There are some continued differences between the Sport Quattro KW engine block and the 3b. Mostly it deals with integration to the rally components and the chasis, which means even doing an equivalent 1-1 swap of the block only involves considerable changes,enough to basically wonder about what Audi was doing back in the 80s when they pulled SQ motors for iron blocks.

The list of changes so far.
1. The oil pan is different. The Sport Quattro casting has a section towards the front which has been cast out of the pan to allow room for the front lower aluminum tube crossmember. All those folks who bought up those crossmembers for use with their cars are SOL without the SQ oilpan.
2. The SQ oilpan uses an internal baffle piece that is mounted between two oilpan gaskets. This sheetmetal piece follows the lower swing of the con rod journals. The oil pick up is different because of this piece too. Also the SQ has one additional bolt from the oilpan into the block whereas the 3b has one bolt location different than the SQ.
3. The SQ motor mounts do not flush up to the iron block on the driver side. The block casting protrudes into the motor mount. Need to grind away part of the block.
4. The front hydraulic pump mounting bracket on the SQ engine interferes with the engine block. Need to cut off an iron tab on the lower front of the block.
5. The heatercore drainback line is 90 degrees on the SQ to clear the different straight tie rods from the steering rack.
6. Different pilot bearing like most later 20v engines. The SQ crank uses an older sytle pilot bearing.

So far those are the only changes. Next step is to put the head on the car and hook everything back up. All the crank seals and major gaskets are the same.

The full A2 were able to get down to about 1000 Kilos with an aluminum cage. I have a steel cage and still have my steel rear fenders and a steel exterior door skin rather than 100% kevlar. So I'm totally guessing at 1150 kilos.

<center><img src="http://pictureposter.audiworld.com/84174/audicarlislerally.jpg"></center><p>I imagine there are a SQ's with broken KW engines needing to know how to do what you are doing.

I know that Colin has wondered about this, and has hunted for the elusive alum block rumored to have been made for non-SQ cars.

Also, check my response to your piston pictures with the comment about my luck with Swain coating.

I just recently have been reading posts on this site, and will post that great picture of you and RS2urq from Carlisle 3 years ago!

Hope all is well, some day will see you on a track up north! Come to one of our ACNA events, VIR is awesome!

Your technical expertise and accept any challenge is awesome.

Phil

meddling with my car's engine on the weekend.

Martin, I'll PM you.

I'll be weighing mine soon, but I have a feeling it's WAY heavier. Like to have a goal in mind. ;-)

No spare, empty, no tools.

I still am contemplating replacing some of the rear glass with Lexan. I think Bruno kept the back end a bit heavy for a reason.

I need to weight it and get it below 1106! Even if i gotta drill out bolts to make them hollow.

I suspect if the rear is a "bit heavy" there's a reason for it. Bruno was the type to research everything to the nth degree. I remember getting into a discussion with him on the dry sump on his 911, and it was a lesson in attention to detail.

Besides, you've already got way more HP than I do!

The Coupe is 1165 BTW.

Sometimes it almost seems Bruno added weight to the back of the car. He mentioned to me once that he didn't like the short Sport Quattro because the back end didn't swing out like his 911s used to.. And summarily, he seems to have taken even greater effort than Audi to lighten up the front of the car. Drilling out the Skidplate, the hood and parts of the unibody. Hollow bolts to mount the driving lights!

So yeah (I was just joking about the weight issue) I have contemplated adding Lexan for the glass though as I think that would be worth it, and ultimately if I add GroupB fenders I'll have to remove the steel rear quarter panels.

bore of 79.5mm. I think some early 5000s without turbos had such an engine. That would have to be the donor block for such a project. I was lucky in that with standalone I can use whatever CR and displacement I can get my hands on. The only issue appears to be the head gasket, block deck to cylinder head issue(using a 81mm head gasket on a 79.5mm bore engine).

But when you start running out of things to cut or drill, you start adding weight to the rear to balance it out.

Have you checked the weight front-rear? Curious.

GroupB rears? I like that idea.

Always need references for spares.

Someone? should start a such a list. I know a few people who are making a part here or there. Be nice to know who's doing what. Although I think anyone who's maintaining one of these probably has the know-how to get creative and make it themselves.