compression on a 1g

[Browniebrown]

Ive searched the forums and didnt find an answer. Im sure its on here but im borrowing a compression tester from a friend tomorrow and wanted to know what the compression should be at. its a 90 laser turbo. Also i did see someone put there results on a dry and wet test. Im new to all this so what is the difference and what should it be on the dry and wet. The car has 105000 miles but it only has about 20,000 on the block. I know im coming off as someone that know nothing but i have owned dsms ive just never done this kind of stuff to them. I used to be someone that just paid to have it done but now I really want to learn and do everything myself. Thanks this site has been a life saver so far.

 

[hotrodssnova]

Your Haynes or Chilton book should give you some service limits. Is it a stock build block?

 

[NeMiZiS]

Compression ratio 7.8:1
Standard compression 164 psi
Service limit 121 psi

 

[Texas_GST]

The compression specifications will vary somewhat based on altitude but the specs given are a good guideline. I'm sure you know how to perform a compression test so what I can tell you is the difference between a dry and wet test. Make sure the results you get on each cylinder are consistent on the number of compression "hits", which are each time the needle fluctuates with each compression stroke. For example I usually do at least 8 compression strokes per cylinder. Also, be sure to remove all 4 spark plugs for best results. Now for the wet test, add 1 teaspoon of oil the cylinder you are testing. The results are going to be higher than the dry test due to the oil providing additional sealing of the rings to the cylinder wall. You are checking for any drastic differences between cylinders to help identify possible problems. I haven't had to do this on a DSM so I can't tell you the limits but generally no more than 10% loss between cylinders is acceptable.

 

[JusMX141]

Ive searched the forums and didnt find an answer.

This opening statement never ceases to amaze me. I'm pretty sure I could search the forums on here for details regarding the ban on commercial whaling in the Antarctic and come up with at LEAST one thread that discusses 4G63 compression results.

http://www.dsmtuners.com/forums/cylinder-head-short-block/445756-compression-test.html

http://www.dsmtuners.com/forums/newbie-forum/448062-compression.html

http://www.dsmtuners.com/forums/mai...53-tsi-compression-test-results-question.html

http://www.dsmtuners.com/forums/newbie-forum/37538-compression-test.html

http://www.dsmtuners.com/forums/newbie-forum/454881-compression-low.html

http://www.dsmtuners.com/forums/maintenance-repairs/456022-compression-leak-down-results.html