Cooling System Questions
- Thread starter Kalun
- Start date
WOW!
I knew I should have kept at my engineering degree instead of switching to geography... /ubbthreads/images/graemlins/blush.gif
I guess in the end though I am still an Air Force pilot with a 4 year degree that I use on occasion /ubbthreads/images/graemlins/wink.gif
So Adam, from what I am interpreting from your awesome engineering of the example system is this:
Increasing the size of the transfer pipe to as large of a size as possible is GOOD (weight increase aside)
If that is not possible, then look at increasing the size of the radiator surface area (if possible) GOOD
However, overall, in a system that is lets say maintaining an overall pressure (at the radiator cap) of 16psi...the water pump should be able to at least generate a pressure of somewhere between 23-26psi in order to keep proper cooling and flow.
Am I thinking right? And if so, what can most "standard" waterpumps produce as a PSI at idle? (or is this really an issue?)
I knew I should have kept at my engineering degree instead of switching to geography... /ubbthreads/images/graemlins/blush.gif
I guess in the end though I am still an Air Force pilot with a 4 year degree that I use on occasion /ubbthreads/images/graemlins/wink.gif
So Adam, from what I am interpreting from your awesome engineering of the example system is this:
Increasing the size of the transfer pipe to as large of a size as possible is GOOD (weight increase aside)
If that is not possible, then look at increasing the size of the radiator surface area (if possible) GOOD
However, overall, in a system that is lets say maintaining an overall pressure (at the radiator cap) of 16psi...the water pump should be able to at least generate a pressure of somewhere between 23-26psi in order to keep proper cooling and flow.
Am I thinking right? And if so, what can most "standard" waterpumps produce as a PSI at idle? (or is this really an issue?)
Chris Duncan
Supporter
awesome Adam,
So your end result figures are
1.5 tubes 3.64 PSI drop
1.75 tubes 1.75 PSI drop
radiator 5.8 PSI drop
1.5 tubes and rad total 9.44 PSI drop
all at 4,000 RPM and 80 GPM (I'm assuming that the typed entry before the calcs, that says GPH, is a mistake because in your scanned calcs you use GPM.
Percentage wise your figure is 5.8/3.64 = 1.6 times more drop in the rad compared to both 1.5 tubes.
IF (dohh) I had added the 1.5 return line my figures would have been
1.77/1016 = .00175
.00175/.00095 = 1.84 times more drop in the rad compared to both 1.5 tubes.
So I got close even though it was probably luck and all I ended up with was a percentage comparison, not hard numbers like your PSI.
Now if we could convert PSI to HP loss. I tried with the Glover pocket ref. , no luck even doing double conversions.
AND Steve graciously contributed some more numbers, Thank You.
from the SAE article (downloaded purchase (PDF))
http://www.sae.org/congress/highperformance/agenda/
(I would post a screen shot but don't want to violate copyrights)
2005 Ford GT - Maintaining Your Cool at 200 MPH
(Written Only -- No Oral Presentation)
Curtis M. Hill, Glenn D. Miller, Ford Motor Co.; Michael R. Evans, David M. Pollock, Roush Industries, Inc
(Roush Ind. inc, so Ford didn't go it alone, with a short time frame they subbed out some stuff, sort of like we do on this forum, sharing ideas)
The new GT has an aluminum rad 16 h x 26.5 w with 2 core rows crossflow (no dbl. bypass)
2" return tube, 1.25" engine to rad.
separate Tstat, swirl pot (called a de-gasser)
8.31 gal. total engine coolant (ouch!) that's over 65 #'s!!!!That is counting a heater core/pipes and water cooled oil cooler. And it has a water cooled intercooler for the blower with it's own separate rad and plumbing to the front, which adds another 1.3 gal of coolant.
Anyway here's the PSI numbers for the new GT rad cooling system.
Engine RPM 5846
Water pump RPM 7518 (their overdriving the WP)
Radiator flow (GPM) 70.9 (close to our data by chance, yeeee haaaa!!)
Coolant Pressure Differential (PSI drop)
Radiator 5.4 PSI drop
(we need to calc our rad without the dbl bypass, this is a larger dim rad also)
Engine to Radiator 19.6 PSI drop
(this includes the Tstat and housing, and 1.25 engine to rad tube,
I guess they want velocity to the rad., maybe this helps minimize
heat transfer in the pass compartment also)
Radiator to pump 2.5 PSI drop
(this is just the 2" tube, rad to engine, and it has some
curves, probably why it's a little different from our
figures)
Engine 37.9 PSI drop
++++++++++++
So you can see that the majority of PSI drop is in the engine and Tstat/housing area. Percentage wise the decrease to 1.5 tubing raises total PSI drop minimally. The 2 inch return line is on a car with a higher RPM redline (twin OHC) and a AC condenser and intercooler cooler in front of the radiator.
Well I assumed that the return line would be the smaller than the feed line because that's how it is on FWD imports, but they have the WP after the engine.
Now I need to figure coolant volume and compare tubing costs and weight.
So your end result figures are
1.5 tubes 3.64 PSI drop
1.75 tubes 1.75 PSI drop
radiator 5.8 PSI drop
1.5 tubes and rad total 9.44 PSI drop
all at 4,000 RPM and 80 GPM (I'm assuming that the typed entry before the calcs, that says GPH, is a mistake because in your scanned calcs you use GPM.
Percentage wise your figure is 5.8/3.64 = 1.6 times more drop in the rad compared to both 1.5 tubes.
IF (dohh) I had added the 1.5 return line my figures would have been
1.77/1016 = .00175
.00175/.00095 = 1.84 times more drop in the rad compared to both 1.5 tubes.
So I got close even though it was probably luck and all I ended up with was a percentage comparison, not hard numbers like your PSI.
Now if we could convert PSI to HP loss. I tried with the Glover pocket ref. , no luck even doing double conversions.
AND Steve graciously contributed some more numbers, Thank You.
from the SAE article (downloaded purchase (PDF))
http://www.sae.org/congress/highperformance/agenda/
(I would post a screen shot but don't want to violate copyrights)
2005 Ford GT - Maintaining Your Cool at 200 MPH
(Written Only -- No Oral Presentation)
Curtis M. Hill, Glenn D. Miller, Ford Motor Co.; Michael R. Evans, David M. Pollock, Roush Industries, Inc
(Roush Ind. inc, so Ford didn't go it alone, with a short time frame they subbed out some stuff, sort of like we do on this forum, sharing ideas)
The new GT has an aluminum rad 16 h x 26.5 w with 2 core rows crossflow (no dbl. bypass)
2" return tube, 1.25" engine to rad.
separate Tstat, swirl pot (called a de-gasser)
8.31 gal. total engine coolant (ouch!) that's over 65 #'s!!!!That is counting a heater core/pipes and water cooled oil cooler. And it has a water cooled intercooler for the blower with it's own separate rad and plumbing to the front, which adds another 1.3 gal of coolant.
Anyway here's the PSI numbers for the new GT rad cooling system.
Engine RPM 5846
Water pump RPM 7518 (their overdriving the WP)
Radiator flow (GPM) 70.9 (close to our data by chance, yeeee haaaa!!)
Coolant Pressure Differential (PSI drop)
Radiator 5.4 PSI drop
(we need to calc our rad without the dbl bypass, this is a larger dim rad also)
Engine to Radiator 19.6 PSI drop
(this includes the Tstat and housing, and 1.25 engine to rad tube,
I guess they want velocity to the rad., maybe this helps minimize
heat transfer in the pass compartment also)
Radiator to pump 2.5 PSI drop
(this is just the 2" tube, rad to engine, and it has some
curves, probably why it's a little different from our
figures)
Engine 37.9 PSI drop
++++++++++++
So you can see that the majority of PSI drop is in the engine and Tstat/housing area. Percentage wise the decrease to 1.5 tubing raises total PSI drop minimally. The 2 inch return line is on a car with a higher RPM redline (twin OHC) and a AC condenser and intercooler cooler in front of the radiator.
Well I assumed that the return line would be the smaller than the feed line because that's how it is on FWD imports, but they have the WP after the engine.
Now I need to figure coolant volume and compare tubing costs and weight.
Chris Duncan
Supporter
didn't hit the edit button in time
"all at 4,000 RPM and 80 GPM"
should have read "90 GPM"
"all at 4,000 RPM and 80 GPM"
should have read "90 GPM"
Adam C.
GT40s Sponsor
Well not too bad for some calculations on the back of a bar napkin eh? We got pretty close. Last night it did occur to me that the engine coolant passages represent a significant restriction. We really don't have a good way of estimating it however. I guess I could strap the coolant system, block and all, to my flowbench. /ubbthreads/images/graemlins/grin.gif
I had that SAE paper and didn't even think about looking at it. Kalun, you have the sample calculations, run through it for the cross flow for us. Maybe I'll look into estimating the horsepower loss. It will only be an estimation though.
Wolfman, you are confusing your pressures. The pressure rating of the radiator cap is for the pressure difference between the radiator and ambient (atmosphere). If the pressure difference between the radiator and atmosphere is higher than the rating, then the cap will open to vent pressure. This is to prevent blowing hoses off and splitting radiators. The pressure difference we are talking about is between the inlet and outlet of the pump. This is a completely different quantity.
I had that SAE paper and didn't even think about looking at it. Kalun, you have the sample calculations, run through it for the cross flow for us. Maybe I'll look into estimating the horsepower loss. It will only be an estimation though.
Wolfman, you are confusing your pressures. The pressure rating of the radiator cap is for the pressure difference between the radiator and ambient (atmosphere). If the pressure difference between the radiator and atmosphere is higher than the rating, then the cap will open to vent pressure. This is to prevent blowing hoses off and splitting radiators. The pressure difference we are talking about is between the inlet and outlet of the pump. This is a completely different quantity.
Hi
FWIW, I measured the space available at the front of my KVA, made a drawing showing what I wanted and took it to a local radiator manufacturer. His only comment was that his experience showed that 50mm nozzles and piping would be necessary for a 5 litre engine. My car uses 35mm copper tube (giving an ID of about 1.3 inches). As there are quite a few bends at the front of the car, I was happy to increase to 50mm tubing for this. It has bottom right inlet and top right outlet with an atmospheric manual vent at top right for use when filling/venting. The core is copper and about 50mm thick with two rows of tubes. The water pump is standard Ford.
Basically, I used the biggest I could fit in. There are no overheating problems.
Regards
Dave Tickle
FWIW, I measured the space available at the front of my KVA, made a drawing showing what I wanted and took it to a local radiator manufacturer. His only comment was that his experience showed that 50mm nozzles and piping would be necessary for a 5 litre engine. My car uses 35mm copper tube (giving an ID of about 1.3 inches). As there are quite a few bends at the front of the car, I was happy to increase to 50mm tubing for this. It has bottom right inlet and top right outlet with an atmospheric manual vent at top right for use when filling/venting. The core is copper and about 50mm thick with two rows of tubes. The water pump is standard Ford.
Basically, I used the biggest I could fit in. There are no overheating problems.
Regards
Dave Tickle
Chris Duncan
Supporter
GT40 COOLANT TRANSFER TUBING COMPARISONS
++++++++++++++++++++++++
TUBING SIZE AND MATERIAL, WEIGHT COMPARISON
Each side, feed and return, requires 10' tubing with 4
bends for a total of 20' of tubing with 8 bends.
(Previous distance given was 9', but closer measurement shows it to be 10'.)
Burns Stainless is the source, U bends and straight tube are
cut and welded to fit.
Weights given are for the tubing and coolant total weight. This is just the coolant in the tubing. With tubing material weights from the Burns site and ethylene glycol at 9.3 #'s per gallon.
6061 Aluminum
1 (.065) feed
1-1/4 (.049) return
total 9.6 #'s
1-1/4 (.049) feed
1-1/2 (.065) return
total 19.9 #'s
1-1/2 (.065) feed & return
total 23.8 #'s
1-3/4 (.065) feed & return
total 31 #'s
2 (.065) feed & return
total 39.3 #'s
304 Stainless (sizes given are in smallest available wall thickness, other sizes are available)
1 (.065) feed
1-1/4 (.049) return
total 22.5 #'s
1-1/4 (.049) feed
1-1/2 (.035) return
total 26.2 #'s
1-1/2 (.035) feed & return
total 28 #'s
1-3/4 (.035) feed & return
total 35.8 #'s
2 (.035) feed and return
total 44.7 #'s
Mild steel weight is close to stainless except you won't have the strength durability especially in the thinner wall sizes.
+++++++++++++++++++++++++
STANDARD CROSS FLOW TO DOUBLE BYPASS RADIATOR COMPARISON
(Using the shade tree engineer numbers because I can't understand Adam's numbers enough to be able to calculate with different initial numbers.)
Standard rad. 5.8 PSI drop
Double Bypass with 1/2 the cross section and double the distance. Something that's confusing me here though is that the Standard rad has the same exact same wall area as the double bypass.
So 1/2 the cross section area adds 5.8 PSI to the drop and double the distance also increases the drop by another 5.8.
So 17.4 PSI total drop for a double bypass rad? So 3 times the drop going from standard to double bypass.
Just a guess here Adam. Please if you only do one more calc make it the comparison of the standard rad to the double bypass instead of the PSI horsepower conversion.
++++++++++++++++++++++++
PSI DROP COMPARISONS
Standard Rad with 1-3/4 tubing.
Total 7.55 PSI drop
Double Bypass Rad with 1-1/2 tubing.
Total 21.04 PSI drop
Using the totals from the new GT
Engine 37.9 PSI drop
Radiator to pump 2.5 PSI drop
Engine to Radiator 19.6 PSI drop (includes Tstat/housing)
Radiator 5.4 PSI drop
Let's use the new GT's numbers and extrapolate a ballpark number for the standard 302.
Engine 35 PSI drop
Engine to radiator 15 PSI drop (using the GT number and subtracting our feed tube drop)
So total 302 PSI drop for everything except the tubing and radiator is
50 PSI.
So total system drop for the new GT
65.4 PSI
GT40 with 1-1/2 lines and double bypass
71.04 PSI total drop.
GT40 with 1-3/4 lines and standard rad
57.55 PSI total drop.
So going from larger tube and a standard rad to smaller tubes and a dbl bypass rad increases the total PSI drop by about 20 percent.
Figuring that total water pump HP drain is about 3 HP max (???) this is negligible.
++++++++++++++++++++++++++
MATERIALS HEAT TRANSFER COMPARISON
Coefficient of Thermal Conductivity
BTU/ft-hr-F (70 F)
Mild Steel 1010-- 26.98
Aluminum 6061-T0-- 104.00
304 Stainless-- 9.40
(higher number means more heat transfer)
Numbers from a Burns TECH ARTICLE chart
So aluminum transfers 4 times as much as mild steel and 10 times as much as stainless, and stainless transfers one third as much as mild.
So you can easily see why Aluminum is better for radiators and stainless is better for headers.
++++++++++++++++++++++++++
MATERIALS COST COMPARISON
The difference in cost/sizes is negligible for these amounts.
Ballpark figures show aluminum and stainless about the same and mild steel being about 1/4 to 1/3 as expensive as stainless or aluminum.
+++++++++++++++++++++++
SYNOPSIS
Weight comparisons between different tube sizes used by various scenarios in this thread show a possible range of 10 #'s for a low and 45 #'s for a high.
Flow comparisons although more limited in sizes than the weight comparisons show a 20 percent difference in total PSI drop.
It looks like for an all out race effort that aluminum tube might be an option to look at for weight savings and heat transfer. For a street car though the stainless, especially in the larger, thinner wall sizes, is better when heat transfer isn't desired in the tunnel area, and durability is more of an issue.
The aluminum is harder to weld, transfers more heat, so thus requires more weight in insulation in a road car, and can also require solution heat treating after welding if anything more than a dead soft strength is desired, thus adding another time consuming and expensive step to the fabrication.
The other comparison of sizes relates to the amount of room available, especially in the firewall area. This says that the smaller tube sizes will be better.
Mild steel is an option if your trying to save money and have a tunnel area/setup that is conducive to accessing the transfer tubing if it needs replacement due to corrosion.
Looking at the Ron Davis sizes of 1"& 1-1/4" supposedly being viable I think I'm going to go with the 1-1/2" stainless as a compromise between the Ron Davis sizes and the standard 1-3/4 size on the original cars. Other anecdotal evidence that ERA is running 1-5/8 with a double bypass rad says this is in the ballpark. (Unless Adam can crunch some numbers and show that a dbl bypass is worse than I'm thinking.)
Thanks for everyone's input.
++++++++++++++++++++++++
TUBING SIZE AND MATERIAL, WEIGHT COMPARISON
Each side, feed and return, requires 10' tubing with 4
bends for a total of 20' of tubing with 8 bends.
(Previous distance given was 9', but closer measurement shows it to be 10'.)
Burns Stainless is the source, U bends and straight tube are
cut and welded to fit.
Weights given are for the tubing and coolant total weight. This is just the coolant in the tubing. With tubing material weights from the Burns site and ethylene glycol at 9.3 #'s per gallon.
6061 Aluminum
1 (.065) feed
1-1/4 (.049) return
total 9.6 #'s
1-1/4 (.049) feed
1-1/2 (.065) return
total 19.9 #'s
1-1/2 (.065) feed & return
total 23.8 #'s
1-3/4 (.065) feed & return
total 31 #'s
2 (.065) feed & return
total 39.3 #'s
304 Stainless (sizes given are in smallest available wall thickness, other sizes are available)
1 (.065) feed
1-1/4 (.049) return
total 22.5 #'s
1-1/4 (.049) feed
1-1/2 (.035) return
total 26.2 #'s
1-1/2 (.035) feed & return
total 28 #'s
1-3/4 (.035) feed & return
total 35.8 #'s
2 (.035) feed and return
total 44.7 #'s
Mild steel weight is close to stainless except you won't have the strength durability especially in the thinner wall sizes.
+++++++++++++++++++++++++
STANDARD CROSS FLOW TO DOUBLE BYPASS RADIATOR COMPARISON
(Using the shade tree engineer numbers because I can't understand Adam's numbers enough to be able to calculate with different initial numbers.)
Standard rad. 5.8 PSI drop
Double Bypass with 1/2 the cross section and double the distance. Something that's confusing me here though is that the Standard rad has the same exact same wall area as the double bypass.
So 1/2 the cross section area adds 5.8 PSI to the drop and double the distance also increases the drop by another 5.8.
So 17.4 PSI total drop for a double bypass rad? So 3 times the drop going from standard to double bypass.
Just a guess here Adam. Please if you only do one more calc make it the comparison of the standard rad to the double bypass instead of the PSI horsepower conversion.
++++++++++++++++++++++++
PSI DROP COMPARISONS
Standard Rad with 1-3/4 tubing.
Total 7.55 PSI drop
Double Bypass Rad with 1-1/2 tubing.
Total 21.04 PSI drop
Using the totals from the new GT
Engine 37.9 PSI drop
Radiator to pump 2.5 PSI drop
Engine to Radiator 19.6 PSI drop (includes Tstat/housing)
Radiator 5.4 PSI drop
Let's use the new GT's numbers and extrapolate a ballpark number for the standard 302.
Engine 35 PSI drop
Engine to radiator 15 PSI drop (using the GT number and subtracting our feed tube drop)
So total 302 PSI drop for everything except the tubing and radiator is
50 PSI.
So total system drop for the new GT
65.4 PSI
GT40 with 1-1/2 lines and double bypass
71.04 PSI total drop.
GT40 with 1-3/4 lines and standard rad
57.55 PSI total drop.
So going from larger tube and a standard rad to smaller tubes and a dbl bypass rad increases the total PSI drop by about 20 percent.
Figuring that total water pump HP drain is about 3 HP max (???) this is negligible.
++++++++++++++++++++++++++
MATERIALS HEAT TRANSFER COMPARISON
Coefficient of Thermal Conductivity
BTU/ft-hr-F (70 F)
Mild Steel 1010-- 26.98
Aluminum 6061-T0-- 104.00
304 Stainless-- 9.40
(higher number means more heat transfer)
Numbers from a Burns TECH ARTICLE chart
So aluminum transfers 4 times as much as mild steel and 10 times as much as stainless, and stainless transfers one third as much as mild.
So you can easily see why Aluminum is better for radiators and stainless is better for headers.
++++++++++++++++++++++++++
MATERIALS COST COMPARISON
The difference in cost/sizes is negligible for these amounts.
Ballpark figures show aluminum and stainless about the same and mild steel being about 1/4 to 1/3 as expensive as stainless or aluminum.
+++++++++++++++++++++++
SYNOPSIS
Weight comparisons between different tube sizes used by various scenarios in this thread show a possible range of 10 #'s for a low and 45 #'s for a high.
Flow comparisons although more limited in sizes than the weight comparisons show a 20 percent difference in total PSI drop.
It looks like for an all out race effort that aluminum tube might be an option to look at for weight savings and heat transfer. For a street car though the stainless, especially in the larger, thinner wall sizes, is better when heat transfer isn't desired in the tunnel area, and durability is more of an issue.
The aluminum is harder to weld, transfers more heat, so thus requires more weight in insulation in a road car, and can also require solution heat treating after welding if anything more than a dead soft strength is desired, thus adding another time consuming and expensive step to the fabrication.
The other comparison of sizes relates to the amount of room available, especially in the firewall area. This says that the smaller tube sizes will be better.
Mild steel is an option if your trying to save money and have a tunnel area/setup that is conducive to accessing the transfer tubing if it needs replacement due to corrosion.
Looking at the Ron Davis sizes of 1"& 1-1/4" supposedly being viable I think I'm going to go with the 1-1/2" stainless as a compromise between the Ron Davis sizes and the standard 1-3/4 size on the original cars. Other anecdotal evidence that ERA is running 1-5/8 with a double bypass rad says this is in the ballpark. (Unless Adam can crunch some numbers and show that a dbl bypass is worse than I'm thinking.)
Thanks for everyone's input.
Chris Duncan
Supporter
Just when you think it's all figured out a big wrench is thrown into the decision making works. /ubbthreads/images/graemlins/grin.gif
From this recent THREAD
2nd image down in the thread, top view of the front area clearly showing both inlet and outlet of the radiator.
It's an RF car with a cross flow radiator that has both inlet and outlet at the bottom. I'm guessing that since these car have a proven track record with no overheating that the loss in efficiency from same end inlet/outlet position is made up for with the gains in flow from the cross flow setup over the double pass type.
I'm also quite certain that this configuration is less expensive due to the tanks being on the ends instead of top and bottom, because it requires less base cores for construction.
So you could have the uncluttered configuration of inlet/outlet at the bottom and the lesser price.
From this recent THREAD
2nd image down in the thread, top view of the front area clearly showing both inlet and outlet of the radiator.
It's an RF car with a cross flow radiator that has both inlet and outlet at the bottom. I'm guessing that since these car have a proven track record with no overheating that the loss in efficiency from same end inlet/outlet position is made up for with the gains in flow from the cross flow setup over the double pass type.
I'm also quite certain that this configuration is less expensive due to the tanks being on the ends instead of top and bottom, because it requires less base cores for construction.
So you could have the uncluttered configuration of inlet/outlet at the bottom and the lesser price.
I appreciate all the calculations here as much as anyone. Lord knows I did enough of them in grad school (always wondered where else I would use turbulent flow and Reynold's #). That being said, when you go to a radiator shop that does business with Griffin, Becool, or whatever, they will only be interested in four or five things, your HP, the size of your tubes supplying the water to the radiator, where YOU want the inlet and outlet tubes, whether you want straight or bent connectors and if you want a radiator cap or a plug for a vent line.
They probably use the formulas mentioned earlier in their computer to determine what is needed. If you want to go to double pass, then they will build it, but it will cost you much more than is needed to. Besides, you have those cooling fans, right??
As to weight, the numbers are interesting from a purely discussion point of view, but I think with 4-600 HP,,,,,,who cares. My wife's overnight bag weighs more than that!!!
Bill
They probably use the formulas mentioned earlier in their computer to determine what is needed. If you want to go to double pass, then they will build it, but it will cost you much more than is needed to. Besides, you have those cooling fans, right??
As to weight, the numbers are interesting from a purely discussion point of view, but I think with 4-600 HP,,,,,,who cares. My wife's overnight bag weighs more than that!!!
Bill
Chris Duncan
Supporter
Bill,
""That being said, when you go to a radiator shop that does business with Griffin, Becool, or whatever, they will only be interested in four or five things, your HP, the size of your tubes supplying the water to the radiator, where YOU want the inlet and outlet tubes, whether you want straight or bent connectors and if you want a radiator cap or a plug for a vent line.""
Ahh, but where did you get your information? Did you copy from a previous builder or did you ask where and how they got those figures?
I think if nothing else this has been an exercise that demonstrates the enormous amount of thought that can go into a vehicle in the design and development stages, especially one that may be raced.
""They probably use the formulas mentioned earlier in their computer to determine what is needed.""
Building a GT40 is different things to different people, it all depends how far you want to go. I want to know what is needed and WHY it's needed before I even go to the rad builder.
""If you want to go to double pass, then they will build it, but it will cost you much more than is needed to. Besides, you have those cooling fans, right??""
Most of the cost increase is incurred in the difference between an upright flow and a cross-flow, due to the base cores used to construct. 600.00 for a cross flow, 900.00 for a upright with these dims, regardless of double bypass.
In an optimized system cooling fans are only necessary for when the vehicle is moving slowly or stationary. At speed they shouldn't even turn on.
""As to weight, the numbers are interesting from a purely discussion point of view, but I think with 4-600 HP,,,,,,who cares. My wife's overnight bag weighs more than that!!! Bill""
Racing builders and teams will kill for a few pounds. Let's see going from a
1-3/4"x.049 tube (original car) at 40.8#'s (tube/coolant),
to a 1-1/2"x.035 tube at 28#'s you just saved
13#'s. THIRTEEN POUNDS.
I'll repeat a previous point, overall weight loss after major items like aluminum heads occurs in small amounts, as do gains for that matter. Ignoring possible small gains or losses can add up to surprisingly large amounts.
What if you broke a GT40 down into all it's main component sections similar to the cooling system? Let's say frame, suspension, body, fuel, powertrain, electrical, brakes, interior, cooling system (did I miss any?). That's 9 component systems. What if you could save 13 pounds in each system? That would be a total of 117 pounds, I hope your wife's bag is lighter or your going to have to bring a hand truck to get it into the hotel.
Weight loss is free reliable horsepower. Any given horsepower figure is meaningless without looking at the weight involved. The magazines always emphasize the HP number when in fact the power/weight ratio is a more important figure. You can get HP/weight ratio back, after adding weight, by adding horsepower at the engine but then you lose in handling and braking. I've often wondered why the kits are typically so much heavier than the original cars and don't think there's any reason why, given today's technology, that the kits shouldn't weigh a little bit less than they do.
+++++++++++++++++++++
Adam,
I'm going with a cross flow with both 1-1/2 outlets at the bottom, no double bypass.
After talking with the rad expert at the builders it's apparent that although the optimum radiator flow-wise is the upright, that is also the least effective from a cooling standpoint in that longer tubes mean more heat transfer.
He also says that flow is still good to the top tubes even though both inlet/outlet are at the bottom due to it being a pressurized system.
Going with 1-1/2"x.035 stainless lines thinking that gains in radiator technology since the original cars will make up for decreased flow.
I think an all out race effort would be 1-1/4 feed and 1-3/4 return in aluminum. You'd be sort of copying the new GT but with less thermal load, no AC or supercharger intercooler, allowing the drop from 2" to 1-3/4" return.
A pat on the back to you for your contribution to this and other threads, hopefully it won't neccesitate the use of a Gurney bubble on your future GT40 /ubbthreads/images/graemlins/smile.gif
""That being said, when you go to a radiator shop that does business with Griffin, Becool, or whatever, they will only be interested in four or five things, your HP, the size of your tubes supplying the water to the radiator, where YOU want the inlet and outlet tubes, whether you want straight or bent connectors and if you want a radiator cap or a plug for a vent line.""
Ahh, but where did you get your information? Did you copy from a previous builder or did you ask where and how they got those figures?
I think if nothing else this has been an exercise that demonstrates the enormous amount of thought that can go into a vehicle in the design and development stages, especially one that may be raced.
""They probably use the formulas mentioned earlier in their computer to determine what is needed.""
Building a GT40 is different things to different people, it all depends how far you want to go. I want to know what is needed and WHY it's needed before I even go to the rad builder.
""If you want to go to double pass, then they will build it, but it will cost you much more than is needed to. Besides, you have those cooling fans, right??""
Most of the cost increase is incurred in the difference between an upright flow and a cross-flow, due to the base cores used to construct. 600.00 for a cross flow, 900.00 for a upright with these dims, regardless of double bypass.
In an optimized system cooling fans are only necessary for when the vehicle is moving slowly or stationary. At speed they shouldn't even turn on.
""As to weight, the numbers are interesting from a purely discussion point of view, but I think with 4-600 HP,,,,,,who cares. My wife's overnight bag weighs more than that!!! Bill""
Racing builders and teams will kill for a few pounds. Let's see going from a
1-3/4"x.049 tube (original car) at 40.8#'s (tube/coolant),
to a 1-1/2"x.035 tube at 28#'s you just saved
13#'s. THIRTEEN POUNDS.
I'll repeat a previous point, overall weight loss after major items like aluminum heads occurs in small amounts, as do gains for that matter. Ignoring possible small gains or losses can add up to surprisingly large amounts.
What if you broke a GT40 down into all it's main component sections similar to the cooling system? Let's say frame, suspension, body, fuel, powertrain, electrical, brakes, interior, cooling system (did I miss any?). That's 9 component systems. What if you could save 13 pounds in each system? That would be a total of 117 pounds, I hope your wife's bag is lighter or your going to have to bring a hand truck to get it into the hotel.
Weight loss is free reliable horsepower. Any given horsepower figure is meaningless without looking at the weight involved. The magazines always emphasize the HP number when in fact the power/weight ratio is a more important figure. You can get HP/weight ratio back, after adding weight, by adding horsepower at the engine but then you lose in handling and braking. I've often wondered why the kits are typically so much heavier than the original cars and don't think there's any reason why, given today's technology, that the kits shouldn't weigh a little bit less than they do.
+++++++++++++++++++++
Adam,
I'm going with a cross flow with both 1-1/2 outlets at the bottom, no double bypass.
After talking with the rad expert at the builders it's apparent that although the optimum radiator flow-wise is the upright, that is also the least effective from a cooling standpoint in that longer tubes mean more heat transfer.
He also says that flow is still good to the top tubes even though both inlet/outlet are at the bottom due to it being a pressurized system.
Going with 1-1/2"x.035 stainless lines thinking that gains in radiator technology since the original cars will make up for decreased flow.
I think an all out race effort would be 1-1/4 feed and 1-3/4 return in aluminum. You'd be sort of copying the new GT but with less thermal load, no AC or supercharger intercooler, allowing the drop from 2" to 1-3/4" return.
A pat on the back to you for your contribution to this and other threads, hopefully it won't neccesitate the use of a Gurney bubble on your future GT40 /ubbthreads/images/graemlins/smile.gif
Kalun,
I was not trying to impune the numbers or their derivation. I too am an analysis driven individual, and I appreciate the derivation of what and why. For the PURELY race oriented people out there, the number crunching can be quite benefical. For those of us who will use our cars on the road, it is not so important to save weight, as it is to choose the right components. Your number crunching has has borne that out. We all want our cars to perform at their best, as that is why we do the work ourselves. The information that you and Adam have supplied is fantastic, and I didn't mean to make little of it. It was meant more as an aside. I am sure that for most (at least me) as we progress with our project(s) can appreciate the relavance of the numbers. Saving weight is important, but many of us will be adding things like stereos airconditioning and the like, making weight not so critical. After all, a 2500# car with 500HP equals a ratio of 5. 2550# equals 5.1. For the racers, that's important, but I would guess that some of us could save a considerable amount if we just ate properly. I also think that unless you are purely a racer, that horsepower to weight ratio could be improved with a few more $$ on the front end of that equation. 550 HP = 4.5 and 4.6.
I think what you and Adam are doing is what this forum needs. I am at a stage in my life where I like to read these things rather than calculate them down to their lowest numbers. Your numbers are either reaffirming my intuitive thoughts, or making me go in a different direction. Please keep on comming with the analysis, as it is definitely helping me with the choices I am making with regards to parts and WHY I am choosing them.
BTW, I do have to use a porter when we travel.
Bill
I was not trying to impune the numbers or their derivation. I too am an analysis driven individual, and I appreciate the derivation of what and why. For the PURELY race oriented people out there, the number crunching can be quite benefical. For those of us who will use our cars on the road, it is not so important to save weight, as it is to choose the right components. Your number crunching has has borne that out. We all want our cars to perform at their best, as that is why we do the work ourselves. The information that you and Adam have supplied is fantastic, and I didn't mean to make little of it. It was meant more as an aside. I am sure that for most (at least me) as we progress with our project(s) can appreciate the relavance of the numbers. Saving weight is important, but many of us will be adding things like stereos airconditioning and the like, making weight not so critical. After all, a 2500# car with 500HP equals a ratio of 5. 2550# equals 5.1. For the racers, that's important, but I would guess that some of us could save a considerable amount if we just ate properly. I also think that unless you are purely a racer, that horsepower to weight ratio could be improved with a few more $$ on the front end of that equation. 550 HP = 4.5 and 4.6.
I think what you and Adam are doing is what this forum needs. I am at a stage in my life where I like to read these things rather than calculate them down to their lowest numbers. Your numbers are either reaffirming my intuitive thoughts, or making me go in a different direction. Please keep on comming with the analysis, as it is definitely helping me with the choices I am making with regards to parts and WHY I am choosing them.
BTW, I do have to use a porter when we travel.
Bill
Chris Duncan
Supporter
Agree Bill, I don't always have time to crunch the numbers and analyze everything down to the smallest considerations, many times other peoples analysis are used directly.
And different ways of doing things are what I think make GT40's interesting. If you look at the original cars the finer points had many variations and the kit cars are even more varied.
And different ways of doing things are what I think make GT40's interesting. If you look at the original cars the finer points had many variations and the kit cars are even more varied.
I was talking with a race machanic the other day. They told me that a front engined car (stock car) realizes about 20-30% of its' cooling from the air passing around the motor. This represents a pretty significant amount of cooling effect; one that a mid-engined car gives up. Anyone have any info on this?
Andy
Andy
In a mid-engine car, most of the airflow around the engine will be along the bottom of the oil pan. I've been wondering what a few well-thought out fins on an aluminum oil pan would do for overall cooling.
Chris Duncan
Supporter
AJS,
Hmmmmm, maybe I'll have to open up the belly pan around the oil pan a little bit then.
Mark,
yes some of the factory Hondas have aluminum pans with fins now.
Adam,
BWAH HA HA HA HA HA HA HA!!!!!!!!
Hmmmmm, maybe I'll have to open up the belly pan around the oil pan a little bit then.
Mark,
yes some of the factory Hondas have aluminum pans with fins now.
Adam,
BWAH HA HA HA HA HA HA HA!!!!!!!!
Just to add my two bits to this discussion. I was watching "Le Mans" again for the nth time last night, there is a scene showing the bottom part of the Ferrari 512 as it's being taken out of their transporter.
You will note the bottom of the oil pan, complete with cooling fins machined in, which I thought was a good idea, but now I'm wondering if they're serving another purpose, that is air management underneath the car at the same time.
There are two cut-outs located on either side of the pan, sort of a split NACA-type ducting arrangement and I was curious if anyone else knew about this set-up and if the intention was both oil pan / engine cooling AND aerodynamic flow.
Rick
You will note the bottom of the oil pan, complete with cooling fins machined in, which I thought was a good idea, but now I'm wondering if they're serving another purpose, that is air management underneath the car at the same time.
There are two cut-outs located on either side of the pan, sort of a split NACA-type ducting arrangement and I was curious if anyone else knew about this set-up and if the intention was both oil pan / engine cooling AND aerodynamic flow.
Rick
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