Reverse Flow Cooling?
12-30-2004, 03:08 PM
#1
Rennlist Lifetime Member
Lifetime Rennlist
Member
Lifetime Rennlist
Member
Thread Starter
Join Date: Jul 2002
Location: Northern Virginia
Posts: 2,130
Likes: 0
Received 0 Likes
on
0 Posts
Reverse Flow Cooling?
Alright, before you crucify me, hear me out. I'm just trying to conceptualize things that might make our motors more reliable and maybe a small bit more powerful.
In a cooling system, the coolant's ability to cool the metal surrounding it is dependant on the temperature difference between the coolant and the metal around it. The bigger the temperature difference, the more heat will be drawn into the coolant and away from the motor.
Given that, wouldn't it make more sense for the coolant to come straight from the radiator and flow through the head first, cooling the material immediately adjacent to the combustion chamber (the hottest area in theory), then flow through the block and back to the radiator?
I was just reading my latest copy of Engine Masters, and while these are domestic V8's being worked on, many of these cars employ FI and high levels of boost and cooling is of dire consequence. A few of the engine builders employ an electric water pump and reverse the flow of the system. If it applies to these cars (some of which make horsepower in the quad-digit range), I would think it could be applied to our cars.
In our cars, I'm thinking the benefit would be two-fold.
First, increased cooling efficiency due to a great temperature difference between the coolant and the head. This may help to make more power, and at the very least would counter some of the issues people have with high-boost motors, I.E. extreme heat surrounding the combustion chamber leading to pre-ignition.
Second, it would allow us to delete the factory water pump, which isn't the greatest design. There would no longer be any worries of a seized water pump destroying your head, as the water pump would no longer be driven by the timing belt.
You would need to source a good electric water pump, fab a custom mount for it and plumb it into the 'outlet' on top of the head (where the bleed valve is).
You would also need to fabricate an adapter for where the water pump goes stock. I picure a part that uses the same shaped gasket as the current WP, and is simply an adapter that allows a hose to be clamped on for the return trip to the radiator.
You also would not need to reverse the flow of coolant through the radiator, so the idea of heat rising with the coolant and hurting cooling efficiency in the radiator is eliminated. You need to make a few custom hoses so the outlet of the radiator (bottom port) is routed to the new electric water pump. One would also be needed for the coolant outlet on the block, routing to the upper port on the radiator.
Has anyone given any thought to this? Again I'm just trying to conceptualize if its possible, or worthwhile. Can anyone see any issues that might arise that perhaps I'm overlooking? Any other ideas/suggestions?
Also, off this topic, but I saw a 400+CI Twin Turbo'd Pontiac V8 running on ethanol, making 2800+ horsepower. There wasn't even a need for an intercooler at 45+PSI, due to the inherent cooling effect of the ethanol. Has anyone attempted to convert their gasoline powered motor to an ethanol motor? The problems are fuel availability and delivery, since typically an ehtanol motor needs almost a 1:1 A/F ratio, meaning you would need at least 2 very large injectors per cylinder, and a pump capable of flowing that much fuel.
Just some thoughts.
In a cooling system, the coolant's ability to cool the metal surrounding it is dependant on the temperature difference between the coolant and the metal around it. The bigger the temperature difference, the more heat will be drawn into the coolant and away from the motor.
Given that, wouldn't it make more sense for the coolant to come straight from the radiator and flow through the head first, cooling the material immediately adjacent to the combustion chamber (the hottest area in theory), then flow through the block and back to the radiator?
I was just reading my latest copy of Engine Masters, and while these are domestic V8's being worked on, many of these cars employ FI and high levels of boost and cooling is of dire consequence. A few of the engine builders employ an electric water pump and reverse the flow of the system. If it applies to these cars (some of which make horsepower in the quad-digit range), I would think it could be applied to our cars.
In our cars, I'm thinking the benefit would be two-fold.
First, increased cooling efficiency due to a great temperature difference between the coolant and the head. This may help to make more power, and at the very least would counter some of the issues people have with high-boost motors, I.E. extreme heat surrounding the combustion chamber leading to pre-ignition.
Second, it would allow us to delete the factory water pump, which isn't the greatest design. There would no longer be any worries of a seized water pump destroying your head, as the water pump would no longer be driven by the timing belt.
You would need to source a good electric water pump, fab a custom mount for it and plumb it into the 'outlet' on top of the head (where the bleed valve is).
You would also need to fabricate an adapter for where the water pump goes stock. I picure a part that uses the same shaped gasket as the current WP, and is simply an adapter that allows a hose to be clamped on for the return trip to the radiator.
You also would not need to reverse the flow of coolant through the radiator, so the idea of heat rising with the coolant and hurting cooling efficiency in the radiator is eliminated. You need to make a few custom hoses so the outlet of the radiator (bottom port) is routed to the new electric water pump. One would also be needed for the coolant outlet on the block, routing to the upper port on the radiator.
Has anyone given any thought to this? Again I'm just trying to conceptualize if its possible, or worthwhile. Can anyone see any issues that might arise that perhaps I'm overlooking? Any other ideas/suggestions?
Also, off this topic, but I saw a 400+CI Twin Turbo'd Pontiac V8 running on ethanol, making 2800+ horsepower. There wasn't even a need for an intercooler at 45+PSI, due to the inherent cooling effect of the ethanol. Has anyone attempted to convert their gasoline powered motor to an ethanol motor? The problems are fuel availability and delivery, since typically an ehtanol motor needs almost a 1:1 A/F ratio, meaning you would need at least 2 very large injectors per cylinder, and a pump capable of flowing that much fuel.
Just some thoughts.
12-30-2004, 03:55 PM
#2
Three Wheelin'
Check out Evan's cooling at http://www.evanscooling.com/. The better heat transfer properties of their coolant could save a lot of money over what you're proposing.
-Jon
-Jon
12-30-2004, 04:03 PM
#3
Addict
Rennlist Member
Rennlist Member
Join Date: Oct 2003
Location: Indy
Posts: 1,750
Likes: 0
Received 0 Likes
on
0 Posts
Well, it all seems pretty simple! 
It is probably a better setup, but the entire cost (machining, custom pieces, electric pump and modified/custom radiator) would be enormous. You would also have a one-off system that you ASSUME works better if at all. (Here is a electric waterpump: http://www.racerpartswholesale.com/elecpump.htm)
I would say that if you are that concerned about heat, adequate oil cooling, a custom radiator and thermal coating on the exhaust components would be your most cost effective solutions. If you want to eek out 1000hp+ you might need these drastic measures.
Didn't Indycars use ethanol back when they were turbos?
Max
It is probably a better setup, but the entire cost (machining, custom pieces, electric pump and modified/custom radiator) would be enormous. You would also have a one-off system that you ASSUME works better if at all. (Here is a electric waterpump: http://www.racerpartswholesale.com/elecpump.htm)
I would say that if you are that concerned about heat, adequate oil cooling, a custom radiator and thermal coating on the exhaust components would be your most cost effective solutions. If you want to eek out 1000hp+ you might need these drastic measures.
Didn't Indycars use ethanol back when they were turbos?
Max
12-30-2004, 04:18 PM
#5
Rennlist Lifetime Member
Lifetime Rennlist
Member
Lifetime Rennlist
Member
Thread Starter
Join Date: Jul 2002
Location: Northern Virginia
Posts: 2,130
Likes: 0
Received 0 Likes
on
0 Posts
LOL well I'm not talking about turning my 951 into a 1000HP monster, thats just plain absurd. Am I wrong in thinking the system would be more efficient if it flowed through the head first?
I dont think it would be simple, but I don't think there would need to be any modifications made to the radiator, you would need 2 custom hoses, which would probably cost another $50, maybe $100. The pump and its controller would cost roughly $500. The custom adapter for the water pump and the brackets to mount the electric water pump would probably be the biggest cost. Along those lines, would it be possible to remove the impeller for the water pump and just use that instead of a custom part?
Granted, I am assuming it would work better, but given that the coolant in the hottest part of the motor would certainly be cooler in a reverse flow setup, why wouldn't it work better?
I agree that adequate oil cooling and thermal coating/wrapping is the way to keep the engine bay temps in check (which is why I installed a KISS oil cooler and thermo-wrapped the headers, crossover, turbine and downpipe). Again, I think the dual benefit of not having the timing belt related issues combined with the increased cooling might make it worthwhile. Who knows, I'm just brainstorming and wanted some feedback.
The ethanol stuff is just dreaming, I know that.
Thanks for the replies guys, keep em coming.
I dont think it would be simple, but I don't think there would need to be any modifications made to the radiator, you would need 2 custom hoses, which would probably cost another $50, maybe $100. The pump and its controller would cost roughly $500. The custom adapter for the water pump and the brackets to mount the electric water pump would probably be the biggest cost. Along those lines, would it be possible to remove the impeller for the water pump and just use that instead of a custom part?
Granted, I am assuming it would work better, but given that the coolant in the hottest part of the motor would certainly be cooler in a reverse flow setup, why wouldn't it work better?
I agree that adequate oil cooling and thermal coating/wrapping is the way to keep the engine bay temps in check (which is why I installed a KISS oil cooler and thermo-wrapped the headers, crossover, turbine and downpipe). Again, I think the dual benefit of not having the timing belt related issues combined with the increased cooling might make it worthwhile. Who knows, I'm just brainstorming and wanted some feedback.
The ethanol stuff is just dreaming, I know that.
Thanks for the replies guys, keep em coming.
12-30-2004, 04:46 PM
#6
Three Wheelin'
Max,
I'm planning to switch to the Evans stuff when I do my waterpump in the next couple of months. I need to confirm that there won't be any issues with running the stock waterpump, but once I get there approval on that it should be clear sailing. I'll report back after I do a few track events in higher temps.
-Jon
I'm planning to switch to the Evans stuff when I do my waterpump in the next couple of months. I need to confirm that there won't be any issues with running the stock waterpump, but once I get there approval on that it should be clear sailing. I'll report back after I do a few track events in higher temps.
-Jon
12-30-2004, 05:24 PM
#7
Addict
Rennlist Member
Rennlist Member
Trending Topics
12-30-2004, 07:57 PM
#9
This is a great post. Reversing the water thro the Head first is very common in hotrodding. Every engine that has had this done always made more power. Its banned from al ot of racing series because of the costs involved etc. It was done some time ago in NASCAR and banned imediately. Its common in engines where the direction is normal and not changed from an OE design. In fact, a lot of high end race engines have the heads and Cylinder housings cooled only and the block is very short and houses the Crank only. The problem is the Water pump has to be an external type and not part of the Front cover assembly. Want some free power, run the coolant the other way. Want some free mileage, keep the water temp constant with very little change and your MPG will go up. The OE's are working on this in a big way. Many new engines have electronic Water Pumps and Electronic thermostats to hold the temps at a constant temp.
12-31-2004, 01:28 AM
#10
Drifting
Join Date: Apr 2004
Location: Tucson AZ, Dallas Tx sometimes
Posts: 2,966
Likes: 0
Received 1 Like
on
1 Post
The small block chevy motors cooled from the block untill the LT 1 motors and then it was reversed cooling. However, there is a natural convetive effect on the coolant after shutdown, the coolant naturaly circulates because of heat differences and the height of the coolant inlets and outlets. I was shown a new turbo center section that uses this principal to cool it after shut down, VERY cool. You would be able to delete the coolant pump and still have ciculation after shutdown.
12-31-2004, 03:41 PM
#11
Pro
Join Date: Nov 2004
Location: Dallas
Posts: 531
Likes: 0
Received 0 Likes
on
0 Posts
Don't do it. GM went to this on their gen II small blocks (LT1/LT4, 92-97 Vettes, Firebirds, Camaros), but went back to traditional cooling for their gen III (LS1/LS6) and gen IV (LS2/LS7) engines. The reverse flow was a band aid to allow them to run higher compression on what was basically a gen I (original design) small block V8. The engines work well and make good power, but it was really just a stop gap measure until they could redesing a whole new motor (gen III engines). As for converting an existing engine, yes it can be done, but while you may hear from a lot of people who "know someone who's done it", I bet you'll be hard pressed to actually find one.
12-31-2004, 09:54 PM
#12
Addict
Rennlist Member
Rennlist Member
“I bet you'll be hard pressed to actually find one”
OK, so maybe I was “pressed” to write this post.
I converted my Espada (4L V12) to reverse cooling, but only to get more uniform temperature distribution, thus minimizing block and head distortions due to thermal gradients.
Normally the coolant enters the block in front, goes up to the heads end exits the heads in the back to be returned to the radiator through a tube in the V. During idle the headers and exhaust will heat up the back of the engine and while driving the airflow will cool the front.
So in either case the back end would heat up more than the front and reversing the flow would counter this phenomenon by cooling the back end more.
Reverse flow has the drawback of pushing air bubbles down with the potential of trapping air. I solved this with a small bleed hole from the front of each cylinder head to the radiator.
I don’t know if this change alone made more power (too many simultaneous changes), but I can run 87 octane gas on an 11:1 CR with very good timing. Before your jaws drop, mind you that this car has relatively hot cams, so there is a big difference between geometric and functional CR’s.
Laust
OK, so maybe I was “pressed” to write this post.
I converted my Espada (4L V12) to reverse cooling, but only to get more uniform temperature distribution, thus minimizing block and head distortions due to thermal gradients.
Normally the coolant enters the block in front, goes up to the heads end exits the heads in the back to be returned to the radiator through a tube in the V. During idle the headers and exhaust will heat up the back of the engine and while driving the airflow will cool the front.
So in either case the back end would heat up more than the front and reversing the flow would counter this phenomenon by cooling the back end more.
Reverse flow has the drawback of pushing air bubbles down with the potential of trapping air. I solved this with a small bleed hole from the front of each cylinder head to the radiator.
I don’t know if this change alone made more power (too many simultaneous changes), but I can run 87 octane gas on an 11:1 CR with very good timing. Before your jaws drop, mind you that this car has relatively hot cams, so there is a big difference between geometric and functional CR’s.
Laust
