ice! This is a perfect example of laminar flow. The whole volume of water is not being used to transport heat. Same thing happens in the radiaotor. The outer part of the column of water is heated and cooled yet the center is relatively left unaffected. Once you "turn" the water then the whole column gets involved in the process of heat transfer.
I learn something new every day.
And my wife said I'm too old to learn! :lol:
Quote from: "moondisc"I learn something new every day.
.......... I do, too. And that's good because I forget something old each day! :roll:
Quote from: "moondisc"And my wife said I'm too old to learn! :lol:
.....No, Charlie. -- She only said you're too * old! :lol:
So it appears my first choice should be the 2000 Durango aluminum radiator with 2 rows. I will give it a try and seee what happens.
Thanks for all the input.
Hey Charlie, when we et a weelend with bad weather, I'll run that manifold out.
About a month ago a similar topic ran on this board. The widely held notion "the higher the water flow, the better the heat transfer" was promoted.
I related the experience of the racing Coopers which were notorious for overheating, and attempts to cure this by removing the thermostat to increase flow rate only made the situation worse. The factory produced a restrictor plate to install in the thermostat housing and this item improved cooling efficiency enormously.
Another contributor wrote "I have heard this exact story and was a common phenom in circle track cars/engines as well. The replacement of the "restrictor" actually made the system cooler than having no thermostat. While the effect was known, the cause was not"
The explanation offered was that the reduced water flow rate by itself would worsen the condition, but the benefit of turbulence caused by the orifice more than compensated for the lower flow rate.
The next time I looked the thread had died, however now this topic is under discussion again I shall continue.
When the effectiveness of these restrictors became evident there were numerous theories of how they functioned. One popular explanation did relate to the effect of turbulence, my conclusion at the time was without a thermostat water might stream out from the head passages allowing air or steam to accumulate and reduce the heat transfer from metal to water, while a restrictor plate would keep the passages full and more than make up for the reduced flow.
In an act of desperation an overheating vehicle without a thermostat had a clamp put on the radiator hose to squeeze it down, -with exactly the same results. This was done to the lower hose due to the short length of the top hose. So it reduced the flow but did nothing to keep the head passages full, and did nothing to add turbulence to water entering the radiator, completely dispelling both theories.
Further, if turbulence and high flow had both been advantageous, a better solution than the restrictor plate would have been to leave out the thermostat and slide a thin walled tube with an array of knobby fingers on the inside wall into the top radiator spigot. This would generate turbulence as the water entered the top tank while retaining the highest possible flow rate.
The restrictor plate was not something cobbled up by a home mechanic but an official part produced by a manufacturer with a factory team which at the time was winning high profile events like the Monte Carlo back to back. However races held in warmer regions were another issue altogether where they were plagued with overheating. If the solution lay purely in increasing turbulance I find it difficult to believe that over all the years these vehicles raced, factory engineers with access to a huge research budget were incapable of producing something like the item described above which I conjured up in a period of about one minute.
So, under some circumstances reducing water flow is advantageous, even though it has been demonstrated over and over again the vast majority of overheating problems -particularly at idle are improved by increasing flow.
My belief -and obviously it is only a personal opinion is, the process of transferring heat energy from engine to water then water to air has a parallel to the transfer of energy in an electrical system.
It is widely believed that to increase the power drawn by an electrical load the load resistance should be made smaller allowing more current to flow. Pep, Choco and others will remember from their student days maximum electrical energy transfer occurs when the load impedance equals the source impedance. This means the belief that lowering load resistance increases power consumption only holds true in situations where the source resistance is zero, or very much lower than the load.
With a cooling system the situation is similar except energy direction flow is reversed. We are trying to shed energy and the proposition a high flow rate always results in high transfer rates assumes a zero impedance sink which is not correct. If the water flow rate is increased and consequently the exit temperature from the engine is lowered, then there is a smaller water/air temperature gradient resulting in reduced heat transfer to the air.
My hypotheses, and I state again I have absolutely no scientific proof to support this is that for each engine and radiator combination there is an optimum flow rate which provides maximum heat transfer, and this is may well be related to equalising the temperature delta across each interface.
For the majority of vehicles, particularly at idle when the pump rotation speed is low the flow rate is well below optimum and increasing the flow rate enhances the heat transfer and in turn improves cooling.
At the other extreme where an engine is working close to maximum power shedding huge amounts waste of heat energy and the water pump is running at about ten times idle speed without a thermostat, reducing the flow rate can bring it back closer to optimum.
So there you have it, make of it what you will, all comments welcomed.
Quote from: "PeterR"About a month ago a similar topic ran on this board. The widely held notion "the higher the water flow, the better the heat transfer" was promoted.
I related the experience of the racing Coopers which were notorious for overheating, and attempts to cure this by removing the thermostat to increase flow rate only made the situation worse. The factory produced a restrictor plate to install in the thermostat housing and this item improved cooling efficiency enormously.
Another contributor wrote "I have heard this exact story and was a common phenom in circle track cars/engines as well. The replacement of the "restrictor" actually made the system cooler than having no thermostat. While the effect was known, the cause was not"
Hey Peter.......I think I contributed to the fray and made the comments that you are referring to. I would like to add more for what I think is going on respectfully.
First, and I like to say this alot.....racing does not translate to street very well, if at all! Simply too much other things going on with completely a differing application and use. Higher rpms, differently designed cooling systems etc. For example, racing motors turn higher rpms for longer periods of time. Just think of that GT40 sceaming down the track at Lemans at top RPMS and what that means to the cooling system? Simply put, racing is just different. It's like comparing oranges and apples. Take my word for it....I know them both.
Also, being an electrical engineer, I can't exactly equated that electricity and fluids do behave anywhere near the same so to speak. Each has it's own indigneous physics that you have to understand.
Now having said that.....I will tell you that no experience that I have had in my professional career of designing high efficiency cooling systems and high efficiency industrial heat exchangers, automotive cooling systems or any text book in my thermodynamics library does reducing the flow (by practicality or theory for that matter) mean better cooling for any reason. If you reduce the flow and your application "cools better" then something else is going on. This is why I made the "cause and effect" statement.......often the wrong conclusions are made.
I analysed your story and it makes perfect sense to me knowing alot about both street and racing cooling systems. But I don't agree with your conclusions necessarily. Your description of how you reduced the flow (and you really don't know what you did sense you probably did not have conclusive monitoring) and this helped in the cooling can be not only related to turbulence but also affecting the pumps efficiency. While I don't know the exacting design of the pump and so forth, I can easily build a case for the pump's design/cavitation issues being reduced or affected by this "damning" effect. This happens all the time in racing. Impellers flying around at warp like speeds are really an anomolous subjects. You don't know how you may affect the output by tweaking the input unless you literally are doing comprehensive fluid dynamics studies. Also, internal flows can get effected by high flowing situations. When the Chevrolet IRL engines first came together they too had a cooling issue that could not be readily addressed. They too found that reducing the flow made for a "better sitution" and did some head scratching. They really wanted the engine to run even cooler but when they turned the wick up it got worse???? They found out evenually that the internal castings of the block and heads (left over from Aurora days) were designed with internal "channels" if you will that had too many and too sharp of a bend in them. These sharp and restrictive bends where setting up eddy currents and cavitation issues that introduced air into the stream making for a less efficient system. After recasting the modifications needed the engines where able to flow about 40% more coolant and all was happy. So, my point is that internals or the whole system design can determine and cause side effects that are completely unknown to the "outside" observer. As long as you stay within the boundaries then adding flow will always enhance cooling.
QuoteSo, under some circumstances reducing water flow is advantageous, even though it has been demonstrated over and over again the vast majority of overheating problems -particularly at idle are improved by increasing flow.
My hypotheses, and I state again I have absolutely no scientific proof to support this is that for each engine and radiator combination there is an optimum flow rate which provides maximum heat transfer, and this is may well be related to equalising the temperature delta across each interface.
This has some truth to it because the overall system "design and capability" is what is in play.
QuoteFor the majority of vehicles, particularly at idle when the pump rotation speed is low the flow rate is well below optimum and increasing the flow rate enhances the heat transfer and in turn improves cooling.
This is true for different reasons even tho flow is not the problem. One has to stay within the boundaries of the system design or you can create all kinds of anomolies.......resulting in effects that are unknow. My point here.
So, for the most part in street cooling applications (and this is why hi flowing pumps were invented) adding flow is a key to cooling better.
Does this make sense??
Thank you, Peter and Steve, for your prticipation in this thread and the previous thread to which Peter referred.
I always learn from your posts, and you both challenge my brain cells by stimulating thought. ...I encourage your continued participation here, if for no other reason than, to increase my knowledge. ....Selfish, but true!
I do not have the formal education which you gentlemen have had, so I obviously defer to most of your statements. .... I tend to look at other examples from the past, and see if the same principles apply to the present concern.
Quote from: "PeterR"About a month ago a similar topic ran on this board. The widely held notion "the higher the water flow, the better the heat transfer" was promoted.
The next time I looked the thread had died...
----Much to my disappointment, as well. I was hoping to get answers to my questions in that thread.
Quote from: "PeterR"...In an act of desperation an overheating vehicle without a thermostat had a clamp put on the radiator hose to squeeze it down, -with exactly the same results. This was done to the lower hose due to the short length of the top hose. So it reduced the flow but did nothing to keep the head passages full, and did nothing to add turbulence to water entering the radiator, completely dispelling both theories.
----While the hose clamp was effective, it MAY have kept the head passages full, and perhaps, did NOT reduce the flow.
The flow characteristics of centrifugal pumps are greatly affected by throttling the suction side of the pump. ....Sometimes flow is improved, in other cases flow is diminished. ....It is possible, you created a "venturi" effect in the suction line, which actually aided pump performance.
Off the top of my head, I can not give you the technical jargon or the explanations to back up this statement, but I can get them if necessary. ...My best friend has been working as an engineer, doing flow testing and plotting pump curves on centrifugal pumps for the last 30 years. ....We have discussed waterpump design and flows many times in the past, but he "loses" me about about half-way into the discussions.
Quote from: "PeterR"So, under some circumstances reducing water flow is advantageous, even though it has been demonstrated over and over again the vast majority of overheating problems -particularly at idle are improved by increasing flow.
----I do not yet see any advantage to reducing water flow.
Perhaps my thinking is flawed here, but I equate the automotive cooling system to a hydronic closed-loop heating system in a house.
...If the flow-rate between the boiler and the radiators is low, a small amount of heat is released to the room. Increasing the flow-rate will increase the amount of btu's transferred by the "heat-sink," even though the water returning to the boiler may be warmer than before. ...The higher flow rate will equalize the temps in the boiler and heat-sink more quickly.
Raising the water temp at the boiler will increase the amount of heat given off from the heat sink.
Quote from: "PeterR"If the water flow rate is increased and consequently the exit temperature from the engine is lowered, then there is a smaller water/air temperature gradient resulting in reduced heat transfer to the air.
---Accepted and agreed.
Quote from: "PeterR"My hypotheses, and I state again I have absolutely no scientific proof to support this is that for each engine and radiator combination there is an optimum flow rate which provides maximum heat transfer, and this is may well be related to equalising the temperature delta across each interface.
---No argument from me, but that optimum flow rate will vary with ambient air temp, airflow thru the raditor, and coolant temps generated in the engine. ....Designing for steady-state conditions is relatively easy, so designing for worst-case conditions seems prudent.
Quote from: "PeterR"For the majority of vehicles, particularly at idle when the pump rotation speed is low the flow rate is well below optimum and increasing the flow rate enhances the heat transfer and in turn improves cooling.
---We must also consider that on engines with mechanical fans, increasing the pump speed also increases the fan speed, pulling more air thru the radiator. Thus, any additional cooling at idle may be partially attributed to this.
Quote from: "PeterR"At the other extreme where an engine is working close to maximum power shedding huge amounts waste of heat energy and the water pump is running at about ten times idle speed without a thermostat, reducing the flow rate can bring it back closer to optimum.
----Too high a pump rpm will induce cavitation or disturbance of flow in a centrifugal pump.
Let's face it, most of the automotive waterpumps use crude, unshrouded, impellers with massive clearances between the impellers and housings. ...High-performance aka high-efficiency, aka high-flow, pumps improve their performance by changing these factors, and do not rely on just changing pump speed or impeller diameter. ...Impeller/housing design is a field of its own.
OUCH! --- All this thinking is making my head hurt!
QuoteFirst, and I like to say this alot.....racing does not translate to street very well, if at all! Simply too much other things going on with completely a differing application and use. Higher rpms, differently designed cooling systems etc. For example, racing motors turn higher rpms for longer periods of time. Just think of that GT40 sceaming down the track at Lemans at top RPMS and what that means to the cooling system? Simply put, racing is just different. It's like comparing oranges and apples. Take my word for it....I know them both.
Agree absolutely, now that I see you are confining the discussion to typical street applications.
Still not convinced however increasing flow is beneficial in every case, though I am relying on my memory of forty years ago.
Leaving engines to one side for a moment. Consider two heat exchangers in series running a common liquid transfer medium.
If the first exchanger has a capacity very much greater than the second, then at maximum throughput there will be a larger temperature gradient across the second element than the first. Conversely if the second exchanger has a larger capacity most of the total temperature differential will appear across the first.
This means for any combination there will be an optimum liquid temperature at which the entire system has maximum heat throughput, and where this lies will depend on the relative capacities of the first and second element. The fluid temperature for maximum heat transfer is not related to the optimum operating temperature.
If increasing fluid rate increased the system capacity it would be possible keep pushing ever larger amounts of heat into the system and watch it come out the other end by doing no more than running the transfer pump faster and clearly this is not so.
In a poorly designed system or if used in a situation the designer never intended, the fluid temperature corresponding to maximum heat transfer may exceed the desired operating temperature of the equipment involved. I suspect that was the situation with the Coopers, as exactly the same engine with the same pump at the same revs did not require the restrictor when used as an inline engine.
Something else that intrigues me is the use of large tube radiators. Without doing any calculations I had imagined that the Reynolds number may have fallen below the magic 2000 level.
QuoteAlso, being an electrical engineer, I can't exactly equated that electricity and fluids do behave anywhere near the same so to speak. Each has it's own indigneous physics that you have to understand.
It is interesting you say that, at the university where I studied engineering my Elec and Fluid Mechanics lecturers frequently discussed eachothers topics as though they were one, and it always amazed me.
You also mentioned thermodynamics which I have to say was the least enjoyable subject I have ever taken. Plotting those Mollier diagrams was so tedious I can still remember it forty years later.
Quote from: "PeterR"QuoteAgree absolutely, now that I see you are confining the discussion to typical street applications.
Still not convinced however increasing flow is beneficial in every case, though I am relying on my memory of forty years ago.
That's what we are addressing here......not racing or high pressure industrial heat exchangers as well. That's why I make the statement that flow is KING in these specific applications! Everything else outside the street application is moot for most if not all the watching eyes. Designs outside this realm vary too much making for anomolies that need a whole semester to muster.
Steve,
A company here is making an electric pump that fits into the lower hose. It has a PWM speed controller taking a signal from the temp guage so the pump speed is independent of engine revs. Have you seen these or had a chance to evaluate them.
The manufacturer claims there is considerable OEM interest.
Quote from: "PeterR"Steve,
A company here is making an electric pump that fits into the lower hose. It has a PWM speed controller taking a signal from the temp guage so the pump speed is independent of engine revs. Have you seen these or had a chance to evaluate them.
The manufacturer claims there is considerable OEM interest.
Peter.......actually this is NOT a new idea. YOu can go to www.stewartcomponents.com and see their "booster" pump. They often have great demostrations at various shows to show the diffence....and WOW......it really boosts performance of the system. This is great for blower motors or high hp motors needing flow. But, you have to add a large fan to augment the demand for more heat exchange at the radiator too. The two upgrades is awesome.
The unit this company makes is intended to completely replace the original mechanical pump
http://www.daviescraig.com.au/main/display.asp?pid=8
Quote from: "PeterR"The unit this company makes is intended to completely replace the original mechanical pump
http://www.daviescraig.com.au/main/display.asp?pid=8
Peter........wow....I am glad you posted this. I can't believe that this pump is allocated to doing duty all by itself? The reason is that the output of this is very low... a pultry 1300 gph/80Lpm or 21gpm max! This is NOT enough flow for squat! Also, they imply that you are going to save a heap of HP doing such when in fact most high efficiency water pumps only take two to three hp at full tilt also viewable at the link below! It used to be that old timey water pumps could take as much as 10hp at full tilt.
Check this link out at http://www.stewartcomponents.com/tech_tips/Tech_Tips_7.htm and look at the flow rates and hp analysis. These guys are very good if not the best in the business for street, high performance and racing cooling issues.
FWIW, even high quality electric pumps having flow rates less than 55 gpm are susceptible to being over taxed under certain driving circumstances. I have run into several guys going to Pigeon Forge for various car shows in the mountains of Georgia, North Carolina and Tenn that have pulled over due to overheating going up long moderate grades. This was primarily due to their use of electric water pumps of volumes of less than 50gpm. For example my 57 with the big 440hp+ 383 with the air on during summer conditions will flow over 70gpm at 2400 rpm engine speed. The flow rates are pretty far apart. I am using the TuffStuff series pumps which mirror the Stewarts Stage I....only chrome!
So, thus my contention that electric pumps are not yet ready for the sole cooling duty on street applications. My understanding is that some OEM suppliers are working on a 75gpm model. Now that is a pump that I will endorse if it's reliable? Would meet or exceed all the conditions of street application......even moderate towing applications....which really produces high heat issues in the cooling systems.
A brief article on this pump appeared in a trade magazine some time ago where there was mention of OEM interest, but until last night I had never been to their web site nor seen any specs.
The unit is much smaller than I had expected and the modest output caught me by surprise too. However there are very few vehicles here with engines larger than 250cu in, the most common being around 120~150 so I assumed it was intended for motors of this size where it probably would have been OK. But as soon as I saw "trucks, buses and boats" they lost me.
Also, I am always suspicious of any claims that an electric motor powered by a belt driven alternator is somehow more efficient than a straight belt drive.
I asked this question (and several others) on two posts which were lost the other day, when the RRT went down. ....I don't know if anyone read them or replied to them.
While the high-flow pumps are rated in excess of 100 gpm, what flow rates are THERMOSTATS capable of supporting?
It seems to me that the thermostat is the "bottleneck" in the cooling circuit, negating the high-volume output of the pump.
Are there flow rates advertised for any thermostats?
Steve, is that flow rate on your Chevy the rated pump output, or is that an actual measurement of flow through your system?
Thanks for all responses!
Quote from: "Bruce Dorsi"I asked this question (and several others) on two posts which were lost the other day, when the RRT went down. ....I don't know if anyone read them or replied to them.
While the high-flow pumps are rated in excess of 100 gpm, what flow rates are THERMOSTATS capable of supporting?
It seems to me that the thermostat is the "bottleneck" in the cooling circuit, negating the high-volume output of the pump.
Are there flow rates advertised for any thermostats?
Steve, is that flow rate on your Chevy the rated pump output, or is that an actual measurement of flow through your system?
Thanks for all responses!
Hey Bruce.......first the numbers from my pumps are measured as tested at a given pressure X. But this is relative. If you have a stock at the same pressure X, because of the inefficiency of stock pumps, the high efficiency pumps will not "fade" due to the design issues.
Also, actually there are many other "bottlenecks" in the coolant jacket that are very restrictive and it's up to the ability of the water pump to "force" flow thru the restrictive manifolds. The thermostat and upper hose are NOT the problem. In fact, you can have rear cylinders run hotter than the cylinders in front of them due to the pressure and volume division due to restriction. The good analogy is the simple "garden" sprinkler/soaker hose. The further away from the source the weaker the stream and so goes the very same thing in the block .....and therefore rear cylinders are less flow!
Look at these typical numbers from a cup engine and would be about the same for a street block as well.
Following is a typical Winston Cup engine at 100 GPM:
Lower radiator hose = 1.5 PSI
Block and cylinder head - each (at 50 GPM) = 8.5
Outlet manifolding = 1.25
Top radiator hose = 2.25
Radiator = 1.5
Total = 15.00 PSI
You can easily see that the block and cylinder heads drop the most pressure whereas this means that the resistance is the most. The thermostat and outlet cavity drops only 1.5 at the outlet and 2.25 at the top radiator hose. While I don't know what the actual numbers are for a standard or stock thermostat, I do know that the higher flowing thermostats are BETTER for three reasons. One is that they support the higher flow rates within the design of the application(s) (ie, very high flowing (in excess of 100 gpm) applications) and two, is that IF they fail ...they fail OPEN...not shut which is in and of itself reason enough to use them and lastly they are very accurate!
And.....you would NOT be negating any high flowing pump whereas the higher flowing/volume pumps would create more flow ....only at higher pressures as compared to their lesser brethern.
Let me tell you...and I have tested these beasts......the stock bodied and impellered water pumps are junk compared to today's aftermarket high volume/flowing pumps. The intake and output cavities are "flow designed" and impellers are super tight tolerances compared to stock, which both breed less cavitation, eddy currents, by-passing, and suction issues. What this all means is more efficient flow and less hp to do it. As seen in above links the typical high efficiency water pump only takes about one hp plus at moderate engine speeds.
While I am sure that there are flow rates at certain pressures for some of these thermostats, it's really moot because they are designed to work inside certain parameters of the application. But, high flowing thermostats definitely flow alot more!
FWIW,..... IMO alot of "hotrodders or builders or whatever" never fully analyze their "cooling" situation for the use or upgrade to high flow/volume pumps, not withstanding the issues aforementioned. Yes, I know they cost more than rebuilt (which I never suggest) or stock or even OEM ....but are worth the muster frankly. I get about a dozen emails a week asking for cooling issues that are easily remedied by either higher flowing pumps and/or higher efficiency radiators. It's usually flow related.
For example, if you put aluminum heads (aftermarket, stock or factory) it is likely that the cooling manifold (internal casting) of the aluminum heads are in fact SMALLER to offset the propensity of aluminum to "heatsink" the combustion chambers. This is very common design practice and the need for upgrading the waterpump is a must to offset the increase in pressure drops! Also, the increase of hp of an engine due to whatever improvement(s) also creates more waste heat needing higher flow rates to compensate. This needs an upgrade. If you add more connnections to the coolant stream or use smaller hoses or lengthen the coolant path, this also affects pressure drops and warrants upgrades as well. If you run your engine at higher RPMs (even tho your pump supplies more flow), stock and/or older pumps simply will drop the efficiency down and/or cavitate more causing all kinds of issues. These are all good issues to consider a high quality aftermarket water pumps.
Also, if you DO upgrade your pump.....you will need an upgrade in cap too. Commonly these high flowing/volume pumps will create more pressure in the system which means a higher cap is needed......especially on downflow radiators where the combination of working pump pressure at high rpms will surpass the caps ability to hold pressure. I recommend at least a 14lb cap!
I know........too much information so I will get off my soapbox!
I never realized it took more pumping power to circulate the water in a multipass radiator. You never know what you can learn by reading thru the posts. Thanks :D
Me again, the proverbial thorn-in-the-side, back with more questions!
Steve, I believe that you have said that a thermostat or restrictor provides necessary turbulence to promote cooling.
So, my questions are as follows:
(1) Is the location of the restrictor/thermostat important?
....Would it not be more beneficial if it were located at the inlet of the radiator?
(2) If the thermostat/restrictor creates turbulent flow, doesn't the flow pattern change back to laminar flow in the radiator hose?
(3) What happens to the flow pattern as the coolant enters the (larger) volume of the radiator tank?
(4) Does coolant flow become turbulent when it is forced to divide into the many small openings of the radiator tubes?
(5) Isn't the flow inside the radiator tubes primarily laminar flow? ....Especially so with wide tubes??
Yeah, I know, lots of questions, but I'm here to learn!