increase horsepower??

[blkfordsedan]

^ ah, HA! well, with that info, we can make B1 engines!!! and then boost the crap out of them.

but IIRC the CRANK journals are the same?

Haha! I like the way you think :p Yes, it appears the crank journals (at least the diameter) are all the same between the B3, B6, the old GLC 1.4 and the 1.5.. I wish I had a bunch of these different engines laying around to experiment on.

BTW- since you have some B6 SOHC experience, do you have any idea what the factory compression ratio was on the first gen ('89 tracer/323) or what the chamber sizes are on a stock head? Reason for asking is: I cc'd my head last night and consistently came up with 38.5 cc combustion chambers. I know I lost a little material when I ground the wall back around the intake valves, but I can't imagine it adding more than about 1cc at the max....I cc'd my pistons (5cc dish) and calculated the compression ratio.........and came up with 8.78:1:eeeeeek:
If the factory CR was only 9:1 then it's probably about right. If the factory CR was 9.2:1 or 9.3:1, then I have an issue somewhere. I used .041"X80mm head gasket and .021" deck clearance (guessed at this). I need to mock up the short block, measure the actual deck clearance and figure out what I can take off the block. I really wanted to be over 9:1 using the FMS cam.

[FestYboy]

i believe the deck is closer than that, but there were 2 different compressions for the 1st gen B6 (manual and auto trans). you'd want the auto trans varient as it had the 9.4:1? ratio (i'm very positive the autos had the higher ratio, but i may be off by a tenth...) the manual had 9:1. you can easily run a "0" deck on a B6. currently, i have a .020" shaved head for just under 10:1 on Scrappy.

[blkfordsedan]

Hmm...somethings not making sense. My motor was from a tracer. No idea if it was ATX or MTX, but most likely the lower comp if there was a difference. The only thing they could change was the piston dish or comp height, and I only saw one offering from anyone. I compared the new pistons to the factory ones, and they're identical. I don't think I can get to 9.4:1 even at zero deck...let alone even close to 10:1. I can't believe I took that much material out of the chambers, but maybe I did. If so, I guess I have a good turbo head, LOL. The head gasket from Rockauto is like .060" which is even worse. I'll have to mock up the rotating assy and measure the deck clearance. Maybe with a better gasket and some block decking I can get over 9:1. The machinist can't remember what he took off the head, but said it was probably just enough to surface it. The chambers are pretty small in cross-section, so milling the head doesn't help a lot.

[Zanzer]

The machinist can't remember what he took off the head, but said it was probably just enough to surface it.

So probably .003-.005". You can go a good bit more than that. Deck that sucka! (the head not the machinist LOL) :mrgreen:

[Zanzer]

Edit per B6 rods and pistons:

I can't exactly remember if the B6 rods are the same in regards to beefiness as the B6D and B6T, but I seem to recall them all being the same (I'm 9hrs away from the parts pile since moving to NJ ). I do remember that the D and T rods are the same and will interchange with the B6. The B6T pistons are quite different though since they have a much lower compression ratio for the turbo. However, the B6D (and T) use pistons with floating wristpins so the D's are a nice little upgrade for the B6 SOHC if you find a cheap set on Ebay or a FS section somewhere.

[blkfordsedan]

Well, look who showed up..................Where you been?

I decided to disassemble the head and take it back for some more milling. I checked the head with a machinist's edge before I took it in the first time, and it was maybe .002" out at max. I told him I wanted it milled .020" to offset the material I ground out of the head, but I'm guessing he only took it maybe .005". I'm thinking I'll have him take another .010"-.015" off. I estimate it should reduce the chamber volume about .90cc for every .010" milled off the head, based on the chamber area. Depending on where I end up on deck clearance, I'll have the block decked as well. Milling .010" off the block should equate to ~1.21cc reduction on a 78mm bore. I wish I would have cc'd the head before I worked it over!

[blkfordsedan]

Anyone know what the recommended "safe" limit is that the head and block can be milled?

[FestYboy]

0.020" is considered safe. and the head gasket may be 0.060, but what's it's compressed thickness? you need to account for that as well.

[blkfordsedan]

I'm estimating .051" compressed for my calculations. Not sure how accurate that would be, but the used (crushed) factory gasket that came off the engine measures about .0515". I figured .010" crush is feasible and the used gasket should be fairly close to the installed thickness. I think I'll spend another $20 and buy a good Felpro PermaTorque gasket. They advertise .039" installed and I'm sure is a better gasket anyway. If I can reduce even .010" by simply switching gaskets, that's a pretty significant gain.....even better than decking the block by .010" since the gasket bore is 2mm bigger than the cylinder.

With everything combined, (remill head, deck block to ~.005" clearance & new gasket) I think I can get up to around 9.4:1. It will cost me another $150, but I think it's well spent if I can go from 8.8:1 to 9.4:1, be assured of a better head-to-block seal and get better exhaust evacuation.

[blkfordsedan]

Just spoke to an engineer at Felpro. He said the gaskets available for my application are "factory" thickness, which is .057" compressed! Even Cometic shows over .050".

Anyone know where a guy can get a thinner gasket? I'm wondering if a MLS gasket from a gen2 B6 like a B6ME or B6D would fit a 1st gen B6? I think someone said the oil return passages are different?

[Zanzer]

Well, look who showed up..................Where you been?

New Jersey

Anyone know where a guy can get a thinner gasket?

You could try a solid copper head gasket. They make them for Mazda engines and some are as thin as .022". The only problem is that when using gaskets below a certain thickness they recommend o-ringing the block. But on the positive side they claim a .010" change in thickness nets around 2.5cc in volume.

[blkfordsedan]

FestYboy was correct. The factory deck clearance is .003". I did a mock-up and measured with both my dial indicator and a machinists edge/feeler guages. No point in decking the block for .003" unless I want to go above deck and protrude into the head gasket bore. Not quite ready to go that drastic yet.
I don't think I want to mess with a copper head gasket at this point. I'm calling everyones tech line, trying to find the thinnest one. Felpro claims most composite gaskets will only crush about .005". Seems everyone sticks to factory spec or thicker on OHC engines, probably due to cam timing issues.

[Movin]

Never heard of this but i wonder if you could take the
metal compression rings from a regular head gasket
and put them on the thin decking shims made to restore
stock head height after surfacing the head, they were made
to go in addition to the head gasket.