VW A1 head question - 1.8 rebuild

[Joe Craven]

I had my first VW engine problem this weekend. The odd thing is that the failure sounds much like the one reported by Ministocker in this thread

http://forums.improvedtouring.com/it/Forum...TML/000306.html (http://forums.improvedtouring.com/it/Forum12/HTML/000306.html)

I've been running this completely stock 1.8 motor for several years including one 12 hour enduro. Motor was running strong, oil consumption low prior to the head problem.

The good news is that I will need to install a fresh head on this motor. The cocked bucket sluffed a lot of aluminum in the motor and I'm sure some of it made it's way to the sump. Oil pressure is still ok - should I worry too much about the lower end after I remove the pan and clean it all out?

I have an local engine rebuilder that I like to use (he's good and actually found some compression calculation errors on my last motor and called me before he machined it wrong). What things are worth asking him to do past the normal head rebuild that might help me get a few more ponies. I can do the exhaust and intake 1" port matching but I wonder if it helps on these motors. My lower end is bone stock, even std pistons. How much can I mill the head to raise the compression .5CR?

Thanks - Joe
#37 ITB VW

BTW, the new suspension seems to work great! I lost it in the 3rd corner of warmup and almost hit the wall due to cold tire temps and much stiffer springs with underdamped shocks. The car is now very balanced with a touch of oversteer in right handers with the tires at operating temp.

[racer_tim]

Joe, with all of the shavings in the motor, the best thing to do is rebuild EVERYTHING. Replace the oil cooler, have the crank balanced/polished, install new bearings, and have the block overbored 0.40 and get the .040 pistons. If you going to do it, do it right.

On the head, get a quote from him as to how much additional it would be to port match 1" into the head and manifold? Also, make sure that he is familiar with the GCR and the IT rules. You can normally do your own 1" port with a dremel, grinder, and some wet sand paper. It does take some time though.

I've got a motor if you want to run the Aug 1-3 Reg/Nat.




------------------
Tim Linerud
San Francisco Region SCCA
#95 GP Wabbit (Bent)
http://linerud.myvnc.com/racing/index.html

[Joe Craven]

Thanks for the offer Tim. In any case, I've been spending waay too much money this year. Doing it right is best, I just can't afford it right now.

OK, I'll change the bearings, oil pump etc. I'll do a leakdown test to determine the condition of the rings. If they appear worn, I'll do the right thing. Is the oil cooler before or after the filter?

The Aug 1,2,3 was going to be a difficult weekend since it coincids with my daughter's birthday. I'm going to take that weekend off (saving a few $$ and keeping the family happier) and plan to return Aug 23,24 at Infineon.

#37 ITB VW

[Joe Craven]

"New" used head is in the shop. Getting new guides, springs etc. 1" port match.

How much should I have milled from a completely stock "virgin" 1.8 head?

[Eric Parham]

Mill the 1.8L head as little as possible (preferably none) to keep the "lip" on the chamber intact.

[Joe Craven]

I did some calculations that estimates that .017 off a stock head will raise the compression ratio to close to 9:1. Of course, I had to estimate what the head gasket thickness will be (measured old one) so I might go with .015 to be safe.

Eric, what is this lip? Is retaining this lip better than gaining a .5CR increase?

Thanks guys - Joe
#37 ITB GTI

[Eric Parham]

Joe, I can't say for certain whether keeping the lip would compensate for 1/2 point of lost compression. It's sort of like comparing apples and oranges. My *guess* is that keeping the lip is actually better, overall. But, if you can find any other way to get the max allowed compression without hurting the lip, you get to keep the benefits of both. No reason to compromise when you don't have to http://Forums.ImprovedTouring.com/it/smile.gif

P.S. -- The lip I'm talking about is the slight concavity in the chamber, extremely close to the gasket surface. Easier to feel with finger than to see. Unfortunately, some heads don't even have all 4 lips straight from the factory.

[This message has been edited by Eric Parham (edited July 29, 2003).]

[racer_tim]

Joe, if your coming to Laguna Seca this weekend, could you throw in the porta-power? I'd like to "play" with it next week.

Thanks

Tim