IMSA DPi Discussion

[Maelochs]

Originally Posted by Damian Baldi

I agree with some part of your comments. But still we have the P2 cars behind the Cadillacs and some of those cars have been testing since last year. The new Continental tyre should been new for everybody so no advantage in that.

Part of it is(or might be) that the teams which tested the Cadillac are the teams which run it ... which means they benefited from the entire test and development program---what doesn't work as well as what does.

The specific IMSA P2 teams --JDC, VisitFL, PR1--got their cars much later, and regardless of how much testing other teams might have done, those teams are still doing basic trial and error---they don't necessarily know what Not to do since they don't know what has been tried and failed.

Also, I wonder how much money those teams have---can they rent track time any time they want? Can they run endless computer sims and correlate all the data? I am pretty sure Cadillac did as much work as was needed, and offered as many engineers as needed, to help the DPi teams make the most of their cars, and I am pretty sure Cadillac did all the numbers-crunching.

Teams like JDC and PR1 aren't going to have access to that many engineers, so everything they do is going to take longer.

Originally Posted by Damian Baldi

Is the Cadillac engine too big to apply a correct BoP? So why then IMSA allowed a 6.2 litres engine? The Gibson P2 engine is 4.2 litres, so can't be so far in overal performance, but it is.

Dude, the Cadillac engine is fifty percent bigger. That is Huge.

Plus the Caddy is a tested architecture V8, while the Gibson is a brand-new engine---Gibson couldn't even supply a spare to VisitFL for the Rolex.

On top of everything, the Caddy has got to have an edge in low-end torque--so no matter what each can post as (restricted) peak power output, the Cadillac engine will always get out of the corners faster (suspension engineering talent being equal.)

I am not saying the two engines cannot be balanced to be fair in competition .... I will say that right now it is almost impossible to discern Why the Cadillacs are all consistently faster---but They Are.

[joeb]

I feel like the reason the corvette dp cars had such a racing advantage over the p2 machines was their big engine with loads of torque that sipped fuel when needed. GM kept that advantage in place knowing how the series bop works.

Of course the caddy's have the most testing and are good teams to start with, but I'm not sure how much the gap can close here with the current competition. The Honda cars came close in the last era, but nobody is currently running that engine. Maybe next year Penske will be in the ballpark.

[Damian Baldi]

Originally Posted by Maelochs

The specific IMSA P2 teams --JDC, VisitFL, PR1--got their cars much later, and regardless of how much testing other teams might have done, those teams are still doing basic trial and error---they don't necessarily know what Not to do since they don't know what has been tried and failed.

Also, I wonder how much money those teams have---can they rent track time any time they want? Can they run endless computer sims and correlate all the data? I am pretty sure Cadillac did as much work as was needed, and offered as many engineers as needed, to help the DPi teams make the most of their cars, and I am pretty sure Cadillac did all the numbers-crunching.

Teams like JDC and PR1 aren't going to have access to that many engineers, so everything they do is going to take longer.

I know and I'm agree with you about the Cadillac teams and their first hand experience, but people from Onroad and Oreca were present at the previous tests giving support to the teams (last year at Sebring while the Dunlop test, and later at Daytona). They could be able to give to those teams you mention the information needed to setup the cars.

The only team present in all the tests was Rebellion, but sadly they didn't take part this time.

[carbsmith]

What is the point of trying to make long winded technical excuses for performance differences in a BoP class? They're faster because the rules let them be, nothing more, nothing less. As long as you have a body and engine capable of running at least as fast as a cost controlled LMP2 car for a race distance nothing else matters.

[Accident]

Figuring out why the Cadillacs are faster is an important piece of the puzzle for figuring out how to balance the class properly moving forward.

This is going to be the second race for the formula, and first on a "normal" race track. Being too heavy-handed with BoP right now could just lead to a bunch of changes that need to be made to "fix" things in the future... Although, being realistic we are probably going to have BoP changes every other race anyway, so I guess it probably doesn't matter.

[godlameroso]

It's not a huge surprise, the difference in the chassis and aero given the same engine is .5 seconds at most. Where does the other second come from? Power, simply more power. Where the other DPi/P2's have somewhere in the region of 580-610 hp, the Caddies are more like 700 hp. If you think that's impossible, you're welcome to your opinion, but the way they pulled on everyone down the straights in Daytona is not down to better aero or suspension. It's sheer outright power advantage, and you'd have to to believe it's anything else.

BOP is easy, .2mm smaller restrictor for the Cadillac, and everyone else back to Daytona power BOP, the Cadillacs will still be in front but not by over 1.5 seconds, as it is now, no one but Cadillac DPi stands a chance at overall victory unless they crash out or have problems with reliability.

[canaglia]

700hp? quite impossible. Guess cadillac is so fast because has the overall best package and something like 20-30hp more than gibson powered cars (that however should be back to 600hp for sebring)

[FormulaFox]

Originally Posted by canaglia

700hp? quite impossible.

How so? The Caddys are running a variant of an engine that I could easily squeeze 800+ horsepower out of in my own garage, let alone with the resources of a major racing team.

Okay, that's not completely true, but the exaggeration is not that far off reality.

[Maelochs]

Originally Posted by canaglia

700hp? quite impossible. Guess cadillac is so fast because has the overall best package and something like 20-30hp more than gibson powered cars (that however should be back to 600hp for sebring)

I have to agree that 700 bhp would be no problem ... but I am not sure how much of an edge the Cadillac engine has, only that it seems to have one.

We know that Gibson asked for a power reduction pre-Rolex to help with reliability ... it seems reasonable that Cadillac engineers found a way to squeeze more power out of their engine despite the smaller restrictors.

This is where IMSA's half-muled BoP procedures infuriate me---we will not see the results of the next BoP adjustments until the practice session before qualifying, by which time it will be to late to make any changes.

I am pretty sure they will be afraid to cripple the Cadillacs---and I am pretty sure Cadillac engineers are already dreaming up tricks to get around any further adjustments ... so what are the chances of there being a level playing field?

[wdave0]

Old saw - "There ain't no substitute for cubic inches."
IMSA claim to be able to match torque curves, maybe with turbos, - NA - I'll believe it when I see it.

[canaglia]

no doubt that GM engine could hit even 800hp if pushed to the limit. But that's another story.
To me gibson lmp2's at daytona were in about 580hp x 930kg, while cadillac dpi's were in about 620hp x >950kg. For sebring, gibson engines should reach flawless 600hp as planned. Proof is that during sebring tests, max speed marked by a cadillac was 174mph, oreca gibson marked 173mph.
So far a 0.75s gap isn't too much to justify a so huge power difference, also because a >100hp more powerfull car and just 1mph faster? c'mon boys....

[MoMedic9019]

Originally Posted by canaglia

So far a 0.75s gap isn't too much to justify a so huge power difference, also because a >100hp more powerfull car and just 1mph faster? c'mon boys....

BoP works. Who knew?

[seanyb505]

You're completely right. There is no incentive to run to a determined time to avoid the bop hammer. Absolutely none.

[canaglia]

Originally Posted by seanyb505

You're completely right. There is no incentive to run to a determined time to avoid the bop hammer. Absolutely none.

these cars have a huge amount of sensors inside... you can't cheat telemetry

[seanyb505]

You're right.

And that matters if:

There weren't ways around it,

And:

The series actually did something to enforce it.

[MoMedic9019]

Originally Posted by seanyb505

You're completely right. There is no incentive to run to a determined time to avoid the bop hammer. Absolutely none.

But GM has never done that... there is no proof....

[carbsmith]

Originally Posted by canaglia

no doubt that GM engine could hit even 800hp if pushed to the limit. But that's another story.
To me gibson lmp2's at daytona were in about 580hp x 930kg, while cadillac dpi's were in about 620hp x >950kg. For sebring, gibson engines should reach flawless 600hp as planned. Proof is that during sebring tests, max speed marked by a cadillac was 174mph, oreca gibson marked 173mph.
So far a 0.75s gap isn't too much to justify a so huge power difference, also because a >100hp more powerfull car and just 1mph faster? c'mon boys....

Top speeds were pretty even at Daytona until the race started.

[Akrapovic]

Originally Posted by canaglia

these cars have a huge amount of sensors inside... you can't cheat telemetry

Aye, that totally didn't happen with Ford last year. Nope. They so didn't sand bag at Spa and then magically find enough seconds to gap the field by miles. Can't cheat the data.

[canaglia]

Originally Posted by Akrapovic

Aye, that totally didn't happen with Ford last year. Nope. They so didn't sand bag at Spa and then magically find enough seconds to gap the field by miles. Can't cheat the data.

Agree with that, ford was hiding their real pace while driving in cruise mode. But you can't hide100hp IMHO

[TF110]

Originally Posted by canaglia

these cars have a huge amount of sensors inside... you can't cheat telemetry

I'd believe that, but Daytona's performance comes to mind. 1:36's in the race were better than anything they ran at the Roar or in qualifying. That was after the bop as well. The Caddy's could go to lmp1-L right now and be as fast or faster than last year's Rebellion and CLM.

[J Jay]

Originally Posted by canaglia

these cars have a huge amount of sensors inside... you can't cheat telemetry

You don't have to if you can cheat the people who interpret the telemetry, providing you are smart enough - and in motorsport, it's usually the rules makers/enforcers that are chasing the engineers in this regard.

For further proof outside of IMSA, if you turn towards Belgium and listen really carefully, you should still be able to hear the Ford GTs doing their slo-mo down the Kemmel Straight...

[TF110]

Originally Posted by J Jay

You don't have to if you can cheat the people who interpret the telemetry, providing you are smart enough - and in motorsport, it's usually the rules makers/enforcers that are chasing the engineers in this regard.

For further proof outside of IMSA, if you turn towards Belgium and listen really carefully, you should still be able to hear the Ford GTs doing their slo-mo down the Kemmel Straight...

That's the one place the Fords were fast, on the straights. They were nearly as fast as lmp2's.

[Maelochs]

Originally Posted by canaglia

To me gibson lmp2's at daytona were in about 580hp x 930kg, while cadillac dpi's were in about 620hp x >950kg. For sebring, gibson engines should reach flawless 600hp as planned. Proof is that during sebring tests, max speed marked by a cadillac was 174mph, oreca gibson marked 173mph.
So far a 0.75s gap isn't too much to justify a so huge power difference, also because a >100hp more powerfull car and just 1mph faster? c'mon boys....

Max horsepower does not need to show up as top speed ... there is this thing called the gearbox .....

I don't think the Cadillacs have 100 bhp advantage, but it has Some advantage, I'd say. if it has more horsepower, it can tun the motor and adjust the gears to sue that power lower down in the rev range. Add to that lower gearing ....

With more torque, more power, and a quicker launch out of the corners, the problem isn't just lap time ... it stops overtaking if your car Also has a slight edge in top speed. The LMP2s can't overtake on the straights, and can't exit the corners as quickly, so what would have would be the Old DP/P2 dilemma, where the DPs could take up the corner and force the P2s to kill their momentum, then power out of the corner.

P2s with quicker lap times on an empty track couldn't actually make a pass in the race. We saw this with the Mazda and the WTR- Dallara-Corvette at PLM last year. The Mazda was faster but lacked the torque.

[Matt]

Originally Posted by Maelochs

Max horsepower does not need to show up as top speed ... there is this thing called the gearbox .....

I don't think the Cadillacs have 100 bhp advantage, but it has Some advantage, I'd say. if it has more horsepower, it can tun the motor and adjust the gears to sue that power lower down in the rev range. Add to that lower gearing ....

With more torque, more power, and a quicker launch out of the corners, the problem isn't just lap time ... it stops overtaking if your car Also has a slight edge in top speed. The LMP2s can't overtake on the straights, and can't exit the corners as quickly, so what would have would be the Old DP/P2 dilemma, where the DPs could take up the corner and force the P2s to kill their momentum, then power out of the corner.

P2s with quicker lap times on an empty track couldn't actually make a pass in the race. We saw this with the Mazda and the WTR- Dallara-Corvette at PLM last year. The Mazda was faster but lacked the torque.

That's the actual reason, not the weight. If you plonked a big V8 in the back of the Mazda it would have had the torque.

[Rcz]

They probably tore out that most of those Dallara chassis parts and rebuilt them back up with their own stuff from scratch. Well, if its true, i wouldn't be surprise.

From what ive heard, the Nissan was 60% rebuilt from the original p2 car for example.