1.8L 16v rebuild first time

[jasonp]

Hi all,

I have raced my 1.8L 16v fro the past 3 years in Canada and I am rebuilding the motor over the winter. I am no stranger to working on my chassis/brakes and I have taken the tranny off and reinstalled it after. I am not afraid of taking the motor out as I am meticulous and will label all the connections for reattachement, etc.

My goal is to improve the motor's (1.8L 16v) performance by boring over 0.040 and whatever other items I can address to improve performance within our regulations (which are WCMA but these are basically a copy of SCCA rules adapted).

My intention is to remove the engine and perhaps strip it down if this is a procedure that I can accomplich within my own garage. Any and all machining would be done professionally and if reassembly proves too complicated, I plan to get my mechanic involved.

What I am looking for is any advice you may have and reference materials that would be applicable to this rebuild. I am currently using a Bentley manual.

Thank you and I will keep you posted as to the success of my operation. :unsure:

Jason, 1987 GTI IT-2 (ITA) race car. www.crankpantz.com

[shwah]

You may find that .040 pistons are harder to find and thus more expensive. That money may be more productive if spent elsewhere on other details. Don't be afraid to go with the .020 pistons.

Certainly have the machinist blueprint/balance within the ruleset - match the lightest stock parts, balance the rotating assemblies.

Also upgrade harware - ARP rod bolts and head studs are a good idea.

Have the machine shop check the compression ratio and move it up to the allowed 10.5:1.

Obviously new bearings and rings should be part of the process.

[jasonp]

I have a very relavent question to ask...

What is the overall gain of a 0.040 overbore? Is it really worth a rebuild or should I just wait until the rebuild is necessary and focus on other aspects of the car? Perhaps a good set of headers? I currently have a 4 into 2 into 1 setup.

Thoughts and expriences on this topic would be helpful as well.

I am running a close second at Gimli Motorsports Park and would like to pass into first. Its a well sorted Honda :bash_1_: CRX that I am racing against.

[Bill Miller]

I have a very relavent question to ask...

What is the overall gain of a 0.040 overbore? Is it really worth a rebuild or should I just wait until the rebuild is necessary and focus on other aspects of the car? Perhaps a good set of headers? I currently have a 4 into 2 into 1 setup.

Thoughts and expriences on this topic would be helpful as well.

I am running a close second at Gimli Motorsports Park and would like to pass into first. Its a well sorted Honda :bash_1_: CRX that I am racing against.
[/b]

You'll get a net increase of 44cc of displacement (1825 over 1781). That's just shy of a 2.5% increase in displacement.

[joeg]

Theoretically, an overbore raise your compression too.

[pfcs49]

all things being equal, it would-however Kolbenschmidt, et al, lower the deck of the piston commensurately to keep CR the same.

[Sandro]

If you think you are capable of doing it then you most likely are. I rebuilt my 16v about a year ago, with the help of my bentley and thats about it. Basically what ever you take out goes back in the same way. What I would recommend is if you have a digital camera take pictures. I took pictures of which way the pistons face, which way the rods go and everything, and I also made notes of the simplest things. I knew I wasnt assembling it the next day and its easy to forget small things a while down the road even though they seem like common sense when taking it apart.

One thing to note is I think its the #3 bearing on the crank has an oil groove all the way around(double check when you take it apart) make sure it goes back in that bearing number, my brother can tell you what happens if you dont. At his 2nd race the engine completely seized, and the crank was toast along with the bearing. The bentely slightly mentions it but does not make as big of a deal as I think they should.

Not sure if it is allowed in what you will be running but if you can balance the intermidiate shaft definately do it. Someone showed me a video of what it looks like on a laith at a much slower speed and its scary to think thats rotating inside your engine. Im sure when you take your engine apart you will find bearing pieces in the oil pan and then look and the bearing from your intermidiate shaft it will be toast, its a common problem with 16v's

[Eric Parham]

Something to watch out for, whether you do the whole engine or just the head, is the resulting compression ratio. The VW 16V engines seem to have come with anything from 10.1 to 10.4 compression, but our rules state 10.0 since that's what's in most of the literature. That means the IT limit is 10.5. If you think you've got 0.5 to work with but realize too late that you've only got 0.4 or 0.2, you may have just made a potential IT head and/or bottom end into a street-only piece. In general, you *might* be able to shave the head 0.5mm *or* the block 0.4mm, but sometimes less and never both. Not sure if this could legally be salvaged with a thicker head gasket...

EDIT: Here's a useful link: http://www.not2fast.com/turbo/compression/compression.shtml