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Ruf CTR and BTR Dyno Results

Old 11-13-2017, 07:09 PM
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Join Date: Jun 2010
Location: Calgary Canada
Posts: 113
Default Ruf CTR and BTR Dyno Results

Hi Guys,
I am finishing the restoration/refurbishment of a couple of Ruf BTR III Motronic, and just had the opportunity to dyno them. Along the way I've also picked up quite a bit of Ruf documentation, and specific information on Ruf CTR #12, which I have the dyno report for when it was new. I've collated all the dyno information, and thought I would share the results, and some observations.

The material that I have to work with is as follows:

1) Dyno of a 1979chassis/1991 factory build RUF BTR III Motronic, 70,000km, done in Calgary, AB with an altitude of about 3,500ft. This car was set up to run .96bar of boost.

2) Dyno of a 1986 chassis/approx 1992/3 conversion to RUF BTR III, 70,000km, done in Calgary, AB. This car was dyno's at 1.2. bar boost.

3) Ruf published results from their CTR "Yellowbird" and BTR "1" with CIS injection.

4) Dyno results from #12 RUF CTR "Yellowbird" in 1989 for its original owner.

While I will attempt to make some meaningful observations, this data should only be viewed as approximate, due to the control differences that include, but are not limited to: New vehicle vs. 70,000km and 25year old one, test altitude/humidity/temperature, boost levels, type of dyno etc. etc.

That said, here is the data:

This is the result of a Dyno run done at the Ruf Factory for CTR#12 for the original owner in 1989.

1000 150 110.6 21.1
1500 233 171.7 49.0
2000 355 261.6 99.6
2500 380 280.1 133.3
3000 440 324.3 185.2
3500 500 368.5 245.6
4000 565 416.4 317.1
4500 540 398.0 341.0
5000 555 409.0 389.4
5500 545 401.7 420.6
6000 555 409.0 467.3 500.9
6500 450 331.7 410.5

This is the result of our 1986 Chassis Ruf BTR III conversion, done in Calgary AB (3,500ft) at RTCS.

RPM NM TORQUE LB/FT Hp Wheel Peak Hp Gross
1000 -
1500 -
2000 203.53 150.0 57.1
2500 204.88 151.0 71.9
3000 271.37 200.0 114.2
3500 366.35 270.0 179.9
4000 542.74 400.0 304.6
4500 597.01 440.0 377.0
5000 572.59 422.0 401.8 430.68
5500 474.90 350.0 366.5
6000 427.41 315.0 359.9
6500 339.21 250.0 309.4

This is the result of our 1979 Chassis RUF BTR III Factory built conversion, done at RTCS in Calgary, running .96 Bar boost.

RTCS DYNO 367HP @ Wheels, 3,500ft above sea level

1000 -
1500 -
2000 203.53 150.0 57.1
2500 230.66 170.0 80.9
3000 271.37 200.0 114.2
3500 379.92 280.0 186.6
4000 542.74 400.0 304.6
4500 515.60 380.0 325.6
5000 495.25 365.0 347.5
5500 474.90 350.0 366.5 392.9
6000 407.06 300.0 342.7
6500 366.35 270.0 334.2

Here is the results of the RUF BTR 1/II CIS engined car, taken from the RUF Brochure.

7.2% loss between Gross hp and wheel Hp

1000 405 298.5 56.8
1500 405 298.5 85.2
2000 405 298.5 113.7
2500 405 298.5 142.1
3000 405 298.5 170.5
3500 420 309.5 206.3
4000 460 339.0 258.2
4500 485 357.4 306.3
5000 475 350.1 333.3
5500 452 333.1 348.9 373.97
6000 400 294.8 336.8
6500 350 258.0 319.2

Just a note about the injection systems and the difference between the RUF BTR III and the first couple of versions which were CIS....

CIS is the Bosch injection system that came out in the early 1970's and lasted into well into the 1990's, and was put in everything from Ferrari and Porsche to VW, Mercedes and Rolls Royce. From what I understand it has its limitations after about 400hp, which is why RUF came up with a Motronic (digital engine management) system for the CTR Yellowbird.

There were no road Motonic systems that were adaptable, so RUF took the MP1.2 system which was Bosch's first dedicated Motorsport digital engine management system. It was used on many of the Group B Rally cars and the endurance Sports Racing cars at the time including the Porsche 962 and the Sauber C9. It was also used on the F1 Tag-Turbo engine. The MP1.2 was characterized by dual injectors, with one set coming in with the boost of the Turbo engines. An adapted version was standard on the RUF CTR and a $10,000 option on the BTR.


1) Extrapolating from the Data, RUF figures there is 7.2% loss between Gross and wheel HP. At least I think this is right.... If you take the published torque curve, plug the numbers in to the HP/Torque equation you come up 7.2% short of the Hp curve, so I am assuming RUF published the dyno-generated torque numbers, and the Gross HP numbers. I could be wrong on this.

2) The CIS and the Motronic BTR 3.4L engines have very different torque curves, at least comparing the Ruf published data and our Dyno Results. Taken at face value, the CIS injection engine produces much more torque at lower RPM, but quite a bit less in the mid-range. I suppose this makes sense as the CIS system was developed for road cars and the Motronic MP1.2 for racing applications. One caveat, I'm not sure the published flat torque curve BTR CIS showing a minimum of 300lb/ft from 1,000rpm to 6,000rpm is that accurate. I've had a BTR CIS and Motronic, and they didn't feel that different to me.

3) The twin Turbo CTR has roughly 100hp more than the single Turbo BTR both running the same injection system. But both cars have the same displacement, rev range and boost, and the BTR even has more peak Torque. How can this be? The CTR maintains a high level of torque over much more of the rev range than the BTR.

4) Whatever Ruf version and whatever injection system, this is quite a bit more power than a stock 930! These Ruf Turbos can weigh anywhere from between 2,600lbs and 3,000 lbs depending on equipment. I weighed our Blue (1979) Ruf BTR III and it came to 1340kg (2,948lbs) with a full tank of fuel and me in it (180lbs) - so curb weight somewhere around 2,650lbs. That and between 370hp and 400 at the wheels depending on boost levels, more-or-less equals the power to weight ratio of the current Porsche 911 Turbo.

5) A 2017 Porsche Turbo S weighs about 3,600lbs and has 580hp, for a power to weight of 6.2 lb/hp. The Ruf CTR weighs about 2,650lbs and has 500hp for a power to weight of 5.3hp, and the BTR III running 1.2bar weighs 2,650lbs and has 430hp for a power to weight ratio of 6.16 lb/hp.

In my opinion, these are the greatest road legal 911's ever made!!
lromanosky is offline  
Old 11-14-2017, 03:41 PM
Join Date: Jul 2007
Posts: 102

Great info, great cars
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Old 11-15-2017, 05:32 AM
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Join Date: Jun 2001
Location: Tokyo
Posts: 416

That info reminds me of my track days. The old tuned 930s where always up there with the new cars. More times than not the tuned 930s won! Power to weight is everything. Last time some 930 racecar with a sequential shifter simply dominated. Plus very few owners of newer cars arenÔÇÖt willing to thrash them.
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Old 12-18-2017, 03:39 AM
Join Date: Apr 2010
Location: Canada
Posts: 13

Thanks for the info Lawrence. Those numbers sound about right. Just for discussion and tabulating sake, this is a dyno chart of my BTRII CIS RUF 930. It made 331hp and 340ft lbs on 0.8bar to the wheels at the same elevation in Calgary, on a Dynomite dyno. Very stable AFR for CIS I might add.

These cars make serious power and in terms of power to weight, pull on the modern cars with ease.

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Old 01-15-2018, 02:16 PM
Thread Starter
Join Date: Jun 2010
Location: Calgary Canada
Posts: 113

With the last problem solved (coil), it is time to list the car...

The description is 4,500 words, and there are links to an 8 part video summary, and to a 375 image Flickr gallery. I think this may be a record for the longest Ebay auction summary...

Lawrence Romanosky,
Calgary, Canada
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