996 GT3 Purchase

[spiller]

1 hour ago, Cam Arnott said:

No joy on the Manthey kit unfortunately......no longer available.

What was the original cost Cam? A dundon exhaust with a tune would probably net similar gains?

[Cam Arnott]

On 02/03/2021 at 09:56, spiller said:

What was the original cost Cam? A dundon exhaust with a tune would probably net similar gains?

Not sure on cost mate. I was thinking of contacting Fitzgerald Racing locally to see if they had anything suitable. I'm guessing they would have tried a few things back in the day to see what made the most power in the Nations Cup cars. FVD also offer an exhaust and ECU package.

[Jason A]

My understanding of the Nations Cup cars were running Motec, a better exhaust - Star or something similar, in some cases taken out to 3.9 litres, better heads. Just depended on how deep your pockets were. This was out of Fitzy’s workshop 

[spiller]

To give an idea, @1st’s ex Nations Cup car put down a figure only slightly less than my 996 cup on the same dyno. Yes dyno figures are not always directly comparable unless it’s the same day but that’s pushing close to 390 crank which isn’t bad at all considering the 6.1 had 360 (?) factory and was rumored to be a little overrated by Porsche at the time. 

[Jason A]

Interestingly mine is logbooked from new as a 3.9 - ex Fitzgerald Racing. So I would say some reasonable $ was invested back in the day by Jim McKewon. Having come from RSR’s back in the day he would have found the stock engine a bit slow. Also ran Ohlins which was very new back then.

[1st]

23 hours ago, spiller said:

To give an idea, @1st’s ex Nations Cup car put down a figure only slightly less than my 996 cup on the same dyno. Yes dyno figures are not always directly comparable unless it’s the same day but that’s pushing close to 390 crank which isn’t bad at all considering the 6.1 had 360 (?) factory and was rumored to be a little overrated by Porsche at the time. 

Yes that seems to be the agreed number post dyno on the Fitzy Falken car - around 390hp - and it also dyno’d with a corresponding 580.4 Nm of torque (!??) at approx 7650 rpm. And we de-tuned the set up for more tractable road use.

Standard spec is quoted at 370 Nm ... 

[Pork Chops]

4 minutes ago, 1st said:

Yes that seems to be the agreed number post dyno on the Fitzy Falken car - around 390hp - and it also dyno’d with a corresponding 580.4 Nm of torque at approx 7650 rpm. And we de-tuned the set up for more tractable road use !

Standard spec is quoted at 370 Nm ... 

Sorry but there is absolutely no way that torque figure can be correct. You’re adding 210Nm of torque off a base of 370?? You’d be lucky to achieve that increase with a massive turbo bolted on. Also power is torque x revs so if the torque improved so massively, and at the same high revs, then the power increase would be commensurately massive, which it isn’t.

I also get very sceptical about crank hp / torque comparisons as nobody does engine dynos except the factory. So what correction factor was applied to get the dyno wheel power figure back to crank? I’ve seen ‘reputable’ workshops use in excess of 1.3 which is pure wank. 

[1st]

Happy to share the data in the interests of  broadening my understanding ... 

 

 

[Pork Chops]

So if 216 kw is rwkw, and we allow a 20% correction for driveline losses and use 1.34 to convert kw to hp, then we get almost exactly 360hp at the crank (factory power). If we adopt a 15% conversion which I believe is more realistic we get 341hp.

The torque figure cannot be at the wheels (it’s already too high for a crank figure) which further confuses things as why express power at the wheels and torque at the crank?

BTW if the power number is at the crank then you’re looking at 289hp.

So that dyno plot doesn’t do it for me, but happy to have it explained to me.

 

[rego]

52 minutes ago, Pork Chops said:

So if 216 kw is rwkw, and we allow a 20% correction for driveline losses and use 1.34 to convert kw to hp, then we get almost exactly 360hp at the crank (factory power). If we adopt a 15% conversion which I believe is more realistic we get 341hp.

The torque figure cannot be at the wheels (it’s already too high for a crank figure) which further confuses things as why express power at the wheels and torque at the crank?

BTW if the power number is at the crank then you’re looking at 289hp.

So that dyno plot doesn’t do it for me, but happy to have it explained to me.

I'm pretty sure the discrepancy is that it's measuring the torque at the rollers rather than the corrected figure which should show as derived torque.

I just found this for you on google image search which shows a DynoLog chart with both total and derived torque figures on it so you can see the difference.

[Jason A]

I would agree driveline loss on a 911 to be 15% due to engine and gearbox configuration

A

[spiller]

Does the brand of dyno not also come down to it? That particlarly dyno being a mustang dyno measures approx 15% less than the typical dyno dynamics from my understanding. 1st and I have both had our cars run there independently and been given very similar information by the operator as to the "correction" factor. In my case mine was merely a power run to check engine health. The operator had absolutely nothing to gain by telling fibs about his dyno. Based on what sort of lap times and top speeds my car has achieved at various tracks and also how it feels on the "butt dyno" compared to my last 996 GT3 (which was a monster with a number of power upgrades), I believe the reading to be very accurate.

[Pork Chops]

Not withstanding any of the above, that GT3 dyno plot makes no sense and I wouldn’t rely on it.

[rego]

1 hour ago, spiller said:

Does the brand of dyno not also come down to it? That particlarly dyno being a mustang dyno measures approx 15% less than the typical dyno dynamics from my understanding. 1st and I have both had our cars run there independently and been given very similar information by the operator as to the "correction" factor. In my case mine was merely a power run to check engine health. The operator had absolutely nothing to gain by telling fibs about his dyno. Based on what sort of lap times and top speeds my car has achieved at various tracks and also how it feels on the "butt dyno" compared to my last 996 GT3 (which was a monster with a number of power upgrades), I believe the reading to be very accurate.

The power on that dyno sheet is corrected (see Cor'd on the top of the power sheet) but the torque isn't and is just the torque measured at the rollers. If it was the corrected value it would say "Derived Torque" which accounts for Diff/Gear ratios, Tyre size etc...

A 991 GT3 RS only makes 470nm max torque, if this 996 made 580.4nm at 7650RPM that would mean it's making 464kw.

[1st]

All helping in broadening understanding ... ... thanks 

The dyno exercise was undertaken to tune the car for road use; they did a great job on the set up. 

[Pork Chops]

4 hours ago, rego said:

The power on that dyno sheet is corrected (see Cor'd on the top of the power sheet) but the torque isn't and is just the torque measured at the rollers. If it was the corrected value it would say "Derived Torque" which accounts for Diff/Gear ratios, Tyre size etc...

A 991 GT3 RS only makes 470nm max torque, if this 996 made 580.4nm at 7650RPM that would mean it's making 464kw.

At last, some sense. Kw = Nm x rpm / 9.5488. Unless you believe it’s making 464kw then it’s impossible it’s making 581Nm at 7,640. 

[spiller]

Been having fun becoming acquainted  with this over the past day or so. Quite different from what I’ve been used to as far as 996 GT3s go!

[hugh]

1 minute ago, spiller said:

Have been having fun becoming aquatinted with this over the past day or so. Quite different from what I’ve been used to as far as 996 GT3s go!

So thrilled you were able to get one again. Is that black? Looks like a CS? 

[edgy]

2 minutes ago, spiller said:

Quite different from what I’ve been used to as far as 996 GT3s go!

Can you expand on this? 

And congrats mate, good to see it finally completed its journey from the tropics! We need an updated garage shot!! Or did you sell that? 😛 

 

[spiller]

59 minutes ago, hugh said:

So thrilled you were able to get one again. Is that black? Looks like a CS? 

Thanks mate it’s good to be back in one. Yep it’s a Basalt Black CS. Black wasn’t top of the list but it had to be a CS and well there aren’t many to choose from these days! This one was particularly attractive to me given it has history with two PFAers

 

58 minutes ago, edgy said:

Can you expand on this? 

And congrats mate, good to see it finally completed its journey from the tropics! We need an updated garage shot!! Or did you sell that? 😛 

 

Thanks mate. First time I’ve driven a stock one, this one is completely untouched, but I can’t help myself and want to change a few things. It could benefit from a more aggressive alignment, single mass flywheel, cup cables/shifter, exhaust and last on the list is final drive. May not go that deep into it though.  Time will tell! The grumpy older brother is still in the garage

 

[edgy]

That is the money shot right there mat!!? Did you say I need to buy a cup now too? 😜

[spiller]

16 minutes ago, edgy said:

Did you say I need to buy a cup now too? 😜

Took the words right out of my mouth!

[micknine01]

Hooray it made it! 
 

Thanks for being so great to deal with, I wish there were more out there like you. 
 

Can’t wait to meet you at the Bend one day 

[spiller]

15 minutes ago, 901er said:

Hooray it made it! 
 

Thanks for being so great to deal with, I wish there were more out there like you. 
 

Can’t wait to meet you at the Bend one day 

Likewise Mick. Largest car purchase of my life and yet the most straightforward deal I’ve ever done.
 

Porsche Easter at The Bend 2022 is calling...

[hugh]

41 minutes ago, spiller said:

Porsche Easter at The Bend 2022 is calling...

Can I come too! Pleeeeease.