Porsche 928

working on the engine build i got pitty for my spare engine , laying in the shed.... which i hauled myself out of the grey race car 10 years ago , running good. So i pulled it inside and demounted all oem injection stuff, which i will never use. Got if filled with a mix ATF/diesel .
This is the oem "300 HP" M28/12 , my build now is the M28/22 "310 HP" , it has slightly more agressieve cams.
This "spare" was used in a few track races and i see indeed some porting on the inlets. ( PO crashed his race 928 and used this one shortly )

It has been here all "BMW" the last years, now my garage seems a Porsche shop :D

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I can mount it later on the engine stand and have a perfect model to design a four 45 DCOE Weber setup... wish i had it build like this in the first place ( instead of the IDA48's ) . With the long cross-over tubing that must be great for torque ! and keeps everything under the hood. This example i found on the net... at least it is possible :cool:

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already one bad surprize…..for track it was OK , but for rally i wanted a shorter diff.... which doens't exist it seems ? In our (manual) transaxle the pinion is one part with the axle going all the way trough the gearbox. Nor Porsche nor aftermarket seems to have build options. Some slight differences in build years/types of 2.6 tot 2.7 and a ( even worse) 2.2 used in the USA cars. O well ,we will have 3 "long" gears , and sometimes 4the for rare long straights. I just hope , for slow corners, it shifts "good" in 1ste , were we are used to be in 2de with short diff's.
Top speed is now 260 km/h , better would be max 200 , so a diff of at least 3.5 instead of 2.7.... pitty.
 
why in god's name didn't Porsche and BMW used the same wheel dimensions ( center /stud centers) ….damned.
I have +20 of both but can't mix them....
at least all ( mine) are 17" so i can swap tires... as we have dry and rain/mud tires….
 
for rally ( instead of the track design ) i need official tech inspection … so again lights with parking/dim/high … i do not feel for remounting the oem lights and the ( heavy) system... ( which i throwed away ) … so the idea of using fixed small tractor lights …. those will be the fasted tractor lights in Belgium
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No problem in how good they are, just to pass inspection. For real lightning in rally we have extra ( not road legal ) spots.
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To test everything before buying a ECU ignition ( the more , IF allowed in "historic" class) i removed the vac from the distributor and had the stator fixed with screws. It is a '82 car.
I see the mechanical advance weights and springs are different what explains the advance curve as to be in 2 stages ….. i think. Never seen that , all the former distributors i have worked on had identical setup , so giving lineair curve up to the stops. With choice of springs we could dial in how fast advance came in . If ECU ignition is not allowed i will see the need to change that , lineair curve and " all in " a bit earlier …
 
had a pre inspection by race authority and all comes fine !! We must add some extra reinforcement plates under the roll cage and weld them to the car ... not that big deal. Also some extra tubes in the rear cross to fasten the seat belts so that they enter the seats holes "level".

Been working on a dual scoop design.... always thought to make one big scoop to clear the carbs/filters but think dual will be more "nice" and less "big" ...final height can only be taken once the engine is back in the car .... think to keep it closed in front and open at the windshield base , there is positieve pressure ( not vacuum as across the hood )
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removed the small oem lights ( think those are fog and cruise lights ) and replaced by ( Porsche 964) air ducts for the oil coolers...still a cone to add.
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headers are 3" , we made the X in 3" , and thought to go dual 2.5" after … but i think we can keep dual 3" all the way... must present the silencers to see...( flow through with packings )
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Very exciting stuff!

Interesting note in this picture. I am curious how well the Webers worked being tilted up so high? Carbs are typically very finicky about being level. Float and fuel level must have been sub-optimal at anything other than WOT...my guess.
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I know this thing will HOWL when you are done!

Ed
 
Belgiumbarry said:
headers are 3" , we made the X in 3" , and thought to go dual 2.5" after … but i think we can keep dual 3" all the way... must present the silencers to see...( flow through with packings )
Click to expand...

Do you also have strict noise level limits (I call them sound level limits) on your race tracks? Both here and in Sweden the 95db limit is all too common on trackdays and also in racing. I think they're planning on making 92db the new standard in Sweden..
 
Yes, Robert , 95db is the official "limit" …. but most rally cars are way above ….. on race tracks they are more "severe" , but most drivers know were the sound measure equipment stands and lift the foot :)

This is Belgian rally "95db" today with Patrick Snijers , he's my age… 62 …. but with a GT3... more budget :D

Porsche GT3 snijers - Search Videos

www.bing.com www.bing.com
 
Okay, it's a shame but what can you do. Lifting the foot at the measuring point might be reasonable on a trackday but harder in racing:D
At 92db you would have to start thinking about managing intake sound/noise too..
That GT3 sure is a sweet sounding car! And I'm sure your 928 will be as well!
 
i forgot to write a upgrade... meanwhile engine is in the car , making connections, full 3" exhaust welded , and a new better 40% LSD installed.
Can fire it up within days !
also al lot of little things... custom supports , Weber commands .. etc.. who take a lot of time ! :oops:


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This post is SO above my level of hobby classic car service/maintenance/keeping it running/magic wand magic, but SO inspiring. It definitely helps me to aspire to higher levels of attention for my Classics. Thanks for posting! Mike
 
no, torque tube is oem...

meanwhile the upgrade LSD is in the car with the same backlash....
Engine runs ! fired direct and after some fiddling screws , timing and synchronisation it runs very nice. Jetting will be done on the dyno.
Due my soaking oil in cilinders the last month it smoked of course terrible the first run .... all gone after half a hour idle...
and new plugs , those were burned "black" :D

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playing with the dizzy….

oem advance is static 10° , up to 2300 rpm + 14° , and from 4000 rpm to 6000 a extra 10° ( total 34 ° in 2 stages )

Weber carbs like more advance static and all in by 2500... so we had a problem
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( for historic rallies we may NOT use electronic ignitions…. )

So i bought a old dizzy ( same Bosch #) to experiment … and think i found a solution !

There is oem a light and heavy weight for the 2 stages centrifugal advance with dedicated springs. .
If i put in there 2 heavy weights ( with their specific spring ) i get 16 to max 18° advance at 2300 rpm .. so i would need 18 to 16 ° static to get the 34 ° total .
That would be perfect i think…. car starts now perfect with 16° static , just a tic , and runs smooth…. ( i don't use vacuum advance)
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problem is Steve , i don't know if there is still a "distributor rebuilder" in Belgium... perhaps 20 years ago. SUN machines are now in musea...
And that Porsche ( Bosch) dizzy is quite different from the more common USA cars …. with weight and spring sets to experiment.
So i needed to buy a second dizzy to have at least a second "heavy" weight & his spring ! … expensive pieces :D

More, was there ever a USA car with a 2 stages advance dizzy ?
 
Meanwhile i also got my winter tires and wheels….. Braid custom ET no nonsense rally wheels 10" x 18" with Pirelli Sottozero 285/35 .
The rallies to come in winter demand street legal winter tires…. but the first rally mid december ,we won't make it , had hoped it, but all this takes to much time and it would become more a "job" instead of a "hobby" …..o well , end Januari there is another one….

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