Curiously enough, I purchased my car without the diffuser, so I run without currently. As I said, all the N1 race cars run without them as far as I can see (so does mine). The Falken car did without the diffuser in the 24H Nurburgring 2002 event as well. There seem to be at least two problems with the diffuser: 1) it's too heavy (there's a big lump of lead in the middle which prevents the thing from starting to vibrate) and 2) the coolers don't get enough air. Also, I've heard a story about a car with the diffuser having a lower topspeed than the one wthout. I'll have to get this confirmed very soon.
Thanks for the offer BTW; having the fins only wouldn't be of much help since I don't have a diffuser to put them on !
In which way are the differences noticeable BTW ?
Coming from the motor racing business- Panoz,Lister, Porsche
and spending a lot of time in the wind tunnel at MIRA .
Yes I totally agree the "longer" or "lower" diffuser blade will help to divide the diffuser into more defined units so the increased speed of the air due to the venturi effect of the diffuser will increase the "downforce".
The trouble with aerodynamic "aids" on road cars is providing
a "stable" enviroment for the aids to work. A race car say a
Porsche GT3rs weight 1200kg uses approx 1000 lb springs on the front and approx 1400 lb springs on the rear use telementry this car will have approx 25mm of suspension movement , a world sport car i.e a Panoz roadster 2000 lb front 2500 lb rear this car weighs 900 kg suspension movement 10 mm this allows you to trim the aerodynamics very precisly a panoz at approx 100 mph
wind speed in a tunnel will produce approx 300 kg of "overall " downforce. A car needs a controlled balanced spread of down force between front and rear aerodynmic downforce.
A 34 skyline uses approx 300 lb springs with 50 mm of preload and has suspension travel of 100mm no stable platform for the aerodynamic aids to work 1 minute you will have the ideal gap between the diffuser fins and floor next minute an unideal gap.
Why did Nissan fit the diffuser you say Homolgation purposes,
if they did not fit it when they "homolagated" the car then if they wanted to use it at a later date it would cost a fortune.
My idea is to use the top face off a aerodynamic device to help stability on a road car i.e the rear spoiler , front lower spoiler on a R34, this gives you a stable enviroment this aid is constant.
The laws of areodynamics are very complex and I know very little inreal terms it is just that I have worked with a lot of very good designer and aerodynamic engineers these people you listen to and learn.
Andre this is why your car doesn,t use a rear diffuser and also aerodynamic devices use air to work cars also use air to cool them i.e oil cooler , radiators etc so there is another story.
I think it would be fair to say that with a diffuser fitted the top end speed comes into play and it is inevitable that there is a drag issue without question and therefore less speed. Our carbon/kevlar whole diffuser is 5lbs lighter than the original nissan one which was one of the original plans however we can also make them from pure Carbon without the kevlar. As with the original item, our diffuser is made up using honeycombe sandwich and under vacuum. At very high speeds ( over 100 mph etc ) it has given the car much more solid presence on the road, cornering at speed was the main difference, you only realise when you take a corner at 90mph and then realise that without the diffuser you only managed 80 etc, it gives you much more sterdiness on the corners enabling you to tae them faster and quicker and with even more confidence. I have tried mine over the past few months before selling one gto ensure we get it right and now the new ones like Weka has are improved over the original one side items that were on my car. Since I had to remove the diffuser for the rolling road day, I havent put it back on yet cos of time but have now noticed a different feel to the car without any diffuser at all. Our development of handling technology and forces has only just begun, we are currently looking at making the whole undercar from Carbon from front to rear, watch this space. I have the moulds ready for the diffusers so if you have the need for one PM me and I will get one made for you with the fins for you to try out on the track.
Peter, See Rupert last week and he now has his rear end sorted, I think he bought it in instead of making it in the end, get in touch with him about it. Also, for the same, in the next few weeks we are going to start looking at a rear diffuser for the R33 based on the R34 one so that should be interesting when it happens as we have alot of flexibilty with using Carbon and manufacturing the bits from scratch, How about a carbon fibre intake plenum Peter?
it is good for more info about forces, your right Glen.
I got our information from a touring car team that has been racing for 10 years and guidance from worldwide Touring Car champion/driver a few times over JAMES KAYE. Its is only when you have raced many different cars and setups that you can truly have an idea of what works and what doesnt and this is why we have listened to the expert with experience. We havent been ' WITHIN' the racing scene for very long, only this year with the tourers infact but we have learnt so much in this year about racing and race setups and racing preparation that we are going to put some of these things into action for next year cos it seems a shame that all this racing info has never been used in very fast road cars before, its surprising. The diffuser extensions are a start to our project, as is well known, you have to balance aerodynamics to get full effect however these fins in particular have maximum effect on cornering mostly. The wing extensions which have been fitted to my R34 and also to Pauls are much more an issue with regards to downforce as we are generating much more on the rear than previously, than is apparent just in common sense without getting into calculations but also noticeable with the handling of the car at very high speeds. We will be working on the front end very soon however both me and Paul have the Nismo front bumper which has much sharper angles and does generate slightly more force on the front end than a standard bumper due to its design but we will be generating more and have plans for windtunnel testing in the future, its not a cavalier attempt to produce wakky trendy looking parts, everyone knows, we use our cars to the max and I wont put anything performance-wise on unless it works or its just pointless. Like Glens car, he now has further downforce on the front of his car with the new carbon looky likey front diffuser but has removed alot of the rear downforce by using the Do-Luck rear wing stays, what effect this has had on his overall handling I am sure will become apparent when ( if ever ) he puts in on the track and under heavy load which is exactly what we have done, you have to get the car working hard to realise what the differences you have made have acheived. ( this is not dig at his mods btw ).
Why does my car go so well for what it is? - Because nearly everything on it is there for a reason, love or hate the mods, they work and if they dont we take em off, thats why Vince has his SUMO POWER fins, cos they work and in kevlar they look nice too. We are only producing 6 sets of Kevlar fin coversions for customers cars as they are not a fashion statement and we dont want them to become one either, if anyone is serious about handling mods then we will make a set for them, otherwise they just stay on my car and the people who realise the difference they make.
Chaps I was looking for more of the built in difusser for my GTR 33, a sort of whole bumper replacement like the one below. That with the side skirts shown and its achieved 500 BHP would finally see my project complete!...Yeh right!
Thats OK, I am not suggesting that anyone has a good or bad setup, only knowing what works from what we've tried so far, Glens Do-Luck extensions are fine however I would suggest that they are more for appearance than anything else as Do-Luck make no mention of downforce or Vortex's in thier literature ( I have a few Do-Luck parts ). The downforce created by our wings is increased but I would suggest that I spend alot more time at very high speeds than he does and maybe even most to be fair and the small prospect of removing the wing for a bit of dragging is best for me, as seen at 10oftb, it returned another 4mph through the beam than without it on but the car was nowhere near as steady at that speed, Ronnie did the same, with the rear wing removed he also increased speed, if we had the time I would have liked to remove my rear diffuser for that day as the drag on my car with that fitted as huge, but, as I say, I use it constantly at high speeds, everyday and the parts are there for a reason, Vince has made a very wise buy with his parts, they are more than just for show.
It is also worth noting that our wing extensions also move the whole top half of the wing further towards the back of the car not just simply up in the air. I am not into circuit driving in particular, I am in for anything where I can abuse my car to the limits make make reality of the parts fitted for a reason, I made 11.85 secs quater mile at Santa pod and a 3.31 0-60mph with the wing ON which is nice cos thats how I use the car everyday in that setup.
The parts work in their own way, well done to Vince, could be worse, he could have bought a 'trendy' carbon bonnet - joking.
Dirk...point taken. You mentioned you are now concentrating on front aerodynamics, are you planning on fitting those front bumper GT type winglets(I dont know what the correct term is )? They are very popular here in Japan and they, as long with GT-style wings, are all the rage! Here is a picture to see what I mean;
I've always wondered if they actually make a perceptible difference to high speed cornering...
Very similar to one of our ideas for the front, winglets sound good, let stick with that then, not very butch though - SUMO POWER WINGLETS, hehe.
Just those alone would make a great difference to the handling in anger. its amazing isnt it, cos you cant see them working its hard to imagine the differences which are being made, unlike a new exhaust or something like that, aero mods get no thanks, only if it looks good.
I don't think I've really lost any downforce. Don't know where you got that from as their is still the same amount of air passing over the top of my spoiler. Having my wing pushed further back over the car produces even better downforce due to it being further back but reduces drag. Bit of a balancing act to get it right, % here % their, but for us mere mortals we wouldn't really notice the difference. Damn perhaps I should have taken mine off at Ten of the Best. Mind you'd I'd still have come second behind Ronnie.
Carbon Bonnet. Just because your's ain't arrived yet .
These diffuser things. Too be honest I haven't seen a lot of cars wearing 'em. I have on top spec particular race cars but they all seem to be sooooo low to the ground. They must have 'em for a reason but I'm not even sure if the Falken car at Nurburgring had 'em on. Anyone got any pics ??
No doubt we'll have some proper technical info put up here soon on downforces etc., knowing the techno heads we have on here .
So serious. Get that chip off your shoulder. Chill mate I still love you .
I think it had to do with clearence of all the oil coolers(diff & 'box) and as it was said earlier that it would have restricted airflow to them. Probably one less thing to worry about ....if a rear suspension member broke or they needed access to the rear diff .... it would potentially waste time to take it off. Thats probably the reason I should think (?)
HAVENT GOT A CARBON BONNET ON ORDER, MINE IS FRP, I DONT LIKE THE CARBON BONNET LOOK ESPECIALLY AS I HAVE A BAYSIDE CAR, I DONT PERSONALLY THINK IT SUITS THE CAR HAVING A BLACK/GREY BONNET, THE BONNET I HAVE COMING IS FRP AND WILL BE PAINTED BAYSIDE TO MATCH THE CAR, AGAIN, ITS GOT A USE, ITS GOT VERY INTERESTING AIR DUCTS WHICH I NEED TO USE IN CONJUCTION WITH ANOTHER MOD WHICH I AM WORKING ON AT THE MOMENT, BUT IT LOOKS NICE TOO THE CARBON BONNET WAS ONLY ANOTHER 100 QUID FROM MEMORY THOUGH. I NOW HAVE MY COUPLE OF TRICK NICE LOOKING BITS FOR THE CAR, THE FRONT LIGHT EYEBROWS AND THE REAR CARBON LIGHT SURROUNDS, THESE HAVE NO OTHER FUNCTION BUT TO MAKE MY CAR LOOK INDIVIDUAL FROM ALL THE OTHER BAYSIDE R34'S.
DONT KNOW WHERE I GOT IT FROM? JUST COMMON SENSE ON THAT ONE GLEN, THERE IS NO WAY YOUR SPOILER GIVES ANYWHERE NEAR AS MUCH DOWNFORCE AS MY SETUP, NO SAYING IT DONT GIVE ANY BUT NOT AS MUCH, AS FOR 10OTB, YES YOU SHOULD HAVE TAKEN IT OFF, MAYBE THEN YOU COULD HAVE GOT NEARER MY TOP SPEED, SAYING THAT, IF I DIDNT HAVE MY REAR DIFFUSER ON LIKE YOU I WOULD HAVE HAD MORE SPEED AS WELL, STILL, HISTORY.
PETER, IF YOU FIND THAT CHIP, GIVE IT TO THE MIDGET AND HE WILL FRY IT FOR YOU, LMAO, SFFTT
Well we need to look at the fins from one of two points:
Vincent asked for our opinions so it's only fair we give them, I have to say I don't like them. They certainly look bolted on and do nothing for the lines of the car. This is purely subjective and should not be a decisive factor for him.
Correct me if I'm wrong, but to gain the highest top speed in the minimum of time, then you need no active downforce whatsoever. Downforce is only of value at high speeds when you are generating lift, and otherwise is only classed as drag. I'd hazard a guess by saying that for 0-60 sprints and 1/4 runs, you would post much better times by taking off both your spoiler and the fins. In fact, you have probably made your times worse by adding the after market versions of both your spoiler and your fins.
Interestingly, when we spent the evening with Mr. Tamura of Nissan project planning and management, a key figure within the design and development of the 34 GTR, he was incensed to hear that we had made changes that would affect the airflow of the car. He took great time and care to explain to me how complex the process was to perfect the car in the windtunnel, explaining to me the exact areas of 'balanced' downforce and aerodynamics.
I am always suspect of aftermarket 'aerodynamic aids' that have not been through such a similar, rigid testing process through the use of wind tunnels and complex methods.
Come on Dirk I'm talking about MY downforce, not yours .
FRP, you should have said as I'd have lent you the £100. Is it the C Westin one your still getting ? I've had a few people say mine looks 5hite and would look better painted but it's personal preferences I suppose.
Gotta say am soooo pleased with me Top Secret bonnet as the cooling effects are very good. Cem also mentioned this about the Nismo one he got off Shin. Had to go with someone like them or Nismo as they are definetly a couple of the leaders in R&D for Skylines :smokin: .
Phew 10 of the Best. I know where your coming from. Wish I had my 6 speeder in rather than the 5 speeder. I was hitting 175-6mph in 4th gear. Was definetly badly over-geared. Don't know how I got down the 500metres second quickest Skyline. Must have been power or driver .