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

subaru impreza EJ20 flat 4 boxer engine - 92mm bore, 75mm stroke 1994cc

mammoth bore/stroke ratio!

 

Im going to do a 2.0 6a cutaway( as i did in the 1.8T section)today as i have a tired block here so itll be in the 16v section if anyone wants a look.
I need to know just how thick things are in there, deck thickness, etc for my engine build thats on the drawing board.

 

Fantastic - thank you in advance for sharing with us

 

More info and cutaway pictures of the standard 6a blockhttp://www.clubgti.com/forum/showthread.php?t=193695

 

So back to this:

So on the maths, the extra 2.5mm of bore (to take it to 85mm), would nibble 1.25mm out of each side, narrowing the cylinder wall thickness between bores to 3.22mm.

Assuming that an ACE block is dimensionally the same as a 6A block, which it should be...

 

Interesting point is if you take that same 1.25mm ''nibble'' amount off the minimum bore wall thickness that I found in places you get 3.19mm.........which is 0.03mm less that the distance you will be left with between bores.
Im beginning to think that the thinness between the bores isent the problem really when it comes to strength as its only that small at that particular tangent,(parallel to crank) whereas its that thin if not thinner to the water jackets in some places, without the support of the neighbouring cylinder.
Now i know you have to take a fairly skimpy head gasket into account and its ability to seal, but im beginning to wonder in what areas most of the bore wobble takes place at 85mm bore, from looking at the cutaways here beside me, between the bore is the last place that worries me to be honest as thrust forces are pretty small there , but bore areas 90 degrees to crank are a different story altogether.
I wonder could you bore outer water jacket to fit some sort of stabiliser to outer face of bore wall, be it a bolt threaded against it or welded to it, and again fixed to outer jacket to cut down the wobble? Hmmmmmm....possibly not...

Another thing that could possibly be done is a hole milled either down or up through block, where the hole just kisses bore and outer casting, a slug say 20mm long could be inserted to transfer a bit of shock/wobble/etc into outer cast.
Plug would need to be a press/interference fit of course and the bore hole plugged afterwards, just an idea.

A close shot of one of many surprisingly thin spots.


This is interesting stuff, keep it going guys!

 

Which bits do you mean? The lower unused cylinder areas? (how must isn't used though? I suppose they don't have to be bored out) or do you mean outer parts with the water jackets?

Agree that the bits between the cylinders look quite well supported!

 

I mean just random bits really Chris, like the part in the last photo at tip of tooth pick, theres a few of these thin areas on each bore at random places, like as if the mould/casting/quality control was poor. There in the high load used bore areas too(not parallel to wrist pin areas)< ive difficulty explaining this area, what I mean is areas of high thrust as opposed to areas between bores if ya get me?
see below for thin areas


Im contemplating cutting my test 6A head i have here into say 20 different pieces to figure out just how far and what size the ports can be brought to. We could be guessing forever and the pictures that exist on the net only show cross-section through the intake and ex port, not enough for me or everyone else to go on im afraid when it comes to radical porting. I feel it would be worthy of cutting one head to see once and for all.
The things im after is the distance from roof of port to spring seat and exact location of oil way in that area too as i intend raising port angle and filling in floor to try and promote flow, as the 16v head is pretty shocking in that regard compared to other heads ive worked on and ported.
I know the audi head that this thread is all about ran pretty standard port entrance size and location, bar the filling of the injector cut out but to be honest i want to see it in there and get all the measurements down on paper, pictures of such things are usless without measurements and lets face it, scaling off a pc screen isent the way forward when waterways are concerned.
I just have to see if i have a 400mm tct alloy saw blade first, ill have a look.

 

Found the 400mm blade and the head is all cut
Pictures up tomorrow, ive a long night ahead and even choosing the paint scheme is a big job as theres alot of different areas, and a LOT of parts.
Should answer ALL questions relating to the 16v head and its internals.
The findings are exciting to say the least.
Stay tuned.

 

you cant say that, 'I have the answer chaps, but im telling you until tomorrow!!' what a rotter!!

 

It'll wait

 

the dust from aluminium is far tastier than cast iron dust i have to say
painting these REALLY GREAT HEAD CUTAWAYS I HAVE HERE IN MY HAND reminds me of doing airfixs as a kid, without the glue laden milky windscreens and crooked transfers of course

 

this thread just keeps getting better, I was hoping you would do a head after you posted the block pictures, and now im really quite excited to see the results.

 

Your are sure serious with that grinder there Brian.
Do you plan on cutting up one type of the VW 16v head?

 

yes the 6a as it the most common casting, i think.., shes all cut every possible way i could picture in my head that anyone will ever need pictures of and its painted up too.
Measurements all down on paper now, just having a break then ill be setting up photoshoot.

 

Come on...

I REALLY want to see these

 

36 pictures on the way round lunch time, sorting and watermarking is taking an age, plus the fact that i want to kill the man that designed vista.
You will not be disappointed.
I dident get to bed at all, i thought of 2 more cuts which display even more, so down to the workshop i went at 5.30, cut them and then had to repaint again to ensure its all perfect.
no hanging around on this job.
ill put a link in here but theyll be hosted in a new thread in this(16v) section.
i wont get any measurements posted until this eve as the rabbits are starting to take over in my head, but its for a good cause.

 

Maximum respect

 

heres a picture to keep you going till then

(delete that after lunch )