The Beast Lives Part IV

[okellyt]

Having fitted the K&N induction system, some time ago and then upgrading the filter to a BMC one. I thought I'd take the beast back down to Parr and see if its made any difference to the power & torque outputs.

Wandered down there this morning - did a comparative test to last time i was down there:

+23.2 PS

+16.2 NM torque

Their view was that on the open road with the better induction and the ram effect of the aero kit air intake I'd get another 20hp

Adjusting the figures to a like for like comparison to manufactures claims (about 12.5% loss in car versus figures with the engine on a dyno) this gives the beast approx 440hp and 500nm torque.

This seems ever so slightly obscene, especially as peak torque arrives at about 3800rpm, for a normally aspirated car thats pretty good

This matches the relative difference of the beast with x51 kit, intake etc but with the Milltek exhaust with the revo turned off was approx 53 hp down on the current reading. Given a manufacturers claim of 381bhp plus a few for the exhaust we're back to a manufactures equivalent of approx 440 hp

More conservatively its 411.5hp on the road, which doesn't sound much until you apply the same losses to a stock C2S which will typically get around 310 - 330.

The engineer was very impressed with the overall figures especially the torque.

I now just have to improve my speed through the corners[]

 

[stevehoenes]

Hi Tom

Sounds like you have managed to get some pretty good gains in power & torque. What with the increased stopping power, you should be able to get your machine to fly through the corners.

To get going quicker through the corners, I think your next step would be to do a couple of driver handling courses. I quite fancy this myself because I am sure that its not just about power or geometry although this clearly plays a major part of it, its also about setting the car up right and doing all the right things as one goes through the bends, (including squeezing your cheeks together). I believe that doing an advanced course would give you (and me) more confidence to carry more power through the corner, and more importantly, how to deal with the car if you over cook it!!!

Not sure if anybody else is up for this or has done any, bit I would like to find out more about doing one, so is anyone else out there interested?

I have just bitten the bullet and agreed to exchange my car for a gen 2 C4S with PDK so looking forward to getting my hands on this for a while. The car is nine months old but is fully loaded with extras, although non of them sadly relate to improving performance. apart from the PDK and sport chrono pack plus!

Steve

 

[garyw]

ORIGINAL: stevehoenes
I have just bitten the bullet and agreed to exchange my car for a gen 2 C4S with PDK so looking forward to getting my hands on this for a while.

[] It was only a puncture!!! I knew you were going on about updating, but you've even surprised me []

 

[okellyt]

Steve

Fully agree with your comments on the driver training. Although I have not done one so far this year, I normally do at least 1 a year.

Mirroring the training courses I have found I am actually quite quick on the slow corners as I spent a lot of time on the low grip training. I am reasonably comfortable with it wagging its tail at low speeds.

Whats clear to me as you stated, is with the high speed corners I have not spent much time and know the car can go quicker but not by how much and when to push it. All these things probably scrub between 5 -15 mph out of some of the corners, needing more power on the straights to compensate. This was exaggerated on the track day as it was the first time I was on track on my own with a 911, so add in the higher grip surfaces, bigger run offs allowing a wider margin for error - others were pushing much harder than I was.

Steve - you'll also find the 4wd gives much higher grip through the corners and its a fairly forgiving system so easier to avoid a big moment. Having driven both 4wd and 2wd, as an average driver I find the 4wd gives me more confidence and more grip/control.

On the Reading drive out I had the beast sliding a bit out of corners following Alex. His car and the C4S behind me were quite stable but the following driver pointed out to me a few occasions where my car had reached its grip limits before he had.

Steve - Congrats on your new car, given our booze filled conversation on the Saturday evening at Llandow I can't say it ws a surprise. You'll love the PDK and 4WD, everyone's going to have to look over their shoulders on the road now with you about that car[]

On the driver training front - I'd definitely be up for a day training if there is a group of people up for it. Gary did highlight one another member was organizing a while ago - other commitments stopped me then but I am sure a couple of regular posters have information they could share on this type of thing.

Any ideas, suggestions?

 

[stevehoenes]

Gary

Yep, quite an expensive puncture in the end!! I have even surprised myself

Tom, Thanks for that, I hope the 4WD will stop the back end skipping out when pushing hard on the narrow roads. Not sure on the breacon road if my puncture was a result of me being to close to the edge of the road or if it was the car skipping over as I was pushing hard after Gary, (No suprise there then). I am a sedate driver on the road under normal conditions so you have nothing to worry about. I am not a technically proficient driver and my only hope is that whilst there is bound to be loads more grip on the 4wd, the C2S just feels such a lively car that is thoroughly enjoyable to drive. I do not think that I have pushed my old car to the limits but its been really enjoyable getting used to what the car, & ultimately what I am able to go to. I look forward to doing a couple more track days in the new car.

Out of the driver course's you have done, was there a one to one driver handling which showed how to get in to and control power slides, apart from the Millbrook one? I would like to get on a course that teaches on the limit handling so that I can really learn the cars capabilities. Its not that one wants to drive like that but great to be in control, if you know what I mean.

I will do a bit of research on the driver training but if anyone has any knowledge on course it would be much appreciated. I know that Porsche do one but its quite expensive, so I will let you know what I find

Have prepped my old car now ready for handover and I hope that all goes well tomorrow, will give you an update in the week, maybe with some pics

Steve

 

[garyw]

I orgasnised a training day at Prodrive a few years back, they have a basalt tarmac section for powerslides and testing, I hear they also now have a circular skid pan.. I learned a lot on the day about skids etc but thought the handling course was a bit small- but I had been to Millbrook in the same month!
I can look into this for the new year as its not so much weather Dependant if there is the interest.

Good luck with the handover Steve, you've certainly acted quickly on that one [] I look forward to seeing the pictures...

garyw

 

[okellyt]

MIRA is very good

They used to do the Porsche courses there

They have numerous low grip areas

A straight with 3 surfaces;
High Grip with or without water
Freshly fallen snow
Ice

Basically they use stone that when wet has the same grip co-efficient as these conditions

The configurations include a straight with 100m of each stone side by side
A small circle with lower grip surfaces the closer you get to the center
A long curve that has these surfaces right in the middle

So you get a chance to develop skills like porpoising, recovering slides and driving in circles holding the slide as long as you can.

There is also a dunlop handling track (high grip surface), like llandow short and lots of curves and corners

And finally a long circumference circuit rather like a curvy triangle but with rounded ends ie Curves at the corners.

 

[Wills]

ORIGINAL: okellyt

Having fitted the K&N induction system, some time ago and then upgrading the filter to a BMC one. I thought I'd take the beast back down to Parr and see if its made any difference to the power & torque outputs.

Wandered down there this morning - did a comparative test to last time i was down there:

+23.2 PS

+16.2 NM torque

Their view was that on the open road with the better induction and the ram effect of the aero kit air intake I'd get another 20hp

Adjusting the figures to a like for like comparison to manufactures claims (about 12.5% loss in car versus figures with the engine on a dyno) this gives the beast approx 440hp and 500nm torque.

This seems ever so slightly obscene, especially as peak torque arrives at about 3800rpm, for a normally aspirated car thats pretty good

This matches the relative difference of the beast with x51 kit, intake etc but with the Milltek exhaust with the revo turned off was approx 53 hp down on the current reading. Given a manufacturers claim of 381bhp plus a few for the exhaust we're back to a manufactures equivalent of approx 440 hp

More conservatively its 411.5hp on the road, which doesn't sound much until you apply the same losses to a stock C2S which will typically get around 310 - 330.

The engineer was very impressed with the overall figures especially the torque.

I now just have to improve my speed through the corners[]

Hi Tom,

Are you actually saying your car was dynoed producing 440bhp at the fly wheel? that's an enormous gain for a NA engine over stock and would mean the standard engine is very constricted from the factory.

Not disputing your numbers you understand just interested as you've added 90bhp and that usually takes a turbo or supercharger a RUF R conversion of a 997 only boasts 435bhp and has a supercharger.....

 

[okellyt]

Wills

Nope, I am not saying it dyno'd 440hp at the fly wheel.

My apologies if that was not clear from the note - I was indicating that if you wanted to compare the figures with manufacturers claims you have to factor in losses.

The guide is about 12.5 - 15 %. So for a stock C2S, if you dyno it you might get less than 310hp for a claimed 355hp.

When manufacturers assess engine power they do so with the engine on a bench in a large controlled temperature room with no exhausts, throttle bodies or similar. This means no air intake restrictions or emissions issues, impact of temperature on power figures and lower frictional issues as the flywheel isn't attached to anything.

What that means is put your car with engine in place on a rolling road or dynometer and you are likely to get a much lower reading than the manufacturers claims.

My car is an X51, not standard C2S, so the manufacturers claim is at least 381bhp (385hp). The relative increases from dynoing it at different stages is approx 53 hp at the flywheel.

So in that case you are correct the car was being starved of air.

Part of the improvements on my car are with the air intake, positioning of the fan and scoops to force colder air into the engine bay at speed. This obviously is not a factor when the car is sat in a small dyno room where they have a fan which can recreate about 10 -1 5 mph speeds. So even then the figures I got were below the actual on road flywheel power.

So the race engineer estimated flywheel power on the road (with the benefit of air flow) as 411.5hp. We got slightly shy of 400hp on the dyno and 369 lbft torque. I could tweak to get the power up a bit but the torque would then drop off.

To allow a like for like comparison with manufacturers claims Add 12.5% to the lowest figure I got (which co-incidentally is close to adding power gains to the manufacturer claimed engine power). Thats where the "approx 440" came in.

I am now at the point that without further drastic changes there is little more power I can eek out of the car. The x51 conversion changes quite a chunk of the engine so the remaining options are really a larger bore (4L conversion), fitting an inter cooler and or supercharger/turbo.

So if you look at RUF, if they are taking a stock C2S typically with 310 - 320 hp on a dyno. Then getting 435 is over twice what I got with my changes. And still a margin higher than my car. If they got the same increase on a X51 car they would be claiming 465 hp. So even if RUF got those figures with the engine out on a bench the increases are still a lot more than I have got.

 

[Wills]

Thanks Tom,

That was interesting, yes I gathered you had the power kit...I'm thinking of adding the powerkit to my genII (381bhp) I think that gets it to 404bhp (ish) so was interested in what you'd got from the dyno with your extra bits and pieces...

I relation to the power drop from the bench tested engine and one dynoed on a rolling road I had my E46 and E92 M3's tested on a dyno dynamics machine (apparently a very expensive and reliable piece of kit) and they both produced figures close to the manufacturers claims i.e 335 (338) and 415 (414) respectively. (figures quoted at the flywheel)

The only dramatic drop I have heard of in stated power is when comparing RWP with FWP due to drive train losses, typically these values vary from 12%-20% depending on the efficency of the drive train and it's generally greater the more wheels that have drive i.e Audi's suffer from alot of drive train losse due to the 4 wheel drive.

I will be dynoing my car soon as its done 3500 miles now, I'll post up the results however I will be very surprised if it's not within +/-10 bhp of the manufacturers claim of FWP.

Naturally the RWP would be in the region of 325-335bhp

Cheers....

Neil

 

[okellyt]

From EVOMS in US - So worse fuel which would drop power but you can see the C2 S dyno's 303 hp. But Porsche USA still claimed 355hp for the car. I believe they "measure" flywheel power but use a conservative algorithm.

The trick with all these things is the Algorithm, They all measure power at the wheel and use a formula to calculate the likely power output at the flywheel and correct for losses. Unless you plug the kit direct into the dyno i.e. Take the engine out and dyno it on its own. The formula is subject to variations and each dyno will produce their own figures and variations.

The thing I have learned over the last few months from talking to race engineers and people who build engines, is to be a bit cynical about the whole power claim thing - The relative changes for enhancements to your car are what matter more than the absolute figure you get. The Fly wheel figures are extrapolated so subject to a range of views and formulas as to whats going on. So there is a bit of black magic about it. So its very easy for some one to correct a figure if there was a pre expectation of the results

I went to a couple of dyno's and got a fair variation in results. the guys I continued to use were the most pessimistic on numbers but know their Porsche's and gave me great advice on tuning the car. I went down the road from me and immediately got a 10hp higher reading but they don't know the cars, so I wasn't confident that I'd get accurate and consistent results when checking the impact of changes on my car. Hence my rather light hearted approach to extrapolated figures I could get for mine[8D]. The only thing I can be confident about is the relative power increases I got out of this journey and the fact its now a real beast on the road for a cooking model car.

I guess with all these things you pays your money and take your chock ice's[]

 

[Wills]

Agreed its all very subjective and I've heard there are plenty of people giving iffy dyno numbers in order to sell kit...I should have bought a Turbo thats easy to tune!

Cheers....

 

[okellyt]

ORIGINAL: Wills

I should have bought a Turbo thats easy to tune!

Cheers.... 

Neil

You've hit the nail on the head. I keep saying that to myself

 

[Wills]

Next time! []