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

It's starting to look like a continental length lunch...

 

More Rioja, Brian?

 

must have passed out from lack of sleep and ali dust poisoning.

 

>> http://www.clubgti.com/forum/showthread.php?t=193826

 

interesting, not directly related but still...> http://www.eng-tips.com/viewthread.cfm?qid=223747&page=9

 

this is all great stuff, nice one - It looks like there are casting variances on the block - I suppose its possible that audi may have x-ray'd the block (or similar) to find items with the least flaws????

interesting link - the flow difference is down to the extractor-nature (or not) of the exhaust system - presumably this is why the VW head can get away with a vertical exhaust valve

 

I remember years ago, anti-reversion chambers were the next big thing in big power, NA Honda B18 engines (ITR engines) and much was talked about benefits to power associated with better extracting of the exhaust gas.

A very interesting subject...

 

Just been reading an article on port shape, 2 heads with the exact same port cfm value were tested, one made 150hp more that the other and it was all down to slight differences in port shape, although they did flow the same. I was stressed that cfm wasn't everything when it comes to ideal port design or efficiency in the real world.
I cant link to the article as its members only, but i though the above was interesting.

 

I have seen some latest spec A4 STW engines in parts a few years ago.
85 mm bore on 88 mm cylinder distances
88mm stroke
The first A 80 STW engines were build with modified 3.6 V8 cilinderhead
(33 / 28 valves in 1990 dtm spec)
Later on they used a cilinderhead similar to ACE / ABF or 9A
I have been told there were special castings made with smaller ports

The injector pocket is closed ( welded )
Cilinderhead is machined under an angle of 1.5 or 2.0 degrees to reduce combustion chamber volume.
Titanium Dell West valves 34 / 29.5 mm (some late engines 30.0mm) with long hollow stems. Valvelash is adjusted by changing solid lifters with another thickness. (No Shims)
Beehive valve springs with a small retainers (ca 18 mm)
The outlet ports were a bit oval at the flange. I think something like 38 x 41 mm

Camshaft with high lift ( 14 > 15,4 mm ) and a sharp nose with a small radius
Hollow steel billet camshafts with lobes about 10 mm wide and super finished
and both cams are connected by gears

Piston pin is 18 mm, 40 mm long
Comp ring is 1mm / Oil ring 2.0 mm
Coated piston skirt
Piston height 36.25 mm / 40,4 with dome
Compression ratio is 14.1 / 14.2 in the latest spec and with a 2nd squish zone
Chamber welded up on exhaust side, The piston was shaped as in a pentroof engine
Pankl Conrods length 152.5 mm , I have seen A and H beams

The engine block had 4 std oiljets and on the other side a second row oiljets
Bores are nakasil coated

Crankshaft weight is 9.8 kg
Smaller conrod bearings / ca 42 mm (VW Polo)

4 knock sensors ( I have been told that these engine ran all the time at the edge of destructive detonation but controlled by the electronics.

 

Bump for new information above, from newly approved user.

 

Interesting info on the cylinder head angle, means the exhaust valve must no longer be at 90 degrees too...

2nd row of under piston oil squirters too.. :-)

 

in racecar-engineering (08/2009) is an article about the Volvo TWR cinderhead an how they bent the rules.
Valve angles and port positions need to remain standard from measured from specific reference points opening the door wide to interpretation.
So they made cilinderheads that cost 13000 to 15000 pound / each
The upper half of the head was cut away and new cam carriers were made from solid
Tappets went from 32mm to something like 36 mm, valvestems were 3.5 to 4.0 mm
The inlet port was under a steeper angle the combustion camber was machined deeper in the
Head and ended up from a pentroof to a wedge. Latest spec engines were 325 hp

 

STW regulations are on www.supertouringregister.com

 

Yep agree,

Good info there!! ties up with what i've heard!!

 

late spec engine has head with timing gear / 2nd squish zone ( page 2 )
bloc with deckcooling and 8 oiljets ( page 4 )

on page 2 is IMO a SEAT IBIZA EVO 2 Kitcar engine ( Mader )
84 x 90 mm
S2000 engines have only 1TB- max 64 mm
late spec KC engines were 272- 276 hp ( on std valve size )
some early engines were used as STW 280-285 Hp
with big valves / dry sump

 

Some more piston pictures, courtesy of HPR - not BTCC originated but believed to be same.

84.865mm, to be exact:

 

Audi V8 DTM 3.6 head, showing ovalised, redrilled head bolt holes, to enable the head to be canted:


(above and below the 'i' of Club GTI).

Pic again courtesy of HPR.

Shows same could be done of a 16V version....


And a couple of racing pics:

 

My guess being that it was canted back(if fitted to a golf) therefore tilting back exhaust valve off its 90 degree axis, and of course in turn raising the attack angle of the intake port....clever stuff.
Btw Chris, im soon near ready to kick off my own job, took a while longer than I thought, was busy.

 

Cool Brian, looking forward to it.

I'm trying to work out which way it's been tilted. Back to that one later.

 

Makes no sense to tilt it the other way, as in forwards if fitted to a golf.