JMortensen Posted February 15, 2023 Share Posted February 15, 2023 This has been a back burner idea for me since bjhines installed one 17 years ago. Last year I installed an oil cooler thinking about doing track days (LS engines get the oil HOT) and so now I think is the time to get the diff ready for track duty as well. Here's John's thread: I'm finally getting around to doing one for myself. I am not a fan of the Tilton pumps, they're expensive and so I started asking around and I got some good info on pumps, so thought I'd share my findings. NASCAR runs mechanical pumps off of the pinion, using essentially a single stage dry sump pump. These are run with a V belt, and then you put some sort of pulley on the driveshaft or the pinion flange. This has a couple advantages, mechanical pumps are gear driven not electric motor with a diaphragm, so should be more reliable. Don't have to remember to turn it on. If you buy the pump used, it's pretty cheap. I bought a pump with a 6.25" pulley and bracket that bolts to a 9" Ford diff for $100. No fittings, no lines, no cooler, but it's a start. When I had my driveshaft built I screwed up my measurements and it came out a bit long. It fits, but just barely. Plan is to take the driveshaft back out, have it shortened, and then either modify a pulley to bolt in between the pinion and the shaft, or weld the pulley either the shaft or the pinion flange, depending on which works out better in the space. I'm still considering how to mount the cooler, how to feed it air, and how big to go. I definitely want to go bigger than John did, as he measured 350* AFTER installing the cooler, at the end of a 20 min session with the 6 cyl working to build the heat. Katman had described breaking the needle off of a 325* gauge in a session with a 6. I want to install, and not worry about cooking the diff again. I have the fuel cell and Accusump offset to the right side to move weight. Thinking I have room to put the pump to the right of the diff, then can run the oil lines to the left side and have the cooler placement somewhere in the stock muffler area. Feeding air thru it effectively might be a challenge. Preliminary thoughts on cooler feeding/exhausting: 1. Put a NACA duct in the quarter window and run a 3" hose down to the floor (can go through the fuel cell cover, and then feed the cooler which sits horizontally. I have doubts that the cooler will flow a lot of air in this position. I don't have pressure readings, but I'm thinking that right behind the open window is not a high pressure zone, and the air will be exiting near the gas tank, which I am hoping might be sucked out by the wake under the car, but I don't anticipate a huge pressure difference. 2. Finally get off my ass and put a flat bottom on the car, at least between the frame rails, which is legal in XP. Plan here was to use thin aluminum, maybe .040" thick. I worry about leaks onto fiberglass or cf that is flammable. If I did the aluminum panel between the frame rails, then I could run some NACA ducts in the floor and maybe a pair of 3" hoses to the cooler, possibly making a fan shroud type of setup so that all the air goes from the hose through the cooler. I think this might be a better way to feed the cooler, but I'm still not sure about getting the air out the other end. Eventually will do a diffuser, and if I leave space between the diffuser and the body I think that the increased low pressure from the flat bottom and diffuser would help to exhaust the air out of the cooler. Might even be able to make an exhaust duct from the cooler to the slot between the diffuser and the rear valance, but I don't think I have the time/funds to do a diffuser and all of that ducting right now. Leaning towards #2, but any thoughts on ducting, the panel, mounting the cooler etc are welcome. Quote Link to comment Share on other sites More sharing options...
tube80z Posted February 17, 2023 Share Posted February 17, 2023 I've seen these setup using one of the NASCAR blower fans (3-inch duct) that draws air from the back part of the cabin and blows it onto the cooler. If you look on ebay they sell all kinds of carbon covers designed to do that are be used in a pulling manner. Setrab oil cooler, https://www.ebay.com/itm/224998346250 Carbon cover and cooler, https://www.ebay.com/itm/175617112356 Carbon bits, https://www.ebay.com/sch/i.html?_from=R40&_trksid=p2047675.m570.l1313&_nkw=Carbon+fiber+Oil+Cooler+duct+&_sacat=0 You can't beat ebay used NASCAR parts prices for a lot of these items. I would recommend you take any used oil cooler to a company the does ultrasonic cleaning. But given this is a diff you could probably just ran solvent through it in the a clean parts washer if that sounds like a pain. When you add the floor you can either cut a hole for the cooler to exit into or add one to the rear valence. The old IMSA Corvettes had an tranny cooler located where the license plate used to sit with a fan behind it. Quote Link to comment Share on other sites More sharing options...
JMortensen Posted February 17, 2023 Author Share Posted February 17, 2023 That first Setrab cooler looks like what bjhines used, small and easy to package, but he reported 350* temps after installation, behind a 6 cyl. I was thinking about going quite a bit bigger, more like the second one. If I ran a flat panel between the frame rails and 2 NACA ducts to feed that carbon duct, I think that would work nicely. Then I thought I should put one or two more in the panel further forward, just to blow on the trans. It's taken me so long to get to this I've forgotten some of what I read about it, but I do remember a Miata guy who had to install NACAs to blow air on the trans and diff without coolers. I think the same guy tried a plastic panel and it melted from the heat. Did DM Gira about this, he seemed to think what I was doing was huge overkill, but I guess that's sort of a theme for me. It really does seem like these diffs get HOT though, and if you're going to do it, might as well do it right. Quote Link to comment Share on other sites More sharing options...
calZ Posted February 17, 2023 Share Posted February 17, 2023 The NACA inlets don't really need to be in an area of particularly high pressure to work. They just require the flow to be attached to the surface. The total pressure coming into the inlet should easily overcome any elevated static pressure on the rear of the car. Quote Link to comment Share on other sites More sharing options...
JMortensen Posted February 18, 2023 Author Share Posted February 18, 2023 (edited) 29 minutes ago, calZ said: The NACA inlets don't really need to be in an area of particularly high pressure to work. They just require the flow to be attached to the surface. The total pressure coming into the inlet should easily overcome any elevated static pressure on the rear of the car. The quarter window right after an open window isn't the best for attached flow. I agree about the pressure at the rear of the car being really low though, so maybe NACAs, even in the quarter window, would work better to feed a cooler under the rear of the car than they would to push fresh air into a helmet in the cabin. Still thinking two underneath in the bottom panel might be better, the flow would definitely be better attached. Edited February 18, 2023 by JMortensen Quote Link to comment Share on other sites More sharing options...
JMortensen Posted February 18, 2023 Author Share Posted February 18, 2023 (edited) Pretty well settled on the idea of paneling between the subframe connectors. Picked up some NACA ducts on ebay. Got a double and two singles with 3" outlets. Will use one or both of the singles to cool the trans, and the double to feed the cooler. Waiting on the pump to show before I buy a cooler. It was advertised as -10 but want to make sure. Any thoughts on thickness of aluminum to use for the undertray? Was thinking .040, but don't have any experience here. Obviously lighter is better (and cheaper too). Online Metals (local) has .032", .040", .050" and .060" Edited February 18, 2023 by JMortensen Quote Link to comment Share on other sites More sharing options...
JMortensen Posted February 21, 2023 Author Share Posted February 21, 2023 Got the pump. Took it out to the shop. Went and looked under the car. My mental image of what was under there was so wrong that now I can't even remember how I thought this would all go together. It is a DEFINITE no go without major trans tunnel hackage and putting the pump inside the car, and I don't want to do that just because of the fire hazard. I'm just stunned at the fact that I thought I could make it work. NO WAY was it going to go on the right side of the pinion, especially with my drivetrain offset to the right. The reality of what is under there is so much different than I thought. It's not like I haven't been under that car for thousands of hours. LOL I guess it has been a little while, but DAMN! 😂 Now I'm trying to figure out if I can use this pump at all. I remember Gian Bowles at one point had an electric motor bolted to the front of his engine that drove a Gilmer belt, and that ran the mechanical water pump. Maybe I could do a small electric motor driving a belt to the oil pump. Or maybe I should just buy a Tilton pump and make my life easier. The other thing that isn't working to plan is the finned LSD cover has spots where you can install fittings for a cooler. Unfortunately they're just barely under my rear toe adjuster, so if I drilled out the spots the fittings would hit the adjuster. I think I could get around that one by putting a stock cover in and drilling it and installing a fitting through the cover, or by drilling out the drain plug like bjhines did. Ugh. This project just got a whole lot harder... Quote Link to comment Share on other sites More sharing options...
clarkspeed Posted February 21, 2023 Share Posted February 21, 2023 Been meaning to chime in but I've been busy with family and work. Some of my thoughts and observations. 1. I think some lsd's get hotter than others. Helical gears hotter than friction disks. I don't know many who run the stock Nissan lsd disks that have had problems or run coolers. And of course most racers change fluids frequently. Greg falls into both of these. And he is not running a 400Hp V8. 2. My R200 with Quaife got pretty warm during 50 minute enduro races. I took multiple readings with a IR gun after. I seem to remember the readings around 250-275 and I thought that might be detrimental to the oil. 3. I installed a Tilton electric pump and a roughly 8x12 plate cooler tucked up under the rear fender. All -8 lines. It did not have any direct air flowing to it and no ducting. My temps dropped drastically to under 200 when the pump was running. The damn thing was pretty loud when running. I then installed a 180 degree temp switch in the cover so I did not have to listen to it all the time. It tended to trip the switch after 2-3 laps. 4. I found a modified cover on EBay. It had 2 -8AN to NPT fittings welded in it. 5. It was a little tricky filling the diff with oil. I ended up filling up to the sight level while the pump was running so it had enough oil. 6. The tilton pumps are just a standard pump with special seals. Viton I think. But on one else has the seals when I was looking years ago. So I ended up buying a pump on ebay. I knew there were people selling the standard pumps as Tilton units, but I have never had a problem with mine. I think it is legit. 7. And finally, synthetic oils don't break down anything like conventional. So maybe look at it as extending change interval? I don't think you could break down even a conventional oil in say 5 or 6 20 minute track sessions at 350F. And I wouldn't have a problem adding a 1Hr Enduro to that if synthetic. But I think after adding the cooler I went to changing diff fluid along with tranny every 3 race weekends instead of every weekend. Quote Link to comment Share on other sites More sharing options...
NewZed Posted February 21, 2023 Share Posted February 21, 2023 How about a separate heat transfer fluid? Like a heat exchanger on the diff cover that flows water or antifreeze and sends it off to a remote air cooled heat exchanger. Like the engine radiator does. Leave the hot oil alone in the diff and suck the heat out of the cover. Quote Link to comment Share on other sites More sharing options...
NewZed Posted February 21, 2023 Share Posted February 21, 2023 Check out this technology. Uses vaporization of liquid to gather the heat and remote condensation to transfer it. Used in the plastics molding industry. No pumps needed. https://www.synventive.com/aboutus/default.aspx?id=44342 Quote Link to comment Share on other sites More sharing options...
JMortensen Posted February 21, 2023 Author Share Posted February 21, 2023 1 hour ago, clarkspeed said: Been meaning to chime in but I've been busy with family and work. Some of my thoughts and observations. 1. I think some lsd's get hotter than others. Helical gears hotter than friction disks. I don't know many who run the stock Nissan lsd disks that have had problems or run coolers. And of course most racers change fluids frequently. Greg falls into both of these. And he is not running a 400Hp V8. 2. My R200 with Quaife got pretty warm during 50 minute enduro races. I took multiple readings with a IR gun after. I seem to remember the readings around 250-275 and I thought that might be detrimental to the oil. 3. I installed a Tilton electric pump and a roughly 8x12 plate cooler tucked up under the rear fender. All -8 lines. It did not have any direct air flowing to it and no ducting. My temps dropped drastically to under 200 when the pump was running. The damn thing was pretty loud when running. I then installed a 180 degree temp switch in the cover so I did not have to listen to it all the time. It tended to trip the switch after 2-3 laps. 4. I found a modified cover on EBay. It had 2 -8AN to NPT fittings welded in it. 5. It was a little tricky filling the diff with oil. I ended up filling up to the sight level while the pump was running so it had enough oil. 6. The tilton pumps are just a standard pump with special seals. Viton I think. But on one else has the seals when I was looking years ago. So I ended up buying a pump on ebay. I knew there were people selling the standard pumps as Tilton units, but I have never had a problem with mine. I think it is legit. 7. And finally, synthetic oils don't break down anything like conventional. So maybe look at it as extending change interval? I don't think you could break down even a conventional oil in say 5 or 6 20 minute track sessions at 350F. And I wouldn't have a problem adding a 1Hr Enduro to that if synthetic. But I think after adding the cooler I went to changing diff fluid along with tranny every 3 race weekends instead of every weekend. bjhines was running CLSD when he measured 350* with the cooler. He picked a pretty tiny one though. I think the solution is to size it up until it's big enough. I'd say you hit the mark, so I'll start where you are at and that will probably work for me. What do you mean by #6, Tilton is just a standard pump with viton seals? Not sure what a "standard pump" is. Quote Link to comment Share on other sites More sharing options...
tube80z Posted February 21, 2023 Share Posted February 21, 2023 17 hours ago, clarkspeed said: Been meaning to chime in but I've been busy with family and work. Some of my thoughts and observations. 1. I think some lsd's get hotter than others. Helical gears hotter than friction disks. I don't know many who run the stock Nissan lsd disks that have had problems or run coolers. And of course most racers change fluids frequently. Greg falls into both of these. And he is not running a 400Hp V8. From what little I know once you go past a 4.11 ratio they heat up a lot more. 17 hours ago, clarkspeed said: 6. The tilton pumps are just a standard pump with special seals. Viton I think. But on one else has the seals when I was looking years ago. So I ended up buying a pump on ebay. I knew there were people selling the standard pumps as Tilton units, but I have never had a problem with mine. I think it is legit. Tilton has a few different pumps. One is made for continuous running and another is for intermittent. Check our https://tiltonracing.com/product/cooler-pumps/ for more info. For most the intermittent pump should work fine. But if you are doing enduro or long races then I'd get the continuous version as a precaution. There's not a huge difference in cost between the two. Quote Link to comment Share on other sites More sharing options...
JMortensen Posted February 22, 2023 Author Share Posted February 22, 2023 (edited) 5 hours ago, tube80z said: Tilton has a few different pumps. One is made for continuous running and another is for intermittent. Check our https://tiltonracing.com/product/cooler-pumps/ for more info. For most the intermittent pump should work fine. But if you are doing enduro or long races then I'd get the continuous version as a precaution. There's not a huge difference in cost between the two. Almost sounded like Clark had found a similar pump with a different name, but cheaper. Britain said that the diaphragm was the weak part of the Tilton. Maybe a gear driven unit would be better. That's what the mechanical one was, and there are these marine fuel pumps which are being advertised as turbo scavenge and diff cooler pumps: https://www.ebay.com/itm/280782665954 Edited February 22, 2023 by JMortensen Quote Link to comment Share on other sites More sharing options...
clarkspeed Posted February 22, 2023 Share Posted February 22, 2023 Mine looks like a Tilton, but didn't have a sticker on it. That's why I thought it may be counterfeit. It came in a Tilton box. Probably had it 7-8 years but only put maybe 12-15 hours on it and sold the car. I think I read somewhere they are actually cheap spa pumps converted for high temp use. Never had any issue with it. No leaks and still moves fluid. Yes Tilton is very proud of it. I do like the idea of a pulley driven pump. And understand your packaging challenges. Maybe it is possible to cut a hole in the deck or tunnel sheetmetal and mount on inside? I have seen that done before with an Alternator. Cover it all back up with a sheet metal box? Quote Link to comment Share on other sites More sharing options...
clarkspeed Posted February 22, 2023 Share Posted February 22, 2023 Oops, forgot the picture. Quote Link to comment Share on other sites More sharing options...
JMortensen Posted February 22, 2023 Author Share Posted February 22, 2023 Looks like RV water pumps are VERY similar. Diaphragm pumps, most seem to have Viton seals. Looks like the lower model Tilton equates to ~$100ish pumps like this one: https://www.ebay.com/itm/184876097420 Here's a slightly upgraded one 10A, 3 GPM, 60 psi, but with 1/2 NPT fittings for about $80: https://www.ebay.com/itm/263473361911 Tempted to try the last one there. Main thing that had me spooked was the plastic pressurized housing, but looking at your pic the Tilton looks plastic too. Was also wondering if it might be better to go bigger on the fittings to reduce restriction and thereby pressure. Just a thought. Bought cooler with -8AN fittings, but it's a Setrab so can change them out. maybe -10 or -12. I have a bunch of -10 from fitting my Accusump and oil cooler. Quote Link to comment Share on other sites More sharing options...
JMortensen Posted February 22, 2023 Author Share Posted February 22, 2023 If I still had the car torn apart I'd probably hack it up for the pulley setup. To retrofit would mean quite a bit of disassembly to clear up space, then major hacking, then trying to box it back in. Just not worth it. The idea of getting a good quality electric motor and running a pulley and then mounting the motor and pump next to each other isn't that crazy, but just adds enough complexity that an electric pump seems like the easy button. Quote Link to comment Share on other sites More sharing options...
JMortensen Posted February 23, 2023 Author Share Posted February 23, 2023 Just did a quick search and the polypropylene that the $80 pump is made from softens at 140 - 150* C which is 284-302* F. Man I am tempted... Quote Link to comment Share on other sites More sharing options...
clarkspeed Posted February 24, 2023 Share Posted February 24, 2023 Found a cool thread on subject. https://www.rx7club.com/race-car-tech-103/differential-oil-cooler-pump-1015407/ Seems Genesis and Mocal also make pumps. Maybe you could find a used one. Also read you should mount pump downstream after cooler to cool the oil some before it hits the pump. Positive displacement pump so doesn't matter. Quote Link to comment Share on other sites More sharing options...
JMortensen Posted February 24, 2023 Author Share Posted February 24, 2023 Nice to see I'm not the only one who has been down EXACTLY this road before. Thanks Clark. This first one looks promising: Found a ShurFlo pump on ebay for $29.95. I've got $100 into the single stage pump. Would be awesome to tie together and get out of it for less than the Tilton cost and not have to worry about diaphragm. I don't know what the adapter to connect the two together is, but seems like should be a common size adapter, going from 5/16 to 5/8. Tried "split collar adapter" and no joy. All of the people saying "Tilton works fine" is also making me question the utility of all of this... Quote Link to comment Share on other sites More sharing options...
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