Ultimate RUF Conversion Thread

[Hansv]

Hi there, Totle;

The NACA-style vents in the tops of the rear wings were actually used on the earlier CTR's only. They turned out to cause some hi-speed instability wich forced Ruf to develop a new way of taking in air for the intercoolers. What they came up with was the more liberally slotted rearbumpers you see here:

[javadog]

The intercoolers on the production CTRs draw air from the area above and behind the rear tires. This area is pretty open on the bottom of any 911, so I'd wager the majority of the air comes from there. I believe the slots in the bumper are there to help cool the area around the muffler. I have been told by people at Ruf that they abandoned the intercooler layout/NACA ducts used on CTR #1 beacause the airflow wasn't what they thought it would be. My guess is the NACA ducts were in a relatively low pressure area. They certainly weren't positioned properly for the airflow in that area of the car and a NACA duct is really better at much higher airspeeds, anyway.

Ruf built CTRs that had a Ruf VIN and also converted various previously-built 911s. I don't recall the exact numbers but I seem to recall the converted cars out-numbered the ones Ruf built from scratch, as Ruf cars. Some were made from Carreras, some from 911SC bodyshells, so they would have the dash structure and other features of those cars. A 930 had the same dash as a 911 of a given year and all of them had the later dashes from 1986.

In some countries, the year that a car is first sold is considered the "model year." That may be how the viper green one "became" an '88, as it clearly wasn't built on an '88 body shell. Another possibility is that a car can be built upon a spare bodyshell purchased from Porsche. Back in the good old days, you could actually buy a complete tub from Porsche as a spare part. Obviously, a bare tub might not have a VIN stamped in it, just like a replacement engine case came without an engine number stamping. Who knows what the story is on this particular car? You can find threads elsewhere talking about it, so perhaps the owner could share some more information on it.

JR

[Hansv]

Hi there, Javadog;

Good info. Fact remains that the earlier, NACA-ducted CTR's didn't have the extra slots in the rearbumper like the later ones. So I assume the extra slots do help the airflow trough the intercoolers and I mistook their function for an intake rather than an outlet.

[javadog]

Hansv,

It's hard to say what the airflow is on a 911, as it varies somewhat with speed but the rear of the car is usually very turbulent and most things I have seen indicate that it's a low pressure area. In any event, comparing the area of the slots with the vastly larger open area under the rear wheel wells give me the impression that the slots' contribution wouldn't be much.

Any turbocharged 911 gets pretty hot around the rear bumper area, so I'd bet the slots are mainly there to vent the heat when the car is stationary, or moving at low speeds.

Cheers,
JR

[dawsongr]

Perfect fit without modification is a lower lip spoiler off a 90s Vauxhall Nova; looks spot on!

[911st]

I do not know what the real reason is that the ducts were pulled.

I would guess that a low pressure area was created by air flowing over the NASA ducts that pulled air out of instead of into the ducts. I doubt it created any instability issues. It just did not work as hoped. Sucking air out from the wheel wheel or from under the car should help stability.

This probably worked against the motors cooling fan's efforts to pull air in and through the intercoolers. The NASA ducts were pulling air and the motor's fan was pulling air. Both against each other.

If RUF had closed up much of the rear deck lid to limit air flow for only to the motor's intake, the fan would have pulled air in through the IC's in the side panels of the motor bay just like it pulls air through the intercooler on a 930's rear deck lid.

Just a guess so please do not beat me up.

[MotoSook]

I recall reading in a magazine sometime back that indicated the NACA ducts didn't draw in air as Ruf had hoped so he got rid of them.

[mamut]

Yes, but who has the high speed record? the one with the ducts of course.

[Kemo]

I really like this thread...great wealth of information. Ill take one with or without ducts That green one is killer

[javadog]

Originally Posted by mamut

Yes, but who has the high speed record?

...the only one that was tested...

JR

[SCHNELE]

All CTR's have the same engine specs and the foil sticker in the engine bay claim a top speed of 211mph or 340km/h with 205/50/zr17 in the front with 44psi and 255/40/ZR17 in the rear with 51psi.

[onboost]

Originally Posted by SCHNELE

All CTR's have the same engine specs and the foil sticker in the engine bay

Did you say foil sticker?!!

P-

[alwaysflat6s]

Those of you that think the ducts didnt' work are correct. Herr Ruf laughed when he recalled a wind tunnel test where the air flowed OUT of the upper ducts. The extra slots in the rear bumper provided all the necessary pull to flow air through the intercoolers. Alois kept the prototype as it was originally built and enjoys seeing those ducts. [If it were a Porsche car, I can't imagine they would admit such a thing. They would pretend that they changed it because.... gas station attendants tried to put gas in there? Hey, it worked once before, didn't it?]

CTRs [as well as some later Ruf turbos] have gone much much faster than that 211 mph. I think Ruf got out of the game once others started the much easier process of building fast water cooled 900 series cars. They still test each customer car but it has become very much an early morning process. Too much, too slow, and ...sadly, too incompetent moving traffic.

There were 29 CTR body-in-white cars and 29 CTRs built from existing Porsche chassis. They are basically identical [but don't forget that each was built to customer desired spec, so there might not be 2 identical cars] and the only distinction is the Ruf chassis number on the BIW car. That distinction is good for about double the value so far. How's THAT for snob factor?!

Sigh. Even after all these years... great cars.

JR always flat 6s....and always a Ruf fan

[SCHNELE]

PAUL! like I said before they are now in my office I just have to get around to making the shipment.

[semprini27]

hi all - new here but a regular on impactbumpers.com .

I'm fitting a RUF style rear bumper to my '88 Targa at the moment and am stuck ! The bumper shocks are a real PITA ! The rear nut on the left hand side is accessible but won't move. It's had hours of heat, chiselling and hitting with a BFH and is still in place. I'm cutting it off tomorrow.

The right hand side seems impossible to access with the oil tank in place ? I can just about get a socket on it but getting a breaker bar on it with any room to move is impossible. Judging by the force used on the other side my chances of removing the right hand one with little or no access seems mission impossible.
Any advice ?

[pete917]

Ive got my RUF bumers sat in my garage and I cant seem to find the time to fit them.

Here's some video footage to give me, and anyone else some inspiration

RUF Yellowbird Drift

[pete917]

Thougou might like this too.......

[Flieger]

bump

[Brian911s]

Hi. Here is mine. Picture Can be found in a early reply in this amazing long good tread.
http://forums.pelicanparts.com/uploads14/+Ruf+Porschen+0301240006007.jpg
Regards
Brian

[umgang]

Has anyone ever figured away to put a splitter on a Ruf front bumper in
lieu of the air dam?