The Mustang Forum for Track & Racing Enthusiasts

Taking your Mustang to an open track/HPDE event for the first time? Do you race competitively? This forum is for you! Log in to remove most ads.

  • Welcome to the Ford Mustang forum built for owners of the Mustang GT350, BOSS 302, GT500, and all other S550, S197, SN95, Fox Body and older Mustangs set up for open track days, road racing, and/or autocross. Join our forum, interact with others, share your build, and help us strengthen this community!

GT350R vs 2015 Z/28 vs GT350 Track Pack

This site may earn a commission from merchant affiliate links, including eBay, Amazon, and others.

Recently Randy Pobst posted times running the three cars at Chuckwalla Valley Raceway. See below. The R was almost three seconds a lap faster than the TP 350. So the questions are:

How much difference do the tires make on the R or Z/28?
Would the Z/28 be faster than the R with the same tires on it?
How much faster would the TP be by just adding the PSC2 tires from the R to it?

http://fastestlaps.com/tracks/chuckwalla-valley-raceway

0Shot%202016-09-07%20at%206.53.52%20PM_zpspss3uolo.png
 
Are they equal or if the Trefeo R faster? I spoke with a Ford engineer that tuned the suspension and asked him that and he insisted the PSC2 was faster but I'm nut sure I'm buying that. If the PSC2 is faster then maybe the Z/28 is just as fast as the R on track?

I'd really like to see these cars all tested with the same tire.

https://youtu.be/rrLQpAt5Mes
 
173
72
Rick, were you able to time yourself on the same track with the Super Sports and the Cup2s? That will be my test. I have not been back to the same track yet with my Cup2s where I also ran my Super Sports.

I am real curious to compare the times because the Super Sports perform like no other street tire I have encountered. They are amazingly good for what they are.
 
I don't keep lap times but it's clear to me the PSC2's are a lot stickier/faster than the PSS. I agree the PSS that came stock on the GT350 (and the Z51 Stingray I drove at the Ron Fellows class I took) are surprisingly good for a street tire. They seemed better than the set I ran on my Boss. (thanks Peter) But they are not as sticky as the PSC2 and I think the Nitto NT01 is also stickier on track
 
173
72
Surprised to hear you don't keep times. I hope to get back to The Ridge before the season ends. I ran consistent 1:58s on the Super Sports, so I will report back on what the Cup2s do if I get out again before the rain socks in.
 
I try and not take it too seriously. I need to drive my car home so I like to leave a bit on the track. I tend to push it a lot more at Thunderhill and will probably get some lap times there next weekend. I only drove my 350 there once with the PSS. It was my first time on track with it and I was taking it easy so I wouldn't have good times anyway.
 

Grant 302

basic and well known psychic
Chuckwalla is a momentum track, IMO. I think the Trofeos are faster and the R on PSC2s are faster at Chuckwalla because of the track. Pretty sure the Z would be faster at say Fontana. R will turn faster and Z will accelerate faster IMO. Lots of variables in play in this comparison. I don't think the Trofeos are bi-compound either.
 
Grant 302 said:
Chuckwalla is a momentum track, IMO. I think the Trofeos are faster and the R on PSC2s are faster at Chuckwalla because of the track. Pretty sure the Z would be faster at say Fontana. R will turn faster and Z will accelerate faster IMO. Lots of variables in play in this comparison. I don't think the Trofeos are bi-compound either.

Randy kept commenting about how well the R puts power down on corner exit when they drove it at Chuckwalla. and, at least in the 1/4 mile they did, the R was faster than the Z. I think Rick's video pointer and comment above is directionally correct...I suspect the trofeo is actually the quicker tire on track.

interesting to see Jason P's times dominating the leader board. I was out at Chuckwalla a couple years ago for two days for one of Chuckwalla's 'schools' and there were only three cars running both days. We split time with Jason P's motorcycle school, so I got a chance to sit through most of Jason's discussions between sessions and I learned a ton from the way those 2-wheelers approach the track. That guy has some serious sack.
 

ArizonaBOSS

Because racecar.
Moderator
8,730
2,734
Arizona, USA
This looks like a chart for production vehicles only :) Not sure what direction they were running, but when we ran CCW in February this year, one of the ST2 Vettes ran a 1:51.81 http://timingscoring.drivenasa.com/NASA_Arizona_Region/2016%20-%20Official%20Results/02%20Chuckwalla%20Valley%20Raceway%20-%20February%202016/2-13%20Time%20Trial%20Results.pdf

My best time was a 1:54.74 :eek:
 
From personal experience and looking at the specs I don't think the Z will accelerate faster than the 350. My Boss with shorter tires was pretty close to the Z. The 350 is not much faster than the Boss from 0-60 but it's noticeably faster from 60-120.

It would be nice to get some actual times on any car with a direct comparison between the Trefeo R and PSC2. My bet is the Trefeo is faster on track but not as good of a street tire.
 
1,022
99
Exp. Type
HPDE
Exp. Level
10-20 Years
Texas
Rick,

Download Harry's lap timer. It is pretty accurate for lap times...MPH is off a little bit but you can pick up an external GPS for less than $100, connect it via bluetooth, and that will give you accuracy everywhere. Harry's is fun to review and shoots good video because it records MPH, RPM, Gear Selection, Coolant Temp, and more if you have the OBD port connection too.
 

Grant 302

basic and well known psychic
FWIW, there was a video of the R and the Z overlaid. IIRC, the Z lost ground in the turns and pulled out a bit harder. That was probably turn/RPM specific where the Z could close the gap. Anyway, if it lost ground in the turns and *didn't* accelerate *somewhere* faster than the R, how would it only be about a second behind in the end?

VoodooBOSS said:
How much difference do the tires make on the R or Z/28?
Between the two I suspect very little. But if you put the R on the Trofeos and the Z on the PSC2, I think the gap would widen in favor of the R.
Would the Z/28 be faster than the R with the same tires on it?
Doubt it. Maybe, if that was with the R's wheels too.
How much faster would the TP be by just adding the PSC2 tires from the R to it?
My guess is about 1.5 to 2 secs. The rest of the ~3 sec difference is in the weight and moment of inertia from the CF wheels and R specific suspension tuning.

I think you're just looking for an excuse to try the Trofeos! ;) Just do it already! ;D
 

REAL 1

Death smiles at everyone. Army Rangers smile back.
There is no doubt that the main delta between the TP and R are the wheels and tires. Put the TP wheels and tires on the R nad then compare. I bet the two are within a whisker of each other.

As to the Z and the R. Both are pretty evenly matched. My take is rubber will be the deciding factor everything else equal.
 
My guess is that the Trefeo's and PSC2's are very close. No question that the biggest delta between the 350TP and the R is the Tires. I've run PSS and R6's (very similar to PSC2's) on the Boss and it was about a 2-3 second delta.

There's no way that a stock Z/28 is going to be quicker than an R on stock rubber. I'd also bet on the TP beating the Z/28 with the wider/stickier tires.
 

TMO Supporting Vendors

Top