Best Track Times in a GT4
06-21-2018, 09:01 PM
#1262
Three Wheelin'
LOL , John...you know the only car I have that my wife likes, and hence will ride in, is the GT4, because it doesn't have F straight pipes or the GT3 sharkwerks bypass!
06-21-2018, 09:03 PM
#1263
Woah woah woah hold on there killer, I Never said replace the PSE system. Valves closed even with race headers is perfectly quiet with no drone, you'd be hard pressed to hear the difference until you open those valves up...KEVIN lol. You know...that I know...that you know...I wouldn't **** off your wife haha
06-21-2018, 09:17 PM
#1264
Originally Posted by AutoquestMotorsports
Race Headers and a Tune is the lowest hanging fruit and best return on investment for the Boxster/Cayman platform, especially the GT4.
06-21-2018, 09:48 PM
#1266
06-21-2018, 09:53 PM
#1267
As a side note - has anyone run a VBOX or aim side by side with Harrys? Last Schnellfest at COTA I did this to see what the base accuracy with a built in iphone GPS was, and it was consistently off, by up to a second (+/-). S/F marker was about the same place, not exactly - but not enough to drive that much difference. Would be interested to get feedback on this. We're toying with some data acquisition solutions for AIs to use, and looks like Harry's will be out of the running.
06-21-2018, 10:13 PM
#1268
Rennlist Member
That was some great driving, especially for first time at WGI! 
Was this ^^ with the GT3 muffler and TPC pipes? You said the full GT3/TPC "gives a fantastic boost in mid-range and high RPM power", but I can't find any dyno data for that combo...do you have some?
https://rennlist.com/forums/parts-ma...l#post15094767
I am considering bolt on's for intake and exhaust...... or just keeping stock, as I have now, and just further adjusting alignment, rear suspension, and (most importantly) tires...RE-71r's IMO are better than Cup 2's but obviously not the level of R7's or even used DH's
Was this ^^ with the GT3 muffler and TPC pipes? You said the full GT3/TPC "gives a fantastic boost in mid-range and high RPM power", but I can't find any dyno data for that combo...do you have some?
https://rennlist.com/forums/parts-ma...l#post15094767
I am considering bolt on's for intake and exhaust...... or just keeping stock, as I have now, and just further adjusting alignment, rear suspension, and (most importantly) tires...RE-71r's IMO are better than Cup 2's but obviously not the level of R7's or even used DH's
I didn't have a chance to dyno the GT3 muffler setup. However, TPC claims a 22 HP increase on the top end and a boost in the midrange, and I have no reason to doubt that -- I don't have any numbers, but the ol' butt dyno was very impressed with how quick the car was with the GT3 muffler. In the long run, however, it's cheaper (and safer) to take the loss on the GT3 muffler kit than to get rid of the wife....
06-21-2018, 10:14 PM
#1269
Rennlist Member
As a side note - has anyone run a VBOX or aim side by side with Harrys? Last Schnellfest at COTA I did this to see what the base accuracy with a built in iphone GPS was, and it was consistently off, by up to a second (+/-). S/F marker was about the same place, not exactly - but not enough to drive that much difference. Would be interested to get feedback on this. We're toying with some data acquisition solutions for AIs to use, and looks like Harry's will be out of the running.
The problem with using Harry's lap timer with the phone's internal GPS is that all smartphones I know of have GPS units that run at 1 Hz (once per second). This actually presents two problems for Harry's. One is that you only have a location read every second, and two, the calculated car speeds are then very inaccurate, so it can't figure out how much time it took to travel to the start/finish location in between the two locations that it read (one before and one after start/finish).
06-22-2018, 12:43 AM
#1270
Harry's lap timer on a smartphone with an external GPS can be very accurate. Last time I was at Sonoma, a used a rented radio transponder for independent timing and got a best lap of 1:50.878. Harry's lap timer with an external GPS sensor (http://gps.dualav.com/explore-by-product/xgps160/) recorded 1:50.89 for the same lap. So for me Harry's accuracy was about a hundredth of a second!
The problem with using Harry's lap timer with the phone's internal GPS is that all smartphones I know of have GPS units that run at 1 Hz (once per second). This actually presents two problems for Harry's. One is that you only have a location read every second, and two, the calculated car speeds are then very inaccurate, so it can't figure out how much time it took to travel to the start/finish location in between the two locations that it read (one before and one after start/finish).
The problem with using Harry's lap timer with the phone's internal GPS is that all smartphones I know of have GPS units that run at 1 Hz (once per second). This actually presents two problems for Harry's. One is that you only have a location read every second, and two, the calculated car speeds are then very inaccurate, so it can't figure out how much time it took to travel to the start/finish location in between the two locations that it read (one before and one after start/finish).
06-22-2018, 07:14 AM
#1271
Burning Brakes
Not to mention, external GPS also use GLONASS and (US) GPS satellites to obtain a more precise position fix. One can typically discern which side of the track you are.
06-22-2018, 12:08 PM
#1272
Tried out Dominion Raceway in June-2018. The best I managed for the day was a 1:32.509 . I could have used some confidence in several corners and I believe there's area to work on. Mods - 20" RE71R's w/ DSC controller.
06-22-2018, 12:14 PM
#1273
Three Wheelin'
That was on the stock GT4 muffler and pipes, not the GT3 muffler. I reinstalled the stock muffler before we drove up to the Glen because my wife went with me and she doesn't like the extra noise.
I didn't have a chance to dyno the GT3 muffler setup. However, TPC claims a 22 HP increase on the top end and a boost in the midrange, and I have no reason to doubt that -- I don't have any numbers, but the ol' butt dyno was very impressed with how quick the car was with the GT3 muffler. In the long run, however, it's cheaper (and safer) to take the loss on the GT3 muffler kit than to get rid of the wife....
I didn't have a chance to dyno the GT3 muffler setup. However, TPC claims a 22 HP increase on the top end and a boost in the midrange, and I have no reason to doubt that -- I don't have any numbers, but the ol' butt dyno was very impressed with how quick the car was with the GT3 muffler. In the long run, however, it's cheaper (and safer) to take the loss on the GT3 muffler kit than to get rid of the wife....
so true...
06-23-2018, 05:42 PM
#1275
Rennlist Member
My first time back to Barber in over two years. Until now, I’ve only driven it as a student of the Porsche Sport Driving School in street cars. It was great to have my Tini here and to be able to run unfettered. The second session of day one proved to be my zenith today, peaking at 1:38.21. This was on very worn tires and way too much fuel in the tank. Just piping you, GeoJoe!