Tweet
As has been posted in my sig, I've been "working on" a B6 SOHC swap for about a year, LOL. The original B3 suffers from excessive blow-by and about a year ago I purchased a B6 from a local salvage yard that I was told "ran good". The plan was to simply install new seals & gaskets and perform the swap in a weekend. Unfortunately, changing jobs and more of life's issues kept me from progressing any further until this fall. When I finally got around to installing the new seals, the J/Y B6 showed some signs of poor maintenance. The decision was made to tear it apart for closer inspection, and what I found was disturbing. The cylinders were packed full of carbon, the oil & compression rings were all stuck and the oil appears to have been "cooked". The piston skirts were worn and the main journals on the crank were worn out-of-round. On the plus side, the block had zero taper, the cam journals in the head were acceptable and the rod journals on the crank were perfect. Plus, parts & machinework for a SOHC B6 are pretty cheap.
I spent a weekend just cleaning up some parts, and the block & crank have been delivered to the local machine shop. The block will be honed ($20), the mains ground -.010" and the rod journals polished ($50). Although I could re-use the original pistons, I will be installing new ones. The originals would be "acceptable" with new rings, but they are wore enough that they may develop some noise at cold-startup. I may decide to over-bore it as well, depending on the cost of machine work. 1mm+ new pistons cost the same, and the increased compression and reduced exhaust valve shrouding would be of benefit. Evenings this week will be spent porting the B6 head, after which it will go to the shop for a 3-angle valve job and milling. I already have a new FMS Comp spec cam that will be installed, and I'll be running a B6 ECU, injectors, intake and exhaust manifold with cat-less exhaust.
The initial goal is to have between 90-95 HP @ crank, while retaining good street/highway manners and mid-30's MPG. All this must be done on a budget of about $300 to $400. I'll post some pics and updates as the assembly process begins.
I spent a weekend just cleaning up some parts, and the block & crank have been delivered to the local machine shop. The block will be honed ($20), the mains ground -.010" and the rod journals polished ($50). Although I could re-use the original pistons, I will be installing new ones. The originals would be "acceptable" with new rings, but they are wore enough that they may develop some noise at cold-startup. I may decide to over-bore it as well, depending on the cost of machine work. 1mm+ new pistons cost the same, and the increased compression and reduced exhaust valve shrouding would be of benefit. Evenings this week will be spent porting the B6 head, after which it will go to the shop for a 3-angle valve job and milling. I already have a new FMS Comp spec cam that will be installed, and I'll be running a B6 ECU, injectors, intake and exhaust manifold with cat-less exhaust.
The initial goal is to have between 90-95 HP @ crank, while retaining good street/highway manners and mid-30's MPG. All this must be done on a budget of about $300 to $400. I'll post some pics and updates as the assembly process begins.
. On a positive note, the Dremel actually works pretty good for delicate work around the valve seats and is slow enough that it won't get you in trouble by removing more material than desired. One of the things I noticed about the Intake runners is that the short turn radius, although not a 90 degree shoulder like in the Exhaust, is still pretty short. When you consider the design of the combustion chamber and the way the Intake port is skewed, it starts to make sense. A short radius tends to cause the air flow to "ramp" off of it, toward the opposite side of the valve, at higher flow rates. If you look at the following pic, I noted the location of the short turn radius in red. You can see that this corresponds to being directly above the valve shrouding (aka swirl dam) in the chamber. When you add the port direction/skewing, you can see the intent was to bias the air flow toward the opposite side of the cylinder (notated by blue arrows) and thereby causing mixture swirl. A little swirl is a good thing...it improves mixture, fuel efficiency and emissions. In this particular case however, we're giving up about 30% of the available valve flow area as a trade-off.
). 
Comment