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Russman's Time Attack Build

Russman

By Russman,
in Motorsport Builds

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Russman
Russman

Pulled the gearbox apart and what a mess! That's what 'clicking 3rd' with hot 295 AO50's will do to a 33 gearbox!  With some bits purchased from another donor box and help from Donny at For

Russman
Russman

Clean and up in the air. Final bits of work required to hit the track in November.

Russman
Russman

Wow. Yeah it has been a long time since an update in this thread. It's been laid up for a while. Sitting on stands and collecting dust. The last 2 years of my life has been a case of home renovation

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Beer Baron Grand Master

Beer Baron

Posted
Posted

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.

Beer Baron Grand Master

Beer Baron

Posted
Posted

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.

Marlin Grand Master

Marlin

Posted
Posted

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.

djr81 Grand Master

djr81

Posted
Posted

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.

Marlin Grand Master

Marlin

Posted
Posted (edited)

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
Beer Baron Grand Master

Beer Baron

Posted
Posted

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.

Russman Grand Master

Russman

Posted
  • Author
Posted

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 :)

MookRG Collaborator

MookRG

Posted
Posted

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.

Russman Grand Master

Russman

Posted
  • Author
Posted

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.

Russman Grand Master

Russman

Posted
  • Author
Posted

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

SimonR32 Grand Master

SimonR32

Posted
Posted

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:

MookRG Collaborator

MookRG

Posted
Posted

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

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