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

85mm.....very dodgey, offset boring IMO

 

I was told by an engine builder the blocks were re-cast using a a slightly different mix of cast iron to prevent air pockets forming,this gave an improved safety factor when boring out that far.

 

85mm Still sounds well sketch to me. Have heard of vw pistons being sold for 85mm bores though. I think porttuning used to do them. Rob, I agree they must be offset but surely with their valve sizes they're going to run into shrouding problems?

Edit: Infinity: Do you mind me asking which engine builder? Not criticizing or judging, just wondering who's rebuilding them these days. Can answer in pm if preferable.

 

BTCC block would be from a deriviative of an ACE. But you would be hard pressed to fit a std sump on that as that area is deleted and the bearing gridle is now part of the of the dry sump system. Also there is an additional webbed area near "2.0" extending to where a tapped hole for a tranverse engine brackett would have been mounted, that is not on the other production engines suggesting this was casting as a one off. Also the bore x stroke combination suggested is not common to VW EA827 motors, more reason to suggest this was a one off type of motor.

Nissan's SR20DE = 86 x 86 = 1998cc in std form

Heads possibly 94 S8 V8 derivative ( 051103373 G), again custom casted and worked to suit their high VE requirements.
217lbft peak @ probably 7000rpm ( did not say but RobT should be right) great achievement back then without VVT or turbo from 2.0litres.

At those peak values, must have very little drive torque below this though and huge cams.


Be interesting to see what they to get 1996cc from this engine.

 

Ooh... one piece bearing ladder for extra strength - just like a rover K-series

 

the regs must have stated that the original-type block was used to the crank center line - otherwise they would have cast an ali block if they were going to all this trouble - in a lot of production-based classes, you are not allowed to change the block material from what was originally fitted to the car although I hear there are quite a few cheater blocks about in escorts

 

the whole point of the thread was to gather/share info and have discussions about the make up of the engine

my info comes from these guy's > http://www.hombre-motorsport.de

they advertise regularly on race cars direct. Let me know what you guy's want to see I'm trying to get details of all of the bottom end parts first. i'll try my best to get info and pictures!!

Just to pick up on that

found this article about the K series which might help explain the reasons behind the ladder / bed plate

from here: http://www.sandsmuseum.com/cars/elise/thecar/engine/rover.html

snippet from link
The engine was constructed in layers of alluminium alloy held together by ten 16 inch through-bolts, from head, through the cylinder assembly and into the crank webbing. This added strength by keeping the structure in constant compression. In stead of fixing the crankshaft in place with separate main bearing caps bolted to the underside of the block, the K-series borrows from racing engine practice. Thus, it uses a deep sided bottom casting, another ladder like the cam-bearing one above, and closed by the sump, which is a conventional steel pressing. When bolted in place, the combination of the main bearing ladder and the block gives the K-series engine an immensely stiff bottom end. This means the engine can safely exploit high crankshaft speeds, vibration is reduced, there is better support for the main bearings, and because the engine is deeper and stiffer in all places, it can be made lighter

 

ARP Main cap studs or similar ! (above)

i've got a set of these for my engine build.

 

Better shot of the rear of a standard ace for comparision .



Edit < mods >

Compared with A4 BTCC:

 

Just noticing the slight difference to the right of the "2.0"

Also picking this up from earlier:

Fascinating what they've been up to, tbh.

 

I reckon that area is the same casting that has been ground down - great pics there for comparison - based on that I think its a stock casting thats been modded by machining - whether the (iron) material is stock remains to be seen as I dont think they could get 85mm out of one without offset boring, and then that screws up the valve placements

 

That's what I was thinking too.

 

Think you are right there about the machining. Looked at it again and bracket hole has been machined to its last thread.

 

From memory, the 5 cyl turbo diesel in some Volvo 850's (around 1996) was an Audi engine, so once they had that they may have evolved other engines from there.

Also, look at the fire ring marks on the head face pics, for an 85mm bore to be spaced like that the chambers would have to be further apart, a normal 83.5mm gasket is very tight.

The head does'nt look "quite" right, not like a normal 16v casting, so maybe as suggested, half a V8 set up. I'd also go with the block being re-cast to line up the bores with the chambers and allow for the bigger diameter... all trick stuff and "production" in name only. They were permitted to use an engine from another model (BTCC Toyota Carina's used Celica based engines) so 1/2 a V8 was still a production item... "imaginative interpretation of the rules" I think it's called!

I remember the Renault Laguna engines from around the same time had the (alloy) crank cases (blocks) cut about severley, adding sections in for extra breathers etc, and there were gear drives on the Nissan engines from memory.

 

You can get an 85 mm headgasket, normal spacing. As you guys have already said, not much meat between the bores though....

 

Ther defo was a lot of swoping about, if memory serves me right the Rouse Mondeos used a Mazda based 2.0ltr V6.

 

same engine but turbo charged http://www.neuspeed.com/supertouring/A4forsale.html

official brochure with specs http://cgi.ebay.com/ebaymotors/1996-BTCC-AUDI-A4-QUATTRO-TOURING-CAR-IMP-BROCHURE-'96_W0QQitemZ220383815290QQcmdZViewItemQQimsxZ20090325?IMSfp=TL0903251610006r14979#ebayphotohosting

 

Friend of mine has a Kit car with Duretec Engine that runs 270 BHP NASP

so i had a look at what else was available from these Engines - 304BHP From a Duratec

http://www.sbdev.co.uk/Duratec/Duratec Taper throttle top of the range kit.htm

 

Notice "only" 195 lb/ft. Nowhere near the claimed 217 lb/ft from the VAG...

 

Indeed... brought down from the 2.5 v6, de-stroked I think... maybe even sleeved down on the bore.