I have JDM B18C gsr all stock besides the intake mounted to a b16 s4c tranny. This is in a 2000 civic Si. I was curious if an average of 30 miles to the gallon is good for a b18c. Also I was curious if getting good gas mileage means you more than likely have good to average compression. I ask thy cause I haven't done a compression test yet and didn't know if good compression is related to good gas mileage

 

it is actually. when compression goes down the engine is less efficient. engines have the best mpg with leakdown under 5%

30mpg is right on the money. chances are when you compression test it the numbers will be even

by the way, don't use those adapter tubes to do a compression test. numbers will be off

 

Thanks for the info race bum. Out of curiosity when I bought the car it had 130k miles and I thought it had the stock b16 in it but I didn't bother to check the engine stamp cause the b-series all look so similar. I bought the car from a Toyota dealer so I didn't figure to much shady business compared to a side auto dealer. But I now know a lot more about the car. The engine is a 1994 JDM B18C SiR-G. I was curious on what you thought the mileage might be on it compared to where the chassis is at (130000) and where the last owner might have swapped the b18c in. I know this would be just a complete guess but thanks if you can give me your best guess.

 

who knows. also did you check the cylinder head for the date casting?

a healthy jdm it engine will read 255lbs of compression. the gsr version has a touch less compression....would think 235-240 would be reasonable. ideally you want to see all 4 read the same.

 

P72-2 93 is what the first number is

 

is the date casting a different number than the one right underneath the valve cover above the header?