How fast will it really go?

[cremmenga]

I was just wondering if any of you guys have ever topped out your cars. I heard that the stock 240z will do consitantly 130's, I am just wondering because I am putting a sbc in mine with about 400-500hp and a Richmond 6 speed, I know I will have to get a new rear end but lets say the gears where the same as stock, and the six speed gears are 1-3.28 2-2.14 3-1.57 4-1.24 5-1.00 6th-.76. I have done the caluculations on the internet and they say it can go over 200mph. But when you come back to the real world and put into effect drag, aerodynamics, etc. what do you think she will really do? any guesses or if anyone has a v8 conversion to tell about would be great. Thanks again guys!!

[seerex]

Hmm I was clocked by a FHP trooper on a overpass as I headed east/north towards daytona at 142 according to him. He stopped me at roughly 85-90 mph about 7 miles up he just knew it was a loud red car and actually he let me go . I raced a 911 sc in this 240z and whooped up on him very badly so it was quick but I wouldn't say fast by todays standards. I had cam and head work done to it , header and a type 2 5 speed. Unknow what rear end , , about the only thing I didn't break and replace. The car was not very stable and what ever speed I topped out at made me a bit cautious of trying again. I would guess< big guess> you will be in the 160-165 range if you can keep it from flying .

[cremmenga]

I was hoping for 170's!!! Damn, anyone else think 170 is possible?

[Pennyman]

With the right gearing, perhaps. But you'd need quite a lot of power to get you going that quick. Not to mention robust running gear to help put the power to the ground. By that point, you might be relatively slow off the line because of the gearing, but you'd have your insane top speed.

[Aussie Zed]

Stick with me here, i've done a bit of a rough estimate and assumed that you have a coefficient of drag of around 0.4 (not unreasonable, but not great either), the frontal area of you car is 2m squared (sorry if you don't speak metric) and that you'll make 400hp at the rpm that the top speed is reached.

i have a nice fat long equation that is used to calculate the theoretical maximum velocity:

Power/Velocity - .5*(density of air)(Drag coef)(Frontal Area)*(Velocity)^2 - rolling resistance*mass*gravity = 0

now if you plug in all the values:

Power = 400hp = ~300kW =~255 Rear Wheel kW (85% driveline efficiency)

density of air = ~1.2kg/m^3

Cd = 0.4 (bit of a guess)

Frontal area = 2m^2 (bit of a guess)

rolling resistance = ~ 0.014 (pretty reasonable assumption)

mass = ~1200kg

acceleration due to gravity =~9.81m/s^2

Solving this on my simple graphics calculator gives me a top speed of 79.58 m/s

Or around 176.8 mph!! :knockedou

As i said at the start there are a few guesses involved here, if anyone has a better guess for the values above, i'll plug them in - it only takes a second to change on my calculator.

Jon

[Murph]

I've had my zed at about 170km/h and I don't think I'd do it again......it's not to steady on the less at perfect bitumen around here.

Now, 270km/h, you'd either have to be either insane, stupid, or both. That speed on a public road would be the later, and nothing else.

[cremmenga]

WOW thanks Aussie Zed that is very cool how you know all of that. I'm very impressed!

I might be able to live with 176.8mph. here where I live 150mph on a public road is not that fast! I will post up some pics and show you what I mean. Nothing but new flat, smooth, straight, black top for mile and miles!! not to mention very few cops! I have done 189mph in a Z06 corvette and I want to get close to being able to run with them! thanks again!

[SteveJ]

On the Zcar.com website, the consensus is that the S30 is as aerodynamic as a brick. Search on that site for LSR. Tony D has taken his 280Z 2+2 with a G-nose up to 178. Without a G-nose, you will hit a brick wall well before that. Considering the profile of the nose of the S30, I wouldn't be surprised if it created lift at higher speeds.

As for seerex's trooper clocking him at 142, I don't have much faith in the police radar between the level of sophistication of the units and the level of sophistication of the user (policeman).

Jon - Do you have an online reference for your calculation? I thought the coefficient of drag would affect the top speed more. FYI: According to this post (http://www.zcar.com/forums/read.php?f=1&i=396183&t=396034) the Cd is 0.43. (Post edited due to finding the Cd.)

[Sean240Z]

http://www.datsuns.com/Tech/tech_aero.htm

On this Datsun Website they have an aero HP calculator spread sheet (doesn't account for rolling resistance). They list the 240Z Cd as approx. 0.465. They also use 80% of the (height) x (width) to calculate frontal area (for a stock 240z this works out to be approx. 50.5"x64" = 18 ft^2 or 1.67m^2).

Cheers,

[cremmenga]

I know for sure I will not put a G-nose on mine! I really really dont' like the looks of them! all in all i think it is safe to say it will haul some major arse!!!

[texasz]

here where I live 150mph on a public road is not that fast! I will post up some pics and show you what I mean. Nothing but new flat, smooth, straight, black top for mile and miles!! not to mention very few cops! I have done 189mph in a Z06 corvette and I want to get close to being able to run with them! thanks again!

Chris, I'm sorry to say that 150MPH no matter where you live is still VERY fast! And very illegal ANYWHERE in the states (2-3x the speed limit). I've not been that high in any car (over 100 yes) and do not recommend it on any public road. It's just plain stupid and irresponsible. Save that for the track where it's a controlled environment and the only person you are endangering is yourself.

I have been rear ended by a guy diing 120MPH and it's not a pleasant experience...I was told that by all rights I should have died in that accident!

Please do not get me wrong, I love speed and my Z...I'm working on a 3.1L stroker for mine. I also intend to keep the craziness on the track and not the public roads! Do I speed? Yes. How fast? 10-15MPH over the limit on the highway only...no more; and never do I speed in school zones or neighborhoods.

I know that you are still young, I was too. Think about this though, what if your child were killed by someone doing something stupid like going 150+ down a public road? Please be responsible.

The Fast and The Furious was ONLY a movie!

[240ZX]

All other things considered......if you plan on speeds over 100 mph (especially 170 mph) you had better do your research on an aero package for your Z. In stock body trim, the Z becomes very unstable as the car attempts to fly...actually it just becomes very light. You may also consider talking to some racers, with experience at high speeds, and find out what is involved in preparing a Z car for the kind of speeds you want to obtain. One thing for sure...make sure you are running equipment (tires included) that can handle the high speed. We don't want to read about your fatal accident in the papers. And......TAKE IT TO THE TRACK, FOR GOD'S SAKES!!!