dead if I'm wrong. top end aerodynamic limitations of a 240

[Guest pvtkary]

my spelling sucks. sorry! I know what youall are gonna say to me, but it isnt the way I want to go. I like the stock lines. Not a lowered/spoiler kinda guy. I like sleepers. A little background. Ive done a number of unconventional v8 swaps, without the aid of kits or other peoples experience on that particular swap. My last one was a 400 sbs in a 1969 opel gt. My design critera is one horsepower to every five pounds in a very streetable fashion. My question for the more experienced is. Without modifying the aerodynamics of my 240 how fast is too fast? Since rearends are cheap, and readly available, I want to keep a few around so I can go for tall ring gear for light to light saturday night hunting, or drop in a short gear in a few hours to go out, and break the sound bearier. how fast can I push this body SAFELY without it trying to lift off or do something else nasty at 1??MPH

[jeromio]

With stock ride height? I was uncomfortable taking my car past 100. Lowering it helped, but it still feels (felt - been awhile since I drove it ) skittish. Several members here have told me that a front airdam makes a tremendous difference with these cars since they tend to lift the front at speed without one.

 

You can source a pretty conservative looking airdam like the BRE-style chin.

[Mike C]

The so called high gear r200 is not very common. Some late 70's cars had a 3.36 and there is a RARE 3.15 but mostly you will be stuck with 3.54. 3.54 and OD with a motor that turns 6000rpm should give you 150mph (I'm not doing the math, save that for you!)As far as aerodynamics,it is prudent to add some mods, like them or not. Lowering to begin, then a front air dam and a way to get air out of the engine compartment if nothing more than pinning the hood up about 3/4". If I recall, the CD of a Z is near .45 ?! Worse than my '69 Camaro's .38, but the Z does have a tiny frontal area.

[Phantom]

I agree with Jeromio. I've owned two gen 1'sa and they both got light at about 105. Any kind of a brisk crosswind at speeds above that and it would be easy to lose control. Conversely, I've modified one with the MSA Aero II ground effects kit and it is solid at 125. Once I get the V-8 in it I'll find its limits.

[Dan Baldwin]

I never had problems up to about 105 with the stock ('cept for T/C kit and steering rack bushings) suspension with good struts in my car. Never went faster with that setup. With 1" lower, twice-as-stiff springs and Illuminas, never had problems up to ~130. Still w/ no aero aids. I've since added a BRE front spook and rear spoiler. Should reduce lift to near nil, and decrease drag. At the faster race tracks (Watkins Glen, Mosport), I do seem to be faster, but the car doesn't feel any more or less stable at speed. It's just fine, like it's always been.

 

BTW, I painted the front and rear spoilers satin black (car is Ferrari red) to minimize their visual impact. From some angles they're all but invisible. Lemme know if you'd like to see a pic.

[Guest Anonymous]

My car lowered about an inch or two front and one in the back with only a msa front and back air dam saw a indicated 125 and still pulling (t56, love it), but I got a bit chicken. It didn't get super squirrely, but pushing a 30 year old car that fast just didn't seem worth the hospital time. I believe a few members have seen upwards of over 150, but they have bigger stones (and motors) than I.

I'd be happy with around 125-130 but work on how fast it gets there unless your looking for some sort of high speed record attempt or something, in which case I'd find a more streamlined car (like a old stude like they use at bonneville even).

 

Regards,

 

Lone

[Guest Anonymous]

Lone at 100 mph, I will just skip the hospital time (no thank you) since the long hood of my old silver Z is pointed skyward and halfway to heaven. Suspension mods like outlined above is in order for cheap thrills over 100 mph or may read pvt closed casket services for pvt kary

[fl327]

do you guys think that different years have different high speed stability. my 75zt loves it up at 90mph, thats the point that if im cruising in 5th im about 15-20 hg and if i stomp it ill be in triple digits and 10psi very fast, and its still pretty stable, but im a chicken and back off at that point- and the suspension is pretty shot, shocks and springs are pretty out and the balljoints are tired lookin and its stock ride height right now, my 72 v8 car was dropped about three inches, had coilovers, subframe connectors, a urethane airdam, big sway bars, you name it, all the bolt ons strut stuff, and it hated triple digits, a combo of the muncie timing me out and the chassis started to get light on me- what gives. the turbo car has a fiber glass airdam, and i can hear it splitting the air pretty loud at those speeds as well, and i think that may have alittle to do with it, but i would not think it would have much effect on top end performance? turbo car also weighs a bit more than the v8 car chassis wise. 2750ish for the turbo and 2400-2500 for the v8 car.

[Guest Anonymous]

I should have prefaced my post with this disclaimer..

 

" These stunts were performed by a professional idiot with little regard for life or limb in a uncontrolled setting on a open circuit highway, using a live crash test dummy, no claim of intellect or reason was used in this testing and it is not suggested anyone other than a professional idiot try these stunts at home."

 

Regards,

 

Lone

[Guest empracing]

excuse the math here but im in km not mph

so my 74 2+2 had the windscreen wipers lifting at 140kph or 85mph the front got light after 180kph or 110mph or so thats wrong i think and after that you took your life in you own hands up to a top of 250kph or off the clock which ever comes first which is 155mph but man if you live youll love it up there!

[Guest 240Z_72]

Don't forget the Land Speed Record of 165.768 mph set by a 280Z 2+2. No engine swap, no nitrous, no turbo, no alcohol, gasoline only.

 

http://zhome.com/Racing/LAND/FlaggZ.htm

 

[randy 77zt]

i have hit 145 but my car is on the low side with a full road race suspension and an air dam.at 145 front felt light.was cruising 120 before i floored it.make sure you have the toe in set both front & rear.any amount of toe out will make the car wander.i do suspension & brake work for a living so i align my own car.a fresh set of z speed rated tires is not a bad idea .

[Guest Perry]

for what it's worth my 280Z with turbo swap was stable up to about 120, and over 100 it got noticably lower, at around 115 it would bottom on a mild highway bump. it is stock ride height with tokico strut cartridges, a front air dam with brake vents in it, and a "whale tail" rear spoiler.

By stable I mean no different in feel from normal highway speeds, just noisier. I had to do it again because my wife didn't believe me that we were going that fast, it was too uneventful for her. 120 is all I pushed it to, no reason to believe it is not stable above that.

After a while in triple digits 70 feels like 20.

Perry

[Guest Carlissimo]

In a younger, more daring time I explored the top end of my Z several times. I found there to be a real aerodynamic "wall" at 150. At that speed the buffeting was real bad, leading me to worry that I was going to lose the hood, the mirrors, or even pop out a window (athough none of that ever happened.)

 

I concluded that the 240-Z body is not real slick aerodynamically (especially with 4 inch flares and fat tires) and that speeds higher than 150 would require a lot of horsepower.

 

Spoilers, and lowering the car can help, but I recommend paying close attention to the suspension. Good setup with high quality/matched springs & struts make a big difference in high speed stability.

 

PS. Never, never, never try anything like this without at least Z-rated tires.