718 GT4 Build Advice

[ralphmusic]

Gearing is a real problem?

JCR 718 GT4 2:19 Silverstone https://www.facebook.com/509664463/videos/pcb.1926... JCR 981 GT4 2:20 Silverstone https://www.youtube.com/watch?v=QcOFNzRCu9c One looked easier than the other but modified v stock

 

[Twinfan]

Are you looking at the JCR exhaust mod or is something else now available?

There are other options available other than the JCR titanium option Jeff - SuperSprint and Fabspeed spring to mind and theirs are in stainless steel I believe. Mine is going to be a new UK designed and supplied unit which will also be in stainless steel. I'm not sure how public (or not) I'm expected to be about it at the moment so apologies for the cloak and dagger secrecy. My car is going away for a few days at the beginning of August for measurements etc to be taken and I think end August/early Sept it should be ready for fitment and testing.

I wasn't planning on swapping out my exhaust as I'm qute happy with the car as-is, however I was offered a good deal on the first unit if my car could be used for development so I'm going to give one a go. I can always swap it back and sell on the exhaust if I decide it's not for me.

Dave, Regarding the exhaust what's your view on warranty ? , I'm in 2 minds the 718 is better with the sports exhaust on but not as good as the 981.

It is all about emotion and the sound is a big part of that, the only downsides are sound and gearing.

My concern is if something were to happen while you are away and the car needs to be recovered to an OPC. You don't have the option to swop the exhaust over and Porsche are always very clear on cars being totally standard to cover warranty claims.

Hi Geoff. In the first 3 years, under the factory warranty, Porsche will need to prove the exhaust swap caused whatever problem I have. Given that the JCR/SuperSprint/Fabspeed/my rear box options will be just a post-cat and post-GPF filter back box replacement, so no issues with engine warning lights and sensors etc, I think it's very unlikely it will cause a problem. JCR haven't had any issues as far as I'm aware and they've done quite a bit of testing.

The problem will be if I want to take up a warranty extension and therefore pass a 111-point check. I'll probably decide nearer the time whether I'm going to bother extending it, so I'm kicking the can 2.5 years down the road

 

[Motorhead]

That's intriguing Dave, and very encouraging to hear that there's a UK supplier in the mix now. Best to keep it under wraps for the time being, but keep us posted on progress as and when. Hopefully their solution will be much cheaper than the JCR mod.!

Warranty is always a sticky issue and US owners always seem to me to have a much more cavalier attitude to it than us, maybe backed-up by the litigation mind-set over there which seems to make manufacturers more tolerant of certain modifications. As you say, you're modifying the system downstream of all the emissions equipment which shouldn't throw-up any CEL issues. And yes, if you want the Porsche Extended Warranty I'm sure the 111-point check will be a challenge if you plan to keep the modded exhaust.

Jeff

 

[Twinfan]

I'll let you know more when I can, probably in the middle of next month. I believe the initial estimate for the stainless steel system is similar to that of the Supersprint at ~£2750-ish, compared to the £4700 of the titanium JCR system. Still a lot for a back box but it's certainly more palatable!

The 111-point check can be got round by switching the exhausts around, but I'm of the opinion that you either play by the rules or not at all. 2.5 years is quite a way away yet though...

 

[Motorhead]

Gearing is a real problem?

JCR 718 GT4 2:19 Silverstone https://www.facebook.com/509664463/videos/pcb.1926... JCR 981 GT4 2:20 Silverstone https://www.youtube.com/watch?v=QcOFNzRCu9c One looked easier than the other but modified v stock

I don't have a FB account Ralph but the YouTube run looked (and sounded!) fine to me.

Incidentally, from online sources it seems that the ratios for the 981 GT4 [and presumably the 718 GT4?] Getrag gearbox are as follows:

1st 3.308 [13/43]

2nd 1.950 [20/39]

3rd 1.407 [27/38]

4th 1.130 [23/26]

5th 0.972 [36/35]

6th 0.822 [45/37]

These happen to be exactly the same ratios as those used in the original Cayman S G87/21 gearbox back in 2005 [source: Porsche Boxster Story - Paul Frère]. I suppose there may have been revisions in that time [apart from the 3rd gear failure debacle] but it's obvious that Porsche haven't been interested in developing the gearbox in line with increasing engine power and torque of the later cars [the original 3.4L engine produced 340Nm compared with the 718 GT4's 420Nm which is the rated torque for the 'box] despite the continuous moaning about the choice of ratios from certain quarters.

Ratio changes? Dream on..! What you've got is all you'll get.

Jeff

 

[DWaldie]

Looks like he managed hangar straight in 4th. That's high gearing for the track. Guess that's why my CS uses less fuel than my wife's old 2l Focus

 

[ralphmusic]

Gearing

Normally you’d hit around 140mph before braking for Stowe. So it’s a trade off, grab 5th, back down to 4th would be normal or stay in 4th and save 2 changes if you are a race driver.

Below is a more normal approach where 5th is selected on the Pit and Hanger Straights but it is only for a short time on the former before reverting to 4th. The higher rev range of the 718 GT4 may of course make keeping 4th more natural than on the 981 car.

[tube]https://youtu.be/ZZI0J6Nrgmk?t=11[/tube]

 

[OliR]

A lot of useful info here, so thanks for that guys. I've pretty much decided to write the PCCB's off, given the cost to repair any issues, our roads aren't the greatest. Plus, that same cost buys an awful lot of track days/tuition/steel rotors and pads. Going to keep the clubsport package, perhaps I think because it makes the car feel a bit more special, and I don't fancy fitting the harnesses myself. Just colour left to choose now actually, thanks for the kind offerings from members, I'm headed over to my OPC tomorrow to take a look at Gentian in the flesh, honestly I'm torn between this and something brighter (Miami, or even Yellow!)

Rest of the spec is:

Black Leather Dash with Yellow Stitching

Chrono

Wheels in Satin Platinum

Bi-Xenon Headlights

Park assist

Cruise Control

Full Buckets

Clubsport Package

Steering wheel centre in yellow.

Climate Control

Smokers Package

Brushed Aluminium interior package anthracite

Racing Yellow Seatbelts

December delivery should give me some time to get it run in before a nice summer track day!

 

[Scrounger]

Here’s a short YouTube video of a GT4 in gentian. Admittedly it’s a US spec car but does show it with steel brakes and may give you an idea on the colour.

https://youtu.be/OoyXC3gzrpw

 

[Twinfan]

Rest of the spec is:

Black Leather Dash with Yellow Stitching

Chrono

Wheels in Satin Platinum

Bi-Xenon Headlights

Park assist

Cruise Control

Full Buckets

Clubsport Package

Steering wheel centre in yellow.

Climate Control

Smokers Package

Brushed Aluminium interior package anthracite

Racing Yellow Seatbelts

Oli, I'd consider the carbon interior pack and the carbon sill guards - they match the P11 bucket seats very nicely and look 'right' on a GT car []

 

[OliR]

Thanks Twinfan, I did consider them, but personally the glossy carbon fibre isn't to my taste, hence the matt brushed aluminium. The door sills do look cool, but that's a lot of money for something thats hidden away most of the time (just my opinion). I have decided on Gentian Blue after seeing it in the flesh, stunning! I'll also upgrade to the LED headlights.

Question about the buckets, they're fairly upright, and I feel like I had less headroom than in my current Cayman, so much so I may struggle to fit in there with a helmet on, could it be that they simply don't go as low as the base seats, or is it just to do with being more upright? I'm 6ft 4" and there was maybe 1/2inches worth of space between the top of my head and the roof lining. Perhaps the tracspec brackets to increase the recline of the seat might give me more headroom? Not worried about the seats either way though.

 

[Twinfan]

Does your current Cayman have the same seats? The folding buckets sit higher and are fixed but the P11s can be lowered using the electrical adjustment.

I find P11s go pretty low []

 

[OliR]

Current Cayman just has the base 2 way seats. I suspect it's a backrest angle thing, as the P11s had more space between knees and steering wheel. Guess I must have a long torso!

 

[Twinfan]

Yep, seats are such a personal thing - what works for some doesn't work for others.

You'll definitely sit lower in the P11 buckets than you do now, the angle thing you'll have to see for yourself. I find it perfect, others say it's too upright especially with a helmet.

 

[OliR]

I think some of those brackets to slightly change the rake angle should about do the trick. It certainly felt more upright, but nothing I couldn't get used to, the problem will be fitting all of me in there with a helmet on.

And now we play the waiting game...

How come you're looking at exhaust options? Having heard one yesterday I think it sounds great, even with the GPF. Didn't the previous car have issues being too loud for certain tracks anyway?

 

[Twinfan]

The car sounds good to me inside the cabin when driving, and I personally would be more than happy with it as-is. However, I was approached to see if I would offer my car as a donor for development of a new UK designed and built stainless steel silencer with my reward being a very attractive price on the first solution - which I couldn't refuse. Assuming all goes to plan OK the car will sound a little better with some more exhaust noise, and as I intend to keep the car long-term I'm going to give the exhuast a go. As I said earlier, I can always swap it back if I'm not happy although I have a feeling once it's fitted I won't want to take it off []

 

[OliR]

GPF equipped cars tend to have the pops and bangs muted, I find. But it was far from silent, which you'd be inclined to believe if you spend too much time on forums!

Interested to hear how you get on. I've seen the JCR one but feel it's a bit too expensive.

 

[Twinfan]

Agreed. £4600 is too much and titanium is not needed on a 1400kg road car. The Supersprint and Fabspeed systems are around half that price, which while still expensive make more sense to me.

 

[Motorhead]

Looks like a solid spec Oli and good to hear that you've been able to settle on Gentian by seeing a car in the flesh - always a good move if you can achieve it - and if you've got your heart set on having the full harness I'd don't blame you for selecting the Clubsport option.

I suppose the only outstanding option is the transmission and presumably there's no news when PDK will become available ROW? I don't know if Porsche are planning the usual summer shut-down this year, but I wonder if we'll hear something in early September for the start of MY2021 which would suit your December delivery.

Jeff

 

[OliR]

Thanks! I did speak to the dealer about the transmission, and the answer was uncertain, in all honesty I've decided on the manual anyway so it's kind of a moot point now. It's not like I'm chasing laptimes, I'm buying the car for the enjoyment, and I don't think you'll be able to buy manual cars for much longer. Fiancee's Mini will be auto, so will be good to keep a "proper" transmission, for practice if nothing else