overboost question?

[smkshow]

i asked this before,but going to ask again,a little differently....what would be a sign of overboosting,besides hitting cut off?....ive ran up to 13psi,with 94 octane gas,off road lodgic module,seems like it was fine.....shouldnt it start pinging like crazy or somthing,or would it just melt a piston with no warning?..thanks...

[ZachT]

i think overboosting has to do with the map sensor (manifold pressure). and if its a stock 'style' logic module with a 2 bar map (2 bars=2 atmospheres, 1 atmosphere=14.7, so 14.7hg-vac, and 14.7 boost) so when you would overboost, you would be hitting 14.7psi or more, and your engine will kinda,,shut down, stay running, but just cut you off, then if you try it again, so will your computer. a 3 bar map sensor allows you to run up to 29.2 psi before your computer gives you the ole....

AND.....again cuts you off.

and remember, you cant just throw in a 3 bar map sensor if you computer doesnt know about it, it'll freak on you.

at 13psi and 94 octane id say your probably not melting your motor, if you hear detonation id say back off, and check your plugs every so often.

zach

[88jbody]

the computer just thinks 14.7 is overboosting...I think 14.7 is a good low boost setting

[smkshow]

low!?.....lol,hopefuly no one takes you seriously....

[88jbody]

Quote:

Originally Posted by smkshow low!?.....lol,hopefuly no one takes you seriously....

daily driving I am running 15-16 psi on a t3/t4 50trim and we still have snow and once my fuel pump and 3 bar map are installed it will be up to 25psi (well and once snow is gone)


the ONLY sign of over boosting is the computer cutting it off.(over boost is just limited by the car electronics)

I have to ask why are you asking this question is there anything that makes you think you are hitting it when you should not?

if you are having driveability issues, missing ect at lower boost levels then that you have something wrong that needs taken care of.

and the reason for that is because that is the maximum the computer and map sensor can read and adjust for. the stock boost setting of lower then that was to keep cars reliable and lower warranty repair costs.


now a stock turbo is no longer very efficiant much over 14,15 psi, but can and will run at 20psi or a bit more, all day long if you change the nessesary things to allow to fuel and run that boost.

at this point turbo timming becomes much more important for turbo life. and you really want to make sure your engine is mechanical sound before pushing the envolope to far.

I started with a stock t1 car, and gradually built it up to 22 psi no waste gate daily driven car. on a engine that had 290,000 kms on it. it finaly dies at 310,000 kms and that is when I put in a stock t2 engine with the big turbo a ported head.

[smkshow]

the reason im asking is,im running 10-11 psi,car runs awsome,no issues at all,i had it as high as 14psi,(never hit cut off yet)its stock,exept for the off road comp.,i was just wondering what the signs would be when the boost is to high,somthin to listen for,so i dont blow somthing up....im happy with it set at 13psi,scared to keep it there though,i usualy keep it at 10psi when daily driving,but you say you set yours at 15-16psi?....if you had my car,what would you run it at?.....

[smkshow]

and hey,too bad about the flames.....

[88jbody]

well you will not be able to run to much really on a stock computer if it still limits the boost to a max of 14.7.

I would run an intercooler and you'd be fine up to just before the boost shutoff in the computer. even a stock intercooler off a t2 would do.

yeah flames have to be one of the most inconsistant teams ever.

[smkshow]

ha!.......the nucks take that crown!!...thanks for the info....