MPSC Rock!
#31
07-06-2006, 05:42 PM
ColourChange,
Thanks for the data.
I agree with the line of thinking and the way to look at the data. Where I somewhat disagree is that the conditions under which you have recorded the data are not sufficient probably to have conclusive evidence.
The reason I am saying this is because I see close to 1.4 lateral Gs on MPSCs or Hoosiers "R" , and street tires cannot get above 1.1 Gs in general, unless there is a banking. In a case like the one I am stating, running with street tires is more likely to make you loose 5 seconds per lap.
When the gap between both tires is closer to 0.2-0.3 G in most corners, and especially under acceleration coming out of a turn in a car that can see acceleration above 1.3 Gs (long), where tire spin, if using street tires, can have a substantial impact on end of straight speed..
The trick with these tires is to get used to run them at their limit. As long as one is seeing 1.1 Gs with R compound tires, it means there is still a long way to go.
Most often this is due to not enough time and practice using them, or not really knowing (having experienced) their threshold limits. I am not saying at all that this is the case here, but in general one can have slower times for a couple of days when he starts using sticky tires, until he gets used to them.
Thanks for sharing.
Thanks for the data.
I agree with the line of thinking and the way to look at the data. Where I somewhat disagree is that the conditions under which you have recorded the data are not sufficient probably to have conclusive evidence.
The reason I am saying this is because I see close to 1.4 lateral Gs on MPSCs or Hoosiers "R" , and street tires cannot get above 1.1 Gs in general, unless there is a banking. In a case like the one I am stating, running with street tires is more likely to make you loose 5 seconds per lap.
When the gap between both tires is closer to 0.2-0.3 G in most corners, and especially under acceleration coming out of a turn in a car that can see acceleration above 1.3 Gs (long), where tire spin, if using street tires, can have a substantial impact on end of straight speed..
The trick with these tires is to get used to run them at their limit. As long as one is seeing 1.1 Gs with R compound tires, it means there is still a long way to go.
Most often this is due to not enough time and practice using them, or not really knowing (having experienced) their threshold limits. I am not saying at all that this is the case here, but in general one can have slower times for a couple of days when he starts using sticky tires, until he gets used to them.
Thanks for sharing.
Last edited by Jean; 07-06-2006 at 06:02 PM.
#32
07-06-2006, 06:07 PM
Originally Posted by Garey Cooper
On the street the MPSC's will drag all kinds of small rocks, rodents, and detritus into the garage which must mean something is sticking to them.
Tim, thanks for the data set. Of course it is always great to have data and I agree with both Garey and Jean in their analysis of said data set.
Again also my own seat of the pants...I am very impressed with the MPSCs.
Thanks all for your comments...as usual I know a bit more than I did before.
#33
07-06-2006, 09:44 PM
Wow, great thread with lots of good info, thanks guys! And glad to see everyone is playing nice in the sandbox again,seems like you all have a lot of good info to share, I learned alot!
#35
07-06-2006, 11:59 PM
Originally Posted by oak
becareful if your using these on the streets!
not sure if the nitrogen is a good idea on the street as the cups take some heat to get them to optimum grip with just air.
they may feel great new, but as they cure and have a few heat cycles it will take some time to get them to heat up for optimum grip, if you aren't careful an heat them up they'll suddenly loose grip!
not sure if the nitrogen is a good idea on the street as the cups take some heat to get them to optimum grip with just air.
they may feel great new, but as they cure and have a few heat cycles it will take some time to get them to heat up for optimum grip, if you aren't careful an heat them up they'll suddenly loose grip!
#36
07-07-2006, 12:02 AM
Originally Posted by oak
from my experience you can get much more lat G's from the MPSC by just lowering the running pressures. I find most that run the cups are on too high of pressures limiting lat G's
#37
07-07-2006, 12:42 AM
I run around 28 PSI cold both front and rear the same on the MPSC, I should go to 26PSI. Target should be around 32-34 hot.
MPSC when cold are a bad boy, I loose grip in 4th easily, but as temps rise, they behave very well. Hoosier are more predictable, but fall off after a while compared to MPSC.
MPSC when cold are a bad boy, I loose grip in 4th easily, but as temps rise, they behave very well. Hoosier are more predictable, but fall off after a while compared to MPSC.
#38
07-07-2006, 01:14 AM
Oh hell yeps when cold they are scary. I switched to Toyo RA1s and the compound is much softer and they're ready to "go" much sooner I found. Those are similair pressures that I run... maybe a little more though. Remember our cars are heavier than even yours!
#39
07-07-2006, 08:12 AM
Jean: I am sure you have a calibration error if you are reporting 1.4 g's on MPSC's on a flat turn. They just can't go that high (I have looked at lots of data on many cars) in long or lat g's. Brand new slicks ... maybe, but MPSC's ... no way.
While you are correct you cannot reach a conclusion from just a few turns, I do reach an accurate conclusion when looking at hundreds of turns and there is a small difference as I stated, a max of 0.1 g's from PS2's to MPSC's. Again, I have online realtime temperature measurement so I know that both tires were in their optimal range. MPSC's are so nasty when cold that I actually have their temps alarmed so I know when I can push it (I flat spotted brand new fronts while testing with my ABS off).
Just for the record, here are typical cold and hot tire pressures, a little difference left to right.:
PS-2
f 27/35
r 28/37
MPSC
f 26/34
r 29/38
Your pressure may vary depending upon tire sizes, sway bar and shock settings (and I have a stage 4) but these should be good starting ranges for most people. I also agree, don't get MPSC's over 40 or they turn into roller skates.
While you are correct you cannot reach a conclusion from just a few turns, I do reach an accurate conclusion when looking at hundreds of turns and there is a small difference as I stated, a max of 0.1 g's from PS2's to MPSC's. Again, I have online realtime temperature measurement so I know that both tires were in their optimal range. MPSC's are so nasty when cold that I actually have their temps alarmed so I know when I can push it (I flat spotted brand new fronts while testing with my ABS off).
Just for the record, here are typical cold and hot tire pressures, a little difference left to right.:
PS-2
f 27/35
r 28/37
MPSC
f 26/34
r 29/38
Your pressure may vary depending upon tire sizes, sway bar and shock settings (and I have a stage 4) but these should be good starting ranges for most people. I also agree, don't get MPSC's over 40 or they turn into roller skates.
#41
07-07-2006, 09:03 AM
Colorchange
Covering all angles of tire behaviour is a very lengthy topic to debate and is certainly not my intention to get there again, I just wanted to understand the basis for your comments of a 0.1G and the maximum 1 second timing difference, which now I know.
It might be premature to jump into a conclusion that the tool is not properly calibrated.. Understanding the characteristics of the track might be more enlightening. This is a brand new track with fantastic grip and a slight banking on some turns (not "'Ring's carroussel level!!), which is what lets me see 1.1 Gs with street tires.
The close to 1.4Gs were seen on different days, different tires and different temps and turns, a problem with my datalogger is very unlikely.
If credibility is of any concern, I happen to be a very close friend to one of the best telemetry experts in the world for Porsche racing, and as such had the opportunity to share and review a lot of my data, just as I have the chance to look at the Motec data of some of the fastest Porsche drivers on the planet and analyze it live during Supercup races.
With that being said, my close to 1.4Gs lateral are certainly accurate.
On the other hand, an "R" compound tire having a grip of 1.1G is certainly far from its full potential and I am sure Chris can confirm that.
I have my answer to the initial question, and since datalogging and telelmetry is a very subjective topic, I will refrain from entering a full debate here.
Thanks for the information provided, and I applaud the level of detail you are working with.
Jean
Covering all angles of tire behaviour is a very lengthy topic to debate and is certainly not my intention to get there again, I just wanted to understand the basis for your comments of a 0.1G and the maximum 1 second timing difference, which now I know.
It might be premature to jump into a conclusion that the tool is not properly calibrated.. Understanding the characteristics of the track might be more enlightening. This is a brand new track with fantastic grip and a slight banking on some turns (not "'Ring's carroussel level!!), which is what lets me see 1.1 Gs with street tires.
The close to 1.4Gs were seen on different days, different tires and different temps and turns, a problem with my datalogger is very unlikely.
If credibility is of any concern, I happen to be a very close friend to one of the best telemetry experts in the world for Porsche racing, and as such had the opportunity to share and review a lot of my data, just as I have the chance to look at the Motec data of some of the fastest Porsche drivers on the planet and analyze it live during Supercup races.
With that being said, my close to 1.4Gs lateral are certainly accurate.
On the other hand, an "R" compound tire having a grip of 1.1G is certainly far from its full potential and I am sure Chris can confirm that.
I have my answer to the initial question, and since datalogging and telelmetry is a very subjective topic, I will refrain from entering a full debate here.
Thanks for the information provided, and I applaud the level of detail you are working with.
Jean
#42
07-07-2006, 09:37 AM
Great info. But I have some follow-up questions...I have been running just on the street with 36/44 psi cold. I have not been able to break the tires loose yet...not even a little bit. Where does this skating you are talking about occur? Are you just talking track speeds? Should I run 26/29 for general street conditions? I never ran PS2s that low as I thought the side walls were quite soft. Thanks for your input all!!!
#43
07-07-2006, 10:20 AM
Jean, I was pretty specific. If you saw 1.4 lat g's on a flat turn on MPSC's, something is wrong with your equipment. If you did that on new slicks ... like I said, I could believe that but you are definitely at the upper end. With banking ... sure.
Actually, I have analyzed Chris's data and it shows that on normal turns (no banking), normal tracks, normal cars (no downforce), about 1.1 lat g max for MPSC's is typical, 1.3-1.4 lat g max for slicks.
Statman: Never run pressures that low on the street unless you plan to drive like a madman. At the track, the tires heat up a lot if you push your car. The hot temps are what you are after and on the street, it is often difficult to heat them up a lot so high starting pressures are recommended. I think the 44 in the rear might be high, but definitely don't go around at high 20's, you'll wear or damage your tires.
Actually, I have analyzed Chris's data and it shows that on normal turns (no banking), normal tracks, normal cars (no downforce), about 1.1 lat g max for MPSC's is typical, 1.3-1.4 lat g max for slicks.
Statman: Never run pressures that low on the street unless you plan to drive like a madman. At the track, the tires heat up a lot if you push your car. The hot temps are what you are after and on the street, it is often difficult to heat them up a lot so high starting pressures are recommended. I think the 44 in the rear might be high, but definitely don't go around at high 20's, you'll wear or damage your tires.
Last edited by ColorChange; 07-07-2006 at 10:27 AM.
#44
07-07-2006, 10:32 AM
Thanks Tim...that's what I thought and why I wanted clarification! So question to the rest...what pressures do you run for street?
#45
07-07-2006, 02:06 PM
ColorChange
The tires where MPSC (not slicks) with about 1000 miles on them or so, almost the same data was obtained with brand new Hoosier R3s05.
I am sure I am at the higher end limit of the tires, which 1.1G certainly is not, that is about street tire territory. As for full slick race tires they see 1.5+ G. The track you are measuring on must have poor grip, the Motec equipment on the 997 Supercup is the most technologically advanced out there.
You are free to disagree of course
Wross, I agree with Colorchange, don't run such low pressures on the street, mid to high 30s is fine, you need to experiment yourself depending on driving style and temperatures.
The tires where MPSC (not slicks) with about 1000 miles on them or so, almost the same data was obtained with brand new Hoosier R3s05.
I am sure I am at the higher end limit of the tires, which 1.1G certainly is not, that is about street tire territory. As for full slick race tires they see 1.5+ G. The track you are measuring on must have poor grip, the Motec equipment on the 997 Supercup is the most technologically advanced out there.
You are free to disagree of course
Wross, I agree with Colorchange, don't run such low pressures on the street, mid to high 30s is fine, you need to experiment yourself depending on driving style and temperatures.