xr4tic

I just cc'd my combustion chambers. Here are the results:
#1: 42.2cc
#2: 42.4cc
#3: 42.6cc
#4: 42.2cc

Piston dish: 8.2cc

I measured #1 and #4 twice, and got the same results, so I'd say it's pretty accurate.

I measured the dish on the pistons while they were in the motor. I did two of them and got 8.2cc and 8.6cc, but the second one had some water leak under the grease seal, so I'm sticking with 8.2cc

Margin of error should be about +/- 0.2cc (the buret was marked off in 0.2cc increments)

The head gasket measured in at 3.244" x 0.048" This is a volume of 6.5cc
I measured the used head gasket, and clamped down on the calipers hard, so it should be a good idea of compressed volume.

Calculating CR:
cc #1: 42.2cc
piston: 8.2cc
gasket: 6.5cc
total: 56.9cc

Swept volume: 445.2cc

CR = (445.2 + 56.9)/56.9 = 8.82:1

The largest chamber (#3) is 8.77:1

The best case scenario (w/margin of error using cyl #1) is 8.88:1
The worst case scenario (w/margin of error using cyl #3) is 8.71:1

Quite a ways off from the specs that say 9.5:1

Also, this head on a 2.0 block (assuming same piston dish volume) would give a 9.6:1 ratio.
Hmmmm.....


I had to edit the numbers, apparently I don't know how to read a buret I remeasured all the volumes.

carace

Do you have the complete APR clutch setup and did it just start to slip bad? I have only got 5,700 miles on mine and now it will not hold any gear higher than 1st. Did you attribute you failure with abuse or do you consider your situation premature for wear? Just curious. There are not many options out there.

xr4tic

I bought mine used with about 5K miles on it from Todd Candey, no burn spots on it and the clutch looked good.

It held fine, then started slipping. And got worse. It has about 10K miles on it now. I wasn't real abusive on it, and most of my miles were highway.

I sent the flywheel to APR to have a new insert put in it, I just got it back, but no bill yet (should be around $100)
The clutch I'm gettin is from Werks of Art. Juan says he has a setup just for the APR flywheel.

carace

<center><img src="http://home.attbi.com/~carace02/Passat/intakeport.jpg"></center><p>on my third one counting the stocker. Anyone know where to get valve guides for these heads? Dealer told me you can't even buy them. I have two spare heads and all the need now is valveguides and seals and they would be ready to go. Here is the final product of my head's weight reduction. I had a local shop do it as I was chicken to try myself. Link is for the preporting to show how much material was removed to gasket match.<ul><li><a href="http://home.attbi.com/~carace02/Passat/preport.jpg">http://home.attbi.com/~carace02/Passat/preport.jpg</a</li></ul>

smallTTs

1)Is piston above block deck @ top dead center? It would have to be about .03 in.(.8 mm) or so to find those missing 4.4 cc's. Possibly pistons are down in the block, which would make CR even lower.

2) Has this head had a valve job? If so, valves could be sunk down into head giving you the 42.2 cc instead of 38 or so. That would be a lot of sinking though.

Maybe a combination of a valve job and negative deck height (piston out of block a tad)?

Mirror|rorriM

A better way to check your compression ratio would probably be to use a compression test and calculate it from that.

xr4tic

You would need less volume to get a higher compression ratio. Losing 4.5cc would get you a 9.5:1 compression ratio.

The pistons were checked at TDC

You could probably get about 1.0cc if you decked the head 0.010" But I'm not sure how far you'd want to go for fear of the pistons hitting the valves

I' not so sure the lower compression is a bad thing. It is on the stock turbo, but for a big turbo kit, it's probably better.

CMH

Yes it would and I will be testing mine this week.

dingster

you have based on how well your rings/head gaskets/valves are sealing. All engines will leak a bit and varies from engine to engine. You don't run a compression test to get exactly how much compression you have but to compare it to a known baseline. How do you get reliable compression ratio based on that? The best way to calculate the ratio is to CC everything and do the math.

swett

My stock clutch is slipping already. I did a hard 1-2 shift the other day and the engine jumped to 7k in 2nd immediately. It never even grabbed. A little scary. I'm glad I let off the gas in time. Even in gear, it seems to be having problems holding the torque at higher RPM's.

I'm favoring the Sachs Sport clutch, but I'm curious how long the Werks of Art clutch lasts. It must be possible to get enough holding power for these cars without going to a puck-style clutch. There are certainly cars out there with more power than ours.

-Ian