'78 GLS rebuild

**Browneye** · 27-07-2015, 06:14 PM

Originally Posted by sports racer

Isn't the AAD motor normally an 8v? I thought you couldn't fit a 16v head to any 8v block?

I've got KR, 9a and a ABF head but all 3 blocks need a rebore and new pistons. If I can fit the 9a or ABF head to an AAD motor it would make things much simpler.

I know it is possible to fit a 20v head to an 8v block by blocking some oil returns and enlarging another.

I presume the same would be possible if the 16v engines had the same cylinder spacing and head bolt locations. Just put one on a 8v block and it should become clear what needs to happen

**twin eng, twin turbs** · 28-07-2015, 09:41 PM

The AAD is an 8v tall block found in audi a4's. Same as 16v ABF blocks, with piston squirters etc 82.5mm bore 92.8mm stroke. No need to block any oil return ports just a straight bolt on for 16v heads. You need new pistons unless you want 8.0:1 compression ratio.

**sports racer** · 28-07-2015, 11:50 PM

If I need new pistons I'm back at square 1. May as well stick with my 9a and get new pistons for that.

**richo** · 02-08-2015, 11:05 PM

Ported and polished, port matched, combustion chambers cc'd, bore matched, oversized 0.5 mm supertech valves inlet and exhaust

**sports racer** · 03-08-2015, 01:20 PM

So envious!

When will this be back on the road?

**richo** · 08-08-2015, 12:22 AM

Stainless steel 316 flanges and tubing. Titanium thermal wrap. 1.75" primaries 2.3" collector diameter

**mads_christ** · 08-08-2015, 05:05 AM

Great looking headers! Did you make it yourself?

**twin eng, twin turbs** · 08-08-2015, 08:48 AM

I made the headers, they are calculated at 781 mm long along the center line of the tubing from the valve to the spiked merged collector. Using capacity, cam profile and peak power rpm desired to determine the length, tube diameter and collector diameter. The 4 into 1 design is for top end power and i would expect next to no gain over the standard manifold and down pipe below 4000 rpm it flows quite well. The best extractors i have seen tested (tectonics tuning) on an otherwise standard 16v abf gained 7 hp, i would be happy with that. The worst i have seen were ashley 4 into 1 gaining 2hp...