JMortensen

FB is great for sharing pictures. For sharing tech info, it sucks. I often respond to FB posts with links to posts here a lot just to save the hassle of typing it out or having to copy/paste. Not an attempt to boost numbers here, but if it works out that way so much the better. When I was an admin here we talked about what the purpose of the forum was, and the general idea was that it should be like a library or an wiki page where people could go to find the info they were looking for. Adding a million posts about the same issue makes searching harder, so that was strongly discouraged. I still think this is the right policy, and I'm sorry to see that it isn't as strictly enforced, and also happy to have had my hand in pruning the information tree in that way. There is a mix of "HybridZ is great" and "HybridZ screwed themselves by being too strict" on FB but seems to me most of the other forums have declining membership as well, and this one seems to have a fairly consistent level of tech postings that is higher than most of the others that I'm on (miata.net beats this forum out, but I think it's pretty safe to say there are a lot more Miata owners than Z owners at this point). I think the response to the funding issue a year or so ago showed what is really going on. Casual Z owners don't care enough to engage in a serious forum, they just want to post pics and have people like them. People who are more serious about modifying or racing are going to stick around, because this is (still) a repository of very good info.

That's the second time I've been wrong in a very similar way in about a week's time: the other was trying to relate a traction vs slip angle curve to a tire that was broken loose. Ah well, thanks for the correction. What did you think about the videos I posted?

Thought this through a little more. I think a better way to explain would be to say that a stalled wing doesn't create lift, but instead creates drag because of the big wake that is created by the flow separation. You wouldn't say that there is more pressure on the rear of the car inside the wake than on top of the car, and likewise there is more pressure on the top of a wing when it flow is attached than there is when it is stalled.

First, let me say that I'm enjoying digging into this, so thank you. Second, I'll point out that I'm not an engineer and have no training whatsoever, but I have read a few books on aero. Third, I think you're missing something here. When you look at a plane wing that is not stalled, it makes aerodynamically EFFICIENT lift. A stalled wing still makes lift, but there is more drag than lift and that's what causes the plane to fall out of the sky. Just look at the yarn on the plane wing. When it isn't stalled, the yarn is pressed down on the wing surface. When it stalls, the yarn is no longer pressed down, and it flails all over the place. This is proof that there is more downforce with the flow attached to the surface than when it stalls. The yarn is literally pressed down on the wing surface. Back to cars: the thing that we're trying to prevent is the rear of the car from acting like a stalled wing, and the reason why we're trying to prevent it is to reduce the size of the wake behind the car and its drag. Also, if we have a spoiler or wing that would be in the region of separated flow, we can make it work. The purpose of the whale tail is to change the angle of the flow off of the back of the car. If the flow over the top of the car points down, you will get lift. If it points up, you will get downforce. You can intuit this if you watch F1 in the rain and see the rooster tails shooting up 20 feet behind the cars, but it's not something that I ever read in a book. There is a guy on youtube that runs Gray's Garage and he does water flow testing with model cars, and he talks about this at some length, in addition to showing the rolling separation vortices behind various models. Pretty interesting. Here's one that compares your whale tail 911 vs other fastbacks with CFD: Here's another where he does the water tunnel testing with an MR2, which is particularly relevant as it has a Pantera style rear deck:

There is another thread about swapping out the belleville washers and making sure the gears are installed properly, but this one will help when it comes to installing it in the housing.

If you look at a Z in profile, you can pretty easily imagine the leading edge of the wing being analogous to the windshield/roof junction. As to the VG's increasing lift, that's not what they're supposed to do. From the original Mitsubishi paper, lift and drag decrease with addition of VGs: https://www.researchgate.net/publication/316855385_Effect_of_Vortex_generators_on_Aerodynamics_of_a_Car_CFD_Analysis

Agree with calZ. I'd like to see some better shots of the yarn on the stock hatch. I would bet that the separation is not that bad; that there is separation, and it is creating drag, but not in a huge way. If you look at the VG test from the windtunnel, it actually shows an INCREASE in rear lift. Unfortunately they also took the side skirts off when they did this test, so it's not really a good indication of what exactly the VGs did. All we can really say is that the net change of removing side skirts and adding VGs resulted in increased rear lift and increase in drag by .04. The VG thing bothers me for a more fundamental reason though. If you look at a low speed aircraft wing, they put the VGs close to the leading edge of the wing. Most everyone who runs VGs on cars is following the Mitsubishi example, but I don't think it's really all that relatable to the Z. The EVO has a relatively flat roof and a sharp rear window angle. The Z has a bubble roof that leads smoothly into the slope of the hatch. I really think that VGs on a Z should be mounted close to the top of the windshield, and getting rid of the hump from the weatherstripping around the rear window is probably as important. https://www.youtube.com/watch?v=SXwVyxorvno Here is a video from a guy on another forum. I know you can't really compare different cars, but the point was to show that it is possible to have some separation without huge roiling vortices coming off the back (which would have the yarn standing flipping all around, including straight up). My GUESS is that this is somewhat similar to what happens on a Z. We do have this shot, but there is a spoiler on the car. Even so, there isn't any yarn pointing backwards or standing straight up.

I wonder where the came up with the torque limit. Breaking welds? Doesn't seem likely since guys are running Z31T CV adapters welded to stock companion flanges. Maybe they're using particularly weak CVs. Maybe they're just under-rating them. In a 510 the U-Joint angularity can be a really serious issue. Haven't heard anyone having problems with Zs in that respect. I think the issue is the semi-trailing arm rear suspension and the ride height that 510 people tend to want. Being that the stub axle is such a weak spot in the Z, I'm not inclined towards anything that doesn't address that issue. Still think the modern-motorsports.com chromoly stubs and companion flanges are a good answer, and I like the Z31T CVs. If that's not enough the full chromoly setup with 930 joints and stubs for the diff and wheel ends from modern-motorsports.com is as good as you're going to get for an R200. Still blowing that up? You're going to need bigger axles, that means F8.8 and some kluged together stub axle for the wheel end, at which point why not SLA and change the shocks and the brakes and then while you're at it...

This thread says 52 lbs for 240 door, loaded, and 68 for a 260. I saw 66 quoted for a 78 280 door in another thread, so they're probably pretty close and it's just the bathroom scales that are different, I'm guessing.

Couple anecdotal points from years gone by: 1. 280 doors are much heavier. My BIL bought a Z junkyard and I helped him move all the stuff. I can't remember the number of doors that he got in the deal, but was upwards of 50. You can REALLY feel the difference after you carry about 20 of them from one side of the yard to a moving truck and lift it into a rack. Pick one up: "Oh shit, another 280 door!" 2. I stripped a '71 in the early 90s which I would now consider to be "'nearly rust free" and at the time I thought was "too far gone." My friend and I lifted the shell, just the 2 of us. Couldn't have weighed much more than 250 or 300 lbs, I'm guessing.

The P36 struts won't fit in the 240 tubes, but will fit 280 tubes.

Considering the fact that his cage didn't tie into the suspension at all, I suppose he needed all of the stock chassis for its stiffness. As far as the aero, what did he have? A box from the dam to the radiator (which he said the guy at the wind tunnel poo pooed), vortex generators, and a spoiler. I think that was it. Maybe a splitter? I don't have VGs but I have a plywood splitter and big spoiler and sheet aluminum box to the rad.

Just as a counter point, I had my 70 set up with L28/ZX 5 speed, R200, Autopower roll bar, Recaros, full carpet with a lot of extra sound deadening mat, and it was 2350, which is supposed to be the curb weight of the later 240s. I think there is a couple hundred pounds in the unibody alone. If you're looking to keep it stock, then you can make the case that the 280 is better because it is more rigid, but I think if you start reinforcing the chassis on either, you can get an equally stiff end result, and miles stiffer than the 240 or 280 chassis as they were delivered. My early 240 now has LS V8, T56, gutted, I think it's a 12 point cage with lots of stiffeners including SFCs and strut tower bars, stitch welded, 15x14 steel rims, huge widebody, FG hood and hatch, Lexan side and rear windows, etc. Weight: 2352. Look at something like Mike Kelly's car which was a 280 with similar amount of cage tubing, LS, T56, F8.8 rear, etc and I want to say his ended up at 2800+.

I think the main advantage is in the pistons. You can get digressive 36mm pistons. In fact I think that's what you get out of the box. 30mm is linear, and you can't swap them out.

30mm gland nuts won't work on 280 housings and 280 housings are a prerequisite for 36mm pistons which is what the 3KGT and BMW run. I've got a set on my car too, but they won't do either of us any good in converting to Bimmer struts.

If you do camber plates and somehow adapted them to stock springs, you'd go down 1.5 and 2.5. If you go coilovers you'll start 1.5 and 2.5 down and then can lower with the spring perches from there. Again, IMO, I'd run the bumpsteer spacer in front to correct roll center and not worry about it in the rear. The rear doesn't have dynamic toe change and camber change is pretty linear, and the roll center will likely be higher than front and above ground, so it's a way-down-the-list thing to do after making camber, caster, and toe adjustable, reducing friction in the bushings, sway bars, better struts, chassis reinforcement, etc. Interestingly on the corner weighting, I recently listened to one of Ross Bentley's podcasts I think it was, and they were talking about the relative advantages of diagonal corner weights vs front corner weights, and the guy he was talking to was saying that having the front corner weights even was more important that getting the diagonals even, as this means less likelihood of locking up a tire under braking. First time I had heard that, and it would imply that moving the battery to the back is probably counterproductive on a Z.

Gland nut is an issue as is converting it to double adjustable, which IIRC requires remote reservoirs. I don't believe you can buy them DA from Bilstein, have to buy the reservoir, weld on the fitting and DIY. Sure would be nice to find an easier solution...

Be sure to post what you do on the Bilsteins. I've been looking at modifying 3000GT Bilsteins. Others have done it in S14s, but it's a big PITA and I haven't done it for that reason. If there is an easier to work BMW solution, I'd love to see it and I'm sure I'm not alone. Best of luck!

The issue with lowering the car and altering the geometry in the front has mostly to do with bumpsteer. The camber curve is very consistent throughout the travel. The caster curve is affected, but that's minor. The bumpsteer curve on the Z is crappy out of the box. You can run the bumpsteer spacers to get it back to where it was (crappy) or you can make it adjustable and minimize it. You can do this with a bumpsteer spacer kit from a vendor like Apex Engineered, or you can drill out the steer knuckles and run shims to fix. Bumpsteer shims are commonly available circle track parts. FWIW I do run bumpsteer spacers to help with the front roll center and have the bumpsteer adjusted with the shims to counter both issues. https://www.apexengineered.com/store/p11/Front_Tie_Rod_Kit.html http://www.colemanracing.com/Bump-Steer-Bushing-Kit-P4444.aspx As it is the roll center in the rear is quite a bit higher than the front and I can tell you from personal experience with a low race car that even very low, the rear roll center is still above ground and higher than the front roll center, which are, generally speaking, the things you want. You can weld a new pin tube under the stock one, Ben Cort did that on his autocross car, and Terry Oxandale modified the bottom of the strut housing to make it longer to raise the rear roll center higher, but it isn't the first thing that I'd be worried about. It's pretty far down the list of things to do IMO. 2 way Bilstein struts are not low dollar. They are very good, but there isn't a bolt on option for them for the Z, so you'll be fabricating to get them on your car. If you want a low dollar solution, there are weld on adjustable struts that are not as good from vendors like Tein and BC Racing. They run ~$1000 or so for the set of 4, and you get coilovers in the process. Be careful sectioning the rear struts on a 280. The tubes are longer and the top insulator is taller in the rear of a 280 than the front. You can just get a 240 or 280 front insulator and run that on top of your stock 280 strut and that drops it down an inch with no sectioning required. If you run camber plates front and back, that accomplishes the same thing but you'll drop the car roughly 1.5" front and 2.5" rear. If you section the rear strut tubes and change out the strut top, you'll have trouble getting the rear of the car high enough. You can literally set the frame of the car on the ground and still have several inches of suspension travel left if you screw this up.

The turbo is bolted directly to the head on that EcoBoost motor, so that's going to make exhaust pretty simple I think. It might also make upgrading the turbo more difficult. Not sure what kind of power you are after, Richard, but here's a vid where they did intake/exhaust/tune on a Mustang and gained 113 hp and 96 ft/lbs:

Yep.

No quality control? How long have these been for sale? Since Ross was selling them at Modern Motorsports, maybe 15 years now? How many have had this problem? Sheesh.

That's the old 2.3L. Heavier than a V8, BTW. I'm thinking the OP is talking about the EcoBoost 4, which makes 310whp out of the box. I am biased because the worst car I've owned was an NA 2.3 Mustang, but I sure wouldn't go that way...

Just put the supports off of the hoop on the sides, they'll fit in around the hatch window. Mine go from the sides of the hoop just below the bends to the top of the strut towers. That one shown above is terrible. If there is a fore/aft load on the main hoop if the car rolls, there is almost no support for it. Would fold like a mousetrap.

If you're planning any aero mods in the back skip it, as it creates massive flow separation and lift. If you check the windtunnel testing info in the FAQ, you can see it has the highest rear lift number of any of the tests. Makes me wonder what people are thinking when they put on the Pantera hatch and a spoiler or wing, or the worst combo, roof spoiler with Pantera hatch. It also increased the drag by .2 which is the equivalent of setting the wing that was tested for its highest angle of attack. So you get all the drag of pulling a wing through the air, and quite a bit less than none of the downforce. If you are just in it for looks, it appears to me like there will be plenty of room for a roll bar. Most of us try to get the main hoop of a roll bar as close to the rear fenders as possible and as tight against the map light area as we can, that's still well forward of where the hatch is though.