Cayman GT4: Where are we up 2 now? Déjà vu Edition

[MrDemon]

. And when we have gone to the next stage will we be satisfied?

Ray

yes very ;-) I am satisfied if the car does not have any main short comings, overall performance is not what I chase.

Hence why I own a 987.2 320bhp Boxster also, it's a satisfying car to drive and that's all that matters to me.

981, 991.1, 991.1 GT3, 718 and GT4 had quite big a flaws at any price for me to like them really as firm keepers.

The new cars in most brands seem they will also have flaws even at any price with these new regs.

The only 2 flaws in the 991.2 GT3 imo are the high cost and cheaper Calipers, calipers is a non issue really, but cost is quite a big factor ! eak I cannot eat Adli beans every day !!!.

But even the GT3 is built to a price, hence they had to bring in the WP for the trick bits now and a car at this price is not going to have £10k race monoboc calipers on it, Ti exhausts and forged wheels. what it does have is all the basics covered in all area's though , so you can buy a set of forged wheels if you wish (BBS Fi-R) when my numbers come up.

 

[Twinfan]

Whoopsy's info on Rennlist was road car - manual only, same spec GT4 vs Spyder, 420bhp - as was Fokker's on PH. Their info matched each other.

Who knows what the Canadian crossword-puzzler was referring to, lots of assumptions. When I spoke with FW he was clear on the Clubsport not the road car but, as they still have final testing, certification etc who knows - for sure we don't. The Manthey VLN session was Clubsport only. So unless SRO regs are going to change to require OEM exhaust in its entirety, I for one am quite comfortable being uncertain.

Here's Whoopsy's post for reference - he's directly commenting on the road car in the pic. I agree things can change though, based on the new testing requirements.

https://rennlist.com/foru...-122.html#post15014653

 

[ralphmusic]

I saw that some time ago. It has been mulled over and regurgitated several times.

The question is whether there will be different exhaust configurations and if the GPF is as power sapping as is suggested, whether this will mean a higher or lower hp rating for the road or race car. I don't know.

 

[Motorhead]

Ralph,

Extract from the 2018 technical regulations for the GT4 European Series:

5.3.1) The exhaust system must incorporate one or more homologated catalytic converters, which should be functioning at all times and through which all exhaust gases should pass. 5.3.2) The noise generated by the car must not exceed 110 dB (A) at 3800 rpm, or at three-quarter maximum revs if this is less.

No mention of a GPF for the current Series but that could change for next year if all the manufacturers are fitting them on their road cars.

Jeff

 

[ralphmusic]

Jeff,

They are indeed the SRO regulations which also specify how ballast and restrictors must be used, if required by BoP of course.

Ralph

 

[Motorhead]

Ralph,

Just out of interest, does homologated infer road car parts or is the use of sports cats allowed? If so, I wonder if some suppliers are working feverishly on low backpressure GPFs..??

Jeff

 

[ralphmusic]

Jeff,

I am certainly no expert on the regs or their application/interpretation, but the defined term 'Original' is used in some sections but not in others

1.2 Original

As fitted to the SRO Motorsports Group-approved series-produced car and in compliance with their Technical Form.

…as used in 5.1 for example

5.1 Type and position of engine

The make and type of engine used must remain original, unless by a waiver of the SRO GT4 Bureau. The position of the engine, the location and orientation must remain original.

5.4 does not include ‘original’

5.4 Exhaust 5.4.1) The exhaust system must incorporate one or more homologated catalytic converters, which should be functioning at all times and through which all exhaust gases should pass. 5.4.2) The noise generated by the car must not exceed 110 dB (A) at 3800 rpm, or at three-quarter maximum revs if this is less. This measurement will be taken at a distance of 0.5 m and at a 45 degree angle to the point of exit of the exhaust. All measures taken to ensure that the maximum noise limits are not exceeded must be permanent in nature, and must not be cancelled out by the exhaust gas pressure. 5.4.3) The exit of the exhaust pipe must be situated at the rear of the car, at a minimum of 100 mm from the ground. Exhaust gas may only exit at the end of the system. Parts of the chassis must not be used to evacuate exhaust gases. Exhaust line protection are allowed

...so GPF or not depends on 'homologated' - I'd guess it might not be required for a year or so but may be in the future given 'close to road spec' nature of GT4 series. Of course the USA race series operate to their own rules and whether their GT4-similar classes will/won't have a GPF will be interesting from a power spec point of view.

Ralph

 

[ralphmusic]

Something from Mercedes on the new emissions regulations.

https://www.mercedes-benz...What%20is%20the%20WLTP

 

[Motorhead]

Ralph,

Good to know that although the more rigorous testing of WLTP will result in higher CO2 values -

....To ensure the taxation system is fair in this transitionary period, new models that have been issued with a WLTP value will also have a back-calculated NEDC value. It is this NEDC value that is used to assign a tax band.

That's until the next overhaul of VED in April 2020 which will reflect solely WLTP values..!

Jeff

 

[ralphmusic]

Jeff,

I wonder whether an upgrade such as my 3.8 will be possible in the future. Maybe I should keep it and have a PowerKit fitted but maybe move to a higher cell count cat in the manifolds.

Ralph

 

[ralphmusic]

If Porsche could come up with an exhaust with 'quiet track mode' for the new GT4 that can be retrofitted to the old one, I'm sure many of us would be potential buyers. We're realistic enough to know that Porsche would charge us £2K++ for the pleasure of having one retrofitted. But it certainly beats trying to get some after market dog's dinner to hang on the back! AFAIK there's nothing currently available aftermarket for the GT4 anyway. The closest thing I can find is this that can be fitted to a GT3 (996 and 997 models I think):

http://www.actproducts.co.uk/product/si06-porsche-gt3-sliencers-pr/

I've yet to ask them if they can make a version for the GT4.

I called ACT; the function of the "agricultural" straps joining the box-entry tubes is to prevent droop on a GT3 installation. The welding looks a little "unfinished"

Putting these on the 981 would require new pipework (essentially the OEM part #1 below without the fancy end tips). A consideration with this is that without some form of additional support, the weight of the ACT silencers might be too much for the clamps and allow both track silencers to droop.

Still it looks like the Gen2 with GPF might be a lot quieter....

 

[Steve Brookes]

Thanks for asking Act more about it Ralph. As I feared it wouldn't be a simple job to modify it for the GT4. And with the increasing news that the next GT4 will have a particle filter incorporated in to the exhaust it sounds like it won't be possible to retrofit the new one to a mark 1.

 

[Motorhead]

Jeff,

I wonder whether an upgrade such as my 3.8 will be possible in the future. Maybe I should keep it and have a PowerKit fitted but maybe move to a higher cell count cat in the manifolds.

Ralph

Yes Ralph, these new more rigorous regulations do make you concerned for the future of after-market specialists. As discussed before, it looks as though even the manufacturers are struggling with their options list as certain individual options could impact emissions under WLTP.

Jeff

 

[Motorhead]

Ralph,

That track silencer does look like a bit of a dogs dinner..! Quite a lot of weight cantilevered off the two silencer exit pipes as well. Not a great arrangement unless there's a supporting strap to the body (bungee chord??).

From your lower picture it's interesting to note that, subject to space limitations, with the mid-engine layout there's ample pipe length between the cats and silencers to incorporate a couple of GPFs.

Jeff

 

[ralphmusic]

Video of excited girl..

https://www.instagram.com/p/Bli9tr_B_Kx/?utm_source=ig_share_sheet&igshid=1402kiaf4hjq2

 

[ralphmusic]

Back to trackday silencers, I met up with Tim at today's Silverstone Goldtrack event, the start of which was delayed until 11am because of a flooded track - WHAT! - apparently the Circuit was watering grass at one of the corners and I guess left the tap on so there was a depth of water on the circuit.

Anyway below is a picture of Tim's unmounted track day silencers showing how these are supported.

and a reminder of how they look mounted on the car

 

[Motorhead]

Do the supports pick-up on the diagonal struts Ralph?

Also, on topic and posted elsewhere: https://www.facebook.com/135114993180047/posts/2122510594440467/

Not great sound quality (I think there could be another car out of sight passing the camera). Is it just my imagination - the change-up sounds quite rapid in the clip? PDK transmission perhaps? Probably just clutching at straws..!

Jeff

 

[ralphmusic]

Do the supports pick-up on the diagonal struts Ralph?

...... PDK transmission perhaps? Probably just clutching at straws..!

Jeff

Jeff,

Re pick-up points I don't know. I've looked at https://www.youtube.com/watch?v=5SamK54Igm0 and

[attachment=981 Exhaust Rear.jpg]

but am none the wiser. I did not ask Tim thinking it would be obvious from pictures and PET file.

I think it is a solid no to PDK.

Yesterday I spoke with a GT2RS owner who is normally very switched into the latest buzz and he was sure, having spoken to AP & FW at Goodwood, that the new engine was 3.8L. When I told him about the several VLN/Manthey attendees all saying 4.0L, his recounted conversations at Goodwood appeared to be more him talking and AP/FW tapping their noses.

I also drove a GT4 at PEC yesterday, trying to understand the material differences between my car and the GT4 on track and road.

After 35 minutes pounding round their two Mickey Mouse circuits at lunch time with little to no other traffic, the obvious differences were engine/drive train characteristics. The GT4 sounds more visceral and whilst I am not used to a manual on track, there did not seem to me to be any great advantage in using higher revs. Mine on the other hand with larger intake and exhaust systems and PDK, generally runs between 5.5k rpm and the 7.5k soft limiter on track, and is always spinning in the higher rev ranges. I can't say I noticed any real difference in grip although with any car one's driving style can induce unhelpful understeer. It was possible to have the rear step out with load transitions under power but I solved that on mine with set-up and DSC. Were I driving that GT4 on the GP track then the GT4 would be quicker with its aero (such as it is), larger PCCB brakes, fully engineered and 10 zillion hour developed suspension, and lighter weight.

Unfortunately, although I had asked for and confirmed twice their road registered GT4 (to drive on track and on some local roads I know), they couldn't find the number plates. So I am back in October to do both track and road for no extra cost. A bit irritating as it is a 380 mile round trip but at least they came up with a reasonable solution.

Ralph

 

[Motorhead]

Just in case you missed it:

https://www.pistonheads.com/news/motorsport/porsche-confirms-concept-study-rally-cayman/38479

Based on the "old" GT4 Clubsport of course, which seems a bit odd considering we're thinking that the new CS could be appearing soon - or perhaps it's not..?

Jeff

 

[Motorhead]

Nothing new to report other than another recent sighting with the latest version of the rear spoiler apparent:

https://www.carmagazine.co.uk/spy-shots/porsche/porsche-718-cayman-gt4-spy-photos-specs-and-info/

Can't really get to love the rear diffuser treatment - it looks a bit Hellfrauds and unfinished to me, but I'm sure that it'll bring some useful aero improvements for the CS race car. Also, the deep central duct will mean a very different silencer arrangement compared with that for the 981 in which there are two interconnecting pipes between the silencers (see Ralph's pic above) and may account in part - along with the GPFs - for the new exhaust note.

Jeff