Initial IMSA 2017 BoP


dbk

The Favor Factory™
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http://sportscar365.com/imsa/iwsc/imsa-sets-initial-2017-bop/

http://files.constantcontact.com/db5636c9001/0727cee9-9398-4ef5-b13f-7498d3ece430.pdf

The adjustments were made from the final BoP of last season. GT looks like it lost a little boost low in the RPM range and gained a tiny bit at the very top. Still the heaviest car with least boost. Three cheers for aerodynamic superiority. Everybody has the same weight they did for the final 2 races of the season last year. IMSA reserves the right to make an adjustment after this weekends Roar Before the 24.

The interesting car to me is the new RSR. Could be a favorable initial setup for them with the new car.

bopRolex24.jpg

BoPRolex242.jpg
 

Specracer

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May the games begin...
 

Cobrar

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They already have.....
 

Xcentric

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What is "boost ratio?"
 

Vince H

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We can look at this two ways. One is that it's BS that the BoP rules detune the GT as much as it does and prevents us from seeing what it can truly do. The other is to marvel at how superior the engineering for the GT is in it's class. So much so that the governing bodies have to cripple it to give the others a competitive chance.

Vince H
 

nota4re

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With all of the chatter and speculation here on how light the production GT may be, doesn't it seem to be a little heavy - even in race trim? With no fuel or driver, the car is 2788 lbs. (Not sure how much "ballast" has been added - typically manufacturers will make the car as light as possible so that they have some freedom to add weight where they want to achieve minimum requirements.) But, in street trim, there's obviously going to be a whole lot more weight to be added - bumper reinforcement, air bags & computer modules, HVAC, sound insulation (some), cats, mufflers, heat shielding, production rims/tires (heavier), AC, fans and heat exchangers, seats, etc.

A while back there was speculation that the car could be at or under the 3,000lb mark which would be pretty remarkable.... but it seems now that street-trim weight is going to be in the 3200-3400lb range?
 

dbk

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With all of the chatter and speculation here on how light the production GT may be, doesn't it seem to be a little heavy - even in race trim? With no fuel or driver, the car is 2788 lbs. (Not sure how much "ballast" has been added - typically manufacturers will make the car as light as possible so that they have some freedom to add weight where they want to achieve minimum requirements.) But, in street trim, there's obviously going to be a whole lot more weight to be added - bumper reinforcement, air bags & computer modules, HVAC, sound insulation (some), cats, mufflers, heat shielding, production rims/tires (heavier), AC, fans and heat exchangers, seats, etc.

A while back there was speculation that the car could be at or under the 3,000lb mark which would be pretty remarkable.... but it seems now that street-trim weight is going to be in the 3200-3400lb range?

Street car and race car weight have no relation. There is a class minimum weight (2745 lbs) everyone starts from and then IMSA adjusts up or down from there. The GT has had ballast added from that minimum weight.

Do you really think there's any relation between a 4,500 lb street M6 and a 2,711 lb GTLM M6? :lol. You get some control over where it goes, not so much how much of it there is.
 

twobjshelbys

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Jul 26, 2010
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Is there any statement on frequency and magnitude of adjustments? There was some discussion that this years BoP adjustments would be fewer and smaller. Last year they were all over the place.
 

PeteK

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What is "boost ratio?"

Ratio of boost to static atmospheric pressure. If there's no boost, that's 1.0. Boost ratio of 2.0 is 14.7 X 2 = 29.4 PSI

Now, the numbers in the chart seem very low. I would expect the boost to be substantially higher than the 1.5 or so in the chart, which makes me wonder if the IMSA rules define it differently than turbocharger manufacturers (e.g., Garrett).
 

dbk

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Ratio of boost to static atmospheric pressure. If there's no boost, that's 1.0. Boost ratio of 2.0 is 14.7 X 2 = 29.4 PSI

Now, the numbers in the chart seem very low. I would expect the boost to be substantially higher than the 1.5 or so in the chart, which makes me wonder if the IMSA rules define it differently than turbocharger manufacturers (e.g., Garrett).

No, your eyes are not deceiving you and you are correct. At times in competition, the GT has been running essentially no boost, wastegates wide open. The race cars are running well under 500 hp.

Part of the reason you saw wild swings in performance from the turbocharged cars in WEC last season was the adjustment to reference atmospheric pressure set on scrutineering day by the FIA. That was part of the kerfuffle over Le Mans qualifying. They put in the reference atmospheric pressure based on predicted race day conditions and the actual whether was more favorable during qualifying. They switched to daily adjustments late in the season, and are going to attempt (oh boy) real-time autonomous adjustments in 2017. Just to be clear, these adjustments do not count as "BoP."

I think IMSA did a pretty good job overall with BoP last season. WEC not so much. It will be interesting to watch them attempt to compensate for millibar changes in real time during the course of hours long races.
 

Sinovac

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They switched to daily adjustments late in the season, and are going to attempt (oh boy) real-time autonomous adjustments in 2017.

Yeah, that will work just fine.
 

nota4re

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Street car and race car weight have no relation.

Do you really think there's any relation between a 4,500 lb street M6 and a 2,711 lb GTLM M6?

Agreed.... and that's because there's typically not a lot of relation between race cars and their production brethren. True for the M6 you cited, true for the Corvettes..... and true for the Ford GTs. Production and race cars are two different animals. Funny though about human nature. When it is convenient/positive to draw correlations to the race car, it is done but when the correlation may not be positive - shazam!, hey they are different beasts.

But back on point. So what is the weight of a NFGT? Why such a big secret? Surely it is known. My guess is 3300 +/- 100lbs.
 

dbk

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Agreed.... and that's because there's typically not a lot of relation between race cars and their production brethren. True for the M6 you cited, true for the Corvettes..... and true for the Ford GTs. Production and race cars are two different animals. Funny though about human nature. When it is convenient/positive to draw correlations to the race car, it is done but when the correlation may not be positive - shazam!, hey they are different beasts.

I'm gonna agree with you that typically there is a big distinction between road cars and race cars because the era of the homologation special has largely been over, and I know what you're getting at.

The thing is, you know and I know that a luxobarge BMW coupe has virtually nothing to do with a homologated race car version. They need something with two doors to race, that's it. The Corvette is closer, but a still distant cousin because what Pratt & Miller builds for GM and what GM sells for $60k have to be very different beasts. Part of why the GT road car is special IMO is because it's much, much closer to the race car than any of it's contemporaries, which is why it would make a terrible daily driver, and you can only enjoy packing your laptop, shoes and toothbrush in the trunk. The coordinated development of the road car and race car are very evident when the car is apart.
 

Cobrar

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Yeah, that will work just fine.


Don't be too quick to judge Paul, that appraoach works really well for the casinos in Vegas. Haven't noticed too many burnt out light bulbs there. ;-))
 

Sinovac

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Me? Judgmental? You spelled approach incorrectly.
 

Cobrar

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Me? Judgmental? You spelled approach incorrectly.

Well, I'll be... Never thought you'd catch that. :biggrin
 

ThatPhilBrettGuy

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....you can only enjoy packing your laptop, shoes and toothbrush in the trunk.....

Enough room for a crash helmet?
 

STORMCAT

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I'm gonna agree with you that typically there is a big distinction between road cars and race cars because the era of the homologation special has largely been over, and I know what you're getting at.

The thing is, you know and I know that a luxobarge BMW coupe has virtually nothing to do with a homologated race car version. They need something with two doors to race, that's it. The Corvette is closer, but a still distant cousin because what Pratt & Miller builds for GM and what GM sells for $60k have to be very different beasts. Part of why the GT road car is special IMO is because it's much, much closer to the race car than any of it's contemporaries, which is why it would make a terrible daily driver, and you can only enjoy packing your laptop, shoes and toothbrush in the trunk. The coordinated development of the road car and race car are very evident when the car is apart.

Remember what Dave Pericak Explained in one of the videos. When they took the plans to the governing bodies for homologation the GT race car requires "0" deviations from road car to race car.. Not for the roll cage, suspension mounts ,, nada.. I don't know is any other car make that claim. The Street car is the race car from a frame suspension layout etc..