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Japdays 2023 at Mantorp Park in Sweden. Got Best Classic car award!

The test data from HybridZ... the numbers for a stock Z (test #2) Cd /CL etc are pretty close to what Kats Posted.

Hi Ali, There's some potential for confusion here between the full-length engine bay undertray of the 432-R (as homologated for race use, made from FRP) and the much shorter splash pan (steel, as fitted to other models) which were designed to perform different functions. The 432-R undertray has a reputation for causing overheating in normal street use during hot weather (it was designed to be used on circuit, at higher speeds of course) and I guess Mr. F would know what he was talking about with regard to the steel splash pan, although I imagine the effect would be less pronounced. Here's what the 432-R undertray looked like:

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

September in Tampa how delightful. I hope they include Gold Bond powder in the welcome bags. Hey let's have a car convention for cars that have shitty or no air-conditioning in 90 degree heat and 100% humidity. I know a lot of the scheduling is based around track availability but I wonder if they would draw more of a crowd if they leaned away from track events and focused on comfort. I have AC and it works pretty well but there is no such thing as an enjoyable "fun run" in September in Tampa. Now in October maybe.

Its my understanding too. I don't think Nissan would have added such a large undertray to the z432r otherwise. If my grey cells recall, Ben240z (on UK forum) I think there are cut outs in the inner wing, on his race car, sort of where the battery goes, so the air entering the engine bay has a place to escape too...

So the thread is balanced, other brands are available!

We have discussed that magazine article. It's probably the best independent analysis available. "Interpart" is / was Pete Brock - BRE. This thread made me think of the Maru Z Keikaku Suishin Iinkai films and that NISSAN did aero testing of the chassis.

All I can say is my stock 240Z started to feel like the front end was flooting at around 90MPH. I put headlight cover on and an air dam and the car feels solid on the road at over 100MPH. As far as drag goes I believe that these changes to the front of the car added about 3MPG. No numbers here, just my own impressions. If you want to talk drag, take a look at the front of my wifes truck in my sig. But the slightly modified small block made it not to noticeable.

Not my car but very close with body-colored bumpers! Edit: the article is incorrect where it discusses the 240Z engine block number not matching the VIN. I sent a note to MotorTrend explaining the difference is intentional with pics of my engine bay data plate and warranty card. https://www.motortrend.com/how-to/where-is-the-vin-number-on-a-car/

I think that’s the gentleman that lives in Ocala Fl.

@SpeedRooThanks - the old links in my bookmarks wouldn't load.... so I used the image I had saved at the time.

THANKS - Last sold on BAT - 15 July 2023 for $39,250.00.

If you have a 240Z then sway bars for a 240Z will fit just fine, a little extra displacement in the engine will have no effect.

Found another backwards item so I guess I have to stop counting now. Air breather hole on the wrong side of the carbs, unfiltered air sucking in through the back and breather on the carbs essentially blocked off.

I am trying to get better spring engagement on my R35 Coil stalks. Here is v5. I hope it works!

73 for bid - no reserve. From the people that sold the Green $310K car. https://auction.owlshead.org/listing/1973-datsun-240z-with-38575-original-miles/?fbclid=IwAR1yrDQcHdODNOaxrnbx1QMZWOF5vVb4rOx3YqcQP2vn8qx8-KiQMPcQLeA

Important that any self-respecting botcher and bodger uses the very cheapest and most unsuitable material for the job, of course 😉

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.

This is my new FAVOURITE all-time thread. Thanks Kats and Alan for sharing such brilliant info. What I don’t understand is - and bear with me pls, I know little about aerodynamics - given that the engine bay pressurises does the blunt nose improve cooling also? And does the standard under tray improve the pressurisation situation? (Apologies if it’s covered in the magazine articles that I haven’t had a chance to read yet). A very experienced member of the UK club (the late Mr. F) used to tell me that the under tray also affect the cooling efficiency, so I’m wondering if this was the reason?

They arrived,

We've had a couple of fuel tanks with leaks on the solder joints at the hose fittings so you can't totally discount that. Hoses are more likely. Dropping the tank is fairly easy even with the myriad of hoses. Just disconnect the ones you can see and bring it down slowly until you can get to all of them.

Thanks Roo, I have seen the magazine but haven't read through whole pages, thanks! You don't need my drawings but hey, I put it just for fun. I have one interesting story to tell which Mr. Miyazaki told me about "front chin spoiler" later on here. Kats

Thanks Alan, According to the comments of Mr. Uemura and other engineers and styling designers, the 1/4 scale model was tested in the facility of the University of Tokyo. According to the book "Prince/Nissan" Kazuo Higaki (Nigensha), as Alan said Prince used to have a wind tunnel at Ogikubo but it had been abandoned since the end of the world war two, impossible to operate. Just like Nissan, Prince engineers brought their 1/5 scale model to the same place, the University of Tokyo. By the way, 1/5 scale is a tradition of the Prince which used to be as an airplane manufacturer. Nissan's used 1/4 scale... A full scale prototype car was tested in the wind tunnel freshly built at Nissan Oppama Chuo- kenkyujyo (Nissan Central Research Institute) at Dec 1968, started operating from April 1969. Kats Attached picture is testing a Prince R380.

@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.

I believe that, after their merger, Nissan had use of the ex-Prince research facilities at Ogikubo, which was linked to Tokyo Daigaku's Aerospace department? I also remember reading that Prince, and subsequently Nissan, had sponsored students in Tōdai's Aerospace department around that period via a bursary scheme. Nissan took over Prince's satellite-launching rocket program, I think? Here are a few stills from one section of the Maru Z Keikaku Suishin Iinkai films. I had believed that this impressive array of research equipment was either part of the full-size Nissan wind tunnel that came on stream in 1969, or was part of the facilities at Ogikubo. We can see both full-size (silver pre-production car?) and scale model research taking place. Maybe the filming even took place at both locations?

The poor old thing.

Hi Roo, Me neither, and also engineers were shocked when they saw the results of Cd and Cl at that time. I will upload the remaining pages. Before that I will try to explain that Mr. Miyazaki told me about how bad the opening front end of S30 was. Just like you proposed, it was the issue of S30 which engineers had to deal with. I will draw a picture by hand, Mr. Miyazaki said S30 front end is so wide that it leads too much air coming through the radiator. Then the air can't go through under the engine because the air was blocked by the air stream which is flowing underneath of the car. At the end, the pressure of inside of the engine bay becomes positive, it pushes the front end. The higher front end gets more Cd worse. This story I think it relates the story of 15mm lower front end of Europe model (except Portugal model). And Mr. Miyazaki even told me there was a test car which had a factory air conditioning coupled with Z432!! (Z432 was not able to make a choice of air conditioning from the factory). During the test of aerodynamics, one day he was wondering why one car had a better value than other cars. The better one had an air conditioner condenser in front of the radiator. Less air gave less lift. That was a Z432. Kats

I totally get why they would have been going with the 'Blunt' nose name for the more aero-efficient 240ZG front end, following on from NASA's use of the term and their pioneering research which they would have been referencing (yes, I think 'Blant' is just a typical Katakana-linked mistake) but I think it is counter-intuitive. I'm kind of glad that they went with 'Grand' (I have often seen it spelled as 'Grande' in period Nissan documentation) as I think it is an apt descriptor.

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?

This is the point of polishing it.

Hi guys, I have watched tons of videos and read the FSM and anything I could find on removing tranny, swapping clutch and maintenance I need to do while in there. I'm gonna put out everything I can think of and PLEASE let me know if I am missing anything. 1: put car on stands, high enough the transmission can be pulled out from. and disconnect battery 2: Pull out shifter linkage with pin on side 3:Remove Exhaust 4: Drain Tranny fluid 5: Remove Driveshaft(mark how driveshaft is attached, remove 4 blts to diff, then slide out of tranny) 6: remove starter 7: Remove reverse switch, slave cylinder, and I believe speedo cable? 8: jack up to hold flat, unbolt from mount and housing, and pull out tranny 9: Go to tranny pull out clutch fork and throwout bearing. clean shaft and housing with brake cleaner. Switchout new bearing onto collar. Grease clutch fork, pivot bolt, inside of throwout bearing collar, and input shaft. Put on bearing and collar and clean excess amount off spindle. 10. Put in clutch alignment tool and unbolt pressure plate. pull off clutch and plate. Unbolt flywheel using bolt in flywheel, transmission housing and wrench. 11. Clean whole area and then use dental pic to pull crank rear main seal. Oil up new seal and hammer back in making sure not to damage (taking time). Remove pilot bearing from crank with pullers and use rubber or plastic mallet to hammer new in. 12. Attach new flywheel using medium strength thread lock, and tighten in star pattern. Use brake cleaner to clean surface of new flywheel. 13. Put on clutch (big spring side facing away from motor) and attach with clutch tool. Grab pressure plate, clean surface with brake cleaner and attach over clutch. Tighten on star pattern.Turn clutch tool to match trans input shaft as best as possible. 14. Get 2" longer trans mounting bolts, cut the head and make slit in top. attach 2 to trans as guide pins. put tranny back in. Pump new oil in side fill plug. Attach tranny mount. slave, starter, reverse switch, speedo cable. 15 Put in drive shaft following earlier markings 16. REMOVE POS REAR BUMPER MOUNTS WHILE EXHAUST IS OFF (i'm not salty, you're salty) 17. Put exhaust back on. 18. Reattach shifter I have a new clutch kit (exedy) thats coming with clutch, pressure plate, throwout bearing. I'm getting a new pilot bearing, rear main seal, flywheel. I've already replaced the slave cylinder and master cylinder. Is there ANYTHING else I need to do while I'm in there or should also replace?