Brumos 934.5

[Flieger]

Hi,

Here are some photos of the Brumos Porsche 934.5 driven by Peter Gregg. Trams Am Champion 1977. (for a month)

The event was a Porsche Club of America Grand Prix Region concours this Saturday at the Queen Mary in the Port of Long Beach, California.

The owner started it but the video I got is too large for Flickr. Needless to say, it sounded awesome. Throaty barks when he revved it, a little unburnt fuel coughed out of the zork, some heady race-gas fumes, and a little turbo whir in the background.

[MikeD930]

Cool! Thanks for sharing the pics. I'm surrprised that this car does not have dual plug setup (based on my observation on its distributor). Did most 934's have single plug setup?

[Flieger]

Yeah, I was surprised by the single-plug ignition, and, as you see in the underneath photos, the Magnesium exhaust valve covers from a 911S.

I wonder if the car was raced again how many leaks from warped valve covers he would have?

[cole930]

God, how sweet is that !!!!!!!

Flieger, kinda reminds me of another sweet, sweet white car you've posted before.

It's got my old school tail , way cool.

Mikie at about 4:30 last nite I was looking for ya. Hope you still have that silly smile you left here with. Don't forget, the shiny side goes up.

Cole

[krasuskyp]

OOOOOOFFFfffff - wowwy.

Cannot imagine having it barked before me - noice!

Interesting the switch from curved to boxed / vented rear quarters. IMO the latter suit the tail more appropriately (or vice versa).

I've never seen that dual fan set up (I'm by no means any proclaimed guru, just a fan - get it? Heh heh). WAY cool (damn, there I go again - sorry).

Tx for sharing.

[MikeD930]

Hey Cole,
I'm still around! Note that I got a new avatar.

krasuskyp,
There's no dual fans although it looks like there's one regular fan but that's part of the bracket/housing in place of the regular fan.

[Flieger]

Do you mean the alternator? It has a fan integral with the pulley to draw cooling air around it, probably a legacy of the part being used in a different, non-air-cooled car. That is my theory, at least.

It sure looks cool, I thought.

[krasuskyp]

Nope! 'm just a dumbarse apparently.

I was too busy drooling / scrolling quickly between dinner and kids jumping on me lap and mistook what now appears to be some sort of mounting 'boss' where the OE fan would normally reside for a 2nd fan. I'm that dumb, see. I'll be OK. Or not.

[Flieger]

Don't be so hard on yourself.

The 935s used the relocated alternator running on a dedicated belt. This was possible because of the flat fan.

The alternator could then be run at a reduced speed, and the fan could be reduced diameter. This helped the engine anciliaries stay together at 9000rpm.

Even relocating was not enough for the most violent 935s like the 935-78. The extreme engine stresses still threw alternator belts so they had to go to serpentine, then multiple serpentine belts to keep the alternator spinning with the engine.

Much the same problem as the 908 had, though for the prototype it the cause was the initial rough firing order vibrations.

[A930Rocket]

I thought about fabbing an alternator mount similar to that one in my old AC compressor location and using a American alternator that could be had at any parts shop cheap. Easier to swap out as well.

[MikeD930]

No worry Paul...you're not dumb! I thought the same thing when I first saw that setup. That bracket looked like a fan.

A930Rocket,
Interesting idea. If you do that then what's going to take place of a stock alternator? That's extra weight lugging around two alternators. Do stock one go bad that often?
Too bad that I could not do that mod since the PO cut off the AC compressor bracket. I wonder how much weight did he saved.

[kycarguy 935]

I know the owner of that car. I had no idea he owned until I saw these pictures on the PCA-Grand Prix region website. I don't live in California any longer so I haven't seen him for a few years.

Very neat piece of history for sure.

[A930Rocket]

I would gut the stock alternator. Too bad we need it to hold up and spin the fan...

They don't go bad often, but it would be nice to have the option when it does puke on us, to be able to buy one at pep boys, advance, etc. for a lot less.

Originally Posted by MikeD94

A930Rocket,
Interesting idea. If you do that then what's going to take place of a stock alternator? That's extra weight lugging around two alternators. Do stock one go bad that often?
Too bad that I could not do that mod since the PO cut off the AC compressor bracket. I wonder how much weight did he saved.

[juicersr]

Originally Posted by MikeD94

Cool! Thanks for sharing the pics. I'm surrprised that this car does not have dual plug setup (based on my observation on its distributor). Did most 934's have single plug setup?

Under Group 4 regulations in 1976/77 no changes could be made to the basic motor (ignition and fueling) of the car which served as the basis of it's homologation, which in the case of the 934 was the 930. Thus the factory was limited to CIS and single plug. It is a testament to the engineering skill of the Porsche racing dept that they were able to extract as much HP (about 550 in 1977) as they were from the 934, mainly through a larger CIS fuel head and metering plate, water intercoolers, and the good old boost knob. Thus, the 934.5, which was essentially a 934 with new bodywork, was limited by the same rules in Trans-am

Of course, after the first seasons, a lot of people ditched the CIS and went to mechanical injection, which allowed for about 700hp.

[Flieger]

I found it interesting that they used what appears to me to be a Kugelfischer pump instead of the regular Bosch unit.

Does anyone know how they compare in performance? The Kugelfischer looks lighter.

[Wayne 962]

Originally Posted by Flieger

Yeah, I was surprised by the single-plug ignition...

These 934s ran CIS injection, and a variety of other restrictions that echoed the street cars. No, CIS and single plug is not a performance option, but I'm pretty sure that it was mandated by the class rules. This particular car probably started out with CIS and then was converted later on (I'm guessing).

-Wayne

[Flieger]

I suppose the flatter Turbo pistons did not suffer as much from single plug as the high-dome, high-(static)compression ratio RSR engines.

Hi Wayne, sorry I missed you. I must have come later. I got there about 1PM and started taking photos of the 934.5 right away. I did not see your 959.

Any comments on the MFI? I know after the first year of 934 competition, they were allowed MFI after the Porsche domination did not materialize right away as the RSR had ruled IMSA (and continued to win even in the Turbo era)

[JohnJL]

Is the car in the recent photos representing itself as the car in the poster? 'Cause they likely arent the same car. Different mirror locations, window wipers, splitters, fenders, arches, rear bumper and cage.

[spence88mph]

Originally Posted by JohnJL

Is the car in the recent photos representing itself as the car in the poster? 'Cause they likely arent the same car. Different mirror locations, window wipers, splitters, fenders, arches, rear bumper and cage.

These 934/935s are more identified by chassis/tub numbers than body panels as factory body upgrades, crash repairs etc made them morf over their racing lives.

[spence88mph]

BTW, awesome post Flieger, as usual!

That car is amazing.