Dual radiators?

[Munki]

Has anyone ever thought about running dual radiators on your s-chassis?? What are your thoughts? And how efficient do you guys think it’ll be?

I’m currently building an S13 with a RB26 swap and I WILL be running AC, and I want the AC to be ICE COLD! The last s13 I had was running an rb25 with ac but it never really got cold enough and on top of that, the engine ran pretty damn hot…

Anyways, with this new s13 I want my engine to run normal temps and at the same time have cold AC. Just don’t know how that’ll work out with a big FMIC, condenser and radiator running front to back with each other…

Since I have a S15 front end on this car I have a decent amount of room on the sides of the FMIC, enough to fit civic radiators on each side… The front radiator area is completely gutted, basically have a custom rad support and all my wiring and fuse boxes are in the glove box area. It’s a tight fit but stock Honda radiators fit perfect, just not too sure what ill do about fans, gonna have to find some thin ones! I also have no plans on running factory rads, gonna buy some thicker aftermarket ones….

What ive done so far was make a mock up of how much space I have to work with, took the dimensions and made a work space in solidworks. Next, I looked online for dimensions of aftermarket Honda radiators and threw something together in a model. Still trying to add in the rad hoses and setting up FMIC piping!

Heres the current progress on the model,


http://img.photobucket.com/albums/v358/venox/1375369856_zps21a38b2d.jpg

http://img.photobucket.com/albums/v358/venox/1375370422_zps74521d55.jpg

[fliprayzin240sx]

Invest into a dual pass radiator, run the stock clutch fan/shroud and run a switch E-fan for the condenser just like the OEM AC setup.

[Gar9854]

Look into higher grade radaitor than a koyo or mishimoto. They are quality radiations but look into griffin or b-cool. If they can keep a twin turbo'd 408ci small block s-10 cool (180ish in the georgia heat) I'd imagine they'd pair well with a 26.

[waxball88]

I have an s15 front too and i still see this being hard to package. Good luck though nice idea.

[Munki]

I have an s15 front too and i still see this being hard to package. Good luck though nice idea.

If my front end wasn't gutted the way it is I doubt it'll work out... Even how it is now, seems like a tight fit but im sure it can work.

[JBPUSA]

@Gar9854 agreed, Griffin is a good brand, also pretty cool idea there OP.


____________
check out our website JB Performance 240sx parts and more (http://www.jbperformance.net)

[Mikester]

First of all, your mock-up is AWESOME so don't think I am being a dick-

You can do all the mocking up in the world; and it won't change the physics of what you are attempting. You need to calculate the cfm of the fans you plan to run, couple that with the specific heat of your coolant mixture, the flow rate of the coolant and the surface area thru which the coolant will pass... I believe Sil80 is the redisent math whiz...

IMHO, all you are going to do is add extra coolant hoses to the system without the gains you are hoping for. Sure, you're freeing up some space between the FMIC & condenser; but airflow thru the condenser is only one facet of keeping the AC cold. The thing that is really going to make or break the AC system is having all of your lines cleaned/purged, new filter drier, expansion valve & condenser, proper servicing with fresh oil and the correct system charge.

As far as your engine running hot, Flip has the right idea... NOTHING will cool better than the clutch fan & shroud- but that could be a serious PITA to work out with an RB26 in an S13. I personally think your best bet will be a set of high quality/CFM fans, some custom shrouding & cooling plate to keep the air routed thru the FMIC/condenser & rad vs. bleeding off to the path of least resistance.

[Munki]

@Gar9854 agreed, Griffin is a good brand, also pretty cool idea there OP.


____________
check out our website JB Performance 240sx parts and more (http://www.jbperformance.net)

Griffin makes small 2 row radiators... They even have one thats a tad smaller than a civic radiator!

Im going to do more research and see if this would be an efficient cooling set up, not worried about fitment cause itll fit!

[Munki]

First of all, your mock-up is AWESOME so don't think I am being a dick-

You can do all the mocking up in the world; and it won't change the physics of what you are attempting. You need to calculate the cfm of the fans you plan to run, couple that with the specific heat of your coolant mixture, the flow rate of the coolant and the surface area thru which the coolant will pass... I believe Sil80 is the redisent math whiz...

IMHO, all you are going to do is add extra coolant hoses to the system without the gains you are hoping for. Sure, you're freeing up some space between the FMIC & condenser; but airflow thru the condenser is only one facet of keeping the AC cold. The thing that is really going to make or break the AC system is having all of your lines cleaned/purged, new filter drier, expansion valve & condenser, proper servicing with fresh oil and the correct system charge.

As far as your engine running hot, Flip has the right idea... NOTHING will cool better than the clutch fan & shroud- but that could be a serious PITA to work out with an RB26 in an S13. I personally think your best bet will be a set of high quality/CFM fans, some custom shrouding & cooling plate to keep the air routed thru the FMIC/condenser & rad vs. bleeding off to the path of least resistance.


True… But I’ve seen people do this on muscle cars and exotics all the time and supposedly they were able to keep things a lot cooler. I just thought Id give this a shot since I didn’t have good experience with the last cooling setup on my RB25 s13. Everything was new on that car, all AC lines, condenser, compressor, rad with clutch fan, and FMIC… Things still got alittle hot every once in a while and the AC never really got that cold. I've ran only stock clutch fans on all my other swaps and never had a single problem, just seems like the RB swaps arnt as easy to cool when its in a s13.

Im just looking for the best cooling and AC set-up, don’t care what it cost and what I have to do! And it would be pretty cool to do something different…

And I dunno if i mentioned this but on this car I will be running a vented hood and will be making custom ducts on the front bumpers for the side radiators if I do go this route. All the duct work will look as if its factory parts, I own a plastic injection/molding company so ill have no probs fabbing up all that fun stuff!

[Munki]

I doubt Im gonna have any problems finding some strong e-fans...

Heres a 12" fan pushing 3300 CFM,
HD Electric Fan 12"x3 3/4" 3300 CFM (http://shop.perma-cool.com/19112-High-Perf-Electric-Fan-12-3300-CFM-19112.htm)

[Mikester]

^^Funny you mentioned a vented hood... Call this coincidence or whatever; but when I switched to a vented hood, I noticed my coolant temps actually ROSE 3-5*C.

When I sold the vented hood & put the stock one back on, coolant temps went back down. Sounds crazy I know- but this was my experience in the relatively hot climate of Okinawa.

I am not trying to detour you froma any course of action... Just trying to throw stuff out for you to consider. I am NOT a professional mechanic, just an enthusiast; so please take anything I say as such.

[dorkidori_s13]

When I sold the vented hood & put the stock one back on, coolant temps went back down. Sounds crazy I know- but this was my experience in the relatively hot climate of Okinawa.

doesnt sound crazy at all. with a standard OEM hood, it covers the entirity of the engine bay and allows proper vacuum/flow thru inside the engine compartment via your fan setup. when you vent the hood, you actually get rid of that vacuum effect. vents help whatevers toward the top of the engine bay dissapate heat, but it heavily affects the air flow rate inside of the bay with the hood shut.

a lot of modern day cars RELY on the way the hoods built for proper airflow thru the engine bays. take that away and you start overheating.

[twinspool]

True… But I’ve seen people do this on muscle cars and exotics all the time and supposedly they were able to keep things a lot cooler. I just thought Id give this a shot since I didn’t have good experience with the last cooling setup on my RB25 s13. Everything was new on that car, all AC lines, condenser, compressor, rad with clutch fan, and FMIC… Things still got alittle hot every once in a while and the AC never really got that cold. I've ran only stock clutch fans on all my other swaps and never had a single problem, just seems like the RB swaps arnt as easy to cool when its in a s13.

Im just looking for the best cooling and AC set-up, don’t care what it cost and what I have to do! And it would be pretty cool to do something different…

And I dunno if i mentioned this but on this car I will be running a vented hood and will be making custom ducts on the front bumpers for the side radiators if I do go this route. All the duct work will look as if its factory parts, I own a plastic injection/molding company so ill have no probs fabbing up all that fun stuff!

Looks like an cool setup but it might be the same effective cooling if the two combined are the same area as a single large radiator that you would typically run. I would guess that the outlet from the motor would divide into the two radiators and the outlet from the radiators converge to the motor inlet? Maybe run an inline swirl pot on the outlet before the divide with tightly shrouded high cfm fans and tight nozzle-like ducting should make things better.

[Munki]

^^Funny you mentioned a vented hood... Call this coincidence or whatever; but when I switched to a vented hood, I noticed my coolant temps actually ROSE 3-5*C.

When I sold the vented hood & put the stock one back on, coolant temps went back down. Sounds crazy I know- but this was my experience in the relatively hot climate of Okinawa.

I am not trying to detour you froma any course of action... Just trying to throw stuff out for you to consider. I am NOT a professional mechanic, just an enthusiast; so please take anything I say as such.

I think it depends on what kinda vented hood your using... Im sure if you install a decent hood that gets rid of most the heat in your bay itll be pretty effective. Ofcourse you wouldnt want a hood letting air in..... That'll keep all that hot air trapped in there!

Looks like an cool setup but it might be the same effective cooling if the two combined are the same area as a single large radiator that you would typically run. I would guess that the outlet from the motor would divide into the two radiators and the outlet from the radiators converge to the motor inlet? Maybe run an inline swirl pot on the outlet before the divide with tightly shrouded high cfm fans and tight nozzle-like ducting should make things better.

I've seen people run something like that. I've also seen someone run straight through one rad to another. Kinda like this \/

http://www.hotrodders.com/forum/attachment.php?attachmentid=45337&d=1272082503http://www.hotrodders.com/forum/attachment.php?attachmentid=45338&d=1272082503


There's several ways to do this, just gotta figure out which method is the most efficient! I want maximum cooling/air flow for the radiator, FMIC and condenser. Guess I have LOTS of research to do... lol

[aligoodn]

I would definitely configure the radiators in a parallel flow configuration. The head loss may be too significant in series for the factory water pump without some help from an external electric pump.

Are you planning to duct the lower outside vents on the S15 bumper to each radiator and leave the middle vent for the fmic and ac condenser? With effective ducting and at speed, you'd be surprised how little area you actually need to meet the heat loads of the engine while the car is moving. The most limiting case for most street cars is idling in traffic on a hot day with the ac running.

I had similar problems to yours in my S14 with an RB26 swap, ac never really worked effectively and the temperature was flaky even at highway speeds when it was hot out. Even upgrading to a dual pass radiator didn't solve the problem, but it did help. My problem was ducting. I built a duct out of aluminum for the lower opening of the jdm S14 kouki bumper and the upper where the grille is (I'm using the normal jdm grille). The lower duct ensures that no air can escape without passing through the intercooler, and behind the intercooler all air is forced through the ac condenser and then the lower part of the radiator. The air from the grille is forced through the upper portion of the ac condenser and the upper portion of the radiator. Using a pair of electric puller fans (no room for the clutch fan), I can now sit in traffic with no concern of temperature rising and when I do lean on the car, I've had no issues with temperatures.

It wasn't enough to just duct the portion that goes to the intercooler, air was still escaping between the fmic and the condenser or the condenser and the radiator.

I think your idea is cool, but I think you can achieve similar results by carefully fabricating proper ducting. Now if part of the reason is to be unique, then I say go for it because it'll definitely be cool (no pun intended).

[Munki]

I would definitely configure the radiators in a parallel flow configuration. The head loss may be too significant in series for the factory water pump without some help from an external electric pump.

Are you planning to duct the lower outside vents on the S15 bumper to each radiator and leave the middle vent for the fmic and ac condenser? With effective ducting and at speed, you'd be surprised how little area you actually need to meet the heat loads of the engine while the car is moving. The most limiting case for most street cars is idling in traffic on a hot day with the ac running.

I had similar problems to yours in my S14 with an RB26 swap, ac never really worked effectively and the temperature was flaky even at highway speeds when it was hot out. Even upgrading to a dual pass radiator didn't solve the problem, but it did help. My problem was ducting. I built a duct out of aluminum for the lower opening of the jdm S14 kouki bumper and the upper where the grille is (I'm using the normal jdm grille). The lower duct ensures that no air can escape without passing through the intercooler, and behind the intercooler all air is forced through the ac condenser and then the lower part of the radiator. The air from the grille is forced through the upper portion of the ac condenser and the upper portion of the radiator. Using a pair of electric puller fans (no room for the clutch fan), I can now sit in traffic with no concern of temperature rising and when I do lean on the car, I've had no issues with temperatures.

It wasn't enough to just duct the portion that goes to the intercooler, air was still escaping between the fmic and the condenser or the condenser and the radiator.

I think your idea is cool, but I think you can achieve similar results by carefully fabricating proper ducting. Now if part of the reason is to be unique, then I say go for it because it'll definitely be cool (no pun intended).

I have a vertex ridge s15 front end, so the side vents are pretty big. Twice the size of the factory s15 vents! Also, the ducting will be super tight on the bumper... Basically, all the air coming into those vents will go straight through the side radiators with help from the e-fans. Same deal with the front vent. I actually might make more ducting between the FMIC and Condenser since there will be a decent gap between the two. I’m also thinking about using the stock rb26 clutch fan and just making a custom shroud that'll clip onto the condenser.

If you figure in the duct work on the front bumper and between the FMIC & condenser, the 3300cfm e-fans, a nice cooling panel and a vented hood, everything should work out pretty damn good… With this set-up I don’t see why my engine wont stay pretty cool and the AC freezing cold…

The only thing im concerned about is the excessive cooling lines, then again it might not even be that bad… We’ll see soon enough. I should be finished with my 370z interior conversion sometime next week, so after that im just gonna start fabbing everything up and hope for the best.

[aligoodn]

Yea sounds good. I remember doing some calculations in college that showed that with proper ducting, the duct entry only needs to be approximately 20-30% of the frontal area of the heat exchanger with minimal loss in cooling efficiency compared to being fully exposed in a free stream. The holes in the radiator are so small that the air flow is turbulent anyways, so there's very little boundary layer effects even with the linear velocity reduction you have with an expanding duct.

[Munki]

Yea sounds good. I remember doing some calculations in college that showed that with proper ducting, the duct entry only needs to be approximately 20-30% of the frontal area of the heat exchanger with minimal loss in cooling efficiency compared to being fully exposed in a free stream. The holes in the radiator are so small that the air flow is turbulent anyways, so there's very little boundary layer effects even with the linear velocity reduction you have with an expanding duct.

That’s some good information right there! There’s tons of calculations though, its kinda mind boggling going through the heat transfer crap.... Some good info on this page! \/

http://www.maplesoft.com/support/help/Maple/view.aspx?path=applications%2fRadiatorDesign (http://www.maplesoft.com/support/help/Maple/view.aspx?path=applications%2fRadiatorDesign)

Sometime this week when i get these lines hooked up in the model im gonna run a flow simulation and a few other test. Hopefully everything runs smoothly!

[Matej]

It would probably be more convenient to just do dual side-mount intercoolers, thus freeing airflow to the radiator and condenser.

Similar to this OEM Audi setup.
http://i303.photobucket.com/albums/nn145/mk405gli/011.jpg

Or make some ducting.
http://4.bp.blogspot.com/_MHfhu_t5KII/TDgkrKaFttI/AAAAAAAABMA/AzQENaPYWIY/s1600/DSC00439.jpg


Though it seems that you are set on doing dual radiators just for the sake of having dual radiators, in which case, go for it.

[PoorMans180SX]

Run Methanol and hotpipe the car, no more FMIC to get in the way... For real.

But if you're set on running regular gas, You need to duct duct duct everything in.

I'd suggest you move the intercooler as far up as you can and duct everything for flow. This way the intercooler isn't blocking the whole grill opening. It should also shorten what looks to be massively long, low-hanging intercooler piping.

[fliprayzin240sx]

I'm telling you, run a stock setup like I described...I've seen enough 800-1K whp RB26'd S-chassis and GTRs that run the stock setup without any overheating issue and AC working properly.

[twinspool]

Man fuck heat transfer! Hate that class! lol Butttt dual intercooler would be a great alternative that way the water pump would not be struggling to pump from one to the other unless you do like I mentioned above with two dual pass radiators like a boss!

[Bleakley]

Edit...

I'm an idiot...