Nizer

Some track footage and other bits here: http://www.porsche.com/specials/en-us/usa/911-rsr/

Unusual sound for an N/A flat six..

996tnz

TLDR version: In some circumstances, yes. Obviously not here though as Porsche will have optimised the RSR for performance under the rule set (and maybe also for some future marketing of street cars?).

FURTHER THOUGHTS: When looking into optimal weight distribution for a road circuit racer some years ago, it generally looked to be around 40:60 front:rear. IIRC, one paper that tested a simulated single-seater on two european circuits (Jerez was one of them IIRC) with different axle weight ratios had a 39:61 split delivering the best lap times, but it was a fairly early and simple study and I can't remember whether aero effects etc were taken into account.

There is increasing freedom on how to get that weight distribution now as blended construction and formerly exotic materials are becoming more commonplace, not to mention electric or hybrid power. But in production cars with steel bodies, or most production based race classes with those, the easiest way to get that kind of weight distribution was simply to have the engine placed somewhere out back near the rear axle.

As for rear-mid (engine just in front of the rear axle) versus rear (engine just behind it) , as I see it, rear has an advantage under straight line braking and early phase trail braking, rear-mid an advantage under late phase trail braking, transition, and steady state. On reflection, under heavy acceleration with sufficiently grippy tires for its power levels, a rear-mid engined car with a similar static weight distribution should also have an advantage during track out as they will understeer less than a fully rear-engined car that's more prone to lifting its front wheels off the track. After all, it's no surprise that dragsters don't have their engines hanging behind their rear axles.

This stuff is like Alice going down the rabbit hole though as no matter how much detail you get down to, there always seem to be further levels of detail that warrant consideration as everything just seems to be an over-simplification of the next level down.

I keep picking up bits over time, and you may be much further along already, but otherwise a search on COG versus neutral steer point dynamic is one interesting place to start.

The relationship between a vehicles turn center, its neutral steer point (the point on its side at which you could push it sideways evenly without yawing) and a vehicles COG is interesting too. Vehicles don't just turn about a line transecting their center of gravity as often put forward. In tight, low-speed turns it is pretty much directly off their rear axle instead, with the turn center moving forwards as speeds rise and corner radiuses increase, ie:



If I'm not too far off in my thinking, leaving aside other considerations like aero center of pressure and suspension dynamics, a vehicle will corner best in steady state at those speeds and radiuses where its turn center transect coincides with its dynamic neutral steer point, and ideally its COG too.

I believe that one effect of the four wheel steering a per some 991s is to broaden that sweet spot by bringing those closer together across a wider range of cornering speeds and turn radiuses.

Mvez

just read the EVO mag article/interview, and you'll learn exactly why they switched to mid-engine. Tires and Aero rules, that's it.

WEC is giving them one less set of tires next year for each race, so they need a car that will be easier on rear tires. Rear engine doesn't allow for the extreme diffuser that everybody else can run.

The fact that they stayed with the NA tells you something. Had the rules not changed to allow this aggressive aero (which is simply to keep them faster than the GT3/GTD cars), and less tires, you can almost be certain they would have never changed to the mid-engine layout.

The GT3R is a wildly potent racecar, and every bit as quick as the other mid-engine racecars. The rear engine layout for customer cars isn't going anywhere, anytime soon.

996tnz

Thanks for that. A great read and here's the link for others:

http://www.evo.co.uk/news/18547/pors...1-rsr-race-car

Gotta love the german honesty there too:

hsmith

I can't wait to see the new RSR in action. I hope it wins the championship this year. Glad it stayed N/A too.

Nizer

Note to Dr. Walliser and Herr Preuninger:

Build a mid-engine 911 with double-wishbone suspension all around for the street/track and we will come.

P.S. Don't forget the magnesium transmission housing.

P.P.S. And please do something about the froufrou interior.

All the best.

FFaust

^^^ Wouldn't that just be a Cayman with better suspension layout?

brake dust

FSW stated in EVO:

You need to look closely at the technical regulations and ask: how do you win the championship? That is always the biggest target

Always thought that the biggest target by far is Le Mans. Don't think NA falt six has the torque to compete with turbos/v8s. No torque sensors as part of the BOP either. But who am I to argue with Porsche engineers!

mobonic

Nizer

CAlexio

Bingo!

Cory M

Here's an article with several nice detailed pictures of the new RSR aero features:

http://www.motoiq.com/MagazineArticl...e-911-RSR.aspx

I hope to check it out (at least the show car) later on this month at the new Porsche Experience Center in LA

winders

I'd like to see photos of the front and rear suspension.....

Nizer

https://www.instagram.com/kz1000s1/

Nizer