SpeedRoo

Anyone know how to decipher the date codes on a 240Z caliper. Have seen lots of numbers on both sides but not sure what they mean.

Is it really necessary to trash other people's car's on here. It's one thing to question if things are done correctly or not but outright criticism is really bad manners.

All sorted, packed and in the mail to @fusion Helps clear out my garage!

I got a set in a lot of bits off ebay a few months back. You are welcome to have them as I have no use of them. If you cover the postage they are yours, would rather see them get used than sit in a pile in the back of the garage. Just PM me your mailing details. Roo

As I return my May 1970 240Z back to original specification I'm in need of a flat mustache bar to fit a R180 diff. The car came to me with a R200 diff, so that is being replaced with a R180. I have 2 curved later mustache bars if anyone is interested in a swap. Roo

@Terrapin Z does it show what Lot S83 the Vintage 240Z went for?

Thanks @hiyabrad $120k seems a fair price for it considering the missing parts. Did it have the original engine?

I think most people are missing the point, auctions are about getting the highest amount possible for the item on offer. They don't care whether they educate the public or not, it's all about the sale. I've seen dogs get sold for ridiculous amounts at auction due to the excitement and euphoria in the room. If they can find a buyer for what they are expecting it's worth then good luck to them., if not it will pop up elsewhere for sale. The armchair experts love to complain and point out why it shouldn't achieve reserve, at the end of the day no one really listens or even hears them and the car sells. The next owner may chose to have it restored correctly but that doesn't matter at the auction. The white 1969 240Z from the same collection https://www.mecum.com/lots/1088318/1969-datsun-240z/ also has a very high estimate, be interesting to see if it sells.

@Carl Beck aero power is the amount of horsepower required to push the car through the air, rolling power is the amount of horsepower to push the object but taking into account the weight and resistance to movement.

Makes loads of sense @kats Drag on a car body increases with the square of speed. In other words the energy required per unit of distance to overcome aerodynamic drag increases in proportion to the vehicles speed. The aero power required for each car to achieve 140kph is G-nose 38.63bhp and Basic 47.35. Basic nose standard 240Z requires 22% more power for same speed. For 160kph G-nose 58.674bhp and Basic 71.98. Basic nose standard 240Z requires 22% more power for same speed. From those numbers you can understand why the G-nose can out-accelerate the Basic nose on the standard 240Z.

@kats glad you are excited. The computations are based on the figures you supplied from the Datsun Japanese aero study and the windtunnel tests done in the USA. The formula used to calculate it is based on published figures, Datsun quoted 150ps for the power, I used their figure. All the data is readily available, no hocus pocus. If you can provide the aero figures for the European 240Z I would be happy to calculate the result. The aero horsepower required to push the standard 240Z through the air to achieve 125 mph would be around 140bhp, this doesn't take into account parasitic drag losses due to tire friction etc.

@kats The Racer Brown car with the G nose/tail spoiler and using a CD of 0.381 would have had a top speed of 160.81mph. The standard 240Z with the same horsepower as the Race Brown car and no aero (CD 0.50) would have a top speed of 146.88mph. The G nose with tail spoiler gives a 10% speed improvement. Standard 240Z with standard 150bhp engine and no aero would have a top speed of 124.89mph Standard 240Z with BRE front and rear spoilers would a top speed of 129mph.

@kats it's late here but I'll run the aero figures tomorrow and give you an answer. The Racer Brown 240Z was running around 240bhp so it should be easy to work out. What horsepower do the blue and yellow car have?

Actually it does the opposite, the opening to the rear of the hood brings air into the engine bay rather than venting it. It's a common place to draw air into the interior of the car for ventilation, hence the vents on the panel there. It's also used to feed air into the carbs on many race cars. Here's a good example.

@Carl Beck that makes sense, was just surprised to see such a standard 240Z break the speed records. Even the 2010 record breaker had the standard bodywork rather than the G nose.

@Kats the early record car had the spook front spoiler, faired in headlights and tail spoiler. What was even more remarkable it had the early rear diff setup with the forward mounting point and angled driveshafts. Considering these supposedly caused vibrations in the standard 240Z they obviously weren't a problem at 150mph!

Found it @Carl Beck https://forums.hybridz.org/topic/55944-windtunnel-test-data/

@Carl Beck very interesting reading. I remember seeing that report somewhere, can you link to it still? Blocking off sections of the radiator opening seems to have the biggest effect, as we mentioned earlier in the tread.

The purpose of the undertray is to speed up the airflow under the car to reduce overall lift. It does cause cooling problems but careful attention to ducting and venting the air from the engine bay keeps those in check. At ordinary legal driving speeds none of this really has much effect but as you get nearer to 100mph the aero has a much bigger influence. The reason the Z432R has the undertray is to homologate the part for racing use, without the front airdam and cooling mods it wouldn't actually have much effect on the cars performance in normal use.

@katsexactly right about the engine bay pressurizing and increasing the drag. We spent a lot of time shrinking the size of the openings and also modifying their shape to cut front end lift and drag on my Aston race car. To de pressure the engine bay we vented the bonnet and ran some Gurney flap lips to help evacuate the stale air. I may try it on on old 240Z bonnet I have and see what happens. There is an old article from one of the car magazines over here in the USA that compared various aero mods.

To give you an example of blunt nose aero, this car has a Cd of 0.326, CLf of 0.92 and CLr of 0.60. It also has a much larger frontal area with a width of 6 foot. The blanking plate to reduce the opening was key in reducing the drag.

I didn't realise the 240Z was such a draggy shape in both standard and modified forms. For such a small front area it creates a lot of drag. Blunt noses can actually be very aerodynamic, the problem is the openings at the front, whether blunt or sharp, they have the biggest influence of the drag and lift figures. Would be interesting to see if they tested the car with the radiator intakes closed off and the effect.

Is the whole report available to view @kats Should make interesting reading. Does it make any reference to aero imbalance due to the large differences between front and rear lift coefficients?

Happy to oblige. PM me you address and I'll get it boxed up and sent to you. Roo