two dumb questions? :)

[Hesh724]

got some manley 85.5mm pistons installed a little while ago. so i guess stock bore size is 85? i cant remember weather they were 8.5/1 or the 9.0/1s' so is a .5 mm bore anything at all? also i cant get my small 16G to go above 10 psi? and will a bore of .5 affect my compression at all? im wondering if these symptoms are related? Low boost, low compression due to bore? fresh valve job and fresh pistons that were checked during valve job. passsed leak down test to.
Please give any insight!!

 

[Aproductions]

I don't know too much about engine builds, but as for the s16g...are you using a MBC? & did you check for boost leaks?

 

[1gDSM4g63]

The bore doesn't have anything to do with the compression piston. As for your boost there probably is a boost leak.

 

[92redtsi]

Stock bore is actually 85.5mm so your pistons are stock bore. Did you get your block honed when it was rebuilt?

But I'm betting your boosting problem is from something to do with your turbo system. So as Aproductions said do a boost leak test and what do you have as far as boost control/

 

[Hesh724]

thats a bummer i was hoping the bore was a help. But ya it was honed and stuff and dude said he would have to bore it a little for the pistons. but im just using my wastegate as my boost control. they said my pistons seal and my valves are good and said my compression is good told me like low 100's but then i read how high it is really supposed to be. but then i watched them do a compression test, and all they did was the screw the guage in the cylinders one by one ofcourse and turned the engine over with the key, and turn it off as quick as possible. i have read this is not the proper way to do a cylinder comp test? but the car is fast as hell and sounds like it has alot of compression so i am not sure if any thing is wrong with it.but ya so the bore isint much huh? darn and i will have to go to the hard ware store and make a bst leak coupler
thanks for the answers!! oh and can someone verify factory piston size lots of others are saying 3.346457 in stock size.when 85.5 millimeters = 3.36614173 in which is a .019 diffrence is this thecnincaly .020 over for sloppy tolerance?

 

[EclipseTical]

thats a bummer i was hoping the bore was a help. But ya it was honed and stuff and dude said he would have to bore it a little for the pistons. but im just using my wastegate as my boost control. they said my pistons seal and my valves are good and said my compression is good told me like low 100's but then i read how high it is really supposed to be. but then i watched them do a compression test, and all they did was the screw the guage in the cylinders one by one ofcourse and turned the engine over with the key, and turn it off as quick as possible. i have read this is not the proper way to do a cylinder comp test? but the car is fast as hell and sounds like it has alot of compression so i am not sure if any thing is wrong with it.but ya so the bore isint much huh? darn and i will have to go to the hard ware store and make a bst leak coupler
thanks for the answers!! oh and can someone verify factory piston size lots of others are saying 3.346457 in stock size.when 85.5 millimeters = 3.36614173 in which is a .019 diffrence is this thecnincaly .020 over for sloppy tolerance?

there is your answer regarding your boost not going above 10.

 

[Hesh724]

so its the wastegate? is it not working i guess 15 psi is stock i bet im not correct with that ? but i took out the bcs restctitor too. i have a slowboy mbc but i am afraid to put it on i dont want to blow my motor but now i want more boost!!!

 

[EclipseTical]

read the bold print in the quote grasshopper before you start with the smart-ass responses...

you have no MBC and are controlling your boost via the wastegate... Hint: What psi does the wastegate open at?n

 

[Hesh724]

I just didnt get it at first with the quote . but ok so now i will check to see what the wastegate is set or stock then i will see about putting the mbc on. and do you think it would be easier to install the mbc? or adjust the wastegate? thanks