Nismo280zEd Posted August 1, 2008 Share Posted August 1, 2008 So I'm reading this, knowing my 280 suffers from overheating. I've always wanted to cut the core support and redo it out of steel tube. My friend has a z31 and the radiator is angled and I wanted to copy that idea, however.... Does angling the radiator forward actually have any effect on the cooling efficiency of the setup? IE does it cool beter or worse or no difference. As long as it doesn't make it worse I would like to do this as it would give me more room for larger cooling fans (3 row AL radiator) Quote Link to comment Share on other sites More sharing options...
74_5.0L_Z Posted August 1, 2008 Share Posted August 1, 2008 I angled my radiator forward as part of an overall philosophy for handling the air that enters the front of the car. I want every air molecule that enters an opening in the front of the car to have a purpose. That is, air entering the front of the car should either cool something or feed the engine. In my case, the forward angle of the radiator allows me to establish ducting before and after the radiator that should reduce the drag coefficient of the car, increase the cooling efficiency, and possibly create a little downforce. The angle of the radiator is only part of the package. For the angle of the radiator to have any meaning, several other things have to happen: The ducting ahead of the radiator must cleanly slow the air (expand) to the face of the radiator. The ducting ahead of the radiator must be sealed to the face of the radiator (I use a rubber gasket). The ducting behind the radiator must reaccelerate the air back into the free stream. It took a lot of effort to establish the radiator ducting on my car. To do so, I designed my front frame rails so that the radiator could sit low and be unobstructed. The frame section that normally crosses in front of the radiator has been moved back in line with the sway bar. The placement of every component on the front of the engine was performed with the intention of keeping the exit plane of the radiator open. The alternator was moved to the bottom, the belt tensioner was kept as low as possible, and the radiator hoses were routed to the sides. It takes a lot of planning to do this right. If you are not planning to attend to all of the details that make the forward angled radiator beneficial, then you would be better off spending the time to assure that the radiator is sealed to the radiator support. The angle of the radiator means nothing unless the other details are in place. Quote Link to comment Share on other sites More sharing options...
g00kb0i Posted August 1, 2008 Author Share Posted August 1, 2008 wow, your car is awesome. every time i see it, it make me want to do a tube frame as well. thanks for all the helps guy, hopefully i get some time in on the car saturday. thanks !! Quote Link to comment Share on other sites More sharing options...
blueovalz Posted August 1, 2008 Share Posted August 1, 2008 My personal experience has been the that the radiator provides no recognizable affect on down force. the air velocity and mass flowing through the radiator is not enough to do this. What did help the downforce issue was that angling the radiator one way or the other (goal was to reduce the "vertical height") which then allows the changing of bodywork and hood angles to promote the downforce (area within the first 2 feet of the front edge of car or hood) Quote Link to comment Share on other sites More sharing options...
Nismo280zEd Posted August 2, 2008 Share Posted August 2, 2008 So is that basically saying the radiator in the z31 was angled only so they could make the nose of the car slope more? Because they don't accelerate the air out or slow it down going into the radiator. I'm mainly looking to do this to get more room for cooling fans and knuckels, I'm not keen on the idea of putting a huge hole in my hood to vent the air... might attract a little to much attention for a daily. So basically I'm better off just putting the radiator infront of the core support? -Ed Quote Link to comment Share on other sites More sharing options...
74_5.0L_Z Posted August 2, 2008 Share Posted August 2, 2008 The main reason that the vette and Z31 angle their radiators is so that they can fit a larger radiator under the same hood line. If placing the radiator at at angle gives you the benefit of using a larger radiator, better fans, or more room, then go for it. You don't have to cut a hole in the hood just because you angled the radiator. The air will find its way out, but if the air exiting the radiator has an easy path to a low pressure area then you have an easier time keeping the engine cool. If you don't plan on some sort of hole in the hood, then perhaps angling the radiator rearward would be best. If you take that path, make sure that you seal the radiator core to the opening so that air will not spill around the edges. Air spilling around the radiator rather than going through the cooling fins absolutely ruins the cooling efficiency. Also make sure you have a good air dam with an under tray so that you create a good low pressure area behind the radiator. For an example of this, look at a new Corvette. Quote Link to comment Share on other sites More sharing options...
Nismo280zEd Posted August 2, 2008 Share Posted August 2, 2008 I don't have a problem venting the hood, but a huge vent might attract a little too much attention and beg to be messed with. I don't have a problem ducting air to vent through the fenders either, infact I think it would be pretty neat. My concern though is... I honestly have no idea how big or small these vents would need to be to effectively evacuate the hot air around the engine, etc. I have to do major surgery to the front of the car anyway, but I don't want to do it wrong and it up with something worse than what I had. I hope that makes sense. I can use common sense and logic to guestimate airflow and size but from what I've seen and learned on here, this is something that even a minor mistake can make a huge difference. Quote Link to comment Share on other sites More sharing options...
chelle Posted August 2, 2008 Share Posted August 2, 2008 NICE work guys! our Lambo has the radiator angled forward and is ducted to flow out through the front bonnet like some of you have and it has never seemed to get light in the front at speed. I never understood why they didn't keep the vents in the hood on the later cars. Quote Link to comment Share on other sites More sharing options...
ZROSSA Posted August 2, 2008 Share Posted August 2, 2008 Have a look at some of the newer wrc cars. They have small vents but are fully ducted. I dont think you need that big a hole in the hood to make it work. Douglas Quote Link to comment Share on other sites More sharing options...
aziza z Posted August 3, 2008 Share Posted August 3, 2008 A little off subject, but what are the wheels on post #1? width/size? Quote Link to comment Share on other sites More sharing options...
Careless Posted August 3, 2008 Share Posted August 3, 2008 those are either SSR Professors or Work Meister S1 2 or 3 Piece. Quote Link to comment Share on other sites More sharing options...
g00kb0i Posted August 3, 2008 Author Share Posted August 3, 2008 i believe theyre ssr's. ssr make all their sizes in 4x114.3. i guess they may be works if he did the 5 lug conversion. Quote Link to comment Share on other sites More sharing options...
Sven Posted August 6, 2008 Share Posted August 6, 2008 While I was finalizing the design of my front end, I did a little bit of research. One of the best references that I found was a web site about cooling wankel powered aircraft. The author of the web page (Paul Lamar ) has since removed the content from the web and published a book with the content. The web page that links to the author is here: http://www.rotaryeng.net/how-to-cool12.html The web page and the book that sprang from it are a great compilation of data that sprang from research on cooling piston engine powered fighter aircraft at the end of World War Two. This book does a great job of summarizing the information from Kucheman and Weber's "Aerodynamics of Propulsion", and from London and Kay's "Compact Heat Exchangers". read Paul Lamar's book. Damn! I knew I should have Pdf'ed that entire site. It was an awesome source of info. I even tracked down and bought "Aerodynamics of Propulsion" because of that page. Looks like I have another book to buy... Quote Link to comment Share on other sites More sharing options...
74_5.0L_Z Posted August 6, 2008 Share Posted August 6, 2008 I too really liked the wankel site and was inspired to track down a copy of "Aerodynamics of Propulsion". Unfortunately, I wasn't able to find a copy for purchase, so I borrowed one from the NASA library. Quote Link to comment Share on other sites More sharing options...
Pyro Posted August 7, 2008 Share Posted August 7, 2008 FYI, 1969 to 78 vette's tilt the top of the radiator towards the engine. It looks like hood vents should be used if the top of the radiator is tilted forward. Quote Link to comment Share on other sites More sharing options...
wondersparrow Posted September 6, 2008 Share Posted September 6, 2008 Well I am definately no rocket scientist, but if you were to push all that air out the hood, would that not cause more lift on the back end? You may create a small ammt of downforce on the front doing that, but instinct somehow tells me it wont overcome the negative effects of the lift on the rear. If you put on proper side skirts and a decent rear diffuser, wouldnt it be better to have that air going under the car? One of the things I was thinking of doing is try and create a good low pressure area under the car from the axel back. Quote Link to comment Share on other sites More sharing options...
VinhZXT Posted September 8, 2008 Share Posted September 8, 2008 The C5's have their radiator tilt back toward the firewall and that's how I got mine set up. I had to do this because I am using the C5 air intake duct. I also have an opening on the top to let air escape if it won't go thru the radiator. Not sure how affective it is yet cuz the car is still not complete yet. Quote Link to comment Share on other sites More sharing options...
Bankai Dan Posted September 13, 2008 Share Posted September 13, 2008 The first car is the "Battle S30" http://www.geocities.jp/kuni_s30z/ Yes, the wheels are SSR Professor SP1. Quote Link to comment Share on other sites More sharing options...
blackwidow Posted September 20, 2008 Share Posted September 20, 2008 From what i have researched the tilt of the radiator, foward or aft, is not what is important. The important factors are ducting and if you will notice most cars make use of the low pressure zone that naturally hapens after the air has hit the front of the car. What this does is use the vacuum of the low pressure zone to extract air through the radiator. Also the opening that air goes through to get to the radiator only has to be around 80% of the size of the radiator. All this comming together causes better cooling, better COD, and more downforce as stated by not causing eddies under the car. Plus you can also vent from your radiator box to your brakes. Plus it is a good time to take some sheet aluminum and make your underbelly look like that of a corvette or elise. Quote Link to comment Share on other sites More sharing options...
Nismo280zEd Posted September 25, 2008 Share Posted September 25, 2008 Is there an easy way to determine low pressure zones on the front of the Z? I know you can rig up sensors and drive around but is there another simpler way? -Ed Quote Link to comment Share on other sites More sharing options...
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