JohnM

With regard to injector flow rate and fuel pressure, the flow will increase pretty much according to the square root of the increase in pressure across the injector - i.e., if the pressure across the injector goes up 50% the flow rate will go up about 22%. Generally the minimum linear pulse time for the injector will increase, which will hurt part throttle fuelling accuracy, and (particularly for high impedance injectors) you will soon reach a point where the injector will not open. Low impedance injectors will tolerate a much broader range of fuel pressures. The fuel pressure can also be lowered to bring an injector that flows too much at the usual rail pressure within a more useable range, again the square root factor applies, but the atomisation performance will deteriorate as pressure is reduced and the minimum linear pulse time will not improve proportionately.

P.S. TAG Electronic Systems did, at one time, offer a number of high and low impedance fuel injectors of various flow rates that were compatible with some of the Bosch mounting arrangements but with much improved linearity and atomisation performance, and for that matter they had high impedance versions of their (normally very low impedance) TSR2.1 motorsport injector, though neither are listed on their <a href="http://www.tagelectronics.co.uk" target="_blank">website</a> nowadays. They may still be able to offer them though, and their fuel systems test/calibration lab is about the best in the world (though mainly for those with very deep pockets looking for ultimate performance).

Bill S.

rmrmd1956,

Thanks so much for providing this performance reference data. You got me on the launch. If you normalize the two curves to adjust for your more aggressive launch, the cars are nearly the same.

Weight can make a small difference. I'm coming in at about 3500 with driver. The difference over 100 is most likely due to where you are in the engine torque curve at your shift points. For some reason, the Ruf may be in a higher torque curve for a longer time.

red9four4

any chance of you posting any pictures of these amazing cars??

red9four4

wow that CLK 60 is ausome <img border="0" alt="[cheers]" title="" src="graemlins/beerchug.gif" />

Bill S.

cjv,

The Turbo R uses a 5 bar fuel pressure regulator with the stock injectors. The ECU varies the duty-cycle of the injector waveform to provide the extra fuel. I think max boost is 1.1 bar. However, Ruf makes the best of the extra boost with special cam grinds, larger turbo housings (hot and cold), adaptive ECU fuel/air mapping and free-flow cats. Not really anything done to the intake other than a free-flow air filter (the 993 and 996 are limited by directing both sides into one intake manifold). On the track and street the car really shines in two ways: (1) very little turbo lag with small impellers and short tuned headers (almost feels normally aspirated) and (2) good use of engine torque between 60 and 120 MPH (most "street" and small track conditions).

Ruf's 550 HP version improves breathing with new heads, larger turbos and a re-mapped adaptive ECU. Titanium connecting rods reduce engine rotational mass to make up for the lag in the larger turbos. No performance numbers are provided for this upgrade.

I rode in Ruf's CTR2. Although the car pulled very strongly, it's large turbos (looked like K27s) had noticeable lag. With the lag, it would be hard to keep up with a newer Ruf on curvy mountains roads or at Willow Springs, even though it has good HP/TQ.

Bill S.

cjv,

You are correct. The R Turbo (996) uses the factory cam. The Turbo R (993) uses a special Ruf grind. I think either Ruf likes the 996 variocam, or is still working on an improvement. I don't know for sure. The Ruf Turbo R cam causes a bit of a rough idle, but has great midrange torque.

Ruf-Racer

Chad,
I think Weissach may be refering to conversons as opposed to true Ruf VIN cars?
Bill: Flew over to Las Vegas to pick up my Ruf after service @ Carl's Place and a great superbowl party! Drove the Ruf to Orange County after a fill up at the Rebel pump in LV! Drove 325 miles at average speed of 72 mph and 32.9 MPG! The drive & high octane does bring back the rumble at idle! Love it!
R <img border="0" alt="[cheers]" title="" src="graemlins/beerchug.gif" />

Deanger

Hey everyone, did you read that, CJV's daily driver is a Mercury Sable. It has a few, er, modifications.... couple hundred extra horsepower, machine guns for slower traffic, but other than that it is pure stock.

Bill S.

cjv,

Cams are tricky. The big guys have done a lot of work in this area to make a V6 (good MPG, low weight) perform like a V8 (good HP/TQ). For example, some use a Continuously Variable Valve Timing Control System (CVTCS) where the cam timing is continuously controlled by the ECU to provide optimal timing at all RPM. The controlling mechanism is quit ingenious, and uses a combination of hydraulics and electronic actuators to vary the cam timing. I was a bit disappointed when Porsche decided to go to a mechanical system, rather than a CVTCS. Probably a cost issue.

Roland,

Thanks for the feedback! It's funny how the Ruf cars grow on you. Being an engineer, I am so "****" about every detail. I have yet to find even the slightest fault in the Ruf car, not even a tiny "ping" when using poor gas at maximum boost. It's adaptive system is quit remarkable and gets great mileage. I hope to get an emissions check soon. I think it will do fine.

When I entered a show last year, several Porsche guys gathered around to ask what it was because of it's unusual idle sound. Otherwise it looks completely stock!

Bill S.

For the record, here's a 0-150 run (15.3 seconds) with a Ruf Turbo R with 91 octane and a soft 2500 RPM launch:

Start Speed 0.0mph
mph s g ft hp
10.0 0.84 0.57 5 34
20.0 1.64 0.62 23 74
30.0 2.16 0.95 42 171
40.0 2.97 0.42 85 106
50.0 3.68 0.70 132 217
60.0 4.31 0.69 183 262
70.0 5.39 0.37 287 181
80.0 6.23 0.57 380 310
90.0 7.10 0.48 489 311
100.0 8.43 0.42 674 321
110.0 9.47 0.41 835 358
120.0 10.60 0.39 1026 395
130.0 12.40 0.21 1360 319
140.0 13.79 0.31 1635 449
150.0 15.30 0.30 1957 494

Pk Power: 150.0mph 15.30s 1957ft 494hp
Peak G: 33.0mph 2.30s 48ft 0.96g

----------------------------------------

Deanger

</font><blockquote><font size="1" face="Verdana,Tahoma,Arial,Helvetica,Geneva">quote:</font><hr /><font size="2" face="Verdana,Tahoma,Arial,Helvetica,Geneva">Originally posted by cjv:
<strong>Deanger,

I can see the forums now, "Mercury Sable beats Porsche GT2." <img border="0" alt="[burnout]" title="" src="graemlins/burnout.gif" />

<img border="0" alt="[hiha]" title="" src="graemlins/roflmao.gif" />

</strong></font><hr /></blockquote><font size="2" face="Verdana,Tahoma,Arial,Helvetica,Geneva">Careful, this is how threads turn ugly (see stage XXX)
<img border="0" alt="[ouch]" title="" src="graemlins/c.gif" />

Bill S.

AP-22 0-150 MPH .cap file for above run:

<a href="http://209.216.20.70/0_150.cap" target="_blank">0 to 150 MPH AP-22 .cap file</a>

Geoffrey

Ahhh, but the sable really has a Porsche twin turbo V8 engine engine in it

Ruf-Racer

WOW! Performance beyond belief! Congratulations. Please get a large fuel cell as well and we are good to go in Nevada!

R

Duane in Miami

Great news Chad. <img border="0" alt="[jumper]" title="" src="graemlins/jumper.gif" /> <img border="0" alt="[jumper]" title="" src="graemlins/jumper.gif" /> <img border="0" alt="[jumper]" title="" src="graemlins/jumper.gif" /> Is the additional HP coming from the intake? <img border="0" alt="[jumper]" title="" src="graemlins/jumper.gif" /> <img border="0" alt="[jumper]" title="" src="graemlins/jumper.gif" />