RedFive

Awesome, thanks a million man!

Uhaul will "let" me tow the Z with a dolly. I just don't want to do that if I don't have to. Like I said, they gave me a dolly a couple years ago, I just didn't tell them I was putting another Jeep on it. This following picture is something I see a lot with the Jeep guys:

It's a good idea Tony, but they're only charging me around $100. My buddy is going to help me pickup the trailer from Uhaul with his F150. I think I'm set. But I'm still questioning the weight. I've read 2800 pounds like Phantom said, but I found on another site that the '76 280z weighs different than the '77 and '78 years. ...?

Uhaul adds in a massive factor of safety. I'm an engineer, I don't need them to do that for me. When I towed my brother's Jeep with my Jeep, by their calculations, they wouldn't have even let me use a tow dolly. So I had to lie and told them I was towing an Alfa Romeo. But somehow I managed to get from AZ to CA without a problem. I'm simply I'm interested in the weight so I can decide for myself if I can or cannot tow it. Why the fuss though? Because I'd rather not have to put the Z on a dolly. I'm sure you guys can all appreciate that. Thanks Phantom, I guess I'll come in under my Jeep's limitations. What made your Z weigh more? V8?

Grrr, I'm having trouble finding consistent numbers. I've got an '88 Jeep Cherokee and a '76 280z. I want to tow the Z to CA. I'd like to put it on a flatbed, but my hitch only supports 5000lbs. Uhaul says their flatbed weighs 2000lbs empty, but can carry a 4000lb car. That's fine and dandy, I'm sure I will come under 5000lbs with the Z on there. But by how much? I keep finding websites with different numbers on how much my Z weighs. Not to mention that it has no bumpers, hatch, or windshield. I'd like to be able to compare this to when I towed my brother's '88 Cherokee to CA with Uhaul's 650lb tow dolly. Again, I can't seem to find consistent curb weights for his Jeep. ....?

Dave, Didn't see your post right away. Yeah, they delay the flow from separating from the surface because they've created turbulent flow. But at the cost of what? A good amount of drag -- at least compared to the wing the WRX has. Okay, I was a little extreme saying the wing's mission was completely different...but I would opt for the wing option on a vehicle way before a vortex generator. Vortex generators are great for high performance aircraft that require maneuverability at very high angles of attack. It keeps the flow from separating from the surface, and the drag trade off is worth it. They're also used on commercial jets sometimes as a safety factor. If your wingtip stalls (when a wing stalls, the flow starts to separate in one spot and then spreads from there as AOA increases. Where it begins and ends depends on the design of the wing), your ailerons become useless and you risk losing control of the airplane. With the vortex generator, you can delay the stall, but again at the cost of drag. Is it worth it? Sure. If that plane stalls and starts going into a spin, nobody on that flight is going to want to fly with you again. But why do I think the Subaru guys made a good decision with the upper wing? Because the only drawback is a little bit of skin friction drag. The plus is reducing separation near the rear window, which not only reduces overall drag for the car, but makes the rear wing useful for downforce. It's a better trade off for the situation. Car designers work pretty hard to make sure flow doesn't separate on top of or near the roof of the car...because it would be loud as hell. In most cars, once they've accomplished that, they don't care too much about the rest of the car. Clearly Subaru does.

It keeps the back window clean too. --Edit-- It's just a side effect. Or you could consider the aerodynamic advantages to be the side effect. Whichever.

Armand, no I have not. But I heard that they think you get better mpg with it up. We noticed this too, but difference in drag was so small that I consider it being negligible. But of course every truck is different... Proxlamus, it sounds like the wing next to the roof is a stock option? In that case it's probably placed correctly. But doing it on another vehicle would take some testing.

Dave, The idea is not the same as vortex generators. Completely opposite. The vortex generators create non-laminar flow, whereas the mission of the wing you posted a picture of is to prevent the flow from separating. Your hypothesis on the function of that upper wing is generally correct, but who knows if it's placed correctly. If it's arbitrarily placed, the free stream might be separated before it even gets to the upper wing, thereby rendering it completely and utterly useless. We just did some research a couple weeks ago on pickup trucks. We found that it makes virtually no difference if the tailgate is up or down. Why? Because the flow is already separated off the rear of the cab, so it doesn't matter what happens after that. In the same series of tests we also added a camper shell and found that the drag increased, mostly due to skin friction. With the camper shell, the separation still occurred (obviously), but just simply delayed until further down the truck. Adding a wing like the one in the photo you have would help reduce the separation, much like the vanes used in the corners of a wind tunnel, or more commonly, the "wings" that some manufacturers mount on the rear of SUVs. Older blazers/jimmys have this...but who knows how effective they are. I could probably run a wind tunnel test in the spring sometime if you wanted. Logan

How much did he charge you?

Aside from the Lotus 7, does it seem to you guys that all Lotus model names start with an E? Why is that?? I've just recently (within the past 10 minutes) found myself fascinated by the original Lotus Elite: Apparently only about 1000 were made. But I was looking for some sort of kit reproduction with no success....?

Mike, I never really thought about them like that. But I drove one a week ago. AMAZING. Simply AMAZING. There's always this though: Though I wouldn't want to get into an accident. It's a fiberglass body with a frame that looks like a big X kinda. I imagine that if you got t-boned you'd get pinned between the t-boner and the frame.

I just test drove a Lotus Elise yesterday. Holy crap, that car is amazing. AMAZING. Completely AMAZING. Needless to say, I'll probably be buying one in the next year or so. WOW.

Yeah, I was searching and reading old posts and I saw that...but we had a pipe that was bigger than a bat and even that seemed like it wasn't going to work... Somebody said in an old post that tire rack might loan out rolling tools....but nobody confirmed...

Has anybody rolled the back/under side of their fenders in? If so, what'd you use? A buddy and I were attempting to do it today while were were doing other body work, but it seemed like we were going to need a really unusually large diameter pipe. Suggestions?

When I read your post, it sounded like there was some question somewhere...

Vortices -- be it in the rear of a truck, car, or wingtips of an airplane -- are low pressure by definition.

Olderthanme: Why 1300mph? Because Re said so? Be careful, Re numbers are nearly impossible to match. Do some reading on it, there are tricks you can pull to match up Re numbers, but it is very much a pain in the ass and sometimes not even possible. Fluid Dynamics is an okay class, but it's mostly pipe flow theory. What you really want is some sort of Experimental Aero class where you get to play with the tunnels or an Aerodynamics class where you have to work Re equations for airfoils and stuff. If you want some tips to improve your tunnel, PM me.

Jon, I think your post is directed at the incorrect person. I was the one expressing an opinion, which somebody decided to challenge because they did not agree with it.

An explanation? I'm not going to waste my time or yours trying to explain the details of aerodynamics. If you knew anything about it, you'd know that an entire book could be written just focusing on aerodynamics for Z cars. I could list a plethora of equations that nobody would understand unless they went through years of training to be an engineer...so what good would explaining it do? I'm not saying you guys are stupid, but this is my field. If we were talking about art, then I would be the one asking questions. In any case, I really don't care if you believe me or not. I certainly know that I know what I'm talking about and have stated my credentials. What credentials do you have that allow you to discuss aerodynamics? Oh you read a couple of books? Great, you must know everything about it now! I've stated observations on here for people to read. If they decide to believe you over me, then there's nothing I can do about that.

Quick question...I'm two clicks away from buying covers for my 76 from MSA, but their site says "his kit includes all mounting hardware, trim, and instructions. It requires no drilling of the headlight cases to install." But I don't want to do any lame double sticky tape stuff. Does it also come with hardware to screw it into the bucket? If not, what's the solution?

I'm an Aerospace Engineer, I've got years of experience to back up my "oh-so-certain comment." Just like people in other fields can "tell by looking" at something, the same is true for a lot of engineering stuff. I'm telling you, the whale tale will increase your pressure drag. If you don't want to hear that, then that's your choice. What I can't tell by "looking at it" is if the advantages of the negative lift ("downforce") outweigh the drag. That's something you'd really need to do in a tunnel. And if you like it or not, the majority of aftermarket crap that people design for cars is for looks. Now you guys say this whaletail creates some amount of downforce and was used in racing before...so then I'm assuming somebody who knew what they were doing designed it. But if you really want to do some serious aerodynamics on your Z, you've got to take the whole car into consideration and not just slap a random wing on there.

Well, it's a good idea to goto a truck scale and see how much the car weighs front and back...

Nobody said anything about including aerodynamic devices at the bottom of the car. Whale tail by itself will increase your drag, period. But I agree about the wing statement. That would be much better.