Welcome Guest!!!

Thank you for visiting the GM Kappa Performance Forum. This forum is the only performance oriented forum for all GM Kappa Platform Enthusiasts.  We hope you will join and share your experiences.  Becoming a member is FREE! If you want to advertise on this forum, email KappaPerformance at yahoo.com.


Registration required to view the forum attachments. Below is a sample of the current top 25 topics.
Supporting Membership has many advantages.


More information on becoming a supporting member or vendor can be found on the sub forum; Site Help and Suggestions; thread - Supporting Members and Vendors.

Author Topic: REVIEW POSTED!! -- Direzza Star Specs on Staggered OZ Ultraleggeras  (Read 3870 times)

0 Members and 1 Guest are viewing this topic.

Ben L

  • Guest
So they make me run in BSP because of the intake and tune.  So I have been feeling really stupid going up against fully prepped Boxters, RX-8s, etc. on the crappy Goodyear F-1 showroom tires.  The car also pushes badly on the stock alignment and bars.  This weekend was the last straw, and I finally scraped enough rubber off the tires to justify stimulating the economy.

I needed rubber I can theoretically drive every day, but which will approach R compound performance when autocrossing.  Dunlop's new Dirrezze Star Specs, with a UTQG rating of 200 (!) have been getting a lot of buzz and seem to fit the bill. 

So I now have a set of 8x18 OZ Ultraleggeras up front, mounting 245-40-R18 Star Specs, and 9x18 OZ's in the rear, sporting 275-35-R18s.  The backset/offset on the rears brings the tire edge no further out of the fender well than the stock 245 rim.  There is considerably more rubber out back now.

The only appearance downside is that they are narrower in profile than the stock tires, so the upper wheel wells look monster truck huge.  Excuse the dirt, but my baby works for a living .  . . .







Since I was planning to upgrade struts and springs to Z0K specs, that will not be an issue for long.

I have a CDC event at Summit Point on April 18, and a full day SCCA Level 2 School the next day at FedEx.  And I have a week to get them scuffed in.

I will give a full review of how they perform in a competition setting then.  I am excited as hell!!

« Last Edit: April 19, 2009, 07:50:12 PM by Ben L »

Offline DeepBlueGXP

  • KappaPerformance Site Owner
  • Administrator
  • Shop Foreman
  • *
  • Posts: 9178
  • Karma: +12/-6
  • Location: Southern Maryland
  • Displaced Buffalo Bills Fan
    • Kappa Performance Forum
Re: Direzza Star Specs on Staggered OZ Ultraleggeras
« Reply #1 on: April 07, 2009, 08:15:37 PM »
Sweet, good luck with the next class.  I have to bow out as I promised ChuckDoc I'd finish his basement and now he has an urgent need to get it done before the end of April.  That means I'll be busy on the weekends.

Offline Morfious

  • SMMM 7 Cup Stacking Champion
  • Upgraded Member
  • Master Tech
  • *
  • Posts: 298
  • Karma: +1/-1
  • Location: Morrisville, PA
  • Tryin' to keep the rubber side down since age 2
Re: Direzza Star Specs on Staggered OZ Ultraleggeras
« Reply #2 on: April 07, 2009, 09:03:31 PM »
any problems with the wheels or tires rubbing in the rear.  I was contemplating getter larger rubber out back, but heard there were issues with rubbing.  Just wondering what your first hand knowledge showed.
Mean GXP Delivered 1/30/2007 $MSRP +$2K
Mods:
Pioneer AVIC D3 Nav System
Solo-Performance Street Race exhaust
Debadged
JPM interior (Doors, steering wheel, shifter, console now with 100% more Chuck Norris)
Custom dash and Flush mounted Valentine 1 Radar Detector
O.Z. Ultraleggera wheels with Dunlop DZ101
DDM Works (Big Brake Kit, backbone, intercooler, valve and coil cover)
GXP ZOK Rear sway bar



Offline spicy3480

  • Solo Performance Sales
  • Vendor
  • Gearhead
  • *
  • Posts: 2556
  • Karma: +1/-4
  • Location: New York
Re: Direzza Star Specs on Staggered OZ Ultraleggeras
« Reply #3 on: April 07, 2009, 11:03:14 PM »
I have 275's in the rear on 9 inch rims and have had no rubbing issues.
Steve Mariano
Solo Performance
516-655-9002 (7 days a week, until midnight EST)
goingsolo2@hotmail.com


2007 Mysterious Solstice GXP
INTRUDER

Ben L

  • Guest
Re: Direzza Star Specs on Staggered OZ Ultraleggeras
« Reply #4 on: April 08, 2009, 07:41:50 AM »
Well, my post-installation inspection showed plenty of clearance in all directions, and the initial neighborhood test drive showed no rubbage.  But I will let you know once I start driving it hard.  No reason with the backset and offset of these wheels that rubbing should be an issue. . . . 

In my eyes, the stance of the car from the back looks great. 

Here's a pic from the rear, please excuse the road grime.  Like I said, she works all week and then plays hard on the weekends!





« Last Edit: April 12, 2009, 08:53:38 AM by Ben L »

Offline sol_man

  • Premium Member
  • Master Tech
  • *
  • Posts: 255
  • Karma: +0/-0
  • Location: Michigan.....
  • Enjoying the cool summer
Re: Direzza Star Specs on Staggered OZ Ultraleggeras
« Reply #5 on: April 08, 2009, 02:11:01 PM »
That looks really good!   :award:
Sly with premium-auto-spoiler-pedals-onstar-xm-monsoon-crome wheels-a/c-headliner.
BSR Tune / GM Performance Exhaust / Xenon fog lights / K&N drop in / Debadged
Best 1/4 - 13.12 @ 102.6 / 60 foot 1.9 seconds
0-60 in 4.37 seconds


Offline captain

  • Founding Member
  • Tech
  • *
  • Posts: 39
  • Karma: +0/-0
Re: Direzza Star Specs on Staggered OZ Ultraleggeras
« Reply #6 on: April 08, 2009, 07:26:10 PM »
I am very interested to see your review after a few races.I went to an evo school for two das and the bug has bitten.I know that I need more and sticker tires to compete.Keep us posted

Offline Acadian

  • Founding Member
  • Tech
  • *
  • Posts: 52
  • Karma: +0/-0
  • Location: Montreal, Canada
Re: Direzza Star Specs on Staggered OZ Ultraleggeras
« Reply #7 on: April 18, 2009, 12:02:14 PM »
any updated pics with the zok suspension installed ?
would really like to see the gxp-zok stance with the oz wheel combo

we need more pics
more pics
more pics
more pics
 :ttiwwp:
Lightweight with no options 2006 stripper ! with added
GXP Z0K SPRINGS, FE3 Bilsteins shocks
GXP Z0K front ant rear sway bar
DDMWORKS stage 2 Eaton supercharger with intercooler
DDMWORKS hi-flow converter and long tube headers.

Offline elff

  • Premium Member
  • General Manager
  • *
  • Posts: 11267
  • Karma: +26/-58
  • Location: Keebler Tree House
    • Ryuk
Re: Direzza Star Specs on Staggered OZ Ultraleggeras
« Reply #8 on: April 18, 2009, 12:44:23 PM »
RobL on the Solstice forum races his car with 295s ALL THE WAY AROUND on 18x8 Ultraleggeras.
 :drool:
It has the ZOK package and I forget what shocks and NO rubbing.
It is still in Pro AS

I will be real interested to hear how those perform.  I am contemplating going with either them or Toyo R1Rs for the same reason,
I got bumped into BSP. 

I don't feel like putting a hitch on the car and buying a trailer for R-Compounds. So I figure I can swap tires at home, drive to the competition, then drive home and swap back to my street tires. 
I did avoid the staggered look because I want to at least be able to swap front to rear.  As such, I'm thinking of going 265/35R18 all the way around. 

Quick FYI - DDM Backbone Brace is ILLEGAL for BSP. Their Probeam is legal as long as you do not bolt it to the Diff.

Offline Dark Tech

  • Premium Member
  • Master Tech
  • *
  • Posts: 288
  • Karma: +0/-2
  • Location: Maryland
Re: Direzza Star Specs on Staggered OZ Ultraleggeras
« Reply #9 on: April 18, 2009, 10:40:05 PM »
What is the offset of the rims in the back?

Offline MGar

  • Founding Member
  • Tech
  • *
  • Posts: 64
  • Karma: +0/-0
  • Location: Ventura, CA
Re: Direzza Star Specs on Staggered OZ Ultraleggeras
« Reply #10 on: April 19, 2009, 05:46:54 AM »
Just an FYI, but I run those same rims (18x9) for a track tire, 275/35/18 Direzza Z1 Star Spec (not DZ101) all the way around, and there is no rubbing, front or back, on full steering lock either way.


2008 GXP
GM Stage II, GMPP CAI, Dejon IC, Dejon Hardpipes & T-bolts
GMPP Suspension, DDM Backbone & Rear Brace

Ben L

  • Guest
Review: Direzza Star Specs on Staggered OZ Ultraleggeras
« Reply #11 on: April 19, 2009, 06:29:01 PM »
OK, just completed to solid days of autocrossing on the new tire/wheel + other goodies set up.  In addition to the Dunlops and OZ wheels, last week Thursday and Friday, I installed a DDM Works 3/8" Race Backbone (tm) and Pro Beam (tm), stealing a little daylight for each after work. 

Saturday bright and early I drove out to Summit Point to run the second Capital Driving Club autocross of the year, on the brand new giant triple skidpad between Summit Main and the Jefferson circuit.  The surface is very tightly grained and dense, as you would expect for a brand new expanse of asphalt intended to function as a skidpad.  On the portion in the center they wet down for skid pad exercises, they applied a tar-like sealer.  On top of this was a fine layer of dried powdered mud, washover from the as yet unplanted dirt areas around the edges and in the centers of the three big pad circles.  We had three runs in the am, and three in the pm. 

The Summit course was flat and very long; nearly 1/4 mile from the start box to the far end (which was a gigantic descending radius sweeper), with tight essess on either side.  Especially in the am, the cool tarmac, the fine grain of the pavement, and the layer of dried fine mud made for very slick conditions.  In the pm, the pavement was hot, and the blasting sidepipes of my fellow club member's Cobras, like terrestrial Zambonis, had blown away the mud.  Point is, I got to test the new rig in a good range of conditions.

Today, I just returned from an all day SCCA Level 2 autocross school at FedEx Field.  The lot at Fedex is way rougher than Summit, and built on a hill.  At FedEx, they use the slope to set up many off camber turns so that gravity could work either for or against you.  We started with seven minutes of figure eight throttle steering drills, where one must find the correct line to just set the wheel and hold it, and correct car position by either lifting off or applying throttle, with no steering wheel inputs.  Then, twelve runs on a slalom drill course, basically three slaloms; including a wild uphill "blind" one where the last three gates were invisible until you crested the hill, and by then, of course gravity was increasing speed.  Finally, they set up a simple but fairly typical autox course, mixing 2 slaloms, a big sweeper, deeply offset gates and tight turn boxes.  We ran drills on that maybe six times, then got eight more runs, and then four more.  So a lot of very hard driving in all kinds of conditions over two days, plus plenty of highway and street driving going to and fro.

The verdict is that the car is completely transformed.  I can say without fear of contradiction that the tires are exceptional; truly, the grip is as close to R compounds as any "street" tire I have tried.  I find my GXP challenging to autocross, because of the strong understeer tendency, and the kind of abrupt way the boost and torque come on with the Wester's Race Tune.  Compared to the F1s, the Z1 Star Specs were like night and day.  Even in traction challenged conditions, they gripped like iron, gave way when they were supposed to and hooked when power was reapplied.  They never rolled over, even when pushed very hard; they handled weight transfers, both fore and aft and very hard lateral weight shifts predictably and tenaciously.  I could pretty much floorboard the throttle through a five gate slalom and toss the car back and forth, and with the Wester's tune, that's kind of amazing.  The extra width of the 275s in the rear kept me out of spins that would have been inevitable on the old Eagle F1 245s.  On long fast sweepers, when I needed to line the car up on a pivot cone, I did not use the wheel; I merely lifted, listened to the "screeeeeeee," felt a perfect touch of slip, and the rear tucked in as neat as you please.  Roll on throttle out of the turn, and she hooked right up.  No drama. 


As to the other mods, the Pro Beam has added considerable stiffness to the rear, and noticeably improved the pushing (I'm still not done fixing that; I cannot carry as much speed around tight corners as I am sure is possible with a little fine tuning).  The Backbone made a huge difference, too.  The front wheels and rear wheels both go the same direction when the torque comes on now, making for far more settled and positive handling than before, which is absolutely necessary for the very quick and smooth weight transfers needed on both courses.

I finished with times I consider pretty respectable, coming within a second or so of the runs my instructor drove today (the teachers drive our cars on a couple of runs each drill).  There was a bone stock Sky Redline on F1s at the school today, which was a good benchmark.  I was two seconds faster than her instructor's best runs.  With more seat time and a little more tweaking, my GXP is going to be a credible autocrosser, thanks to the Dirrezas, and DDM's substructure!
« Last Edit: April 20, 2009, 01:59:35 PM by Ben L »

Ben L

  • Guest
Re: Direzza Star Specs on Staggered OZ Ultraleggeras
« Reply #12 on: April 19, 2009, 07:14:11 PM »
What is the offset of the rims in the back?

DT -- Offset is 55 mm for the 9 inch wide OZ Ultraleggs.  Backspace is 7.20 inches.

Offline elff

  • Premium Member
  • General Manager
  • *
  • Posts: 11267
  • Karma: +26/-58
  • Location: Keebler Tree House
    • Ryuk
Re: REVIEW POSTED!! -- Direzza Star Specs on Staggered OZ Ultraleggeras
« Reply #13 on: April 23, 2009, 11:14:19 AM »
Ben

I do hope you know, the backbone brace just bumped you from Street Prepared to Prepared.
Same goes for the Probeam if you tied it into the Diff.

Cool review on the tires.

Offline elff

  • Premium Member
  • General Manager
  • *
  • Posts: 11267
  • Karma: +26/-58
  • Location: Keebler Tree House
    • Ryuk
Re: REVIEW POSTED!! -- Direzza Star Specs on Staggered OZ Ultraleggeras
« Reply #14 on: April 23, 2009, 11:39:45 AM »
Ben

To give you more clarification.  Section 15 covers both the probeam and backbone brace.
SnapOn Bob put up a good fight on the brace and was denied.

For the Probeam
From section 15.2 C of the 2009 Solo Rules
 Strut bars are permitted with all types of suspension. Strut bars
may be mounted only transversely across the car from upper
right to upper left suspension mounting point and from lower
right to lower left suspension mounting point. No other configuration
is permitted. Only bolt-on attachment is permitted. Additional
holes may be drilled for mounting bolts. Interior trim
panels may be modified to allow installation of strut bars. Holes
or slots may be no larger than necessary and may serve no other
purpose. This does not permit any modifications to the frame or
unibody beyond the allowed mounting holes.

For the Backbone Brace
From Section 15.2 E-5
5. No cross-car/lateral/triangulated connections directly between
the driver’s side and passenger’s side SFCs are permitted.
Connections to OE components such as tunnel braces or
closure panels via bolts are allowed and count as the third
point of attachment. No alteration to the OE components is
permitted


The bolded part is why you no longer qualify for BSP.
If you are only playing around for sheer fun, your local chapter probably won't care.
But, if someone protests your car, the Red Brace will be an easy disqualification.

Ben L

  • Guest
Re: REVIEW POSTED!! -- Direzza Star Specs on Staggered OZ Ultraleggeras
« Reply #15 on: April 24, 2009, 07:34:37 AM »
elff -- Thanks very much for this helpful, if not entirely welcome, information.

I did not tie the Pro Beam into the diff.  I swear!  And I also did not alter the OEM tunnel brace at all!  It is sitting on my porch in exactly the same condition as when it left the factory.   :lol:

I really am not too concerned about where I end up, class wise.  I am trying to get the most neutral handling I can, and I am happy to run it wherever it ends up. 

SCCA Washington DC Region is the most serious club (I run with at least three), and there are about 7 or 8 cars in BSP regularly.  I really have very little chance of ending up with a podium finish against the top guys on R compounds.  So I doubt I'll get protested.  But next event, I'll check out what's in BP, and switch I guess. 

I've also been told at SCCA WDC tech that my intake and "pirate tune" takes me out of BSP.  They also mentioned my hard intercooler pipes, but the stock pipes were hard too, no?  Honestly all the persnicketiness about car classing is one of the things that turns me off about SCCA Solo.  For some folks, its part of the fun.  For me . . . not so much.


Besides. I'll tell you and the other autox nuts here a little secret:  Shhhh.  The GXP is not my "real" autocross car.  That one is the Factory Five Racing Type 65 Daytona Coupe I am building.  Its purpose-designed from the ground up for long-circuit autocrossing and time trials, and to be street legal enough to drive to a from events, trailering R compounds.

Its going to paint this week.  I hope . . . . :yay:

SCCA finally settled down and put all Cobra replicas, including coupes, in XP, where we can stuff about anything we like in.  Here are some progress pix:















« Last Edit: April 24, 2009, 08:02:17 AM by Ben L »

Offline elff

  • Premium Member
  • General Manager
  • *
  • Posts: 11267
  • Karma: +26/-58
  • Location: Keebler Tree House
    • Ryuk
Re: REVIEW POSTED!! -- Direzza Star Specs on Staggered OZ Ultraleggeras
« Reply #16 on: April 24, 2009, 09:16:58 AM »
I've read through the rules a ton and the CAI and Intercooler Pipes should not bump you.
I can see you arguing with someone about the brace
Look, is not modified at all.
You never state it can't be swapped
Hahahahahaha

Make sure you post pics of your project car when it is painted. That really awesome.

 

Powered by EzPortal