Project Rear Mounted Radiators

[Murci-Me]

Dual fans on a single pass radiator will cool better than a dual pass radiator with dual fans.

Wrong.

The way that was supposed to read was "dual fans on a single pass radiator will cool better than a single fan on a dual pass radiator" (I edited that posting to reflect this). I already posted that a dual pass is only (at best) 5% better in cooling than a single pass.
Do you have some proof to the contrary, or is this just an opinion?

[plans4sale]

Dual fans on a single pass radiator will cool better than a dual pass radiator with dual fans.

Wrong.

[Murci-Me]

If you do not have your radiators yet consider dual pass radiators.  You can find them at www.summitracing.com.  Just do a search.
Dual pass means the water goes through the radiator twice by-way-of both inlet and outlet being on the same end of the radiator.  The water goes in the inlet and has to pass through once to get to the other end tank and then back through once more to get to the outlet.  They claim to offer better cooling per radiator size.  I am using dual pass and find them effective.
I just can't wait to see how wrong I am about this.  Murci-me, are you there?  Maybe we need another Rube Goldberg solution.

RT

Copied to preserve.

[Murci-Me]

Yup, great point!

[01Lambiero]

Thank you, Jim for that pointer of the "caps".  I completely forgot about the check-valve in the caps.  I thought that I had it covered by installing higher pressure caps.  Live and learn.

Jim

[jdinner]

If you are running more than one radiator cap, make sure to plug the vent port on the cap neck on all except the one you use to fill.
You will want a ‘VENTED’ or ‘CLOSED’ radiator cap if you have a ZERO PRESSURE reservoir tank.
You will want a ‘NON-VENTED’ or ‘OPEN’ radiator cap if you install it on a PRESSURE reservoir tank.

Any cap, no matter the pressure, will draw air back into the system as the liquid cools down. If you have the Honda rads with the caps on them you now have two places for air to collect during cool down. Plug those ports.

[Murci-Me]

Most "heatsinks" on electrical components are constructed of Aluminum, due to its remarkably fast heat transfer and dissipation properties. Second is copper, steel is last.

[Murci-Me]

Nice work Cliff! I agree with you on your flow suggestions, faster vs. slower.
The reason for 2 fans is because of the space in front of the radiator, or lack thereof. Theres usually no more tan just a couple inches between the face of the rads and the wheelwell liner, causing a very poor and turbulent airflow as the air tries to make a 90 degree immediate turn to go thru the radiator. Also it guarantees that any air in front of the radiator is forced to pass through it instead of around it. A single fan on the rear of the radiator (in the "pull" position) looses power trying to pull air through the radiator, which is very restrictive through the vanes. A 1000cfm fan looses about 40% of its airflow because of this, and much is lost around the sides of the radiator as well. Having an additional and equal fan in the "push" position assures full flow through the radiator, and minimizes airflow around the sides which does nothing to assist cooling.
My friend has a G24 with a front mounted stock Fiero radiator, but has a 3800SC in back. The angle at which the radiator is mounted in front greatly reduces its flow, especially since when the air comes through, it has to make a sharp turn to go down to exit. His car was constantly overheating, even with a huge pulling fan. We mounted an equal pushing fan in front of the radiator, and the car has never overheated since.

[cliffs custom fab]

as far as a few ideas, i have to agree with running them in series  it is a lot easier to do. this is what i did on the last set up i did. i took and added a fill neck between the rads (higher but between them) i also went with alum. tubing as much as i could for the durability, which in turn i was able to keep the soft hoses short. the fill neck between the rads is mainly for filling the system. and i put i stronger cap on it. the expansion tank has a cap also which is accessible easily in the compartment.  which is where you can maintain the system. the rads i used are more oe sized and configured like the oe ones. which made it much easier to plumb. they are triple core 1.5 thick with 1 1/4 outlet 1 1/2 inlet. i think one way to slow the flow down is with a bigger lines. in regards to what your pump pushes if you have smaller lines then the flow will move faster the bigger the line the the slower and you can hold and move more volume. trick is to much volume and your pressure can almost become stagnant. which would not be good either. thats just pumping 101 i learned as a fire fighter many many years ago. now with racing all my other years i learned that the overall volume is key to your system how fast you move that volume is key to the efficiency of it.  now im no engineer how ever i can the distance difference to a normal front engine design over a mid engine design  with the rads in the rear . thier is considerable difference is the distance that water travels and how it is plumbed in our app. oe lambo design is more efficient in parallel for the distance of plumbing and rad placement. we on the other hand are using a motor set up (in most cases) that was meant for a front engine front rad set up, moving the rad far away from the pump changes a lot of things plumbing it makes sense to do a series set up. also if your running a low horse power low rpm motor you might even want to change the size of the lines to be a bit smaller to help keep good flow. not to much as you dont want the water traveling to fast or it wont cool enough. say maybe if the normal was plumbed with 1 1/4 lines and now that you just added 6 ft or more line to the system. the pump is working over time to push all that extra volume. well maybe an 1 1/8 line would help restore the flow that you pump likes. alright alright ill shut up now. just a thought i really cant see why four fans instead of two. and it might be possible that some of you guys might be running more of a stagnate problem rather than an air flow problem. if air was that much of a problem why is their not 4 fans on the oe application. dont take me wrong guys im not trying to be ignorant to anyone. just had to figure these kind of issues out before in my day. different kind of cars but same issues. so its just a thought.
anyone wants info on these rads i use just email me

[Murci-Me]

"opinion" is not science. Science is based on fact, not trial and error.
Lambojayso is right, you must have functioning batwings, and I don't mean just capable of raising and lowering. They must be fully ducted to channel the air through the radiators unobstructed.
I realize there are alot of self made engineers on this forum, thinking that trial and error is a valid substitution for education+experience.
Science is the PROVEN statistics of a given problem, and the proven outcome of the solutions. Yes, the dual pass radiators do cool better than the single pass, but its LESS THAN 5%. Is that what you guys are looking for, 5% better cooling?
Push/pull fans will only fight each other when they are of different CFM's. It wouldn't surprise me that you (RT) would "try" 2 different fans and then in your moment of brilliantcy determine its inefficient.
The facts are that dual pass rads only cool at best 5% better than single pass. The fact is that given the problems with rear mounted radiators on these builds (limited space, poor airflow), the answer is to use the largest possible SINGLE PASS radiators that will fit, slow the water flow to insure better cooling, and use dual fans OF THE SAME CFM on each radiator.
Go back and try it RT, you'll see I'm right.

Mercy, mercy, Murci-me...
You seem to be upset at me.  All I did was inform builders that dual pass radiators were a viable option for them.  You even agree they will give a 5% better cooling.  I don't know where you got that statistic but let's say it is correct.  With all the problems we have cooling these builds wouldn't we want to get the best we can.  After all you suggested aluminum tubing with a guess that would supply an advantage.  An advantage I disagree with, but that is my right to disagree and I stated why.  Let the readers decide who is correct.
You also seem to assume/suggest that I am a self-made engineer with no education/experience in the field.  Designing machinery was not only my profession, I was recognized as a leader in my field and headed departments for internationally sold machines.  My products are in use around the world yet you think I would "play around" with dual fans on one radiator and try to make them work on a trial and error basis.  LOL
As for the batwings, OF COURSE THEY MUST DUCT AIR TO THE RADIATORS!  Just how stupid do you think everyone is?
Please, stop.

RT

Well I'm glad to hear you are NOT one of these people on the forum that think just because they changed their own brakes that they are suddenly a brake expert.
I too have several accomplishments, and hold 4 current patents for machinery I've designed that are licensed to companies and in use.
I have a masters degree in Electrical Engineering, and a Bachelors in Mechanical Engineering. I worked 2 years on the Los Angeles Metro Rail project as a traction power engineer, designing power substations for the Metro rail. I've also worked for Hughes Aircraft Radar Systems Group, Rocketdyne, and worked as lead engineer (@25 years old) for ground support engine on the space shuttle program at NASA/JPL in Pasadena CA. I developed an attachment that saved Rocketdyne over $8 million yearly to test flow valves while still attached to the engines, negating the need to tear down the engine to test them. The stuff we do on here is not rocket science, nor does it need a university degree to figure out. None the less though, what i've learned in my past jobs has given me the knowledge to eliminate what wont work from what will.
Everybody is entitled to their opinions, but i'd rather rely on experience and knowledge.

[Murci-Me]

 It wouldn't surprise me that you (RT) would "try" 2 different fans and then in your moment of brilliantcy determine its inefficient.
.....
Go back and try it RT, you'll see I'm right.

This is uncalled for Mike. RT is a well respected retired engineer and has many years of experience in this field.

I to am an Engineer, or did you forget that? Look back at his posts, he is constantly calling me out with his jabs and sarcasm. I only respond to his comments, such as in this case.
I don't care who he is or what he's done, wrong is wrong. I don't state my opinions just the proven facts, and the FACT is dual pass radiators only cool (less than) 5% better than single pass radiators. I have nothing against anybody on here, but when people come on to attack me with their comments, references and opinions I will defend myself.
I'm sorry his feelings got hurt with my "Rube Goldberg" reference about his batwing mechanics, but I stand by what I said about it and the Lamborghini engineers obviously agree with me.

[RT]

"opinion" is not science. Science is based on fact, not trial and error.
Lambojayso is right, you must have functioning batwings, and I don't mean just capable of raising and lowering. They must be fully ducted to channel the air through the radiators unobstructed.
I realize there are alot of self made engineers on this forum, thinking that trial and error is a valid substitution for education+experience.
Science is the PROVEN statistics of a given problem, and the proven outcome of the solutions. Yes, the dual pass radiators do cool better than the single pass, but its LESS THAN 5%. Is that what you guys are looking for, 5% better cooling?
Push/pull fans will only fight each other when they are of different CFM's. It wouldn't surprise me that you (RT) would "try" 2 different fans and then in your moment of brilliantcy determine its inefficient.
The facts are that dual pass rads only cool at best 5% better than single pass. The fact is that given the problems with rear mounted radiators on these builds (limited space, poor airflow), the answer is to use the largest possible SINGLE PASS radiators that will fit, slow the water flow to insure better cooling, and use dual fans OF THE SAME CFM on each radiator.
Go back and try it RT, you'll see I'm right.

Mercy, mercy, Murci-me...
You seem to be upset at me.  All I did was inform builders that dual pass radiators were a viable option for them.  You even agree they will give a 5% better cooling.  I don't know where you got that statistic but let's say it is correct.  With all the problems we have cooling these builds wouldn't we want to get the best we can.  After all you suggested aluminum tubing with a guess that would supply an advantage.  An advantage I disagree with, but that is my right to disagree and I stated why.  Let the readers decide who is correct.
You also seem to assume/suggest that I am a self-made engineer with no education/experience in the field.  Designing machinery was not only my profession, I was recognized as a leader in my field and headed departments for internationally sold machines.  My products are in use around the world yet you think I would "play around" with dual fans on one radiator and try to make them work on a trial and error basis.  LOL
As for the batwings, OF COURSE THEY MUST DUCT AIR TO THE RADIATORS!  Just how stupid do you think everyone is?
Please, stop.

RT

[jdinner]

 It wouldn't surprise me that you (RT) would "try" 2 different fans and then in your moment of brilliantcy determine its inefficient.
.....
Go back and try it RT, you'll see I'm right.

This is uncalled for Mike. RT is a well respected retired engineer and has many years of experience in this field.

[Murci-Me]

"opinion" is not science. Science is based on fact, not trial and error.
Lambojayso is right, you must have functioning batwings, and I don't mean just capable of raising and lowering. They must be fully ducted to channel the air through the radiators unobstructed.
I realize there are alot of self made engineers on this forum, thinking that trial and error is a valid substitution for education+experience.
Science is the PROVEN statistics of a given problem, and the proven outcome of the solutions. Yes, the dual pass radiators do cool better than the single pass, but its LESS THAN 5%. Is that what you guys are looking for, 5% better cooling?
Push/pull fans will only fight each other when they are of different CFM's. It wouldn't surprise me that you (RT) would "try" 2 different fans and then in your moment of brilliantcy determine its inefficient.
The facts are that dual pass rads only cool at best 5% better than single pass. The fact is that given the problems with rear mounted radiators on these builds (limited space, poor airflow), the answer is to use the largest possible SINGLE PASS radiators that will fit, slow the water flow to insure better cooling, and use dual fans OF THE SAME CFM on each radiator.
Go back and try it RT, you'll see I'm right.

[RT]

Good point gtxdon.
Any method used to remove heat from the engine will help.
I also have a deep sump pan and an oil cooler with two 6" fans that will remove heat.
My engine is 383 cu in putting out approximately 650 HP and requires sizable cooling.  During testing I found no cooling problems. I used dual-pass radiators connected in parallel with equal piping, single electric fans, stainless steel water piping, the above mentioned pan and oil cooler, ceramic coated headers, fan cooled exhaust, and have the double-scoop deck lid over the engine.
Everything you can do to remove heat is worth doing.

RT