Z reclassified from GT2 to GT3!

[preith]

In an effort boost the number of GT3 entries, the SCCA competition board has agreed to move the Z over from GT2. More appropriately, the rules have been written to encourage the older uni-body cars to come out of mothballs. The requirements are a minimum weight of 2200 lbs (w/driver), 15x7 wheels (w/cantilever slicks), GT2 spec L28, and the only draw back, a 35mm SIR (single inlet restrictor). The current EP Z-cars would be right at home with an L28 transplant; they're already on the same wheels and rubber. The inlet restrictor would be one area where some creative engineering would probably pay off.

As little effort would be required in my case, I’m seriously considering converting, however I’m not up to speed (no pun intended) with the race slicks they use. I assume Hoosiers are the preferred choice, but what size and compound do the production guys typically use?

[jmark]

Cool. I think the Z will be very strong in GT3.

[mark belrose]

In an effort boost the number of GT3 entries, the SCCA competition board has agreed to move the Z over from GT2. More appropriately, the rules have been written to encourage the older uni-body cars to come out of mothballs. The requirements are a minimum weight of 2200 lbs (w/driver), 15x7 wheels (w/cantilever slicks), GT2 spec L28, and the only draw back, a 35mm SIR (single inlet restrictor). The current EP Z-cars would be right at home with an L28 transplant; they're already on the same wheels and rubber. The inlet restrictor would be one area where some creative engineering would probably pay off.

Interesting. I wonder how much down-jetting my vintage C Production with triple 50 Mikunis and velocity stacks would require to counterbalance the inlet restrictor. Probably a lot. Anyway, in lieu of the velocity stacks, I've been mulling over fabricating an air cleaner assembly which draws in air forward of the radiator support. Perhaps there might be a bit of horsepower to be gained with the cooler air vs. that collected nearer the header.

My unibodied car comes in at 2140 lbs. sans me. It seems if the tube-frame cars need to up their weight to meet min. specs, it would be pretty easy for them to ballast their cars for improved weight distribution.

Mark

[preith]

Interesting. I wonder how much down-jetting my vintage C Production with triple 50 Mikunis and velocity stacks would require to counterbalance the inlet restrictor. Probably a lot. Anyway, in lieu of the velocity stacks, I've been mulling over fabricating an air cleaner assembly which draws in air forward of the radiator support. Perhaps there might be a bit of horsepower to be gained with the cooler air vs. that collected nearer the header.

My unibodied car comes in at 2140 lbs. sans me. It seems if the tube-frame cars need to up their weight to meet min. specs, it would be pretty easy for them to ballast their cars for improved weight distribution.

Mark

Just thinking out loud, but with a 35mm SIR I wonder if 50's would be the best choice.

The TWM airbox would be an obvious choice, but hear they don't pass the SCCA stall test, which essentially is blocking off the intake and forcing the engine to stall.

The GT2 tube cars have a miniumum required weight of 2080, so they'd have to balast a whopping 200lbs. I suppose it's not out of the question, but most of them are running 16" wheels and believe it not they don't want to go to 15's.

[Ron Carter]

The TWM filter box pictured above has not been tested in a ram air situation so I am not sure it would be the best solution. To me it seems that fuel injection (if legal) would be the way to go here with a single plenum intake that matches the manditory 35mm "restriction".

Mark for your car a hose that points to the caburators and a large heat shield would be the way to go. a good example is Craig Carter's 510 that has a large heat shield. I will see if I can get you some photos.

[mark belrose]

Mark for your car a hose that points to the caburators and a large heat shield would be the way to go. a good example is Craig Carter's 510 that has a large heat shield. I will see if I can get you some photos.

Looks pretty similar to the setup on Steve Link's brutally fast 510, where he has isolated the carbs from the rest of the engine compartment.

It's something for me to consider in the future. Unfortunately my limiting factor (besides not having a running car due to broken crankfire) is driver ineptitude. No substitute for seat time - gotta get my butt out there. Watching the incredible GT2 finish at Sebring last night really got me motivated to get my car back on the track.

Mark

[Ron Carter]

Yes, Mark you are right, but there is a cost involved with brutally fast. First, it does not hurt that Steve's dad (Floyd Link) was a member of the BRE race team and can build a 510 motor that will survive at 8500RPM without crankfire, (can you imagine what it would cost us for such a motor). Two, Steve broke two direct drive comp transmissions and lost his motor last weekend at Fontana. He never made it to the trophy race...

So, sometimes being fast can cost a lot of money too.

[mark belrose]

Hey Ron, I'd read your writeup of Fontana including Steve's mishaps. I wonder if he still has the resources obtaining the parts to fix those trannys. I guess if anyone does, he does. I think I went the right route getting a T-5 vs. keeping those old boxes with irreplaceable parts alive. That'a also my rationale of running a stroker at 13.25:1 vs a 2.4L at over 14:1 to stay competitive. Sure, it keeps me in VARA's "modified" category, but I have no inclination to have to replace bearings every race or two as some of the Porsche boys are required to do.

Mark

[Ron Carter]

In the past I have not had much of an opportunity to speak to the guys with VARA and this outing gave me a chance to talk to John Wilkins at length. He is building one heck of a 2.4 CP3 motor for his car. Some I am sure the P guys will be unhappy how well his new motor does compaired to his last motor.

I also know a little bit of the back story behind Steve Link. Quite a bit of that information is second hand from Ed Johnson. Steve has a very large collection of very hard to find parts. Most, if not all he will not sell. He has spent thousands of dollars buying up a fairly large quantity of hard to find parts for his gearboxes, and rear differentials. Unfortunately, there is only so much available and these parts are harder and harder to find. I know that Steve had some very special parts in the trans that he first had in the car, and wished that he could have kept that transmission alive, and had to go to a gearset he did not like as much with the second tranny that also went south at Fontana.

I can relate keeping those old transmissions alive as it is part of my life too. I have a spare ultraclose and a spare med close roadster box for the roadster and hope that I don't kill two transmissions in a weekend, as that makes for a $1600+ weekend if those two transmissions are salvagable and rebuildable.

As we both know racing is an expensive sport. I live for the next time I get to drive my roadster...I just dread hurting, and then getting replacements for those rare parts.

Take care, hope to see you out at the track soon. Will you try HSR this year? We are going to be at Fontana in June.

R

[HowlerMonkey]

Sounds like backlash from a decade ago when they mandated no new GT1 or 2 cars could be built with IRS and had to go with live axle.

My memory may not serve me well in this case but I do remember the ruling.

[Carl Beck]

That'a also my rationale of running a stroker at 13.25:1 vs a 2.4L at over 14:1 to stay competitive.

Mark

Hi Mark:

What type/brand of racing fuel are you running and what octane?

thanks,

Carl B.

[Ron Carter]

Hi Carl,

We run 110 to 112 octane leaded race fuel. VP or Sunoco at most tracks.