[ky350]

Read that the Porsche 911S won Motor mags PCOTY easily this year. The journo's were singing the Porsche's praises and basically could not find any obvious faults - wow!

So this go me thinking / dreaming. Since the Porsche costs approx $230K, could we make a Porsche rivallying modified Z for no more than $100K? Below I have listed some of the mods I think we'd need to have for the Z to equal or better the Porsche.

Power wise, need:
1. APS TT (please no arguements on engine life) is needed to match / better 911S power : weight.
2. Higher spec twin plate clutch / flywheel combo to handle the increase in power.

To achieve 911S neutral balance, need:
3. Adjustable sway bars front and rear
4. Adjustable coil over suspension (in cabin adjustability preferred - EDFC???)
5. Wheels / Tyres - 275/35R19 all around (will 275's fit in the front without fender adjustment?). Use same Michellin Pilot Sport as the 911S.

For stopping power:
6. Upgraded brakes (at least for Touring model)

General:
7. Better seats to keep driver / passanger from sliding / shifting during hard driving.

What else is needed?

I estimate that these mods alone would cost at least $35K (new purchases), pushing my Touring + mod prices to $100K.
I'd love to have 911S equalling or better performance and save over half the cost of the Porsche!!!!!

 

[davidm]

What do you mean by '997S rivallying performance'? Do you mean in terms of feel, straight-line acceleration, grip or handling? Or all of the above? Also in terms of acceleration, do you mean in terms of of-the-line aceleration or rolling accleleration? Or both?

Some of these things might be easier to do than others. For instance the power-down traction of the 911 is mostly due to its weight-distribution and I'm not sure if there's anything that one could do to to the 350Z to get it to a 911 level.

ps. I'd settle for the plain-vanila 997 level of perfrormance. They just tested one in Wheels and returned 4.9sec to 100kph, 10.9sec to 160kph, 13.8sec to 180kph and 13.2sec over 400m.

 

[scathing]

Keeping it under $100K, I'd probably do something similar to a Touring.

APS TT kit
StopTech brake upgrade
Nismo LM GT4 rims
Tein Type CS suspension with EDFC and Cusco swaybars
Lightened flywheel (stock clutch seems to cope OK)
Cusco 1.5way LSD

That should cost around $100K all told, with installation.

If I could get another couple of grand, a bottom-end rebuild and a slightly more aggressive set of cams would be on the cards.

 

[ky350]

DavidM - by 911S performance, I want the Z to rival or outperform the Porsche in all catagories.

WRT acceleration, the APS TT should see better than 911S acceleration in both off the line and rolling acceleration (those Wheels timed numbers are **** impressive, especially if not the S version).

WRT feel, I doubt that the Z could give as much feedback through the steering wheel as the Porsche and again I suspect that the Z's gear box does not feel as good either - I'm prepared for compromises here.

WRT handling, I'm confident some mods in this area would see a more neutral Z on a race track when beening pushed to 9 and 10 thenths, to at least equal the 911.

Scathing - our wish list are fairly similar. Why do you think you'd need a different LSD???

 

[mr rizk]

You are all porsche wannabees, but if anyone needs help in robbing a bank to buy one COUNT ME IN !!! Dibs on a yellow one.

 

[scathing]

Originally posted by KY350@Mar 6 2005, 01:26 AM
Scathing - our wish list are fairly similar.  Why do you think you'd need a different LSD???

I'd prefer a more aggressive LSD to improve the handling.

Viscous LSDs don't have the same response as a clutchpack diff, and can't be tuned. Well, I suppose you can keep replacing the fluid until you find one that has the viscousity you like, but its easier with a clutchpack (and the Cusco is adjustable).

It also has a greater torque transfer capacity than the factory diff, in case that becomes an issue. I've read some articles where people have "broken" their viscous LSDs by trying to pull powerslides with ultra-sticky tyres. The amount of force pushed through the liquid has done some weird shock effect and removed its ability to change its viscosity under load.

The other thing is that a the 1.5 way effect of this LSD would be preferable than the 2 way effect of the viscous LSD. This should make the car turn-in better as it will further remove understeer from the drivetrain. So I can either have just as much traction under power as the factory LSD and less understeer while off the throttle, or the same amount of understeer when turning in and more grip when punching out of corners.


Since its a street car, I would consider adapting a R34 GT-R rear diff (which I understand is helical). While ultimately not as adjustable as a clutchpack LSD, and other issues that make it not as good on the track, the LSD effect a helical diff generates is smoother and more progressive, and so probably more streetable.


For the wheels, I'd definitely stick to 18's. While 19's look nice, there's more rubber and rims available in 18". I'd consider the LM GT4s (which look awesome on the 350Z) or some Gram Lights in 18x9 (to keep them ADR legal). Unsure which design, but probably the 57F's (which are a favourite of mine, and what I'm looking at getting for my car in 17x9)

 

[davidm]

If 997 performance and feel/involvment are the objectives then I'd take a different approach from you guys. To strat of I'd stay away from a turbo as I can't see one having the same throttle response, consistancy of the power delivery with one ... at least not to be able to compate with a 997. Also having that kind of power will distance it even furhter from a 911 as 350Z can't put that kind of power to the ground in the same way that a 911 can ... even a stock 350Z has more problems putting the power to the ground than a 911.

Where I would start is with shedding 150kg or so from the car. Amuse has most of the lighweight parts and I would guess that for the cost of the twin-turbo you'd get most of the important ones .... low 1300kg should be the goal. Part of this should be lighter (and more sportier and huggier Recaro seats). I'm just guessing, but $20k should do it here.

As far as the engine goes I would not mess with it too much ... ideally, just improve the breathing, get it to spin to 7000rpm, and improve the top end. 230kW would be enough. Though, it needs a lighter flywheel to make the gear-changes more positive and 'crispier'. Besides that the gear-box in the 350Z is very much on par with a 911 ... I'd even say that the 350Z gearbox feels better. So that's another $5k here.

The two things above should give the car ~5.5kg/kW weight-to-power figure and should give it close enough acceleration to a 997. Also the lower weight should help with the traction and hence improve the launch.

Next I would put on 8.5" wide wheels at the front and 9.5" at the back. I'd stay with 18"ers but would want to fit 245s at the front and 275s at the back. Then I'd replace the springs and shocks with something adjustable ... same with swaybars. Then I'd spend a weekend at the track to tune them. $6k should cover this if one shops wisely.

Also it would require the Brembos from the track model ... or something equivalent. Again $6k should cover this if one shops around.

Though I'd say that should do it, and if we started with a 350Z Touring, which is $59k, then I'd need $37k for the mods listed. That would land me just under $100k. For this you should have a 350Z that can stay with a 997 in terms of acceleration as well as lap-times. Off the line there's not much that could be done to keep the 997 honest as it has a significantly favourable weight-distribution for power-down, and I don't think that there's anything that one could do to a 350Z to get it to that level. I would not mess with the steering feel as 350Z has this in spades and not much to complain about even next to a 911.

 

[Ztrack]

[/quote]

Firstly I'd have to agree with you on getting the power to the road, the 997 has this part down pretty dam good compare the the 350Z but your statement on the matter of throttle response with the APS TT is not completely accurate, the TT has no and I mean no lag it not like a low torque 4 cylinder WRX or EVO, to start with it doesn't require a bagfull of revs to get it on boost, just imagine your car with another 120rwkw, its quick and has great throttle response, that's why they try and increase the capacity of the RB26 motor to 3Ltr, more torque which the 350Z has already. Come for a drive and see what I mean and tell me if I'm wrong!

Cheers

 

[davidm]

but your statement on the matter of throttle response with the APS TT is not completely accurate, the TT has no and I mean no lag

I didn't mean to imply that that the TT is laggy, or unresponsive. Just that it will be laggier, and less responsive than an NA engine. Afterall, a turbo by its design introduces both to an engine (no matter how little, or insignificant one may feel that may be).

Come for a drive and see what I mean and tell me if I'm wrong!

Hey, you'd know better than me, but I'll certainly take you up on the offer in the near future

 

[aps]

[/quote]

Interesting comments David though I'd have to disagree and I own a 997 S Porsche, an awesome car I must say.

The APS Twin Turbo system on the Z would have better throttle response and power across the entire rpm range by a country mile, not even a contest, the Twin Turbo Z would win hands down in this part of the comparison contest.

From there on in it would be a real battle to match the 997S though with thorough suspension tuning and better brakes who knows, the Twin Turbo Z car may well provide the 997 a good run for the money, certainly would be a hoot to try.

In terms of performance I believe that an APS TT systenm would give the 350Z a very decent edge in terms of acceleration though of course the tyres, brakes and suspension would reqiure major tweaking to try and match the Porsche 997S.

Interesting thread guys, keep your thoughts coming, no doubt the 997 S Porsche is awesome though lets not give in without a decent battle.

Peter

 

[nizmo pete]

This is an interesting thread

The 997S weighs 1425kg the Z 1450kg.
The Z is wider in the track & longer in the wheelbase despite being a fair bit shorter overall.
Add a set of light weight wheels, 9" wide in the front & 11" on the rear & use the same Michelin tyres as the Porsche but use a 245 width tyre on the front.
All I would do to the suspension would be to fit some adjustable front top A arms to dial in a little more neg camber & a set of stiffer adjustable sway bars & a set of Eibach progressive rate springs.
Change out the front seats for some light weight buckets & I would estimate the Z would now be a little bit lighter than the Porsche. (the stock Z wheels & tyres are very heavy)
I would then put the 4 spot Brembo,s to the rear & put 6 spots with larger 2 piece rotors on the front.
For mumbo you just cant go past the APS TT set up on a HP for cost basis. I would just uprate the radiator & fit an oil cooler. Not sure what our weight would now be.
Pete how much weight does the TT kit add?
I would estimate this set up in the hands of a good driver to be capable of a 1'47" lap time around Eastern Creek. There has been no times set for the 997s that I am aware of but I,d think that it would be hard pressed to beat that time but would go very close.

 

[Nuff]

I think that it was mentioned that the weight of the full kit is 65kg, but I'm not sure if this weight includes packaging or just the kit. Also radiator and oil cooler would add another 10-15kg (that's just a guess and it includes the extra coolant). As for suspension, I would install swaybars and HKS Hipermax II coilovers, they seem to be one of the best for the track, while still being good on the street. They also offer a lot of adjustment.

 

[ky350]

Rizk - yeah I am a Porsche wannabe cause I ain't got no HKS kahounas dangling under my bonnet!

Scathing - despite having read about helical / 1.5 and 2 way diffs, I cannot remember anything about their similarities / differences and advantages / disadvantages. I guess if I did upgrade the Z as I wished, I'd leave the OEM diff until it broke and then do some serious research for a stronger replacement. Thanks for the explanation.

DavidM - I have thought of stripping kilos of the Z, but it would be impossible to get to 1300kg without losing the niceties. I have thought over and over again where we can save weight, and I struggle to get more than 40 - 50kgs out of the car before making serious sacrafices (ie air con). However, at 1300kg and with some suspension mods the Z would be as quick as the 997S.
BTW, Ive never driven a 911, but I keep reading about the steering feel as being telepathic. As good as the Z steering feel is, I have never read any ravings as extravagent as those for the 911 on the Z, so I assumed that the 911 feel is several notches above the Z's. Mabye only one notch above?

ZTrack and APS - I suspected that the TT had great throttle response as its design was for outstanding low to mid range torque and a small sacrafice for top end power production.

APS - did you sell the 911 Turbo for the 997S?

NismoPete - agree with what you said, but I have a feeling that the 11" rear in combo with the 9" fronts would result in way more grip in the rear giving understeer, something I was trying to get away from and produce a more neutral handling Z.

Nuff - I seem to recall ZTRACK having said the the TT only adds about 20kgs. If you were going to do a lot of track work, then a larger radiator and oil cooler would be mandatory.

Thanks for the feedback guys.

 

[davidm]

I have thought of stripping kilos of the Z, but it would be impossible to get to 1300kg without losing the niceties. I have thought over and over again where we can save weight, and I struggle to get more than 40 - 50kgs out of the car before making serious sacrafices (ie air con).

For about $20k I would think that we can save more than 50kg, from the Zed. Seats (while still retaining their comfort) should be able to account for 15kg saving. Then the wheels will give us another 12kg. That's 27kg, but the rest of the weight would be saved by replacing body-panels as Amuse did. If I remember correctly the rear hatch was ~20kg ligher and the 2 doors saved ~30kg so those two things alone give us another ~50kg. Flywheel and battery could give us ~15kg saving which should put the total saving at around 90kg.

Amuse did manage to bring the 350Z to 1300kg ... they did keep air-conditioning and stereo from why I can remember but I think to get to that weight one would need to spend at least $40k. I was aiming at 1330 - 1350kg here as I thought that might be a bit more cost-effective. I'm just pressuming that $20k or so should do it. It's always the last few Kilos that cost the most to shed.

BTW, Ive never driven a 911, but I keep reading about the steering feel as being telepathic. As good as the Z steering feel is, I have never read any ravings as extravagent as those for the 911 on the Z, so I assumed that the 911 feel is several notches above the Z's. Mabye only one notch above?

I have driven most of 911s, but not the 997. The steering in the 911s was great, but I don't remember it being noticably superior to the 350Z. If anything, I drove the 911s before I got into 350Z and I do recall still thinking how good the 350Zs steering feel is after the 1st time I drove it. I would not say it was better than the 911, but IMHO it was up there ... I can't think of many cars with better steering feel than the 350Z. Boxster is great, but I would not say better than 350Z in this respect. Though, usually it's the cars without power-steering that have great steerign feel. MX5, Elise and even MR2 come to mind. Though I don't wish no-powesteering onot anyone as it does make for tough steering on the limit (ie. the steering can get really heavy when the car steps out).

ps. Oddly enough I preffered the steering feel in the 4WD 911s than the RWD ones. It probably had something to do with the nose being better tied down and not so 'wondery'.

 

[Nuff]

If you guys are serious about improving the steering feel you might want to get the 350evo Spherical Bearing Kit, 350evo A-Arms, Nismo Drop Links, also change the upper pillow ball mounts to solid type, most of the coilovers do it already. That should remove most of the slack that is inherent in our suspension because of the rubber bushings and it would become razor sharp and a lot more responsive, but it would also become very notchy and you would be able to feel every grain of sand through the steering wheel. Some will love it, others will hate it.

 

[Nuff]

As for loosing weight, you can loose roughly:
-10kg battery
-23kg spare wheel + tools + foam + matts from boot
-12kg wheels
-5kg Stoptech 2 Piece Rotors (Track only) and you save even more if you get drilled rotors instead of slotted
-14kg ATS twin plate flywheel, less or more for other flywheels
- 1kg? Lightweight aluminium lug nuts
- 30kg Ti Exhaust
- 2.5kg? Cats, just a guess
- 5kg? Headers, just a guess
- 20kg for two Bucket Seats with lightweight rails (that's according to GY-Z on my350z) also adjustible seats will loose next to nothing in weight, surprisingly our seats are already quiet light.
- 5kg aluminium front bumper (don't crash into any one)
- 8kg? remove the subwoofer and rear speakers (the stereo is crap anyway, the 2/3 or was it 1/3 of the rear speakers are blocked and you can't hear them anyway)
- 2.5kg? for subwoofer steel plate
- 1kg? lightweight pulley

So the total comes up to around 139kg, that's fair bit of weight, so the car would weight around 1314. So since stock powe is 206kw that would give us a power ratio of 6.4kg/kW, that's Monaro CV8 power ratio. Let's assume that the above exhaust mods would give us 230kW at the flywheel, then the power ratio would be 5.7kg/kW, this is HSV Clubsport R8 power ratio. And if you have a setup like Richie (Z350Lover) then with my rough calculation of him having around 260kW (he might have more, but I'll be conservative) at the flywheel the power to weight ratio would be 5.1kg/kW. The only car with similar power to weight ratio i could find was Porsche 911 Turbo with 5.0kg/kW. Add one of the 3.9 final drives to the 350z and it would be a killer sports car.

Also it's possible to remove the rear wipers, replacing hatch glass with lexan, removing electric motors from mirrors or even replacing the mirrors.

Disclaimer: some of this are guesses and the weights could be quiet off, if you find a wrong weight (or bad math for that matter), fix it up below.

 

[nizmo pete]

Are we building a track car or a every day road car that may get the odd track day.
For a road car the Z needs a lot more mumbo to be able to take it up to the remarkably good job Porsche has done with the new 997S.
The Z's stock suspension components are all light weight forged alloy with very good bushings. Rose jointing a suspension for road use is not a good idea, unless of cause if the original design was poor. But its not.
Pillow balls are also not a good idea on a double whishbone front end road car as they introduce to much NVH.
KY350
The 11" rears are needed to get that APS power to the road & with there ability to be run at a lower pressure the footprint would be even bigger.
Its not really practical to run bigger than 9" on the front and with a bit of tuning of it should be able to dial out a lot of the understeer.
Most of the worlds magazine road testers have given the Z thumbs up in the handling department in multi car tests. They seem to be a bit harsh on the ride component in single car testing. But it is this firm hard ride that is what makes the Z such a good handler.

 

[Nuff]

Peter, I'm just throwing numbers and ideas around. The only thing that I've done so far from that list is removed the spare and foam from the boot since I needed more space.

 

[davidm]

Are we building a track car or a every day road car that may get the odd track day.

I pressumed it was the later ie. 'every day road car that may get the odd track day'.

 

[nizmo pete]

[/quote]

I also assumed it was the later, therefore dont you think spending up to $20k to reduce weight by 50 to 60kgs is a bit over the top.
I,ll give you an example.
David you have been on the track a few times and probably have taken passengers on some of your laps. Now have you really noticed a big difference to the handling & lap times when carrying a passenger?
With an APS TT set up I bet you & your passengrs would feel a huge difference & I would also bet your lap times would lower noticibly