JMortensen Posted February 24, 2023 Author Share Posted February 24, 2023 (edited) Looks like "shaft adapter" is the term that gets you what you need. 5/16 to 5/8 is not a common size, but 8mm to 16mm is and 5/8 to 5/8 is. Found 2 solutions: put a sleeve over the 5/16" shaft that is 5/8" and then run a straight adapter, or run the 8mm to 16mm. The problem is that there is a flat on the 5/16 and a key on the 5/8 shaft. I suppose I could just get the 5/8 to 5/8, drill a hole in the 5/16 to 5/8 bushing and then use a set screw on the 5/16 side. That should work... Thinking I'll buy the same type of motor Big Al did, along with a bushing and an shaft adapter and see how nice the pieces go together. Should be pretty simple in theory. Theory doesn't always translate to practice though. EDIT--Found a premade adapter for $16. https://www.ebay.com/itm/292457042171 EDIT 2--Bought the motor. Will verify shaft diameters then order the adapter. This is great. Don't have to spend another $200 or try to get rid of the part that I already purchased, and I'm sure the motor will hold up as it's what they use for the other style pump, gets rid of the diaphragm. Thanks Clark, you saved the day. Edited February 24, 2023 by JMortensen Quote Link to comment Share on other sites More sharing options...
JMortensen Posted February 24, 2023 Author Share Posted February 24, 2023 (edited) On another front, I went out to my shop yesterday to look paneling the bottom some more. Grabbed my magnetic 4' level and slapped it on the bottom of the fuel cell that I had mounted at a 7* angle many years ago, in preparation for making a diffuser. Thought for sure the diff cover would be in the way. Nope. It cleared by 1/8" or so. When I get the cooler on I'm going to run the standard cover, so more clearance at that point. So then I held a piece of angle up to the frame rail and figured out where it intersected the level. From that intersection to the back of the car I've got about 42". So I can make a 3.5 foot long diffuser and it will fit under the car, and the height of the diffuser in the back works out to about 6" tall. Also, the control arms are high enough with sectioned struts, camber plates, and droop limiters that I think I can make the diffuser full width between the tires and not hit anything. I had thought that the diff cover would be in the way and that I'd have to make a shorter steeper diffuser, but nope. Can go fairly huge. So now I've got all of those plans going in my head. Thinking I'll do AL and figure out the sizes with less hassle and expense, and then maybe redo in FG or CF later on down the road. I run the car with a bit of rake so I might have to have the outer fences extend lower than the center to keep it close enough to the ground to be effective, but I did crack open Competition Car Aero and they showed that a 10* diffuser was best on a similar height 350Z, and that it worked even better on a raked chassis (basically the rake doesn't affect the flow attachment, so raking the chassis improves the effective angle of the exhaust of the diffuser). That's good stuff. So might try to build at 10* and just fit it where it fits. I don't think the diffuser entry will be that much further back with the extra 3* of angle. EDIT--Looks like the difference in length between a 7 degree diffuser and a 10 is .259". Edited February 24, 2023 by JMortensen Quote Link to comment Share on other sites More sharing options...
tube80z Posted February 24, 2023 Share Posted February 24, 2023 Those adapters can be found in the McMaster catalog and come in all sizes. You can also drill one side or the other too. I may do the same thing you have shown if I decide that a v-belt mounting is more trouble than going this way. At least with the electric motor on the pump you could run the oil while the car is stationary to cool it after a track session. Quote Link to comment Share on other sites More sharing options...
JMortensen Posted February 24, 2023 Author Share Posted February 24, 2023 2 hours ago, tube80z said: Those adapters can be found in the McMaster catalog and come in all sizes. You can also drill one side or the other too. I may do the same thing you have shown if I decide that a v-belt mounting is more trouble than going this way. At least with the electric motor on the pump you could run the oil while the car is stationary to cool it after a track session. I found one on ebay for $16. Posted the link as an edit. Cheaper than mcmaster.com Quote Link to comment Share on other sites More sharing options...
tube80z Posted February 24, 2023 Share Posted February 24, 2023 McMaster reference was to find a part and I figured you'd use that to get a cheaper price. I rarely use them myself unless I'm in a real bind and need something right now. It's cool that I can drive over to a warehouse and pick it up. Quote Link to comment Share on other sites More sharing options...
clarkspeed Posted February 26, 2023 Share Posted February 26, 2023 (edited) I really like the idea. Edited February 26, 2023 by clarkspeed Quote Link to comment Share on other sites More sharing options...
JMortensen Posted February 27, 2023 Author Share Posted February 27, 2023 (edited) Pulled the 4.11 out today. Gonna swap the LSD into the 3.54 and sell the 4.11 and the finned cover. I'm thinking diff is probably worth $1100, cover $300, but I'm kinda out of touch on pricing. Thoughts? Also, figured out what to do for the paneling on the bottom. Going to do alumalite for the center and side splitters, and alumanate for the diffuser. I had forgotten about alumalite, and had never heard about alumanate, but I found this video and reintroduced myself. Now I'm looking at different diffuser shapes, rather than just a straight one. I'll definitely make this more complicated than it needs to be, and probably end up with something pretty cool. This guy has some interesting bits, but I really don't like the gurney after the front fender opening. That seems totally backwards to me. I get it, there is a vent on the back side of the flare, but some dive planes in front would do the job much better. I do really like his diffuser though. Edited March 3, 2023 by JMortensen Quote Link to comment Share on other sites More sharing options...
calZ Posted February 27, 2023 Share Posted February 27, 2023 I'm confused what you mean by the dive planes would do better. The Gurney flap is to lower the pressure behind it and help get air out of the wheel wells, not create downforce by themselves Quote Link to comment Share on other sites More sharing options...
JMortensen Posted February 28, 2023 Author Share Posted February 28, 2023 (edited) Sold my cover in about 10 min for $320. If you've got one you want to sell, ask for $400 is my advice... Dive planes make a large vortex that flows down the side of the car. Top side of canard is high pressure, bottom side is low pressure. As the air passes spills off the sides and back of the dive plane, it spins around to mix and return the pressure differential back to zero. The vortices down the side of the car would help to suck the air out of the fenderwells. About 4:30 into this one he draws it, and it looks like the drawing is actually the thumbnail for this video. Convenient if you don't want to watch: Edited February 28, 2023 by JMortensen Quote Link to comment Share on other sites More sharing options...
calZ Posted February 28, 2023 Share Posted February 28, 2023 I try to avoid making absolute statements without having run the CFD, but I'm pretty doubtful that you'd get even close to the same benefit from the vortices that you'd get from a Gurney flap. The vortex lowers the pressure in the area, but not like the flap would. The flap essentially creates a vacuum behind the flap that the vent air has to come out and fill. Quote Link to comment Share on other sites More sharing options...
JMortensen Posted February 28, 2023 Author Share Posted February 28, 2023 Gurneys work by deflecting attached flow and creating turbulence. The flow in this area is already detached and turbulent because the flow around the wheels and wheelwells already makes a low pressure area. It's like putting a spoiler in the middle of a hatch back. If the air isn't attached, it's not doing much, if anything. Google "cfd race car sedan" and you won't find one that has flow lines that are attached in that spot. I found this one that really shows the problem. I stuck the gurney placement on the Subaru in green to show the problem. If you're talking about putting a gurney at the leading edge of the fender opening to create even more turbulence in the wheel area, that's a different story. I have those on my car. Quote Link to comment Share on other sites More sharing options...
calZ Posted March 1, 2023 Share Posted March 1, 2023 A Gurney flap creates suction on its rear side. The flow doesn't have to be perfect, and you aren't getting laminar flow anywhere on a car. Look at basically any racecar with a radiator ducted to the hood. There's a Gurney flap to increase the suction in its wake. Flow isn't binary. It isn't clean or dirty, and pressure isn't just high or low. There's varying degrees to all of it. The smoke in the Ecoboost picture you posted is still flowing through that area, even if it's a little messy. The more you vent out the top and rear of the wheel well, the cleaner the flow will be alongside it because there won't be as much spill. He's done a pretty good job of that on the car in the video, so the flow by his wheels is likely even better than the aforementioned Ecoboost picture. Quote Link to comment Share on other sites More sharing options...
tube80z Posted March 1, 2023 Share Posted March 1, 2023 On 2/27/2023 at 2:43 PM, calZ said: I'm confused what you mean by the dive planes would do better. The Gurney flap is to lower the pressure behind it and help get air out of the wheel wells, not create downforce by themselves According to the video they wanted to reduce drag. That mod will increase it. This video is a total waste of time. It's mostly opinion from seeing what a bunch of other people did on youtube and trying that. No data logging, no attempts at actual testing, etc. If you look at Julien Bailey's youtube videos he shows you how to test this stuff for real in simple ways. The gurney should be on the front of the fender and not the rear. Cary Quote Link to comment Share on other sites More sharing options...
JMortensen Posted March 1, 2023 Author Share Posted March 1, 2023 Yeah, I did think it was weird that they blocked above the diffuser to "decrease drag" but allowing air over the diffuser would decrease the wake behind the car, decreasing drag. Saying you don't know what you're doing isn't the best way to sell your idea either. The main bit I got was that Alumanate material, which I had never heard of. I'm going to put the angle on the OUTSIDE of the diffuser too... I'll look for Julien Bailey. I've been watching AJ Hartman's stuff and trying to find other sources, so that's helpful. Thanks. Quote Link to comment Share on other sites More sharing options...
JMortensen Posted March 1, 2023 Author Share Posted March 1, 2023 Julian Edgar maybe? Julian Bailey is a DJ. Quote Link to comment Share on other sites More sharing options...
calZ Posted March 1, 2023 Share Posted March 1, 2023 3 hours ago, tube80z said: According to the video they wanted to reduce drag. That mod will increase it. This video is a total waste of time. It's mostly opinion from seeing what a bunch of other people did on youtube and trying that. No data logging, no attempts at actual testing, etc. If you look at Julien Bailey's youtube videos he shows you how to test this stuff for real in simple ways. The gurney should be on the front of the fender and not the rear. Cary The flap will add a drag component, but the hope is that the added suction on the vent outweighs it. Hard to tell without testing or simulations though. Agreed on it just being guessing, though. That's what a huge amount of the amateur racecar aero you see is. Very few people have the knowledge or resources to properly test small changes like that. Wings and airdams are easy to measure, but smaller features get hard to isolate and measure. Quote Link to comment Share on other sites More sharing options...
tube80z Posted March 2, 2023 Share Posted March 2, 2023 20 hours ago, calZ said: Agreed on it just being guessing, though. That's what a huge amount of the amateur racecar aero you see is. Very few people have the knowledge or resources to properly test small changes like that. Wings and airdams are easy to measure, but smaller features get hard to isolate and measure. That's where I want to disagree. While many amateurs' may not have access to CFD, wind tunnels, or advanced DA that doesn't mean you can't test these things in a more scientific manner to remove the butt dyno from the experiment. As Jon pointed out I messed up the name of Julian Edgar who has a decent book and a YouTube channel that promotes the content. If you sit through his videos you'll get the high points of what's needed. If you have a newer gopro you also have a data logger and you can record old school manometers inside the car to see if you're change made a difference or not. There's simple coast down testing that can be used to determine drag, etc. It doesn't appear this person did any of that and copied what looked useful here and there. If someone paid for a lot of development and has the same car as you do then this process may work but you also need to know what to change to keep the car balanced. One of the downsides of downforce is that weather has an effect and the more you add (downforce) the more you'll need to change things to stay balanced. Hope that helps, Cary Quote Link to comment Share on other sites More sharing options...
tube80z Posted March 2, 2023 Share Posted March 2, 2023 23 hours ago, JMortensen said: Julian Edgar maybe? Yep, I'm a moron Quote Link to comment Share on other sites More sharing options...
calZ Posted March 2, 2023 Share Posted March 2, 2023 I'd put the use of manometers above the capability of your average car builder, but fair enough. Quote Link to comment Share on other sites More sharing options...
JMortensen Posted March 2, 2023 Author Share Posted March 2, 2023 I'm pretty sure I can use a manometer, but I don't want to drill a million holes in everything to test. I've seen it done where they have tested in maybe 20 spots around a paneled floor and then kinda guessed at the numbers in between and then used that data to convert to pressure and get an estimate of downforce. Would be cool to do, but I think for all of that I'd rather put pots on the shocks and look for suspension compression. Although I'm sprung pretty stiff, so that might not work as well in my case. Quote Link to comment Share on other sites More sharing options...
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