So, while I know more seat time will improve the lap times (FYI, I have plenty in SM and others, just not in the GTR), I am thinking of some aero. You can def feel the car "lighten" up on the banked front straight at the Nashville Superspeedway at ~145mph. I am no Newey, but my thoughts...

1) Rear wing: looked into Tikt, but they said it will require some milling/drilling for it to work. Have an email into APR to see what they have. I don't see any GT4 wings out there (assume they mount in stock position), unless someone on the forum wants to be rid of theirs
2) front splitter: not inclined to remove stock front active lip unless you tell me it is an easy reversal. Also don't want to make any hole that would be visible if a return to stock was desired.
3) canards: my understanding they are not that helpful without the front splitter - same issue about holes I want to avoid in visible areas.

Any input would be appreciated.

thanks,

jose

 

pics of the AMG GT4 aero for you.

 

Not fair to tease.

 

GT R here too. I used to run a very similar track here locally at California Speedway (the avatar in my pic is from that track). 14deg banking as well on the front straight though a little longer than Nashville Superspeedway based on comparison. Mine felt stable at that speed and beyond (might have touch 165mph).

Just thinking aloud here. Aside aero mods, which suspension setting and tire pressures were you running? OE Cup 2s? What's the setting on your fixed rear wing? And was it a one time thing or you feel it every lap and every track outing?

 

Hoosier R7 @ 32-34 psi hot

Did notice just now that I think my rear wing is in not in max angle of attack - will adjust.

Only the car's second time at NSS. First time I was hesitant to push as hard as I was not confident with the brakes (resolved w tikt ducts).Previously, only got into session 2 at AMP when PS self destrcucted. Have had it up to 140 before at the Autobahn in Joliet and felt stable, but that was on a flat straight as opposed to the curved bank.

Maybe the wing adjustment will do the trick. Thx for the reminder. Will report.

 

The OEM aerodynamics of the AMG GTR are very well-balanced, with the front splitter’s downforce matching the rear wing's downforce, and the venturi effect from the active aero profile helps keep the car stable and planted on both straights and high-speed corners.

Switching to a GT4 type rear wing would require upgrading the front splitter as well in order to keep the downforce balanced between the front and rear, as both will increase drag and slow the car down. Since the AMG GTR-Pro and AMG GT4 are lighter than the GTR, their larger rear wings and splitters have less of a negative impact.

While upgrading for aesthetics is perfectly valid, it’s unlikely that these changes will make the GTR faster. If speed is the goal, I would recommend focusing on the chassis setup first—stiffening the chassis and springs, maybe using uniball bearings, and then tuning the ECU for a bit more power at the higher RPM range, and last maybe consider switching to 335/30 or 345/30 rear tires (140s).

If you primarily track on high-speed circuits configuration like Nashville Superspeedway (which I believe runs counterclockwise/left turns only), you may be up to the challenging task of adjusting camber for an asymmetrical setup (left side different than the right as you go only left). Additionally, reducing the rear wing angle to 0 degrees would minimize drag on such oval tracks.

However, in reality this asymmetrical camber and rear wing at 0 deg wouldn’t perform well on more technical / road course circuits, which I am sure you do as well.

As for the rear wing angle, Personally, I prefer a bit of oversteer in high-speed corners, and I’ve found that setting the rear wing at 4 degrees (measured at the center) works best. At 10 degrees, I experienced too much understeer and noticeable drag/wind resistance.

I hope this feedback is helpful to you!

I have attached herein an interesting article from AMG's Gustavo Estrada about the GTR's aerodynamics.

 

GP,

Thanks for the reply. A few comments.

1) Certainly aware that any changes in the rear would necessitate enhancing the front end. Would not do the one alone.

2) I would be grateful if you could help in pointing me towards the chassis/spring changes. I have pretty good traction with current camber/tire set up, but lesser roll and taking the twisties flatter would be welcome.

3) I am current running 335 Hoosiers in the rear.

4) Car has Renntech Stage 1 package.

5) Plan on running Barber/NCM/Atlanta, so will keep the camber balanced.

6) Thanks for the reading material. Am a nerd, so will consume it.


j

PS Will be adjustinng the wing and agree, suspension fun first.

 

It looks like you're heading in the right direction and know what you're doing

Quick question: I noticed in another thread that you're running 315s on the front. Are you using the OEM GTR rims for this setup? I ask because 315s typically don’t fit safely on a 10" rim.

Also, my comment regarding speed and tires was about increasing the tire diameter from the OEM 325/30 to 335/30 or 345/30. Given the added horsepower, this would increase top speed in each gear. The Hoosier R7 in 335/25 (a smaller diameter than the OEM) offers less speed at redline in each gear even compared to OEM. But if you're finding other significant benefits with the R7, then my point might be moot

Regarding the chassis stiffening and springs. I did not do it on my GTR (which I don't own anymore and there was not much availability back in 2019), but my friend used Renntech (expensive) subframe and I'll find which spring rate he is using. In any case, driving his car feels very planted and tight on the track. Amazing beast.