Cayman Racing

[ralphmusic]

Almost a year after a Cayman was entered in a FIA GT4 class race in Nogaro, where it finished 1st and 2nd in the two races, the USA season has started at Daytona. Clubsport and team built Caymans entered in the GS and ST classes in the Continental Tire SportsCar Challenge were fastest in the amusingly named "Roar Before the Rolex 24" practice sessions.

See http://sportscar365.com/i...sc-roar-before-24-test

It will be interesting to see how Caymans fare racing in 2016.

 

[ChrisW]

It will indeed ...

I've just ordered a set of wets for my GT4 ... I reckon that Pilot Super Sports should do the job

 

[ralphmusic]

A rennlist thread covers the recent Daytona practice weekend and discusses the Caymans entered with a video at the end of a couple of laps in a team-built 3.8L manual Cayman. It is not clear whether the build started with a road GT4 or a Cayman shell + parts.

[link=http://rennlist.com/forums/gt4/912004-gt4-clubsport-racing-for-first-time-at-the-daytona-roar-before-the-24-a.html]http://rennlist.com/forum...r-before-the-24-a.html[/link]

 

[spyderman]

A few shots of the race Clubsport at Autosport. I was told the UK allocation has all been sold - no surprises there!

 

[ralphmusic]

The Porsche GB guy on the stand at Autosport confirmed what Manthey said at Essen in that the Clubsport PDK box is standard 981 PDK with 7th gear removed. Good to hear this as it removes any concern about the box's torque load capacity for 3.8L engines and confirms the positive USA experience of racing 3.8L PDK Cayman, and Boxster and Cayman 3.8L PDK road cars.

 

[ralphmusic]

A very interesting talk by Rick DeMan on their Cayman GT4R own build manual race car which ran at Daytona

[link=http://rennlist.com/forums/gt4/913894-deman-motorsport-visit-photos-videos-and-feedback-5.html]http://rennlist.com/forum...os-and-feedback-5.html[/link]

- see Post# 63

Video alone is here [link]http://www.youtube.com/v/lJyqH9YFSQg[/link]

 

[ralphmusic]

The first race in IMSA's 2016 Continental Sportscar Challenge was yesterday at Daytona where GT4s came third in GS, 5 secs behind two Ford Shelby GT350R-C and in the lower ST class, GT4s were first and second, so a good start to racing in the USA.

 

[ChrisW]

Very interesting ... particularly the reference to the issues of the Gen 1 engines ...

Also the tuneability of the GT4 engine --- just fit 991 throttle bodies and pick up 30 bhp ??

 

[ralphmusic]

Also the tuneability of the GT4 engine --- just fit 991 throttle bodies and pick up 30 bhp ??

No, a few more things are required, it is mainly intake restricted and it has the consumer 400 cell cat in the headers. Take a look at the Modified section of the forum.

The GT4 does have a 78mm throttle body v 82mm in 991S. Basically for 420PS you need 1 GT4, IPD plenum + new Y tube and a modified length breather tube, standard 991S 82mm throttle body, BMC paper filter, Cargraphic 200 cell headers, and a tune, Litchfield or Jens Ehresmann/Cargraphic's kit. A better exhaust (cat back or shift the cat to the back boxes) might yield another 10PS. You could also fit a single mass flywheel as AP's assertion that the GT4's dual mass is almost as light as a single mass item is pure tosh.

I have 412PS and 419Nm in my 3.8 Cayman S PDK converted last year by Jens' group.

Beyond that, Powerkit heads etc will get you up to 440PS with longer/stronger top end through improved breathing, then 4.0L or 4.2L conversion which will yield bigger % torque gains than % power increases.

 

[Motorhead]

Ralph,

As you say, a promising start for the GT4 in the US. Rather than me ploughing through the IMSA Rules, what mods are allowed for the IMSA 2016 Continental Sportscar Challenge? I presume that there are two race categories.

Jeff

 

[ralphmusic]

First, PDK cars have to carry an additional 100 lbs of ballast v manual cars...

The simple answer is GS class allows more extensive mods and a purpose of the class is to allow American made cars to be more competitive. The simple explanation by the organisers on their website is somewhat out of date but is:

Grand Sport (GS) - As with all Continental Tire SportsCar Challenge cars, GS class cars start out as stock, production model cars that race with minor modifications only. The GS class contains the top performing cars and include the Aston Martin Vantage, BMW M3, Chevy Camaro GS.R, Ford Shelby GT350R-C, Ford Mustang Boss 302 R, Nissan 370Z, Porsche Cayman GT4 and Porsche 911. The engines are tuned to produce between 350 and 405 horsepower and are cabable of speeds in excess of 160 mph.

Street Tuner (ST) - The ST class is also production based with much of the car using the same stock parts you would find on your passenger car. This class is limited to four- and six-cylinder and rotary engines. The ST class includes the Audi S3, BMW 128 and 325, Honda Civic Si, Hyundai Genesis, Mazda MX-5, Nissan Altima and Porsche Boxster and Cayman. The engines are tuned to produce between 170 and 240 horsepower and are capable of speeds in excess of 135 mph.But feel free to plough away with the link below..[8D]

[link=http://www.imsa.com/sites/default/files/uploads/2016%20ICTSC%20Technical%20Regulations%20Jan22%20.pdf]http://www.imsa.com/sites...lations%20Jan22%20.pdf[/link]

 

[Motorhead]

Re PDK, that's a significant weight penalty Ralph considering the additional weight of the PDK 'box over that of the manual.

Perhaps the Americans have a downer on high-tech stuff: Pushrod engines may use aftermarket blueprinted or adjustable length pushrods, provided they are of the same material and configuration of the OEM part.

Pushrod engines....!

Jeff

 

[ralphmusic]

.. and they would not allow diesels like Le Mans!

 

[Motorhead]

Perhaps they get some things right then..!

Jeff

 

[MrDemon]

Also the tuneability of the GT4 engine --- just fit 991 throttle bodies and pick up 30 bhp ??

No, a few more things are required, it is mainly intake restricted and it has the consumer 400 cell cat in the headers. Take a look at the Modified section of the forum.

The GT4 does have a 78mm throttle body v 82mm in 991S. Basically for 420PS you need 1 GT4, IPD plenum + new Y tube and a modified length breather tube, standard 991S 82mm throttle body, BMC paper filter, Cargraphic 200 cell headers, and a tune, Litchfield or Jens Ehresmann/Cargraphic's kit. A better exhaust (cat back or shift the cat to the back boxes) might yield another 10PS. You could also fit a single mass flywheel as AP's assertion that the GT4's dual mass is almost as light as a single mass item is pure tosh.

I see jens is not going to use cargraphics manifolds now and has designed his own, looking forward to the results. And I hope Cobb will make not having to spend £5k on a new ECU bring the price down for a 420BHp Gt4.

 

[ChrisW]

Many thanks for the detail ... I was being a little flippant but ...

What would the extra 10% in power cost ?

Would it create any cooling issues ?

What if any are the advantages of starting with a GT4 over starting with a standard car ?

The disadvantage is £40k less to spend on modifications ...

But is this where Porsche build a GT4RS ? It would be so comparatively inexpensive for them to fit the best bits from the start ...

 

[ralphmusic]

Chris,

Modifying is only for the brave as the lack of interest in the UK testifies to.

First find someone you trust..

Jens did mine in Germany, but he has just left for a month's vacation in Chile.

Litchfield (of GTR tuning fame) have tuned some 991 Turbos with the Cobb Accessport, the advantages of which are that the tune is loaded via the OBD port, is reversible and they will develop a tune individual to a particular car and it's extra bits. Jens' tune is a reprogram of the ECU, and only they can return it to standard (unless you buy a spare ECU and have the original cloned) but they have a lot of experience of 9x1 series engines.

All of the parts I listed can be bought in the open market, although there is a slightly modified bit of tubing for the plenum due to the different run length, but it is not special or unique tubing.

If you go to the Cargraphic's web site (Cargraphicts.com) you will see Jens' kit with all the parts I listed including and the price for the kit. Jens has 'licensed' his kit to Cargraphics. It can be fitted by a competent motor engineer.

Alternatively, you could buy the parts and have Litchfield fit them and do you a custom tune. I am going to see Litchfield in a week or so to see what they can do for normally aspirated 9x1 series engines and will be posting the findings here. They have not tuned a 9x1 NA engine yet.

BTW on Jens's new header. He has used M&M for a couple of years and has gone through several versions on his modified Boxster, so he's doing a deal with them to help them reach a larger market.

Send me a PM if you want more detail outside the forum.

Ralph

 

[ChrisW]

Many thanks, I'll work on my driver training --- and watch out for an RS --- maybe

But your enthusiasm and detail are very much appreciated !!