The Beast Lives Part 3

[okellyt]

Just a quick update on the beast

Went to Parr today to put the beast on their dyno. I then spent some time with their race engineer who also does the dyno.

In terms of getting a real power figure I have been foiled - they couldn't get enough air into the beast - its an enclosed room with a fan but mine has 2 intakes, so one was not getting any air and the engineer indicated the other intake wasn't getting enough air. So he wasn't happy with the figures he got.

However we did get a proper torque figure (much lower revs) - peak is approx 430Nm at just over 3000 rpm. So 10nm up on the theoretical power kit value but at 1500 rpm lower. It pretty much stays above 400Nm (with some peaks and troughs) through to 7000 rpm.

The engineer was very impressed with this as a real in car measurement (torque did fall off a bit at higher rev's in line with the engine breathing problem). So given most quoted figures are before you put the engine in the car, where lots of losses kick in thats a fairly serious figure for a normally aspirated car (for a like for like with manufacturers figures, you need to allow for an approx 12.5% loss ie 488 NM, best guesstimate for adjusted power is around 409+ bhp).

However on looking further at the car - the engineer indicated that with the new set up the engine couldn't get enough air in to generate its proper potential. The exhaust and remap generate the high torque - with low back pressure it was pulling gasses through very efficiently - more efficiently than the car to get air in..........

The flashy carbon air intake box from the x51 kit seems to be the problem, which is highly ironic. It gets very hot and holds the heat too efficiently (the ambient temp in the box was higher than the engine bay) so the air going in gets hotter, expands and a) messes up the air flow, reducing air into the engine and b) the hot air expands is less dense and therefore the engine get less air, so a double whammy.

The engineer indicated they had had similar problems with their cup cars and in order to improve the breathing and power they resorted to a more direct link from intakes to engine. He drew for me what he thought would improve matters and the guy's then had a dig around to find something similar. It looks like the nearest (non home made) solution is the EVOMS air intake.

If this does what is intended its will reduce slightly the peak torque but also shrink the variation over the rev range and keep the torque higher towards the top end revs - this will also result in an increased power figure ie provide more consistency in torque and power curve (acceleration) across the range.

If anyone has any experience with an EVOMS intake please drop me a note with what you have found.

Will let you know how I ge ton with the EVOM's in the next week or so when it gets fitted.

 

[Faz]

Tom, that's interesting, our cars are very similar on power although mine's not X51. As discussed earlier mine has EVOMS V Flow and GT3 aerokit and the rear deck lid has quite large air scoops which must be helping. See what difference the V Flow makes but then consider a GT3 rear deck (although you are meant to fit in conjunction with GT3 front end, otherwise front goes light at speed). I'd have thought you'd get close to 420 bhp with your set up, so considering our cars are some 150 kg lighter than 997tt you should leave them for dead on track. []

 

[okellyt]

Faz

thanks for the note - I have definitely thought about buying the aerokit, to get more air in as well as the fact it looks the cannine's appendages.

Yep in theory the car should have at least 420bhp and possibly does when under way and there is plenty of airflow. 409hp was a conservative estimate based on what they got in the dyno - the engineer did point out the car was being starved of air and was not producing anything like its real power potential. It was still giving readings about 50-60bhp up on a stock C2S

As I put earlier the flashy Carbon x51 box seems to be its own worst enemy with a higher ambient temp in the box than in the engine bay - hence we're trying the EVOM's, the engineer (who does the Parr Carerra cup cars) felt this should make a significant improvement in top end power and torque[]

So I think your right - EVOMS and a better air flow body kit should give it some real teeth, however as it already goes almost as quick as a GT3 but has much smaller brakes, I'd best also look at them or with all the extra umph I won't be able to stop. [&:]

 

[okellyt]

Just thought I'd give a quick update on the Beast

Some more changes

Seeing the post about brakes the other day and hitting 24k miles - I thought I'd check them. Front 2 were pretty much shot, rear 2 almost on their last legs.

So I though it was time to changes the brakes

Fitted the 997.1 GT3 brakes - 350mm Front with 6 pot calipers and 340mm rears with 4 pot calipers. Also fitted the EBC Yellow Brake Pads.

Those helpful people at Porscheshop also came up with a possible remedy for the air intake issue - swapping out the carbon in take box for a K&N Intake.

So I toddled off to Halesowen last Thursday to get these new bits fitted.

We had a good look at the bespoke air holes in the x51 boot lid and discovered that the rubber fittings were huge and talking them out, we could put a standard 996/997 rubber intake in. So that ran into a standard K&N pipe to the air filter. The filter we positioned just under the engine bay fan, making sure that we maximized any air flow over the filter. The 2nd hole we removed the rubber and left open to aid general airflow into the engine bay and cooling

The Results

Just happened to be off with the better half to see her parents in Cheshire on Thur evening and then dropping over to Yorkshire for a long weekend on the Friday. Perfect way to bed in the new brakes and try out the changes

The brakes - are hugely confidence inspiring - I haven't really braked hard at all yet but even under fairly light pressure they pull the car up very consistently and very firmly. There were a couple of times braking gently from 70[8|] to junctions I nearly needed up stopping quite a way short. Great feel huge reserves of stopping power even with some pretty enthusiastic driving

The Intake - first and most overriding impression; - the noise, its stunning. gone is the reedy sound at higher revs.This thing really barks[] From about 3k (variaocam change over) it starts to emit a very pleasing growly gurgle.

The power - noticeably more, I took a while getting used to it but my Wife said she noticed it had far more grunt and acceleration from the first time I put my foot down. For me it was harder to spot as I was not familiar with the roads and bedding in the brakes I was concentrating on lots of other things as well.

There has been a change in some of the character of the car. as the Parr engineer indicated, getting more air in takes a bit of the edge off the initial torque but fills it out more over the range.

So initially at 3k revs where previously it started pulling very hard, its merely brisk - Now it kicks very hard from about 3.5k and keeps pulling harder and harder round the rev range. even after extended driving. Where previously when the engine had been warm for some time how hard the engine pulled would drop off at high revs.

The more I drove the car over the weekend the more I noticed the extra grunt. Both the better half and I think its created a least as much extra grunt as the previous change (Revo stage 2 and Miltek exhaust).

A couple of the mechanics at the garage guesstimated that I should see approx another 30bhp (basically halfway between the claimed dyno gains for the 996 and the 997GT3). The previous upgrade got me around 22bhp so this seems about right based on how the car feels.

As a by product by removing the restrictive rubber around the engine bay intakes the engine temp was slightly lower even under reasonably enthusiastic use

In terms of getting more air into the engine the only thing now I can sensibly do is get the Aerokit for the C2S, it will also give it better grip through faster corners.... hmmm......

 

[YvesD]

Tom,

Reading your latest expolits is just making me miss mine even more.

Does anyone know where it is ? I'd like to buy it back !!

Yves

 

[garyw]

Good call on the Brakes Tom [8D]

garyw

 

[okellyt]

Gary

It definately needed them, the standard brakes were struggling to cope before the latest power upgrade.[:-]

 

[tscaptain]

I can see the fun in all these upgrades, Tom, but did you consider just buying a GT3 in the first place?[]

 

[okellyt]

Yep

Was vetoed by the financial controller - on the premise it looked too much like a mid life crisis and one of my other siblings already has one so I had to have something different.

While now its pretty similar in terms of outright performance, brakes etc it is actually quite a different beast. This is still a fast road going car, not to upset GT3 owners who will point out that it is now really easy to live with everyday, the point remains that the GT3 is a track day car thats good to drive on the roads; mine is a fast road car with some of the compromises removed so it can be nearer to what it should have been.

It's a subtle distinction but its make quite a difference when you drive them.

I probably should have got a turbo but it seemed like an awful lot of money when we were looking (once specced another £30k+ on this car). Although the turbo is undoubtedly much faster point to point it also lacks the noise and the feel - the latter does slow me down, I am probably better suited to a turbo in driving style, but its more fun at lower speeds

I now have something that is much more personal and some what rarer than a standard car, thats quicker than it looks (even with the aero kt if I get it) and has its own character.

 

[Geoff_Fields]

Fitted the 997.1 GT3 brakes - 380mm Front with 6 pot calipers and 350mm rears with 4 pot calipers. Also fitted the EBC Yellow Brake Pads.

Having upgraded my brakes in a similar way a couple of years ago this raised a few questions.
Firstly 997.1 GT3 front rotors are 350mm steel or 380mm ceramic. I found that the GT3 rotors had a different bell/top hat offest to the 997S. This would have meant the discs would not have been centralised in the calipers. In fact the caliper pegs would foul the rotor unless machined/bodged. So 997T 350mm discs had to be substituted, which were of the correct offset.
Could you advise exactly what discs you are using, including part numbers if possible. Also have you added spacers to the rear calipers to move them out 10mm to clear the new larger discs?
Because of excessive surface cracking experienced on the front discs I am currently looking at alternatives such as Alcon and Cargraphic products. One of my considerations is that I would prefer to keep to 350mm fronts, which still allows a space saver wheel to fit! I don't trust that awful foam stuff.

 

[okellyt]

Geoff

Sent you an email

Good questions to which i don't know all the answers.

 

[okellyt]

A quick update

Got out this morning for a run on my ususal route before the rain came. No passengers, half a tank of fuel which is how I normally compare changes

Noticably quicker with notcably more shove at the top end of the rev range, acceleration in 3rd from 3.5k revs is bordering on brutal.

There is a little run - a very narrow old bridge on a 30 limit running into a short national speed limit on a smooth right hand curve switiching to left hand curve then into a bit of a shallow corner and short straight to a 30.

I normally sit at 30mph in 3rd until the national limit sign and floor it, measuting which point I hit my target speed - With Powerkit only it was just before the shallow corner. With Remap and Miltek it was about half way down the left hand curve before it. Now its at the end of the first right hand curve[]