Jump to content
SAU Community

Recommended Posts

Hi guys, I'm trying to figure out some potential aero improvements for the 4door and keen for some input.


The goal would be to have more downforce to improve high speed stability. The one time I've been at the track in the car it didn't exactly feel planted doing 199km/h up the back straight at Sandown.


Would a rear undertray/diffuser help with this? There's a massive cavity under the boot area in the R34 sedan - is there anything similar to the GT-R undertray available for it?


nengun-3603-01-arc-performance_diffuser.



With the front of the car, this URAS bar looks very trick, however I wonder if it makes any actual difference?


2505090694_363d1f2bd0_z.jpg?zz=1



I'm currently running Origin rear window and boot lip spoilers but they probably don't do much. Would a bigger drag style wing help with downforce?


11181346_546acf2ec1ce0.jpg



Any other tips are welcome too!

Link to comment
https://www.sau.com.au/forums/topic/459687-r34-sedan-aero-improvements/
Share on other sites

Yes that's an option, have you tried that? It'd be great to hear experiences on what difference it makes.

quite a few build on hardtuned that are dedicated track cars. some have seen great results with info on what part of wakefield it had the most effect.

  • Like 1

maybe the top secret style rear diffusers for the coupes will work on the Sedan?

I'm pretty sure the under boot area is slightly different dimensions in the sedan compared to the coupe but perhaps with some modifications. I'll need to get the tape measure out.

quite a few build on hardtuned that are dedicated track cars. some have seen great results with info on what part of wakefield it had the most effect.

Cool thanks I'll see if I can find the right threads!

Found some good threads on the R34 GT-R rear diffuser:

http://www.sau.com.au/forums/topic/405318-r34-gtr-v-spec-rear-diffuser-aero-data/

http://www.sau.com.au/forums/topic/456810-r34-rear-diffuser/

This was really interesting, sounds exactly like what I'm after:

i put one on my previous GT-T and there is an easily noticeable difference at high speeds. Cruising around, nothing, but at 80-100km/hr+ you could definitely feel the car was more stable. Even my gf sitting in the passenger seat noticed it and she a) didn't know it was on b) i hadn't even told her i put it on. Maybe it's a bigger difference to a lighter GT-T, but you could definitely tell the difference.

there are naca ducts in the standard diffusers.

as for the Z-Tune diffuser having 2.2 times more downforce..... that's relating to the front smile.png - diffusers can be front and rear. The front Z-Tune diffuser is mix of CF and magnesium... looks sex, can't buy em though unless you're a Z-Tune owner (or know one i guess) - hate to think how much they are...

Maybe I'll just start with a cardboard stencil and DIY it ... what's some decent material for this? Aluminium, what thickness?

Edit: Also found that East Bear do a 4door rear diffuser (at a ludicrous price) so they do exist: http://www.nengun.com/east-bear/rear-bumper-diffuser-r34

Edited by V28VX37
  • Like 1

Need full undertray as just a rear diffuser will still allow airflow above and below rear diffuser, full undertray will prevent that

Yeah a full undertray would be better but I reckon having a rear undertray with a tight leading edge would still help.

I'm thinking something like in the GT-R rear section:

r34_nissan_skyline_gtr_picture%20(19).jp

I'd love to make one out of aluminium if I had the skills (this is obviously the front):

undertray1.jpg?v=1418778087

Edited by V28VX37

That front undertray looks great, ive been wanting to make a full undertray ever since i install a cf rear diffuser, i cant see how a rear diffuser will do much without a full tray

Yes indeed. Just to clarify, when I'm talking about rear undertray I mean the whole rear section, not just the diffuser. I agree a diffuser by itself probably won't do much.

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now


  • Similar Content

  • Latest Posts

    • Hi,  Just joined the forum so I could share my "fix" of this problem. Might be of use to someone. Had the same hunting at idle issue on my V36 with VQ35HR engine after swapping the engine because the original one got overheated.  While changing the engine I made the mistake of cleaning the throttle bodies and tried all the tricks i could find to do a throttle relearn with no luck. Gave in and took it to a shop and they couldn't sort it. Then took it to my local Nissan dealership and they couldn't get it to idle properly. They said I'd need to replace the throttle bodies and the ecu probably costing more than the car is worth. So I had the idea of replacing the carbon I cleaned out with a thin layer of super glue and it's back to normal idle now. Bit rough but saved the car from the wreckers 🤣
    • After my last update, I went ahead with cleaning and restoring the entire fuel system. This included removing the tank and cleaning it with the Beyond Balistics solution, power washing it multiple times, drying it thoroughly, rinsing with IPA, drying again with heat gun and compressed air. Also, cleaning out the lines, fuel rail, and replacing the fuel pump with an OEM-style one. During the cleaning process, I replaced several hoses - including the breather hose on the fuel tank, which turned out to be the cause of the earlier fuel leak. This is what the old fuel filter looked like: Fuel tank before cleaning: Dirty Fuel Tank.mp4   Fuel tank after cleaning (some staining remains): Clean Fuel Tank.mp4 Both the OEM 270cc and new DeatschWerks 550cc injectors were cleaned professionally by a shop. Before reassembling everything, I tested the fuel flow by running the pump output into a container at the fuel filter location - flow looked good. I then fitted the new fuel filter and reassembled the rest of the system. Fuel Flow Test.mp4 Test 1 - 550cc injectors Ran the new fuel pump with its supplied diagonal strainer (different from OEM’s flat strainer) and my 550cc injectors using the same resized-injector map I had successfully used before. At first, it idled roughly and stalled when I applied throttle. Checked the spark plugs and found that they were fouled with carbon (likely from the earlier overly rich running when the injectors were clogged). After cleaning the plugs, the car started fine. However, it would only idle for 30–60 seconds before stalling, and while driving it would feel like a “fuel cut” after a few seconds - though it wouldn’t fully stall. Test 2 – Strainer swap Suspecting the diagonal strainer might not be reaching the tank bottom, I swapped it for the original flat strainer and filled the tank with ~45L of fuel. The issue persisted exactly the same. Test 3 – OEM injectors To eliminate tuning variables, I reinstalled the OEM 270cc injectors and reverted to the original map. Cleaned the spark plugs again just in-case. The stalling and “fuel cut” still remained.   At this stage, I suspect an intermittent power or connection fault at the fuel pump hanger, caused during the cleaning process. This has led me to look into getting Frenchy’s fuel hanger and replacing the unit entirely. TL;DR: Cleaned and restored the fuel system (tank, lines, rail, pump). Tested 550cc injectors with the same resized-injector map as before, but the car stalls at idle and experiences what feels like “fuel cut” after a few seconds of driving. Swapped back to OEM injectors with original map to rule out tuning, but the issue persists. Now suspecting an intermittent power or connection fault at the fuel pump hanger, possibly cause by the cleaning process.  
    • For race cars, this is one part where I find having the roll cage bar having gone through a hole in the floor better than the build it up on a ledge inside... The Merc I help on, the main hoop ends are marked on the car, and the jack is marked... Jack goes under a few inches and lifts one whole side of the car up... Removes that fight for long slim jacks for race car duties!   My biggest issue for the daily drivers I work on, is my jacks don't go high enough. The jacks start out on a few blocks, jack it up, then start a second jack under it on more blocks, and then I can get an axle stand under it. My axle stands are presently in use, and are nearly fully extended. The car is sitting with barely more than a cm of clearance to get the wheel off the studs! Sarah's Kluger is the same, as it has an ungodly amount of droop available in the suspension and a distinct lack of good jacking points!
    • Happy? Yep, my to do list is getting shorter and shorter. Either this light approaching is the end of the tunnel, or I'm about to be hit by a train... Ha ha ha   Also, Duncan isn't that far out of town that you need to make a multi day drive out of it. 😛
×
×
  • Create New...