924Board.org

[Juho]

Im very new to aero stuff only read couple of books what do you think would be the most easiest way to to lower drag and introdouce more downforce. I think most easiest way would be smoothen out the front bumper , make a flat foor with couple of naca ducts for transmission and rear spoiler. making a flat floor would require probaly require radiator venting out of hood with a duct. SMALLER mirrors would probaly help also. What do you think?

edit: how also the underbody is made on 924 especially in rear i think it would make a perfect airfoil and diffuser setup

[BC931]

For its day the 924 was one of the lowest drag co-efficient cars available. The rear wing made a big improvement, if you don't already have it. Taking the mirrors off would help a small amount, but those are handy at times.

Take a look at the factory race car photos for ideas. Maybe a front air dam would help redirect the air, but remember to balance the front/rear lift mods. IMHO, I don't think a floor pan, nor diffuser will make a noticeable difference.

I don't know which car you have, but a NA 924 is probably too power limited for any significant improvement. Recall that a 924S is actually faster than a 944, with the same engine, but the aero helps the 944 handling.

[Cedric]

I dont agree, all wind tunnel data ive seen on in different reports and tests shows than working with the underbody should be first priority. Especially as it looks pretty bad from the start.

The top is more difficult since its pretty good already. A 944 rear wing and 944 flush windscreen would help for drag and rear lift, and some aerodynamic mirrors, other than that i would guess theres no really big gains without some work, and tests to see that the correct things are being done.

Juho, I guess you have seen Julian Edgards youtube channel. Some good tips there on undertrays, aero mods etc and how to DIY-measure aerodynamic modifications.
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1980 924 Turbo
www.instagram.com/garagecedric/

[BC931]

[Juho]

Ive read some aerobooks and watched ALOT kyles engineering channel on youtube, hes a ex f1 merceders aero guy, i agree the undertray is the BIGGEST PRIORITY and how 924 underbodies are, there should be HUGE gains, with the rear especially, also i think new front bumper should be made to co op with the under tray.

Look at downforce figures of factory sports cars with and without undertrays. huge dufference

Least imo undertray would need transcooling and way to monitor temperatures and naca ducts. Front would need duct to exit the radiator heat out of hood. I try to work on a water tight scan of the car when its summer but i think its hard, ,maybe modeling a rought shape of the car in example blender would be the way to go.

Also i dont think our 924 is THAT drag coefficent (my friends saab 9-3 is more drag coefficcent) it has a good basis to improve though with its shape.


if our car is "power limited" shouldn't the aero be the main focus. You can see through out the history how teams for example in indy and f1 with lower budget has got competeting chance by doing better aero. Just my opinion though.

[Cedric]

Will you track the car? Thats a very important factor for the cooling, if its only for road driving its much less of an issue. Pretty much any car you can buy today has more or less flat underbody and front undertray, sporty or not.

The Cd was very good back then, but not so much with modern standards. I would think its mostly the underbody that drags it down. But of course, modern flush windows etc would help. What helps our car is the small frontal area, so Cd x A is still pretty good. Remember to cut that spare wheel welll out if you can

Regarding low power race cars, i really like the 1960s panhard CD race cars, the underbody of those is incredibly smooth and a super long diffuser. 225km/h with 78hp is quite impressive.

But for lap times it depends, for fast tracks aero is a no brainer, for very small tracks the weight of the aero could in some cases not offset the added weight.

Air dams are good if you arent allowed to do anything with the underbody, to keep flow out. But if you can its always preferable to have air flow under the car and keep it as high speed as possible by a smooth floor and possibly a nice exit at the rear to keep expansion losses small.
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1980 924 Turbo
www.instagram.com/garagecedric/

[hayeslewis]

I have to second Cedric's opinion. I put a full width big ass air dam on my race car and picked up from 109 to 111 at the end of the summit point straight.
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Hayes Lewis
1979 924 HP
1979 924 ITB/HP???
2007 Armada
2013 Hyundai Elantra
1972 MG Midget Vintage project
Unstable electrified three wheeled Bicycle truck

[Juho]

[Juho]

IM going to try draw a basic model of our car in blender to try to improve aero

[morghen]

Well first of all...what do you want? less drag? or more downforce?
What sort of racing will your car be doing?

You can do some general improvements to reduce lift...like Cedric said, the part that needs the most work is under the car.
Cutting off that rear spare wheel housing and building a rear diffusor will help a lot with rear end grip for example....but then you'll need to balance the front so it wont lift on you...so a front end splitter calibrated with the rear diffusor...and yeah, smooth belly is also a good idea, especially in some areas.

But without proper data acquisition and proper tools and understanding this is a hit and miss thing with a lot of trials and testing and guessing.

Anyway, i'm not sure what experience you have with racing and tracking but you also have to ask yourself the following question: What is it that i'm after? Because if you just want to have fun...you can surely do it without investing 3 years into improving the aero of the 924.
The 924 has loads of aspects that can be improved, especially for a track oriented 924...but then again so do we.
Sometimes the best investment is in our own experience actually doing the thing we want to rather than improving our gear.
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https://www.the924.com

[Juho]

I can aquire the data when i get the car 3d modeled in blender or i scan it. I can run simulations on simscale, i have acess to unlimited hours.

I know rear diffusor need to be balanced with front one but first i would need to corner to weight the car to know the weight distribution so i can make the aero to match it so the car doesent change how it handles in different speeds

My only goal is to learn tbh and only experience is fsae. I enjoy more improving my skills and knowledge about cars and making them faster than driving on track. I could spend hours and hours in simscale trying to improve aero of on wing profiles but its alot more enjoyable to work on my own car and to put to stuff i learnt on test.

my ultimate goal is to work on motorsport industry one day and ive been reading alot of books of suspension geometry and aero, i think me experiencing this stuff on this level will help me

[Cedric]

[Juho]

I haven't done full car cfd, i talked about it with a friend and he told me that it was almost impossible to make a 3d scan of a car watertight. I agree that i wont get useful numbers from cfd but i think it can highlight the the places where there is place for most of improvements.

Short list of the cad models
turbosquid: Very inaccurate
humster3d: 100 bucks In accurate still but better.

I have my kinect 3dscanner and my school has 40k$ scanner which i have access to.
so for the model i think the best way is to model a rough shape of our car or scan it and somehow make it water tight

Underbody aero i think would benefit doing cfd because ive watched how the fsae cars underbodies are made and small changes can improve massively downforce.


edit: Atm im reading: Race Car Aerodynamics Designing for Speed by Joseph Katz

[MikeDanger]

I wonder how much the flush window and the late (smooth) rain gutters make?
and a 951 style under spoiler?

the 931 was .31Cd and the 951 was .33 if im correct? the 951 also had the under body panels and the extra trim under the sides between the wheels.

also Have installed aero mirrors and removed the powered radio antenna.

lastly will be making some side skirts based on 968 pieces, but with a small lip at the bottom.
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It was either this or a giant box of legos

[Juho]

I think the improvements on 951 are doing something since the drag coeffiency is only 0.02 higher but it must be make at least some more downforce with the upgrades.

but usually production cars make lift isntead of downforce so idk really how much improvement there is in terms of pure downforce.

Side skirts would help alot with flat floor imo because it would help to trap air better under the car and with a small lip even better