mehoff

POC has listened to it's racers and created a new spec class for the 3.2L Carrera's: Carrera Spec. The primary impetus for this class was to allow driver's to develop their Carrera's to a scope that promotes spec-level competition at speeds/handling capability far superior to that of the standard stock classes.

This scope is a derivative of one of the most competitive (and largest) POC field: V3. As a result, the allowed modifications have been extensively tested and a "top-tier" car can be developed immediately without having to experience the growing pains typically associated with new classes.

Lastly, and MOST IMPORTANT, the spec significantly restricts engine development (and puts strict dyno-tested caps on bhp and torque) that keeps costs in line and prevents the GT / Spec911 style engine-related arms race.

The primary difference between Carrera Spec and PCA class E are:

Short Gears Allowed
Wide Body Allowed (with fiberglass panels)
Leading Edge Rear Wing allowed
Weight Reduction

The cost to develop an E into a Carrera Spec will be negligible, and when taking it account the significant performance advantage gained, could become very appealing to those racers.

Primary difference between Carrera Spec and Spec911:

Wide Body Allowed
Leading Edge Rear Wing allowed
17' wheels allowed
NO ENGINE DEVELOPMENT PERMITTED

The later point keeps the costs well within reason comparatively and will enable a builder to get the car to the podium without expending $100k+!! That being said, if we could get half the numbers of the Spec911 guys with the same competitive balance I would consider Carrera Spec a resounding success.

Without further ado, I present Carrera Spec (note: this is already locked in so this is informative, not a request for suggestion, though those would be appreciated as we move towards the inaugural 2014 season):

This is a classification for Porsche 911 racing cars that allows for a specific set of modifications that have been carefully chosen to provide competitive performance with maximum reliability and contained costs.
Any modifications not listed, as follows, are NOT allowed. Rules will be maintained by a committee which will be appointed by the drivers of the Carrera Spec Racing Group.

All cars must comply with all current POC-GCR safety requirements.

Chassis, Body and Interior

Any naturally aspirated Porsche 911, to 1989 is allowed however all cars must run the stock configuration (USA) 3.2L Carrera engine. All 1974 to 1983 Porsche 911 may be updated to the 3.2L spec. Carrera engine.

Minimum weight for cars with driver is 2450 lbs for 74 to 89 G body cars. Factory turbo body cars will run a minimum weight of 2500 pounds with driver. Narrow body cars without turbo flares will run at 2400 lbs minimum weight with driver.

Fiberglass and composite body panel replacements are allowed, including body “turbo” flares and sunroof panels. Front air dams may be used as long as it doesn’t extend forward of the stock bumper (excluding bumperettes). (993, 996, 997 and slopenose body configurations are not allowed)

Rear wing choices are free. Leading edge rear wings with “wicker bills” are approved. Leading edge rear wings may not extend above the factory roof line, behind the rear bumper and a maximum size of 9.75” x 60”.

Interior modifications are free.

Engine Specifications

All engines must be Porsche (USA spec) 3.2L, stock bore (95mm) & stroke (74.4mm), with a maximum of 9.5-1 compression ratio.

The class will allow a maximum 235 H.P. and 195 ft.lbs. torque curve spec.

Stock camshafts and rocker arms, stock port and valve size and single plug heads required.

Stock, or equivalent, connecting rods with aftermarket rod bolts are allowed.

Crankcase and crankshaft machining of any kind is free.

Valve springs and retainers are free.

Ignition system is free. Change to the OEM DME control unit or replacement “chip” is allowed.

Stock induction system is required. Forced induction is not allowed.

Engine oil system and cooling is free.

Intake system must be stock from the air filter housing face to the air flow meter. Air filter is free.

Exhaust system is free.


Transmission and Clutch specifications

The transmission must be Porsche model 915 or model G-50.

Differential (LSD) is free

Gear ratios are free

Clutch and flywheel package is free.

Transmission coolers, lubrication and shift linkage is free.

Suspension Specifications

Stock suspension pivot axis points must maintain stock location

Front spindle height is free and must use original equipment components.

Single external adjustable shock absorbers are allowed.

Torsion bars or coil-over spring suspension components are allowed in front and/or rear.

Altered steering arms or steering rack/arm spacers for bump steer is all allowed.

Suspension bushings & motor mounts are free, but must maintain stock configuration

Anti-roll bar (sway bar) systems are free

Alignment settings are free.

Tires & Wheels

Maximum wheel size is 8x17” front and 9x17” rear

The spec tire will be the Kumho V710.
(Contingency tire program to be determined, pending availability and price.)

One new set of 4 tires allowed per weekend event.

Brakes

All cars must run Carrera or 911SC brake calipers, steel/vented rotors with any pad combination . Only Factory turbo body cars may run stock turbo style brakes. All cars must run a stock Carrera or 911SC master cylinder.

Brake lines, pad material, cool air ducting, master cylinder, brake balance control and fluid are free.



ANY MODIFICATION NOT SPECIFICALLY MENTIONED IS NOT ALLOWED

flatsics

interesting rules

Astroman

Nooooooooo! (of course you expected comments from the PCA peanut gallery)

Get rid of the those $15K transmissions and allow $1K brake upgrades!!

For me, the ultimate Carrera spec rules:
stock motor
stock tranny
lightweight
narrow body
no aero
big brakes
small tires...

Now THAT would be fun (and much cheaper).

mehoff

I fought the good fight to stay narrow body, but we had too many legacy cars that it would have blown out of class to be feasible. Aero was a universal desire....the speeds these cars hit atbour tracks would preclude door to door racing otherwise. Right now (no aero) i have to pucker up nice and tight to go flat through turn 8 at WSIR and through the roval at fontana, and that still usually requires a change of underwear once a weekend!

Cant understand desire for more brake; my stock calipers are more brake than i'll ever need, and my car weighs 2,700lbs right now. I unerdstand for longevity on enduros, but we're sprint race focused in SoCal.

As for tranny, when rebuilding the cost to go short gear vs stock is not that much more.....my "stock" tranny costs a fortune!

mehoff

....

Astroman

Jack, so do these rules represent a typical POC V3 car? Is this a way to standardize the cars in that class?

Regarding the brakes... the SoCal tracks must not have many 5th gear to 2nd gear corners... Road America has a wild one. Road Atlanta too. I hear COTA has about 10 of them. But Watkins Glen has no 2nd gear corners (ie heavy brake zones) and true, my brakes work fine there. But at Road America against 944 S2s with ABS, I'm at a big disadvantage...

eric523

Maybe a little premature on the rules posting and a few assumptions made that may be more opinion than fact, but glad that you are excited nonetheless!!

The rules are still under review currently so there might be some minor changes before they are put into the GCR in final form.

We really hope the class will make the members happy!

Sean F

no passenger seats?

Streak

Max 235hp but no engine development allowed?

eric523

I think he meant no more NEW development beyond where they are already at. Which is still more of an opinion, because you can guarantee that people will still try and maximize area under the curve if there is a max number. That max number of 235 is still being discussed as well. So like I said, a little premature on public posting of the rules...

Doug007

With an open ignition system I'm sure you could do some interesting things to make a nice flat torque curve just under 195 ft*lbs. Of course, it would have to decline a bit after 6300 rpm to keep you under 235 hp Wonder what the 3.2s will rev to in race trim...

mehoff

Good catch...in previous drafts we were supposed to keep stock ignition system. Not in love with that.

The motors are "stock spec", meaning every internal piece needs to be within stock specification (with the exception of gt3 oil pump being allowed). The engines are still expensive, but nowhere near the $25-40k monsters being rolled out up north.

Don't think we'll be able to get to 235hp; I don't like that number. I've seen 5 motors, including mine, roll off the dyno and all were 223-226bhp with 193-202 torque.

eric523

indeed, this is a DRAFT of the rules ONLY! It would be best to have made an official announcement with completed rules. This posting will only add to confusion and misinformation going out about our new exciting class...

Vampire

How do Kumho V710 compare to Hoosiers from a lap time and Heat cycle point?

mehoff

My bad, this was forwarded to me as final by the drivers collective that pushed it through. BOD better not make any substantive changes!!!

As for the v710's, they are about 3/4 second slower assuming an average 1:40 lap time, and dont fall off through about 7 heat cycles (similiar to r6). The benefit is that theycan be run to about 16 HC as decent practice tires, which the hoosiers cant. Also, $300 a set less is nice.