The dyno sheets of Ian's engine seem to no longer be listed on the J&S website....they can be found here:

http://bbs.scoobynet.com/showpost.ph...98&postcount=4

 

Found Steve Wong's site to be a great source of information on the subject, if only I looked into this earlier:

http://www.911chips.com/ignition.htm

The full load Porsche ignition maps listed (especially 964RS) should give you a good reference point to compare your current ignition map against. This is what produces the graphs during full power runs on the dyno....everything at lower loads is just there for driveability/economy ;-)

In other words are you running 19degrees advance between 6 - 6.5K revs under full load (pedal to the metal)??? If so you are running with the same maximum power output a RS ignition map would produce. That is not to say that the RS map can not be further improved upon....

When running significantly below RS advance this would be an indication that with careful tuning more power can be had. If you are already at RS levels I'd thread with caution.

The above literally takes only 1 minute to check in your current map table.

BTW I'm surprised at what little advance our twin plug engines run at...

 

evoderby,

Thanks for the links. They are very informative. Really appreciate your insight on the subject. Once the car has finished some extra work being done over the next few weeks I will drive it and then visit the tuner armed with this extra knowledge. Not being a Porsche specific tuner they may well have not optimised the ignition map as far as they could have. I like the idea of teh aftermarket knock sensor to, so will look into that further. The tuners view was that at 1.1 TCF around 310 bhp was possible form teh engine with more agressive tuning, so we will see if a final round of tuning can find those extra Horses. Id be quite happy with similar to 1994 993 (3.8l) Carrera Cup car output of 308 bhp and 272 lbft torque as a headline figure assuming no compromises on driveability. I really dont think we will get that much more for the engine. the rest is down to Dyno set up and TCF translation I suspect.

Interestingly I had Steve Wong build me two chips based on AFR data from the dyno. The difference between the first and second chip with optomised AFRs was marginal (1-2hp) on WOT. Probably within the margin of error for two different day Dyno runs on same equipment with same operator (fuel differences, ambient temp differences etc). The LINK ECU is definately finding more power from the engine especially the area under the increase curves which is much fatter, but I guess the new injectors will also have helped.

Ill keep everyone informed on my other thread and hand this one back to Camlob :-)

Cheers

 

Evoderby - Sounds like good stuff. I am talking with Richard C. and my tuner to see if it is compatible with the tec3r. But we noticed, the engine plateau's at a certain point where no hp is gained despite advancing. So my tuner does not get over aggressive where we go to the point of hearing knocking, then reducing timing.

But we will look into it. Tks

 

Evoderby - Just found out that the tec3r comes with a knock control system that can use the stock knock sensors. Ill check with my mechanic if its so.

 

Hi Camlob,

By the sound of it your tuner has indeed already been tuning the ignition on the Minimal advance Best Torque methodology:

"But we noticed, the engine plateau's at a certain point where no hp is gained despite advancing"

Having the knock sensors in place on the Tec3 seems like a good safety feature! One thing to keep in mind is that a knock sensor is basically 'just' a microphone that doesn't only pickup 'knock' but all kinds of 'noise*' in a certain spectrum. This means the Ecu needs to be carefully calibrated to recognise when noise is in fact knock and intervention is called for.

*noise: valve train, piston slap, controlled combustion, knock....

This goes as far that installing different engine mounts or a roll cage into an otherwise standard car can alter the noise characteristics in such a way that the OEM ecu / knock sensor is no longer correctly calibrated.

Also keep in mind that most ecu embedded knock controls are not as advanced as the J&S control. They offer great safety when calibrated correctly, but often have a protocol of retarding a fixed amount of timing on ALL cilinders (say 6 degrees) when knock is detected, and a further fixed amount of timing (say 4 degrees) if afterwards there is still knock. (Modern Bosch units do feature adaptive knock control which brings advance back to the brink of knock, the most advanced is Saab's ion sensing knock control which works on a completely different methodology)

This (unadaptive control) as said is safe but costs huge amounts of power. The J&S is able to calculate which cilinder is knocking and only retards that single cilinder and only with the minimal amount of timing necessary to counter knock. This is a good reason why Ian Whitside's F3 engine was able to gain 8% in power with the J&S fitted.....

Anyway...how's the rebuild coming along?

 

Sorry it has taken a while to find the data from the car you mentioned, but I think these are the dyno sheets from the 9m Motec conversion that you referred to. The car is a yellow 964 Carrera 2 race car that had been fitted with a standard 993 Varioram engine, bought by a French customer who had driven a 9m converted 911SC race car fitted with a 993NVR engine on Motec. Said customer preferred the power and torque delivery of the NVR motor so he had us do the same to his new car, hence the VR came off and a set of NVR manifolds fitted. The engine was stock with 993 silencers and X pipes (no cats).

I've converted the files to SAE power rather than my usual DIN standards. The peak numbers from the graphs are:
Varioram Motronic: RWHP 219bhp, FWHP 268bhp, FWT 369Nm (green)
Non Varioram 9m Motec: RWHP 255bhp, FWHP 322bhp, FWT 404Nm (blue)

During the initial dyno mapping of the Motec we hit a problem as the engine suddenly failed to deliver the expected performance, eventually traced to a failed coil, so just for interect the third graph is the NVR engine with 9m Motec but running with one coil down:

NVR 9m Motec, 1 coil: RWHP 238bhp, FWHP 309bhp, FWT386Nm (red)

The conclusion to make with any dyno testing is that if you want meaningful comparisons you can only use the results from the same dyno under the same test conditions (i.e. corrected to either SAE or DIN standards).

For the record, here are the DIN numbers (which I normally quote):

VR Motronic: 225bhp/275bhp/380Nm
NVR 9m Motec 1 Coil: 244bhp/318bhp/397Nm
NVR 9m Motec: 263bhp/333bhp/417Nm

Hope this fully answers your questions??

 

Thanks for asking these questions Harald.

Unfortunately the DIN to SAE conversion is not a linear relationship, you have to calculate the factor for the ambient (intake) temperature and pressure on the day you run the tests. Whilst I do have the conversion formulae written down somewhere, I normally just use the inbuilt correction factor calculator of the dyno software to change between DIN & SAE, so the numbers that I have given were calculated by the software using the inbuilt weather station records of the ambient conditions on the days I tested the engine.

That said, even allowing for correction factors, all aircooled engines make more power on a cold day to a hot day due to improved cylinder head cooling. There's no doubt about this, I've proved it to myself on every car I've dyno'd and is why I often do evening sessions in the summer months when a car needs to be optimised for colder temperatures.



The transmission loss difference is simply due to the peak rear wheel HP point and the peak engine HP point occuring at different RPM/wheel speed, so you cannot directly compare the relationship between the two numbers I have provided as the wheel losses are different at each point. For reference, at 5940rpm the 9m Motec NVR with new coils made 255.6rwhp with 63.3hp rolling losses for 318.9fwhp, hence losses are approximately 20%. As you rightly say, losses vary significantly due to tyres, temperatures & wheel geometry, so where this car had 20% losses others have recorded less than 15%. Again, it is down to the dyno operator to ensure that he keeps as many test factors as constant as possible when testing to get meaningful results....

Hope this covers it?

 

Hi Colin,

I was wondering if you could please provide more details on this set-up of your client. Specifically, how successful is it in reducing the engine noise? Does he have a street muffler on the car (is a street muffler with ITBs possible)? Does it hinder performance?

Also, with regards to street behaviour for ITBs, are there any reasons to believe that a 993 on ITBs would be less streetable than the older M3, which came with ITBs from the factory?

Thanks in advance!

 

Camlob- What is the source of the fuel pressure regulator used?

 

Unfortunately I have not had the chance to experience or test the effect of the airbox modification on the ITB car, however from experience I would say that it would not affect performance. The reason it was fitted is because he lives local to Goodwood circuit who are particularly hot on drive-by noise limits, at full chat the induction roar from the ITB with foam filters was tripping the meter at one point on the circuit. With the new set up he can now drive flat-out everywhere.

Streetability of an ITB's is all down to how well they are made & adjusted, how well they stay in sync (left to right and along each bank) and how well the engine has been mapped. A well made system, correctly set up should be easily as good as a factory car with plenums.

 

Only ever use a non-adjustable Bosch FPR as it eliminates the possibility of someone screwing around with the system.

We can supply a billet adapter for the stock 993 FPR which makes it a direct fit on the end of the fuel rail. The stock 3.8 bar regulator is fine for most applications up to 400hp, over that you may want to consider a 4.0 bar or 5.0 bar version.

 

Excellent Colin, thanks very much!

I didn't realise that although SAE to DIN is listed as linear relationship (1.0139), the correction factor used in dyno measuring due to varying ambient temperatures and air pressures is in fact different in SAE and DIN.

In the possible interest of others reading:

*SAE uses 25C and 990 millibar as a zero correction base

*DIN uses 20C and 1013.25 millibar as a zero correction base

On a 30C / 1000mb day an uncorrected 250 DIN RWHP as actually measured on the rollers would be corrected into 260.

Had the rollers be scaled to read SAE HP than 247 RWHP would be measured uncorrected, which would be corrected downwards into 246.


The respective formulas are:

* SAE CF = 1.18 [ (990 / air pressure mb) x ((temp C + 273)/298)^0.5 ]-0.18

* DIN CF = (1013.25 / air pressure mb) x ((temp C + 273)/293)

 

Hi Guys,

Without labouring too much further on the dyno TCFs mentioned in this thread, I took the opportunity to send this thread to my Dyno Operator. Hes a man of few words having spent the last 12 years using iterations of the Dynapak hub dyno only - but has seen many clients results using roller type chassis dynos in the past.

Obviously my concern was focused around finding the optimal amount of performance from my own engine. He declined to make any guesses as to what may be left on the table other than to comment that they had advanced iginition to the point they were happy with and could supply LINK data on iginition maps when I visit them.

In relation to the above thread their views were that Colins comments regarding the in ability to compare results between two dynos and operators were spot on. In effect stating it was a comparitive tool only. Their experience with the Dynapak 4000/5000 is that RW figures will be in the range of 3-5% more generous than a "typical" roller style dyno in a similar test environment. If you apply this logic it would appear the results we obtained are in close correlation to what Colin obtianed on a similar specification engine. Talking RW numbers does reduce speculation but they were at pains to state is was still conjecture non the less. They still stand by the 10% (or 1.1 mark up) as the most realistic/conservative TCF for their dyno in their experience. They sent me the 1.1 charts and g-force in gear charts I will post later when I can figure out how to make them smaller to upload.

Non the less well give it one last session to optimise iginition and performance once the car is back from the work its having done on it (and the 3 week wait for the new rear window which decided to explode when the rear demister was used on a cold morning outside the dyno room!). I guess the proof will be in driving the new set up....

Cheers

 

Who made the unit in the red square below?