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By the way Beavis Eipgam is Magpie spelt backwards in case you did not realise who it was.
While I don't usually spend my nights working on forum name anagrams, I knew it was you from the pic of the car.
Don't worry I'm watching you closely, you provide great info and insight for us other grassroots time-attackers
Looked at some data to see if the drag has changed since the mods have been done.
3 years of data from WATC when I was going down the main straight and had gear changes. The distance used was 507.2m.
Each time was on 205/50/15 brand new AD08R's
2017 the car had a different splitter, increased rear wing AoA (Singular end plates), lighter wheels 8" rims and no rear mud flaps.
2016 - previous splitter, 7" 6UL's (lightest wheels I have).
2015 - previous splitter, 6.5" rims (heaviest), rear wing was higher.
Between 2015 and 2017 there is a 1.2% increase in acceleration, there have been no changes to the engine!
The 2016 data whilst looks like an anomaly, looking at the graph shows that the acceleration at about 3835m starts to flatten whilst the TPS is at 100%. It would appear that this was the start of my 2017 fuel pressure issue...
With reference to the above anomaly in the 2016 data, the injector duty cycle dropped to almost zero around the same time. This could also have been the start of my fuel pressure issues. This issue, drop in injector duty cycle has not shown again since the fuel pressure issue has been fixed.
As purchased and modified over the years. #63c (black headlights) was the number for WTAC 2016, #98c was WTAC 2015, #c63 (blue headlights post WTAC 2016), #81c post WTAC 2017
Mark, I know you get a million suggestions from well wishers on the forums, but the good idea's fairy is sometimes hard to ignore. And some of this is DIY aero, some is not.
"If I were you" since the car is now no longer road registered, I would look at going to open Class for WTAC if that is the event you are always working around. It solves your tire problems, it gives you a million more freedom in terms of rules and who cares where you come on the leader board. I am assuming your loyalty to the event would not create an issue for selection for the class, and the uniqueness of the entry. Then you can run 225/50/15 AO50's and be super happy and go all the fasts. (yes the height is not super good, but trust me you will be happy you did (or 215)).
Onto the aero, I wouldn't reinvent the wheel, pay cash dollars to ThePass and grab that wing when the dollar is good, as Ryan said it solves 3 issues at once, and it is proven.
Aero 2 - I am getting a new exhaust done over xmas, and with this a diffuser will be made, yes probably not as good as a CFD designed one, but if you are in no rush hold off on that as if it works I will have a mould.
Aero 3 - I also have side skirts, probably a picture somewhere back in this forum of them, and hence I have moulds, however untested at this stage.
Would anyone be interested in a full front to back under body for an na. I have a rough design now in getting finalized for my 90. The front is similar to lrb then all the way back into a diffuser. If there is enough interest i will sent it to my local laser cutting friend that does all our work stuff for a quote.
Does lowering the leading edge of the bonnet actually reduce drag? I'm not sure how much it will help. It will move the high pressure zone backwards which might create more downforce over the bonnet area but it would reduce the downforce at the front splitter.
Most low drag cars actually have the nose up higher with a focus on diverting air to either side rather than over the top of the car.
I have no data but can assure you the car is not suffering from lack of front downforce, we had to crank the rear wing AOA by almost 10 degrees to balance out this new splitter, despite the fact that we added a diffuser as well.
In areas that are grip limited only (where engine power does not change cornering speeds) my corner speeds were fairly similar to Emilio's 1:44.984 video, despite the fact that he's on brand new 245 A7 and I was on 205 R7 past prime time.
Keep in mind that the wing is a 71" wide GT-1000, 10 degrees AOA change is massive.
Most low drag cars actually have the nose up higher with a focus on diverting air to either side rather than over the top of the car.
Been thinking more about this comment, I keep trying to come up with examples of this being the case when this is not rule driven and having a hard time.
Can you show an example for this?
Closest thing I got was the front fenders on LMP1 prototypes but that is a rule driven change in the last few years because of the added vents at the top of the fenders (which is a rule that was set forth to reduce the chance of roll over, IIRC).
10-31-2017, 10:53 AM
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