Jump to content
SAU Community

Recommended Posts

Put a gurney flap on it Russ......

that's what I was getting at. without gurney flap it's not doing nearly as much as it could be. especially with a very flat shape like that. it will be low drag which is good, but low downforce too which is not.

yeah a big part of the downforce comes from that little 20mm flap on the top. it's been tested many times. most of the jap wings (the real ones that work) come without gurney flap for street cars who just want the look without all the drag and with gurney flap for track cars. yes it is adjustable but past a certain angle it will not make any more downforce and the wing will stall. hence you need the flap. if you can't buy one for the wing they are easy to make/have made.

What Baron has already said Russ, it's very important, and honestly, without it, it's an oranment.

A small 20mm gurney will massively increase the downforce, and really, creates bugger all drag, because all is it doing is creating a high pressure zone on the top 20 to 40mm of the wing's surface, pushing it down.

Without it, all you have is a blade running through the air, and when you increase the angle of attack, you are creating as much horizontal drag as you are downforce. Very inefficient.

What Baron has already said Russ, it's very important, and honestly, without it, it's an oranment.

A small 20mm gurney will massively increase the downforce, and really, creates bugger all drag, because all is it doing is creating a high pressure zone on the top 20 to 40mm of the wing's surface, pushing it down.

Without it, all you have is a blade running through the air, and when you increase the angle of attack, you are creating as much horizontal drag as you are downforce. Very inefficient.

That is fine but how much rear downforce do you really want/need. No point having it if you cannot match it to the front downforce which is always the more difficult of the two to generate.

Sure, but it's not difficult to match that downforce with a 4 inch splitter on the front, which is simply creating a high pressure zone in front of the front bar. I assume Russ is adding a splitter given it is so easy, (along with a decent undertray to minimise front lift).

The rear wing is typically actually only going some way toward negating the lift generated by a sedan shaped car (low pressure area around the base of rear screen).

That's my take on it anyway, and of course I'm not an aerodynamicist, but I read a lot. :P

Edited by Marlin

yeah me too being an amateur aerodynamicist. I have read a lot and have a fair bit of practical experience with sedans and some open wheelers too (which are a piece of piss compared to the bunky cars we have).

yeah big aerofoil wing is fine but as marlin said big trade off in drag v downforce and they can only generate so much before the angle of the wing goes too far and it's in stall. gurney flap adds heaps. as far as the front goes you want an undertray to reduce lift (even better if you can incorporate an upside down type wing shape into it which creates a negative pressure zone - downforce), splitter which helps guide the air where you want it (up and over the car), even front anti-dive plates/carnards help create front downforce and grip.

too much rear downforce can be a bad thing in that you end up with high speed understeer (not nice!) but it's pretty easily tunable and to be honest most of our tracks are not fast enough for most to notice anything other than a really bad downforce imbalance. the small imbalances between front and rear downforce don't seem to cause too much grief, but you only need to look at cars with good rear wings through turn 1 at eastern creek to know if they are working or not. same goes for the front aero. lots of time to be gained through T1 at EC with more aero at both ends.

anyway, the main point is for a wing on a circuit car the gurney flap is an important tuning tool. should definitely run one or at least try one.

Thanks for the input guys. I honestly didn't consider it. They guy making this wing for me has mostly made drag wings and is only making what I'm asking him to make.

It has a big surface area and I expect a big increase in downforce compared to what I've had. The front splitter/undertray I am fitting also isn't huge. It's a start and I could easily get this guy to make up the gurney flap and a bigger undertray when I have a better idea of what I want.

It's all testing to me as I have had little exposure to the big dollar stuff you guys have seen. Feel free to invite me into your pits at superlap *wink-wink* Ben :)

I've got a 25 with 26 internals with a 6 Boost and 44 tial, i dont have any creep issues, runs really well now.

On another point, did you think about keeping the stock inlet manifold????

the reason i say this is on my newest engine, we used a Greddy plenum, tomei cams and 26 internals, when it was tuned the engine was extremely lazy, didnt come on full power till around 5k, after much deliberation we decided to put the stock manifold back on, now the car has picked up around a 1000rpm of useful power and it hasn't even been retuned yet.

I dont mean to hijack your build thread, just curious.

See how the gate pipe is at 90deg to the flow of the exhaust gases. That's what was causing all our issues with 6boost manifolds... should reweld the pipe to angle with the direction of flow, like the photo roy posted a while ago

This was considered but couldn't be done without redoing the whole manifold. Tuning tomorrow. See how we go...

I've got a 25 with 26 internals with a 6 Boost and 44 tial, i dont have any creep issues, runs really well now.

On another point, did you think about keeping the stock inlet manifold????

the reason i say this is on my newest engine, we used a Greddy plenum, tomei cams and 26 internals, when it was tuned the engine was extremely lazy, didnt come on full power till around 5k, after much deliberation we decided to put the stock manifold back on, now the car has picked up around a 1000rpm of useful power and it hasn't even been retuned yet.

I dont mean to hijack your build thread, just curious.

Yeah Roy is a big fan of standard manifold. Good for torque and mid range response. From what we saw when it was on the dyno this comes on really early anyway. We'll see tomorrow.

New 10mm slip on spacers are a perfect fit on the front. They were custom made for us locally. Also have Nismo long wheel studs installed.

These were needed for inner clearance for the front. Now effectively 10.5 +5 lol

post-10715-0-57127400-1308579080_thumb.jpg

Custom tailshaft loop made to accomodate the big exhaust and way stronger than the standard one.

post-10715-0-80576000-1308579194_thumb.jpg

This was considered but couldn't be done without redoing the whole manifold. Tuning tomorrow. See how we go...

Ah fair enough, that is a bit of a bugger! Hopefully all goes well then... My GTR did have a 6boost and 90 degree pipe and I had issues holding less than 18psi, fingers crossed all goes well today :cheers:

Yeah Roy is a big fan of standard manifold. Good for torque and mid range response. From what we saw when it was on the dyno this comes on really early anyway. We'll see tomorrow.

fair enough, will be interested to see how you go. Looks like it'll be a good thing when its done.

Good work

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

    • Had I known the diff between R32 and R33 suspension I would have R33 suspension. That ship has sailed so I'm doing my best to replicate a drop spindle without spending $4k on a Billet one.
    • OEM suspension starts to bind as soon as the car gets away from stock height. I locked in the caster and camber before cutting off the kingpin. I then let the upright down in a natural (unbound) state before re-attaching it. Now it moves freely in bump and droop relative to the new ride height. My plan is to add GKTech arms before the car is finished so I can dial camber and caster further. It will be fine. This isn't rocket science. Caster looks good, camber is good, upper arm doesn't cause crazy gain and it is now closer to the stock angle and bump steer checks out. Send it.
    • Pay careful attention to the kinematics of that upper arm. The bloody things don't work properly even on a normal stock height R32. Nissan really screwed the pooch on that one. The fixes have included changing the hole locations on the bracket to change the angle of the inner pivot (which was fairly successful but usually makes it impossible to install or remove the arm without unbolting the bracket from the tower, which sucks) and various swivelling upper arm designs. ALL the swivelling upper arm designs that look like a capital I (with serifs) suck. All of them. Some of them are in fact terribly unsafe. Even the best one of them (the old UAS design) shat itself in short order on my car. The only upper arm that works as advertised and is pretty safe is the GKTech one. But it is high maintenance on a street car. I'm guessing that a 600HP car as (stupidly, IMO) low as you are going is not going to be a regular driver. So the maintenance issues on suspension parts are probably not going to be a problem. But you really must make sure that however your fairly drastically modded suspension ends up, that the upper arms swing through an arc that wants to keep the inner and outer bolts parallel. If the outer end travels through an arc that makes that end's bolt want to skew away from parallel with the inner bolt, you will build up enormous binding and compressing forces in the bushes, chew them out and hate life. The suspension compliance can actually be dominated by the bush binding, not the spring rate! It may be the case that even something like the GKTech arm won't work if your suspension kinematics become too weird, courtesy of all the cut and shut going on. Although you at least say there's no binding now, so maybe you're OK. Seeing as you're in the build phase, you could consider using R33/4 type upper arms (either that actual arm, OEM or aftermarket) or any similar wishbone designed to suit your available space, so alleviate the silliness of the R32 design. Then you can locate your inner pivots to provide the correct kinematics (camber gain on compression, etc).
    • The frontend wouldn't go low enough because the coilover was max low and the upper control arm would collapse into itself and potentially bottom out in the strut tower. I made a brace and cut off the kingpin and then moved the upright down 1.25" and welded. i still have to finish but this gives an idea. Now I can have a normal 3.25" of shock travel and things aren't binding. I'm also dropping the lower arm and tie rod 1.25".
    • Motor and body mockup. Wheel fitment and ride height not set. Last pic shows front ride height after modifying the front uprights to make a 1.25" drop spindle.
×
×
  • Create New...