IMSA The pro-speech dedicated IMSA BoP to let the other threads be free!

[broadrun96]

Originally Posted by JT240Z

It's all about the money and not about the entertainment value. Got it.;

Uh, you've summed up non club racing in a nutshell there

[Adam43]

It’s like a revelation.

And in club racing it is about the money and the entertainment (for the competitors).

[veeten]

In other words, Adam43, that old saying... "Ignorance is bliss..."

[Adam43]

Seems so!

[broadrun96]

Originally Posted by Adam43

It’s like a revelation.

And in club racing it is about the money and the entertainment (for the competitors).

Yeah, bring that up to guys running ChampCar (Lemons). The guys who won last fall at Road Atlanta won because they donated the most money and had a serious car. Ok, most of the complaints were more come on man over real anger. And most had fun and would be back but even then money wins

[seanyb505]

Vir qualifying - are Porsches still nerfed? I thought they'd mostly worked out the cruddy Daytona bop. All gtd cars at the bottom of the order, and patrick pilet in the pfaff Porsche around midfield gtd am.

[joeb]

Originally Posted by seanyb505

Vir qualifying - are Porsches still nerfed? I thought they'd mostly worked out the cruddy Daytona bop. All gtd cars at the bottom of the order, and patrick pilet in the pfaff Porsche around midfield gtd am.

I think there was an adjustment this week on the Porsche, and then a 2nd tweak I think I saw in a s365 notebook.

[tomcug]

Maybe next year we'll have more adequate BOP for the 911 GT3 R, with all the actual racing data gathered on different tracks. This year running a Porsche in GT doesn't do any favors...

Originally Posted by seanyb505

I thought they'd mostly worked out the cruddy Daytona bop.

Somehow they did (Pfaff won at Sebring) but still hit or miss depending on track.

[broadrun96]

It appears the car is not well sorted outside of its preferred setup. Been a few times Pfaff has moved forward decently in race after poor quali but the GTD folks seem to be stuck in place. How far off is it from the car in other series? It doesn't seem to be lighting up the world anywhere I've seen

[PhilipR]

It is quite strange in gt3.
Sometimes the new development seems to be a bit off - Audi R8 2019-2022 comes to mind - seems it was quite struggling. But with the 2022 update it was back to being a consistent front runner

Or it could just be BOP - car has yet to find its BOP spot. Maybe next year with more knowledge and better BOP the car will be regurarly at the front again

Same goes for the other new GT3s this year. The Lambo and the Ferraris have not really set the world on fire either - yes the ferrari won the 24 hours of the Ring but there it seems the BOP was really good for them

The most consistent cars seems to be the Lexus, Merc and Aston - which are also the oldest in the championship meaning BOP and cars are very well understood. I do not count the Vette as it is not a proper gt3 car

Same goes for the other new GT3s this year. The Lambo and the Ferraris have not really set the world on fire either - yes the ferrari won the 24 hours of the Ring but there it seems

I do wonder if the Vettes and Ford's will have the same issue with BOP in IMSA next year "wink wink"

[Adam43]

Good article in Racecar Engineering on BoP in GTD. Mainly on IMSA, but talks about differences with FIA.

A few takeaways:
Macau, WEC and IMSA share data to help each other although the BoP process is different (no torque sensors in IMSA, still air restrictors) and there are some key differences between the series which mean they aren’t directly relevant to each other.

Torque sensors and IMSA specific testing at Windshear might come in the future, but it sounds like costs are a reason why this is not done at the moment.

The IMSA controlled test sounded interesting. Parc ferme conditions all the time. Teams told the fuel and tires and ride height, wing setting etc… to remove gaming the system. They don’t have long to go through all the data. The article talks about this a lot. New cars are always a challenge to BoP.

Originally Posted by Matt Kurdock

We are looking for small magnitude changes throughout the season that are ultimately driven just by simulation, not from on-track performance.

Worth remembering and is pretty fundamental to what BoP actually is.

They are worried about different tracks. Daytona, Sebring to start doesn’t help! As before Daytona gets some extra aero restrictions because of the impact of drag there.

[tomcug]

https://www.imsa.com/wp-content/uplo...P-01102024.pdf
New BOP. Similar to the WEC one, Caddy getting lower weight and less power, Porsche more power but also more weight. The Toyota of IMSA gets the biggest penalty compared to last year.

[joeb]

Originally Posted by tomcug

https://www.imsa.com/wp-content/uplo...P-01102024.pdf
New BOP. Similar to the WEC one, Caddy getting lower weight and less power, Porsche more power but also more weight. The Toyota of IMSA gets the biggest penalty compared to last year.

That is a heavy Acura! they will need to try and save weight somewhere, i suggest not putting as much air in the tires....

[tomcug]

Originally Posted by joeb

i suggest not putting as much air in the tires....

Fun fact: If Shank hadn't cheated at Daytona and (theoretically) finished last in class, that would've been easily enough to win the championship by a big margin (almost 2800 points). So it's not worth cheating

[Adam43]

How have the IMSA lots changed their BoP since the beginning of this GTP era?

The performance bits:

Weight (Kg)

-- Bulletin --	--- Track ---	Acura	BMW	Cadillac	Porsche
12/1/2023	ROAR	1030	1030	1030	1030
17/1/2023	Daytona 24	1030	1030	1030	1030
8/2/2023	Sebrign Test	1030	1030	1030	1030
13/3/2023	Sebring Race	1054	1040	1038	1048
31/3/2023	Long Beach	1045	1036	1031	1036
4/5/2023	Laguna Seca	1049	1031	1030	1038
4/6/2023	Watkins Glen	1053	1038	1037	1043
29/6/2023	Mosport Park	1046	1031	1030	1037
21/7/2023	Indy Test	1046	1031	1030	1037
27/7/2023	Road America	1044	1030	1030	1036
7/9/2023	Indy	1047	1031	1030	1037
7/9/2023	Road Atlanta	1046	1031	1030	1037
10/1/2024	ROAR	1072	1031	1030	1051
		ARX-06	M Hybrid V8	V-LMDh	963

Max Power (kW)

-- Bulletin --	--- Track ---	Acura	BMW	Cadillac	Porsche
12/1/2023	ROAR	500	500	500	500
17/1/2023	Daytona 24	500	500	500	500
8/2/2023	Sebrign Test	520	520	520	520
13/3/2023	Sebring Race	520	513	513	517
31/3/2023	Long Beach	520	515	513	515
4/5/2023	Laguna Seca	520	512	511	514
4/6/2023	Watkins Glen	520	513	513	515
29/6/2023	Mosport Park	520	513	513	515
21/7/2023	Indy Test	520	513	513	515
27/7/2023	Road America	520	513	513	515
7/9/2023	Indy	520	512	512	514
7/9/2023	Road Atlanta	520	513	513	515
10/1/2024	ROAR	520	514	510	519
		ARX-06	M Hybrid V8	V-LMDh	963

There is suddenly a bigger spread with the power:weight. Although if you comapre to WEC there is still a much narrower spread.

This is more set my the manufacturer really, but for completeness (and boringness):

Nmax (rpm)

-- Bulletin --	--- Track ---	Acura	BMW	Cadillac	Porsche
12/1/2023	ROAR	9512	8000	8800	8158
17/1/2023	Daytona 24	9512	8000	8800	8158
8/2/2023	Sebrign Test	9512	8000	8800	8158
13/3/2023	Sebring Race	9512	8000	8800	8158
31/3/2023	Long Beach	9512	8000	8800	8158
4/5/2023	Laguna Seca	9512	8000	8800	8158
4/6/2023	Watkins Glen	9512	8000	8800	8158
29/6/2023	Mosport Park	9512	8000	8800	8158
21/7/2023	Indy Test	9512	8000	8800	8158
27/7/2023	Road America	9512	8000	8800	8158
7/9/2023	Indy	9512	8000	8800	8158
7/9/2023	Road Atlanta	9512	8000	8800	8158
10/1/2024	ROAR	9512	8000	8800	8158
		ARX-06	M Hybrid V8	V-LMDh	963

And now the energy bit:

Energy Allocation (MJ)

-- Bulletin --	--- Track ---	Acura	BMW	Cadillac	Porsche
12/1/2023	ROAR	920	920	920	920
17/1/2023	Daytona 24	920	920	920	920
8/2/2023	Sebrign Test	930	930	930	930
13/3/2023	Sebring Race	917	905	905	912
31/3/2023	Long Beach	914	907	903	907
4/5/2023	Laguna Seca	915	902	902	907
4/6/2023	Watkins Glen	917	905	905	909
29/6/2023	Mosport Park	914	902	903	907
21/7/2023	Indy Test	914	902	903	907
27/7/2023	Road America	915	904	904	908
7/9/2023	Indy	917	902	902	907
7/9/2023	Road Atlanta	915	903	903	907
10/1/2024	ROAR	920	908	902	917
		ARX-06	M Hybrid V8	V-LMDh	963

Stint Energy Replenishment Rate (MJ/s)

-- Bulletin --	--- Track ---	Acura	BMW	Cadillac	Porsche
12/1/2023	ROAR	23	23	23	23
17/1/2023	Daytona 24	23	23	23	23
8/2/2023	Sebrign Test	23.25	23.25	23.25	23.25
13/3/2023	Sebring Race	22.925	22.625	22.625	22.8
31/3/2023	Long Beach	22.85	22.675	22.575	22.675
4/5/2023	Laguna Seca	22.875	22.55	22.55	22675
4/6/2023	Watkins Glen	22925	22.625	22.625	22.725
29/6/2023	Mosport Park	22.85	22.55	22.575	22.675
21/7/2023	Indy Test	22.85	22.55	22.575	22.675
27/7/2023	Road America	22.875	22.6	22.6	22.7
7/9/2023	Indy	22.925	22.55	22.55	22.675
7/9/2023	Road Atlanta	22.875	22.575	22.575	22.675
10/1/2024	ROAR	23	22.7	22.55	22.925
		ARX-06	M Hybrid V8	V-LMDh	963

[Adam43]

Originally Posted by Adam43

There is suddenly a bigger spread with the power:weight. Although if you comapre to WEC there is still a much narrower spread.

This didn't really make much sense, because I noticed I didn't attach the chart.

WEC comparison here: https://tentenths.com/forum/showpost...&postcount=547

[Adam43]

No BoP change between ROAR and race weekend.

[joeb]

Originally Posted by Adam43

No BoP change between ROAR and race weekend.

There is still time before the race.....

[broadrun96]

What, you don't trust IMSA saying there will be no changes before the race. When have they ever been less than truthful in the past

[Adam43]

More weight on the Ford would be funny.

[Adam43]

Originally Posted by V8 Fireworks

Do Acura need a cut in weight to be competitive for race victory (running 20kg more than Porsche, 40kg more than Cadillac)? Or are they just doing not a good enough job?

It's worry that even if there is a late Pace Car to catch up, they do not seem fast enough to keep up with Cadillac or Porsche when all three cars are pushing.

Watching a race that is a Porsche commercial when it's meant to be BOP and is not about building the best car is rather depressing. If they built the best car -- fine, but did they?

Context: Based on top 100 laps in the race by half distance, Acura are about 4 tenths off the quickest car. The slowest Porsche is about 4 tenths slower than the fastest Porsche. 7 tenths covers the entire field.

They led a bit and still have some of their cold tire advantage.

Let's see how it goes.

[V8 Fireworks]

Originally Posted by Adam43

Context: Based on top 100 laps in the race by half distance, Acura are about 4 tenths off the quickest car. The slowest Porsche is about 4 tenths slower than the fastest Porsche. 7 tenths covers the entire field.

They led a bit and still have some of their cold tire advantage.

Let's see how it goes.

Of course. It could be HRC's fault for choosing their slower team to continue with.

It is a shame to see a beautifully engineered car with a 2.4L Indycar engine that came out of the box so well, now be unable to pull away from the others.

What's the evidence that the Acura should be 20 kg heavier than the Porsche?

Dear oh dear, the Acura is now falling behind at almost 0.5s-1.0s/lap. Is this simply because Deletraz is an inferior driver? Inferior car tuning by Wayne Taylor Racing?

Or HRC USA and Oreca built a second-rate car?

But how can it be a second-rate car if it has to carry 20-40kg more than the competition -- it's baffling. Could the 20kg more than Porsche be worth exactly that 0.4s/lap?

[V8 Fireworks]

Originally Posted by seanyb505

Vir qualifying - are Porsches still nerfed? I thought they'd mostly worked out the cruddy Daytona bop. All gtd cars at the bottom of the order, and patrick pilet in the pfaff Porsche around midfield gtd am.

BOP is necessarily in GT3 as the cars are completely different.

BOP should be less necessary in GTP as the cars all have similar power and similar downforce. It seems more like a penalty for building a car that is too good.

Plus or minus 20kg is easily the difference between winning and losing...

[Adam43]

Originally Posted by V8 Fireworks

What's the evidence that the Acura should be 20 kg heavier than the Porsche?

Some of the Porsche are slower than Acura and some faster.

What’s the evidence is that it shouldn’t have 20kg?

I really don’t know. All I can see are the lap times. Only thing I know is that they are all ridiculously close. The context I gave shows Acura are as close to the front as the spread across all the cars from the same manufacturer. It is also as close as LMP2 lap time spread which is practically single make.

We could well see a change post Daytona and as we move into Sebring though. But what would the evidence be that this is fair and it isn’t just giving them a bump for a poor showing?

[V8 Fireworks]

Originally Posted by Adam43

What’s the evidence is that it shouldn’t have 20kg?

That's the same question!

This is why competitions like Formula One are so much better! The same minimum weight for everybody. The same fuel flow and fuel weight for all the power unit manufacturers too.

Originally Posted by Adam43

Only thing I know is that they are all ridiculously close.

The Acura is 1:10 off the lead, it was 1:00 back 10 laps ago, it is going backwards at a great rate of knots... That's not ridiculously close in BOP racing terms -- we expect to see cars nose to tail for the whole race, a la GTE at Le Mans, if the BOP is set correctly.