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Back with impressions and data from a track day with the DBJ wing at COTA. Notes:
1. I ran the wing at 3 degrees AoA.
2. Significant improvement in high speed stability and grip over the stock wing. Braking wiggle at high speed is essentially gone which increases confidence, and braking G forces were higher as a result.
3. I was able to carry more speed through the esses and the carousel as the rear stays planted and I can get on throttle earlier.
4. In the DBJ run I had stock over axle pipes with GPF which reduces power vs the stock wing run where I had Akra OAP. Lap time comparison below both had similar traffic that I passed just before the esses, and I was 1.4 seconds faster with the DBJ wing vs stock even with 30 degree higher ambient air temperature than the stock run. Blue line is with the DBJ wing, red line is with the stock wing.
I was surprised at how well the wing works over stock, especially at such a small AoA. It also looks great in my opinion, I wish I had got it sooner! There is even more time on the table leveraging the grip improvement as I get more experience with the car. Thanks again for designing and making an amazing product Jacob!
Very cool results.
How did the front end feel with the added downforce in the rear? Is the front lacking in additional downforce now?
The DSC isn’t the only solution to rear end wiggle… the problem comes from rapid weight transfer unloading the rear which has an effect on dynamic toe vs what is set statically.
I’m seeing a lot posts of proclaiming, like it’s a save all.
Granted, DSC is a simple option (+ I ran one) but does also has drawbacks in how it can changes the feeling and feedback of the car, if you’re already used to the GT4 feeling.
Any decent alignment + adjustable toe links will cure this rest wiggle behaviour. Because it is caused by weight transfer, it also has a lot to do with how you get on the brakes.
@electron mike Did you add anything other than removing the 2 plastic pieces for the ducting, to the front, to balance the forces out? Or maybe this is a case where you want a little extra over what we have in back to further bleed out that high speed braking wiggle.
Thanks for sharing this and the follow-up comments.
I think we now know where the GT4RS is going to get its seconds from at the Ring.
Cool, want to sell me your stock wing? It might be cool to put one on a Spyder!
I think I'll keep the stock wing.
Originally Posted by TRZ06
Very cool results.
How did the front end feel with the added downforce in the rear? Is the front lacking in additional downforce now?
Originally Posted by phefner
@electron mike Did you add anything other than removing the 2 plastic pieces for the ducting, to the front, to balance the forces out? Or maybe this is a case where you want a little extra over what we have in back to further bleed out that high speed braking wiggle.
Thanks for sharing this and the follow-up comments.
I think we now know where the GT4RS is going to get its seconds from at the Ring.
The balance is very good with my setup and the DBJ wing, but I will emphasize my car is not stock. The larger 265 front tires and aggressive alignment make a huge difference in front end grip, and the smaller front to rear 265/285 tire stagger I run helps balance the handling as well.
The DBJ wing helps immensely with high speed braking, but the overall high speed stability and when rolling on the throttle at high speed is also improved significantly. The other great thing about the DBJ wing is that it is highly adjustable from 1 to 10 degrees of AoA, so it can be tuned for driver preference/track/setup/etc.
One thing I have learned hanging around race teams at track days at COTA is that setup is an art form. Rake, ride height, alignment, stagger, bar stiffness, spring rates, aero, weight distribution, etc make a huge difference. I have tinkered a bit and learned from others and my mistakes on my 981 GT4 and arrived at a handling setup that I love. It's a blast on track!
I removed so much weight from the back of the car with the Akra OAP and JCR rear exhaust section that I need to add more rear downforce to re-balance the car!
The designs by jacob full carbon wing is highly adjustable from 1 degree to 10 degrees of attack and adds measurable downforce to the rear. It will be fun tinkering with it on track to find the optimum balance. It also looks great in my opinion in exposed carbon fiber. I like the OEM GT4RS clubsport wing as well, but it is obscenely expensive so the DBJ wing is a nice option.
More pictures and track impressions after I get out to COTA next month to try it.
Mike:
Thanks so much for the development work on our cars!
Checking out the designs by Jacob site, there seems to be a couple of wings available....
Thanks so much for the development work on our cars!
Checking out the designs by Jacob site, there seems to be a couple of wings available....
Which one did you get?
Cheers,
Colin
I have the 1450mm wing. It mounts to the stock uprights in about 10 minutes and requires no modifications to the car. Jacob also has a 1450mm RS wing which has a swan neck mount as well as a larger 1600mm wing. Link to the one I have:
I have the 1450mm wing. It mounts to the stock uprights in about 10 minutes and requires no modifications to the car. Jacob also has a 1450mm RS wing which has a swan neck mount as well as a larger 1600mm wing. Link to the one I have:
Like your setup and alignment Mike. Very similar to what I will be running soon, with the exception of 305/30-19 rears.
The clubsport cars help balance the increased rear wing aero with more front rake, so I hear from JCR and others. Don't have any specifics on that, but I would imagine lowering the front a few mm at a time would be helpful to increase front down force. I will be at COTA next weekend and will talk with anyone I can find that has a clubsport.
Like your setup and alignment Mike. Very similar to what I will be running soon, with the exception of 305/30-19 rears.
The clubsport cars help balance the increased rear wing aero with more front rake, so I hear from JCR and others. Don't have any specifics on that, but I would imagine lowering the front a few mm at a time would be helpful to increase front down force. I will be at COTA next weekend and will talk with anyone I can find that has a clubsport.
I was mixing it up with 4 GT4 clubsports in my run group at COTA, and Esses Racing who setup my suspension also runs several of them in races. The big difference is the clubsports are MUCH lower (pic next to my car below). The clubsport front splitter is about 1.5" off the ground, mine is 4.5". I have to run a normal ride height for the street, but I don't feel my car needs more front downforce as it sits. YMMV
Last edited by electron mike; 04-03-2021 at 10:40 PM.
I believe the graph shows the 981 stock wing, not the 718 which supposedly "makes 50% more" ?
Still the best test is real world of course.
The DBJ graph is comparing to a 981, but the 718 GT4 wing itself only makes 20% more downforce than the 981. The remainder of the increase is due to other aero improvements including the diffusor.
My .02 is that the improvement over stock on my car with my setup is immediately noticeable and a great improvement which is shown in my lap data as well. YMMV
04-02-2021, 05:37 PM
