Audi A4 BTCC / STW engine specs - 305 bhp from an N/A valver.

Chatting to infinity recently, he mentioned that the old BTCC Audi A4s used to use 16 valve 2.0 engines.

Which of course can be traced straight back through, via ACE/6A/9A, to the original 1986 Golf GTI 16V KR-engine.

From here:

Strange looking cam cover under that carbon - are the cam covers Audi V8?


inifinity's been scouting for info on these and will chime in soon.

They're seriously modified bits of kit, but nevertheless interesting


Update 4/11/2010, specification sheet gained so far:


Car

Length	4.48m
Race weight	1040kg

Engine

Component	Supplier	Detail
Engine block	Audi	Cast stamping: 05? 103 021 J, 86mm bore spacing
Sump		Combined dry sump / lower half of main bearing girdle
Cylinder head	Audi
Crank	Omega	88.1mm, cross drilled
Pistons	Mahle	85mm, 18mm pin (definitely in V8). Step 5 engine: 0,4- 0,6 mm above deck
Piston rings	Goetze
Piston squirters		Eight instead of four
Conrods	Oral	153mm
Valves	Del West	Inlet: 34mm, Exhaust 29.5mm (some late engines 30.0mm) with long hollow stems.
Valve springs	Scherdel
Cams	SCAM	straight cut toothwheel interconnecting drive
		Step 5 engine: Inlet > 14.87 mm lift / 4.2mm lift @ TDC / 107 degree / valve clearance 0,13-0,18 mm
		Step 8/9 engine: 15,4 mm lift
		Inlet exhaust 13 mm lift / 4.65 mm lift @ TDC / 107 degree / valve clearance 0,18-0,23 mm
Cam followers		Individually sized to adjust valve lash - no caps
Throttle inlet	MTK slide throttle	44mm
Airbox	ROC
Injectors	Bosch	B 280 431 128/1 (128 is a motorsport injector)
Fuel regulator	Bosch	B 280 550 113 (runs at 5 bar)
Spark plugs	Bosch	H3CS; Step 5 engine: F2cs ( heatgrade 300)
ECU	Bosch	Motronic MP 1.8
Electrical harness	Bosch
Battery	WKG
Alternator	TAG
Exhaust	Mecom
Catalyst	Prototechnik
Fuel cell	Uniroyal
Fuel pump	Bosch
Dry sump tank	Mecom
Oil pump	Audi
Oil pressure	4-6 bar
Water temp	75 C
Engine weight	89 kg dry without clutch and air box
Output	See 16 valve engine race outputs here

Note: all above data covers the 1995/6 seasons.


Brakes

Component	Supplier	Detail
Discs (front)	Alcon	343x32mm
Discs (rear)	Alcon	330x28mm
Calipers	Alcon
Brake pads	Performance Friction
Master cylinders	Alcon

Transmission

Component	Supplier	Detail
Gearbox & gears	Audi
Diff internals	Audi, ZF, FFD & Torsen
Driveshafts	Lobro
Propshaft	Lobro
CVs	Lobro
Flywheel:	Titanium, steel outer ring
Clutch	Fichtel & Sachs	Carbon

Chassis

Component	Supplier	Detail
Bodyshell fabrication	Audi Sport & Matter
Composites	Divi
Front suspension	double wishbone
Rear suspension	?
Dampers	Koni
Springs	Eibach
Ground clearance	45mm (min)
Rear wing		Side profile < 150mm x 150mm, no closer than 100mm from the car
Wheels	OZ magnesium	8.2 x 19" forged
Tyres	Dunlop	215/650 19

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

Valvetrain - DTM V8 spec for ref

Component	Measurement	Weight
Valves - inlet	32.9mm / 108.55 x 7mm	55 grams
Valves - exhaust	28.0mm / 110.55 x 7mm	43 grams
Bucket	35 x 28.6mm	53 grams
Double springs	free length 41.65 mm	60 grams /78 grams with retainer
Valve lift	12.9 mm

 

spotted these on a aussy forum and a regular of here link to 16v discussion http://www.vwwatercooled.org.au/newforum/upload/archive/index.php/t-18771.html

 

Oh hell yea!!!!

Mmmmmmm......

 

8 bolt crank pulley - I wonder how many 4-bolt ones they broke before they went that way?

I'd love to see a pic of the head porting (and get it on Mr Hillclimber's flowbench).

 

I remember seeing some pix of these engines, and the porting work was not porting but physical machining out of the head, inserting new blocks so angles and geometry was totally different.

 

Sounds a similar method to the Judd/Brabham heads - major surgery on the casting before they started.

 

I suspect a total re-work of the compression chamber shape, from the peculiar 16V design, valve angles being the regs restriction.

 

Thanks for starting the thread Chris!!

As Chris was saying, I've been trying to document as much info about these engines as possible, i.e tech spec's what parts were taken from VAG bins etc etc and to try and un-ravel the mystery of how they achieved >300 hp from a VAG 16v motor.

Although the A4 engine wasn't the most powerful on the grid (with that trophy going to the Volvo 5 cyl 850, also rumoured to have some Audi genes in its engine and the Nissan primera with a whopping 330 hp from a 2 Ltr!!)

That crank pulley looks very similar to the one found on an A4 2.8 V6 from the same era?? its also 8 bolt!!

I can only image the vibrations these engines have to go through, every component was superlight for maximum acceleration. Lets see what we find

anyone know how I can put pic's from ETKA up on the forum??

 

Which bits? I have some TWR BTCC Volvo engine drawings

Press "PrtSc" and drop it into Paint. Cut it about, and pop in photobucket.

 

The original castings were rumoured to be from the old Audi 5 Cyl, 10v and 20v, but Volvo had cast them from ali?? The volvo needed a a strong lump, its a massive car!! Been snooping around my own volvo, an 850 T5R volvo's attempt at homologating splitters and spoilers into there race cars and the old quattro stuff is similar? can't confirm it though?? maybe some of the quattro guy's may know

Cheers Chris!

V8 Cam cover, similar but def not the one,

 

Ah, it's got to be a bespoke cast cover then - dry sumped motor etc

 

maybe it was for cam lobe clearance

 

the early volvo engines were very similar to the original Audi 5 pots, however they were quicker than Audi at developing the design, into what now powers the focus RS

awesome looking engine, are these the highest powered NA valvers ever produced?

 

So were they copied under licence, or just similar?

 

kit cars were realistically 260-270hp so these must be the most powerful vag valvers using the original engine design - they are likely to have an aweful powerband though - IF thats right, its one hell of an output with the design they have if they cannot move the valve centers

 

Well done with the information some very good stuff .

what cam spec's would they have been running ?

 

Virtually impossible info to get a confirm of, I would have thought?

I'm going to rake this TWR BTCC Volvo info I've got, get that on the table too. Never realised I'd do anything with it.

 

VCC 5 pot was a Reno engine with an extra cylinder.

 

They certainly were a higher spec, than the kit cars, dry sump, big valve, high compression etc etc. But then the kit car was built for rallying, much longer engine life is required.

Although valve location was fixed. they may have got around that by moving the head around on the block...... elongated head bolt holes anyone!!

To my knowledge these are the most powerful valvers made, the Audi 80 STW was also raced somewhere I think Italy so i'm presuming the engine was a development from that!?

some pics

Audi 80 STW

 

any thoughts on why the drivecouplings are not in the normal place or am I looking at something different?