GRM Project Cars 2 - Series 7: Enduring someone else's car choice

Interesting TJ. I am going to have to pit no matter what. I am just trying to figure out the best tire versus car set up strategy is. Low downforce with a very loose car will make the tires on soft make it and lap times are ok but you have to drive the car the entire time. The margin of error is quite small. I always feel like I am under driving the car as stepping over the grip line will put the car in to a spin that is non recoverable even in slow corners. 

 High downforce on hards and I am a little slower but the car is easy to drive. Eventually it starts to push a bit and the braking zones get longer. And I will probably need to take on more fuel. 

I am going to be on tonight I need to work with the hard tires and see how much aero I can pull out while being able to keep it to the floor through the first couple corners and through the sweepers on the back strait. 

Brad, nice meeting you in person and thanks for the coffee. 

I will jump on tonight to do a bit of testing.

Brad, if you show up tonight, I have a tune for the Corvette I got of the net I can send you.  It looks pretty similar to stock, but it's the tune of the fastest Corvette on Spa.

In reply to aircooled :

I’m interested in what setup you come up with for Spa, especially in terms of what downforce you like. I’m currently running a fairly high downforce setup that is fast except on the kemmel straight and the fast part leading to the final chicane. I’ll be glad to send you my setup, but won’t be on again until Sat/Sun.

Current status...

I have tested alot over the last couple days and last night I focused on high downforce using hard tires and it is a bit faster over all the the low downforce with soft tires.  Also (and this is a big selling point for me to use the high down force) is that it is much more driver friendly.  For an hour race you want comfortable and easy not somthing that you ahve to be up on the wheel every second of the race.

Other things I have learned.

Brake balance has a huge impact on tire ware

The rake of the car also contributes to tire ware as more rake will add more down force to the front of the car.

Rake also has a big impact on top speed when combined with high aero settings.  Again the more rake the more aero drag you get and less top speed.  

Rake can be used to fine tune aero BUT at low speed it is not as effective due to less speed (ya I know kind of obvious) but what is not so obvious is that at high speed the effects of your aero settings will actually overcome any handling adjustments you make with rake.  SO for instance the two little lefts in the back strait 
(particularly the 2nd one the car will Handel in accordance with your aero settings and what ever your rake is supposed to be doing it really wont as the aero forces will overcome it.  BUT you still will get effects from Rake in your set up in places like the big left hand downhill double apex sweeper near the middle of the course.

I also re tested fuel millage and my car uses 3.4l per lap.  If we average 140 second laps we should be at 26-27 laps.  Especially if some one tries to run the race with out a pit stop (I am looking at you 911 drivers).  So for my car to make 27 laps I will need 92L of fuel so I have to pit no matter what.  Considering my car may actually burn more fuel as the fuel load gets low pushing me up to as much as 3.6l a lap at a minimum I will need to add 10L. To be safe I will be adding 20 as the time difference is really not that much.  Something like 7 seconds and running out of fuel after running for 59 minutes would really suck.   Pit strategy is also going to be interesting as TJ and I saw the undercut really does seem to be a thing with the AI cars.  I wonder how much it will be an thing with the Non AI cars.  Another thing to keep in mind is to be sure that I you don't pit to early and then not have enough room in the tank for the required fuel.  So making the undercut to early with out keeping an eye on the amount of room you have in the tank for fuel will have to be takin in to consideration. 

T.J. said:

Brad, nice meeting you in person and thanks for the coffee. 

No Pics?  

I don’t think 27 laps is possible unless Sauce goes crazy.  Would have to average 2:18 including the first lap and possibly a pit stop to finish lap 26 before time expires. 

I agree I wouldn’t want to run out of fuel, but 26 laps is the longest plausible race I think. 

SIn reply to dean1484 :

No pics. Just a random meeting in the Charlotte airport. 

T.J. said:

Brad, nice meeting you in person and thanks for the coffee. 

For sure.  It would have been a beer if it would have been on the return flight.

In reply to BradLTL :

Well, I’ll be back at that airport tomorrow around 7pm. I could just get a beer then and put it on your tab. 

Anyone planning on doing some laps tonight? I’m planning on watching as much LeMans as possible, but will probably take a break for a bit this evening and may run a practice race. 

I would join you later. Going out to dinner shortly back in a couple hours. 

Looked for you TJ. But never saw you on line. Ended up watching the 24. 

In reply to dean1484 :

Me too. Did a practice race just now and have settled on my preferred strategy. Made some spring/damper changes to reduce the tendancy to oversteer at turn in. I stiifened front slow bump and rear slow rebound hoping to slow the weight transfer to the front during braking. Then went one click siffer on front springs as well. 

Now that I'm back from a wedding weekend I'll probably be on tonight to try a full race since I haven't done that yet. I think my setup is pretty good but it needs a long run test to know. 

Ok, I can confirm that TJ is correct about the lap count, 26 laps is all that can be expected.  

I am going to make another couple small tweaks to the car but I think I'm pretty much set on strategy.  I'm actually really excited for this race, I have a car that isn't terrible and from my estimations I think TJ and I will be really close.  

I'm going to try a few more setup tweaks as well. Just trying to get the car to be better over the full race distance, but I am pretty happy with it as is.

Going to try some revised damper settings. Still end up with oversteer when the tires are worn a bit at turn in after hard braking. I have my diff pretty well locked, engine braking at minimum. Moving brake bias forward helps a bit especially for the turns where I insist on trail braking. I think I am learning a bit about using the dampers to fine tune things, but we'll see. Some times it is hard to know if a small setup change actually makes a difference of if things just get better with more practice laps run.

The springs (and I guess ride height plays into this as well) control how much weight is transferred fore/aft under braking or accelerating, but the dampers control how fast that weight transfer takes place and I am trying to get my car to be slow to transfer weight forward, but quick to transfer it to the rear. Seems to be working.

In reply to e30Matt :

Looking forward to this one too. Should be a fun one. I think I am done tweaking setup, now I just need to be able to do 26 laps without a big error.

Should be a fun race. I ran the full race again and I could just make it on fuel. This leads to the question of stopping or not. I think I could make it on hards. I can easily make 13 laps on softs. Last night I got 15 laps on a set. Another interesting thing was my 2nd set of softs wore much less than the first but I think it was because I wAs driving slower as I was talking to TJ. 

I think the plan is going to be run softs and pit around the middle of the race. Get tires and a splash (5l) of fuel in case we end up going 27 laps. 

Sauce I ran all my testing with the setup you modified and it is a bit looser than the one I have. It also tends to ware the front tires a bit more. It still makes 13 laps on softs with pit issue I just have to be carful in two corners to not loop the car. 

I need to practice passing AIs without incident at this track.In my practice races for the final minutes I come up on backmarkers and frequently get taken out trying to get by them. 

 Best idea I have is to skip qualli, start last then give them a 30 second head start. After a few laps I should catch up to the back of the train, then learn where to (and where not to) pass them without too much risk of crashing. 

Major dif changes. Consistent laps in the 19s. I still am on the fence about how much fuel to add but I think I will at least add 5l.

Well, my test race went rather poorly. The changes made the car faster, but the tire temps and wear was significantly increased. I went back to the old setup and ran for a while with no issues so that's what I'll be going with. 

I was happy with my setup until last night when I started mucking around and making big changes to my diff. Now I need to do another long run or two to see how these different diff settings work over the long haul. If I can't make time to test them out today, I will just revert to my earlier setup.

It is funny how little tweaks can make big differences in driveability, pace and tire wear.