Hello All,
I have been doing more modifications to my 4.8L MGB GT V8, Road and trackday car. I couldnt find any details of someone adding a fully functional rear wing to an MGB in the net so have just jumped in at the deep end with my design.
Here are some photos would appreciate some feedback as to what you guys think.
So far have only driven on the highway upto about 80mph and it seems very stable. I now need to try it on track.
To complement the wing I am also fitting a front splitter that will extend back as far as the front crossmember.
(http://i76.photobucket.com/albums/j30/V8bloke/DSCN0299.jpg)
(http://i76.photobucket.com/albums/j30/V8bloke/DSCN0302.jpg)
(http://i76.photobucket.com/albums/j30/V8bloke/DSCN0297.jpg)
(http://i76.photobucket.com/albums/j30/V8bloke/DSCN0300.jpg)
Cheers
Mark
Whether it works or not, it looks mean. You should contact Jim Blackwood, he has a wing on the back of his car but his is a roadster. As thorough as Jim is I'm sure he has lots of data on his wing.
I always enjoy seeing photos of your car! (We need to get your page of the Photo Gallery updated to show your work properly.)
I'm enthusiastic about your idea of adding a splitter. The benefit should be substantial. Will you use it around town, or just for track days? If it's strictly for track days, maybe you can set it lower and extend it outward to front and sides further.
There are two winged MGBs on this site: Jim Blackwood's MGB (http://www.britishv8.org/MG/JimBlackwood.htm") and Phil's Leonard's RV8 racecar (http://www.britishracecar.com/PhilLeonard-MG-RV8.htm). I don't recall seeing any measurements of how well those wings work. It would be very interesting to put load cells under the mounts to see how much downforce is created. Of course lap times are the real measure of success.
Please keep us posted as you evaluate these concepts!
The larger the front splitter, the more wing you will need to balance the car out, the more angle of attack the more drag,
it's a tradeoff.
Dave
The last couple of races we've been running Phil's RV8 without the wing and doing quite well. We may need the additional downforce with a stronger engine, but for now it's pretty well balanced as it is without.
Thanks guys, I am really looking forward to experimenting with the new setup. Anyone who has seen my videos on youtube (v8bloke) will see that I have always been battling with oversteer so I am hoping the wing will help reduce this.
It will also be interesting to see how much straight line speed will be reduced by the extra drag.
To try and see what the airflow is doing I am going to attach some 5ft lengths of thin fabric ribbon to the top of the windscreen so they trail back over/under the wing. Then using my Gopro and suction mount attached to the roof drive at varying speeds to film how the ribbons trail. Dont know if it will work but worth a try!
Next trackday is on the Silverstone GP track on 2nd Sept so will post the findings.
Cheers
Mark
You might also take a look at Mike Sawatsky's (spelling?) heavily modified BGT track only car. He's running both a splitter and a wing and has been very detailed in his experiments with both. He has several threads on this board and at least one over on BritishV8. Might be worth a look.
Mark Sawatsky's MGB-GT Racecar Build Thread: <a href="http://forum.britishv8.org/read.php?13,18284">
part 1</a>, <a href="http://forum.britishv8.org/read.php?13,23257">
part 2</a>, and <a href="http://forum.britishv8.org/read.php?13,31745">
part 3</a>. (I think the aerodynamic stuff is mostly in part 2.)
Thanks
Looking forward to some testing. The good thing is that I can remove the wing easily for comparisons.
Mark
I had thought about testing different aerodynamic effects such as this. It would be real easy to hook p a potentiometer to measure suspension deflection at speed. You could run with and without and measure how much the suspension changes with each.
mark,the tuft testing should be very revealing if you can get adequate pics ,can you move the wing up and down ? then you can
see where it is most effective without running the wing at a severe angle of attack (AOA) minimizing drag, also you can see the effect of downwash off the back of the wing. If you run a front splitter with the flat bottom going back as far as poss. it WILL
create down force, contributing to the already poor weight distrbution and if you run the wing at an exagerated AOA you will get the resultant drag,, maybe just try a few tricks with the rear wing and your existing front air dam, see how that feels,of that and as Gary says with the capability to measure true deflection would be the icing on the cake.
Dave
With the Arduino it would be very easy to hook up an LCD and a potentiometer (and a whole lot more).
http://arduino.cc/playground/Learning/SerialLCD
http://www.arduino.cc/en/Tutorial/Potentiometer
Quote...contributing to the already poor weight distribution...
Mine measures about 49/51... Mark's can't be too far off that. Is that poor? What's the target then?
wow this is getting interesting.
mine is 52/48 F/R i thought that was quite good.
Those ARE good numbers, better than I thought,(obviously) the other, generally still applies however.
Dave
50 / 50 weight distribution is the optimal split for a front engine - rear drive car. it's not unusual for FWD cars to be over 60% on the front axle ... but then, their rear tires aren't doing a whole heck of a lot.
mine is 52/48 F/R i thought that was quite good.
and it IS pretty good. anything better than 55 / 45 is getting towards purpose built race car territory. it's normally kind of hard to get that much balance out of most cars because there's often a significant portion of the engine which sits forward of the center line of the front suspension.
Here are some photos would appreciate some feedback as to what you guys think.
you remember the Dodge Daytona / Plymouth Roadrunner from 1970?
it became somewhat of an "open secret" ( because the design got outlawed, so the engineer and aero guys didn't mind talking about it ) that the designers considered the UPRIGHTS to be almost more important than the wing itself. they acted as high speed stabilizers, just like you see on an airplane.
you can see some vestiges of this thought process on Cup cars today with the 'shark fin' that runs down the drivers side of the car..
as such, if you spend much time over 100mph you may want to consider full body uprights rather than those weight savers you're running now.
Aircraft Spruce and Specialty sells airfoil shaped aluminum struts. That is what I used.
Jim
The cup cars are using this splitter effect trying which keep the air flow on the sides or deck,, the sharp edges create vortices which aid in that effect.
Dave
The new wing and splitter have had their first test.
Definateley reduced oversteer in fast turns.
http://www.youtube.com/watch?v=HnDjFI_m5i8&feature=plcp
Heh. I do believe I see a spinner at 1:10.
That's amazing how you're *murdering* that Evo in the corners. Is he running stock rubber?
It sounded like you're geared just a little short for the front stretch on that one dry pass near the end when you were pursuing. You ditch your passenger and I'm sure that will come into play a lot more often.
Todd
I believe he was using Toyo R888 tyres.
I much prefer not having a passenger.
Very happy with the aero upgrades. Just need to experiment with angles.
Mark
Hello again all.
Well, it would seem that the rear wing is producing quite a lot of downforce. I know this because my exhaust is grounding at high speed (130mph+) over slight undulations which it never did before.
I have had an idea that almost seems too simple, but I think could work to reduce drag at high speed.
Just to recap the car is a road legal MGB GT V8 4.8 which is modified for trackdays not racing.
I have been experimenting and found the best angle for maximum downforce and the best angle for minimum drag. The virtical
distance between the rear wing mounting hole for both these setting is less than 30mm.
I was wondering if I could use a strong spring for the rear wing mount each side that would compress at high speed/downforce (80mph+) so giving maximum effect at lower speeds but less effect and less drag at high speed.
it would take a bit of trial end error to get the spring rate right and I could use my Gopro camera too see what is going on. Also I could factor in adjustable stops to set maximum and minimum angle.
How stupid is this? as it seems just too simple.
Mark
Mark, the super modifieds like those in the picture do the very thing you're talking about, I've never looked at one up close to see how they manage the up and down movement , but the wings definately flatten out at speed and come back up on deceleration. these cars run big V8 engines and are direct drive ( in/out box),, oh yeah,,,, they ARE roundy round cars.
Dave
supermodifieds.jpg
Thanks Dave
I like a challenge
Now I have come up with a linkage that will effectiveley soften the spring after the initial 20mm of movement.
It will take a while but I will post up the vid hopefully of the linkage in action.
Mark
They use "wing cylinders" and you can see them in the photo. There is a controller for it in the cockpit so the driver can adjust it, I think it is some sort of brake cylinder. I am considering the use of these on my wing but will be tying it to the suspension so it works like the mechanical linkage I had before the IRS. Common sizes are 8", 10" and12" travel. I have not seen anything shorter. Speedway sells a hydraulic cylinder now but it is not available in the 8" size. Diameter is 1-1/4". Cost about $140 each. If I use these I will need suspension cylinders with about a 3/4" bore and 4-1/2" of travel. This system holds the ride height constant by applying more downforce if the body lifts.
Jim
It would be nice if it was that easy, just add a wing and be done.
If traction is the game then yes. there is a formula to figure out the down force area needed. Down force is like adding weight, so spring rate changes.
The front may also need down force to compensate for the rear down force. tires also a factor to include in the formula.
Then angle of the wing etc etc.
Wings create drag which means that they use hp/torque, top speed reduces.
It would be more beneficial to reduce drag first and add the needed down force.
I would start by closing every opening in the front, reduce the air intake on the radiator, be surprise how little you need.
Many books in this area. I am doing the same with my GT I want less drag,
Bill
Post up some pictures of what you are doing to the GT, I'm fabbing the front sheetmetal now so would be the ideal time to make changes. Start a new thread so we don't hijack.
Will do.
Minimizing the grill opening, closing all openings in the radiator support, smooth front valance, reduce the front bumper size and recessed in to the body, will see the possibility of minimizing the rain gutter in front of windshield it is a big air brake
May have to add spats to the front fenders, will determine when is done. The radiator does not need a big opening. I am closing the grill from inside the grill. The opening will be about 50% of the radiator at the grill and 100% at the radiator, funnel effect. I ma going back to woirk on it next week.
GTBodyWork017.jpg
GreenGT047.jpg
Will post when I complete the radiator opening.
One picture
GreenGT046.jpg
Forgot to mention that the openings you see in the front balance will be close. You can also see the chin on the front balance, that lip will hold a small lip spoiler sticking out forward about 1". Once I get it running will use wool strings to check the flow of air around the fenders, that will tell me what I should do.
chin spoiler is similar to the Z06 Vette
GreenGT102.jpg
From my understanding thru folks I have worked with a typical opening to rad size should be about 1" to 6" ratio, but like what has has been discussed previously you still need the pressure differential back of the rad to work.
Dave
it would take a bit of trial end error to get the spring rate right and I could use my Gopro camera too see what is going on. Also I could factor in adjustable stops to set maximum and minimum angle.
How stupid is this? as it seems just too simple.
Too simple? Wait til it breaks, we'll see how simple you think it is then. ;-]
you can get little rubber sliders for the shaft of the adjustment piston which will show you exactly how much maximum compression at speed is. Obviously, that won't work for extension.
Mark, "If" you were to attach the rear wing struts to the rear end or uprights,(unsprung weight), you would not need more spring rate.Using rubber blocks to limit suspension compession, prematurely, can lead to rapid slide of the tires, on that end,(spring of near ifinite rate). I'm not suggesting this, but on early days of winged Indy cars, they did this. Problems arose because the verticals were "triangulated". One failed, there was a crash, and USAC banned suspension mounted wings.Its a good concept, the application was flawed. Footnote, so now high downforce cars can use springs fron the railroad/lol. Onward, roverman.
Well here is my idea built up and ready for testing.
(http://i76.photobucket.com/albums/j30/V8bloke/phone035.jpg)
(http://i76.photobucket.com/albums/j30/V8bloke/phone034.jpg)
(http://i76.photobucket.com/albums/j30/V8bloke/phone033.jpg)
Now need to do some testing.
Mark
Mark, it looks great, excellent range of adjustment and you could change spring rate or motion ratios for further adjustment
capability, nice fab work by the way.
Dave
You may have a little rocking from side to side so watch for that. If it does, watch out for a harmonic. I think it is stiff enough that you will be OK. It looks pretty good. Not sure how your mechanism works though.
Jim
Here is the final design all fabricated and finished.
(http://i76.photobucket.com/albums/j30/V8bloke/car013_zps58ba6d57.jpg) (http://s76.photobucket.com/user/V8bloke/media/car013_zps58ba6d57.jpg.html)
Sister car now has the same DRS system.
(http://i76.photobucket.com/albums/j30/V8bloke/car017_zps4a43ba2d.jpg) (http://s76.photobucket.com/user/V8bloke/media/car017_zps4a43ba2d.jpg.html)
(http://i76.photobucket.com/albums/j30/V8bloke/car006_zps7f25e275.jpg) (http://s76.photobucket.com/user/V8bloke/media/car006_zps7f25e275.jpg.html)
Stunning performance improvement. The Wing and drag reduction linkage works just great. knocked off 3 seconds from my best time at Castle Combe.
http://www.youtube.com/watch?v=YqNfmSKs9YU
Man o man that's better than a roller coaster ride! I would like the spectators perspective from the stands as well.....down the straights what do you think you top end speed is.140 mph? Just a guess.
Hee hee. This is why all circuit racing should start with the fields inverted by qualifying speed / points.
You're just murderizing them. Looks like you're mostly just eating them up with motor down the straights though. Are they still pretty much up to your speed in the corners? Or are you just really taking it easy with the side by side stuff, due to this being practice and with amateurs?
I see you're still getting throttle loose even after the tires are warmed up. You're definitely not short power. Is there anyone out there who would be 'in your class' if this was a real race? Were there cars close to your speed and you just never ran near them?
David, Yes top speed on this track must be aproaching 140mph! the speedo goes right off the scale (140) but havent a clue how accurate it is.
Todd, there were a few very fast cars there including a Nissan GTR and a Honda powered Lotus Exige but we never seemed to get together on track.
Here is a clip of the new Home brewed DRS in action. I am so pleased that it works exactly as I intended.
http://www.youtube.com/watch?v=-uR8Lx33jEw
Cheers
Mark