Seth Thomas

I wondered if that was the case because you can see the wear on the sidewall.


TC and SC. I knew you ran one or the other. You could see the car in your video activate the brakes on the corner exit of T7, T10, and T13. It does it ever so slightly but just enough that you can see it on the brake chart of the video.

TRAKCAR

I feel it in T7, but not in T10 and T13. I wonder if its the bumps, not like its needed to keep the car in line, so it TC only I think?

It does make me a bit sloppy going on throttle I've noticed.
I also see it out of other corners where I cant feel anything and the car doesn't really struggle for grip?

Also my rear pads will not wear, they last more then double the life of the fronts.. But thanks, I will start looking for it more closely!

When SC comes on, you really know it :-)

Jean

The Manthey GT3RS did shave the 2.7 seconds fitted with light magnesium wheels, -3.5 front camber on stock Cup 2, suspension mods, lowering 15mm from stock, front and rear underbody from the 911R, and downforce setup. Sportauto is the most reliable mag tester around. If anything, this should just show the potential of these cars with chassis mods and the right setup.

m3irish

Do you know what they ran in the rear for ride height and camber? Is the 15mm off factory setting or new suggestion to keep from rubbing?

Macca

Pete. I ran the DSC in the GT3 on track and road for a year with tuning and support from Ton at TPC and local distributor Jeff Delio a US guy who worked as a rave mechanic with Randy P. He's now back in US. I did a write up on one of the boards but it may have been GT4 board.

In summary I found the DSC initially made me around 0.4s a minuteman quicker. It worked well in some corners not others. It also puts more work on individual tyres you can see the TPM readings changing differently the OEM PASM. I also found it weighted up the steering which I liked but it also introduced understeer in certain orders which I didn't like. I found I was quicker but messier. I removed the box after 12 track days and achieved a personal best on all three of my favourite tracks so I guess I was still getting faster naturally. I preferred the predictability of the OEM but I do not run the same track regularly but three tracks mostly. This means there are often compromises as I ran one DSC map which we tweaked numerous times.

Essentially to me DSC acts like factory PdCC active roll bars.

I've sold the DSC now preferring the feel of the car on the track with the factory PASM.

One area I preferred DSC was in fast tight. back roads. The suspension was more compliant in a straight line and loaded up better in corners with a better steering feel.

I loved my DMS headers but blew holes in my back box after 5 track days. Also melted some wiring and almost the water pipe back there. Cost 3k to repair.

I've tried various cambers with MPSC2 and settled close to factory (-2/-2).

What I learned from 25 track days and 18000 miles with the car is it's set up well stock. You can move the wear lines on the tire shoulder with camber but it doesn't matter as it will heat cycle before it cords.

Next GT3 I'll leave it stock other than slight camber and roll bar tweaks and RT RE10 pads when they make them. Thanks for the recommendation Pete!

Mika911

According to the article, its 3.5 degrees allround and whilst they mention the car was dropped 15mm at the front for HH, there's no mention of height adjustment at the rear.

Would be good to verify this with Manthey, as the figures often get misquoted in the frenzy of a track test.

Martini991RS

Hi Trakcar,

Thank you for your very detailed and thorough report. My experiences are quite similar to yours in that I find the springs/dampers are a little too soft and that chassis/suspension tuning will yield quicker lap times for the car and that it has great potential. Have you tried the Trofeo Rs? In my experience it is undoubtedly quicker than cup2s but I think YMMV depending on alignment/setup and whether you can maximize the tire or not. (I think you can)

Also undoubtedly I think the DSC module does improve the car significantly and while it's hard to put a specific number I think the 1 second improvement is a good number. My own estimate is around .7 with my time being around 2:02 on our local track.

Are you planning on swapping out springs anytime soon?

rm21

Peter - Thanks for the detailed writeup on the DSC unit. I'm running one on my Cayman but I made some other changes when I added it so it is hard to tell how much of a difference it is making. I'm about to add the tractive dampers, so I'll post something on the complete package once I've had it out on track. All I can say for now is that combined with GT3 sway bars, I've shaved two seconds off my personal bests at two different tracks with my new setup.

In term of the RS setup, I don't have an RS, but I've driven three of them on track. Prior to the last one, I frankly wasn't impressed relative to my old GT3 setup. I was never able to beat my best GT3 times in a stock RS. Granted, my GT3 was hardly stock, having a Crawford wing, cup bushings and wider 265/325 Trofeo tires and a track alignment that also lowered the car. Two of the RS's I drove had the DMS headers, which do make a clearly noticeable difference in power. The last RS I drove was Phil's at the Smokies event. It felt dramatically more confidence inspiring than the other two RS's. Phil said it was lowered as far as possible and had solid cup bushings all the way around. Phil didn't have a lap timer installed, but I have no doubt I beat my PB at AMP in his car despite having Phil as a passenger. Here's hoping Phil will be at Road Atlanta or VIR so I can give it another test! One of the variables that I don't believe gets discussed enough is ride height/rake, which I believe makes a huge difference, at least in terms of driver confidence. To me, the stock RS seems like it rides really high, and I can feel the higher COG. The other thing I can't understand is hearing so many drivers diss the Trofeos. Everyone I drive with at Road Atlanta that has tried the Trofeo immediately says it makes a huge difference and that they will never go back. I think it is worth at least a half second at that track. These are guys who are all running really good times (I don't believe opinions matter unless you are driving the car close to the limit.) My wear patterns on Trofeos were also very even compared to the Cup 2s. I think the Manthey changes validate the fact that the RS is epic, if setup correctly, and that the stock setup is certainly leaving some potential on the table.

TRAKCAR

^^ Thanks Macca, you are right, that car is very good stock. they don't NEED upgrades but everything is a compromise so you can adjust it a little to your liking / tolerance and local roads track.

Martini 991RS, not for now, I like the car soft. and now with DSC more or less fixing my main issues of feeling so much lean and outer tire edge wear, I'm good. Plus I hate experimenting and I dont want to buy "We cant tell you what or how but this is better".

Then there is a next RS coming, if I can get it no, if I cant maybe I mess with this car a bit more.
rm21.
Thanks!

I think the DSC is faster, feels better for sure.

I never tried Trofeo's.
Nothing against them but going through all the setup settings myself and driving the car home in the rain I haven't want to try a different tire, messing with reference sector times.

Could be fun next winter to see if I can hit a better lap time at Sebring but I first want to get lucky with new tires on a cold morning as-is to see if I can go faster on MPSC2 to prove DSC lap time to myself (And TRAKCARNATION, hahahahaha).
If I get a lucky day, my next set will be Trofeo. I'm sure it also matter how hard a track is on the tires..

Then there are those that stick 19" Hoosiers on the car and that's something I am trying to learn about as well. That would mean dusting the trailer off..

With the RS its size, the wheels size and so its ride height are its handicap.
We cant go as low as a GT3 and more down force we cant say with a GT3 over 100MPH.
100% sure a 991GT3 is faster on Hoosiers than a RS on Trofeo's.

Rake; I am the recommended track ride height minus one turn front and rear and I cant go down without rubbing front or rear. But yeah, rake is a big deal in setup. Tire for tire its easy to see the RS has more grip.

Good dampers always make a difference but I'm not one for playing with the parts too much because I just drive myself nuts with my inability to set up the car, the time and hassle chasing my tail.

I'm lazy, drive car, drink beer, drop car of at shop in between events if it needs anything, didnt even bother to buy the tools to remove the wheels.
Ive never even washed it myself because I will see how beat up the clear bra is. Ignorance is bliss hehe..

Lots of adjustability, no room to adjust anything on RS LOL. I think the 21" was a mistake.

This is such a great car that I may keep it mostly as a daily driver once the warranty runs out so I don't want to do too much to it but we will see..

For now, maybe a couple more events and I need to get my *** in gear and ask Goldcrest if I can leave my truck and trailer there for the summer.
Try the Trofeo's after the first weekend at Road ATL...

Martini991RS

My 911.1 RS "Clubsport" rear diffuser so far. Have taken it out to track and so far seems to have affected slightly the acceleration but improved high speed cornerning stability greatly (either that or I'm rusty and I am late on acceleration or my cornering speeds are lower or all of the above because I'm rusty hehe) but definitely without a question high speed cornering stability is improved. Even if it is a slightly slower car overall it is a safer car and I am willing to lose up to .5 seconds overall in exchange for not having to worry about the rear coming loose in high speed sections.

Kobalt

Part number on diffuser?

Jean

Martini,

The diffuser you have (doesn't seem like a Porsche diffuser?), might not give you the expected incremental downforce, not meaning at all to say it is not good.. But from the pictures, it seems to leave the underside mainly open. An effective rear diffuser would go all the way to the subframe mounting points, flatenning the bottom and improving aero by reducing air resistance, same with the front underside. Also the beauty about good diffusers is that they do not impact the drag coefficient, while increasing downforce, so your top speed should not be impacted in any manner.

Like everything else related to aerodynamics, its the good mix of things that makes a good setup, and that might include having to change the height of the rear wing and probably extending further back for a clean air flow... or not. Only a wind tunnel and data can tell the truth. Generally speaking though, a good diffuser designed by Porsche for a certain body type, on its own should bring a noticeable improvement.

If you had any datalogging before and after, you would be able to determine where and why your lap times are impacted, top speed, etc..it could be that the diffuser is actually increasing your drag.

Martini991RS

Hi Kobalt it's a custom job.

Hi Jean thank you for your constructive feedback we based it on the 911R and the 991.2 gt3 and the spy shot 991.2 gt2rs diffuser we just made it taller and extend further back. My lap time was actually similar to the last time I drove 6 months ago but since then have put on a lot of other stuff. I have a professional driver testing and setting up for me who lives in the circuit and if he thinks it is an improvement I will take his word for it. Laptimes don't lie but track conditions are different day to day and more importantly brand new tires are really expensive to use as a control for every small incremental change. Brand new tires will always produce quicker laps. So it's hard to say for sure but I think diffuser is an advantage over no diffuser. Of course ymmv much like dsc computer boxes and trofeo R tires.

Jean

Martini, Sorry my bad, from the last picture it looked like you only had the fins.

And agreed about different lap times and days, but might be worth it to get a datalogger and look carefully at the data with and without splitter on the same day, a professional driver would have a tough time quantifying cumulative gains in split seconds across a full lap without looking at the data. It would just help you validate this great initiative you did.. And share with us the results so that we all buy it

Martini991RS

Jean no worries, I appreciate your constructive and positive tone regarding the matter and yes we plan to test it with a logger later on. Yes the diffuser goes the whole length of the under tray cover. The problem is we only have one under tray cover at the moment and the other one is on order might be here in a month? I don't think it will be fair to test it with and without the under tray cover. Surely that will exaggerate the effects of the diffusers. And yes even though we are anticipating a small change in the lap time, the more interesting test will be whether the top speeds at the end of sections will be the same or lower or higher (because of the higher carry speed)

changing springs too next week. will keep you all updated.