[333pg333]

Steve, ahh, ok. Understood. I think a little bit lower c/r will be a good thing overall. You can do all that stuff with Motec, but it sure ain't cheap. Lets just say that I don't imagine those Motec guys going hungry anytime soon. The new Link Extreme offers similar tuning capability so I hope to be able to take advantage of that for next season on the 3L motor.
Hey, can you post a link to your videos again. I seem to have misplaced it.

Craig, if you haven't seen Steve's videos then whatever indecision you may have between turbo and supercharging may be solved. It's a bloody quick car.
Having said that, I don't have a problem with turbo lag on the track. I'm not sure what numbers you're thinking of and what class cars you want to bring down, but even now with my bog standard internally 2.5L, I'm pulling on the quickest GT3s on the track at Wakefield and I think I can get to them at Eastern Creek too. You could comfortably do a 400whp turbo and not too far behind Cup Cars on some tracks. Here's a bit of video from the same day you were at Eastern Creek with us. The EVO in front is fully built, c/f body, 400+bhp. The Red car in front is a modded 996 GT2 so my little thing isn't doing too badly especially with some understeer. You'll notice that I was cheating by using the unapproved weight shifting device, hehehe....
http://www.youtube.com/watch?v=GNHjD3Da5RU

Seven30, not strictly true. Our gearboxes can handle pretty decent power. Plenty of 500+hp cars with 968 trannys and some 951 versions. The axles and CV joints are a different prospect. However there is a school of thought that having these as a possible weak link may not be a bad thing. Snapping an axle or CV cage is a lot cheaper than making alphabet soup with the tranny / LSD. In truth, for high power versions of these engines, the headgasket is the major stumbling block.

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[flash]

lol - beware of link - i'm guessing on who is selling you on that, and i'd never trust him on anything again - the shop i am using for the dyno tuning had a very similar experience with him - money spent with no completion

as for the tranny, there is a weak spot in the 1-2 synchro hub, but in a race car you don't use that much - in a street car, it would be a different story, and the power limit comes in much earlier

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[Seven30]

Not wanting to derail the discussion, I think the SC vs. Turbo discussion should take into account the more abrupt power delivery of a turbocharged engine when pushing the limits of the 968 design.

As you all know, the parts Patrick mentions are the ones that Porsche beefed up in the 968TS. And he is probably right in having the drive shafts be the weakest (and cheapest) link.

Please note that I wrote 500 torque as opposed to 500 horsies, with the former being my ultimate goal after the rest of the car is sorted [img]style_emoticons/<#EMO_DIR#>/smile.gif[/img] The driver can't handle much more power right now anyway [img]style_emoticons/<#EMO_DIR#>/laugh.gif[/img]

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[flash]

while a turbo would provide a less smooth transition running up the revs, the reality is that if you are pushing the car, and going through the gears, there isn't that much of a difference in the shock load on the box - abuse is abuse

all that being said, 500 torque on any centrifugal SC is pretty much a no-go, no matter which way you go

remember that boost of an SC is rpm dependent, and there is a ceiling to how fast it can spin - getting 500 ft/lbs would require not only dropping the compression way down, but also would require a very large unit, not likely to fit in the car, and would no longer be streetable, nor qualify in pretty much any race category, so you may have created something that can't be driven

do lots of homework on this one, and do lots of math

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[Seven30]

Thanks for the clarifications, I guess I need to look for a well reputed turbo engine builder for my ride then [img]style_emoticons/<#EMO_DIR#>/smile.gif[/img] Hopefully, I'll find one in some of the other threads here.

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[flash]

that all depends on what you want to do with the car - i think you would be hard pressed to use more than 350 ft/lbs or 400hp, even on a track, unless you were extremely competitive in the highest of classes

numbers are just numbers, and they can easily bring about more trouble than good - it's more about the curve, and where the power is that makes a car faster

like i said, think long and hard before diving into a VERY expensive project - anything with that kind of power can easily set you back $50k - there is a member here, who is doing a turbocharged engine, that has spent more than that, and it still isn't done

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[333pg333]

Well the Link itself isn't the problem. It's a good system used the world over.

The funny thing is that the hp / tq numbers we discuss in relation to our cars is <i>really</i> small compared to many other modified marques. Having said that, we are still able to keep up and / or beat many of these cars on the track. Sure, the uber modded ones are out of our immediate reach, but many a supposed 500hp car struggles to match us on the track. So going back to Bob's point, 350-400hp in our cars is going to be a big step up for virtually most people coming from an n/a motor. Also the t/c cars won't be as linear in response to an s/c, let alone n/a. Different driving styles are needed.

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[flash]

i hear about the link, but then i know somebody who called in the exclusive US distributor to tune an engine with it, and he could not do it - he is supposedly the "expert" but threw his hands up to the buyer and said "that's up to you" - this is the same clown that said he knew the motronic in and out, i paid $750 to come in and tune the sc kit, and the guy had no clue whatsoever where to begin - i told him to go home - i paid him nonetheless, but that was $750 down the toilet

i won't do anything that guy supports or sells, as i just don't believe anything he has to say

i wouldn't buy anything like that without full support anyway

bottom line, that unit sits on the shelf, nothing more than an expensive doorstop

big numbers are fine for chit chat, but this engine does not need the same numbers other ones do to provide the same level of performance - the car does a lot for you - i've driven some really high horsepowered cars, and this one is much easier to drive faster with less power

i plan to build a track car - it will be a fiberglass bodied speedster cab, with a full tube cage - weighing in at about 2200lbs, i plan to install a 3.2 liter supercharged engine with about 10 lbs boost - that will make about 375hp and about 350ft/lbs - i doubt very seriously that many cars will be able to keep up

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[333pg333]

I can't argue or agree with you. Separate occasions, separate stories. Guess he'd have his side too which I haven't heard either.

Nonetheless, not to derail your thread. I'd like to see that trackcar you propose. That would be something special.

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[Dubai944]

Anything over 300whp will make for a very quick 944/968 based track car. Set up properly they can easily keep up with most similar or slightly better power to weight cars regardless of age.

Patrick, some links are here:

First one is chasing down a 360whp Evo with 'only' 305whp (7lbs boost) (both cars were tested on the same dyno):



This one I posted previously cutting up traffic on the short track:




This one I also posted previously somewhere and is a good comparison between supercharged and nonsupercharged on the same track. The top frame is my car naturally aspirated with 210whp, bottom is with no other changes to the car except bolting on the original 4.5lbs supercharged setup which dynoed at about 275whp from memory.

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[333pg333]

Love them. We just need to organise you a better camera and location. [img]style_emoticons/<#EMO_DIR#>/smile.gif[/img]
The one with the Evo looks similar to mine chasing a 400whp one around Eastern Creek although your car looks stiffer and with more grip than mine. Loved the passing move under brakes.

Definitely puts supercharging on the table as far as I'm concerned.

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[craigawoodman]

Dubai944 - what was the drop in lap times N/A to S/C - given that everything else was the same and over what sort of lap distance/time.

What do you see as the biggest differences in the car's performance (i.e. traction with more HP, etc).

THe balance of the N/A car is bloody good (not too much power to enduce a throttle induced spin), etc. You can nearly bury your foot onto the throttle as soon as the car has the front wheels pointed where you want to go. With more power, I am thinking throttle modulation will be a much bigger part of driving on a track (along with more gear changing as the revs come quicker).

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[333pg333]

Well you can see how quickly Steve can get back on the power Craig, but that's also a stiff chassis with cage and some pretty decent KW suspension that has been setup / dialed in over time....oh, and slicks!

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[Dubai944]

Craig,

The extra power across the rev range makes a big difference. The thing I like most about the supercharger is it just makes the engine feel like a much bigger N/A, no lag or reduced throttle response that I have experienced with some turbo cars. With boost it also has the bonus of pulling much harder at the top end of the rev range whereas it previously would run out of steam a little. I am generally in the 5 to 7500rpm range most of the time and it pulls like a train (I do have modified cams and exhaust).

The short club circuit is 2.46km. (2nd and 3rd vid above) My lap times average 1.5 -2 seconds a lap quicker on that circuit which is really hard to achieve on that circuit. My best ever lap time on the club is 1:07.8 as opposed to a previous best N/A of 1:10.2
On the National circuit (first vid) my lap times are about 3.5 seconds quicker, and on the long Grand Prix track (5.4km) over 5 seconds a lap.

I have never had power traction problems unless I am really brutal on slow corners as I run a Guard Transmission 80/80 diff and sticky 305 Dunlop racing slicks.

Patrick the suspension is Moton, not KW!

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[333pg333]

Ahh, yes. I forgot you were on Motons. You still running 900/1100lb springs Steve? I've just shifted up to 800/900lb and like 'em so far.

Had David Wall take it for a spin the other day at Eastern Creek. For our O.S. friends, he's kind of equivalent to Patrick Long in the US. He couldn't fit into my car very well and this affected his driving but you can see how quickly he gets it up to speed. Talent and practice, talent and practice. [img]style_emoticons/<#EMO_DIR#>/wink.gif[/img]

http://www.vimeo.com/14636523

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[Seven30]

The amount of horsepower "needed" depends on the track and the car owner's ultimate goal with his car. The horsepower needed on a Mickey Mouse track is less than on the mighty Nordschleife.

If you have to obey by class rules that's one thing, if you need a daily driver that's another, and if all you care about is lowering your laptime outside of any class that's something else.

What I've learned from this tread, and thanks for sharing guys, is that getting a smooth running high powered 968 is quite a challenge.

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[FraMac]

I wonder if now is a good time to post about my supercharged 968 Clubsport <img src="/forum/images/smilies/968/blink.gif" class="smilie" alt="" /> <img src="/forum/images/smilies/968/cool.gif" class="smilie" alt="" /> <img src="/forum/images/smilies/968/laugh.gif" class="smilie" alt="" />

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[94SilverCab]

There is never a bad time to mpost about a 968CS S/C....<img src="/forum/images/smilies/968/rolleyes.gif" class="smilie" alt="" />



Regards,



Jay

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[flash]

absolutely - start a new thread about it though, so it gets the attention it deserves

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