boost higher than normal

[cndctrdj]

chances are the cat is bad....

also, what are your exhaust cat temps

 

[sx sonic]

Most unfournate, hope you get it resolved quickly.

I don't see how a post turbo exhaust restriction would increase boost. If the turbine slows down so does the compressor and thus its flow/psi. Maybe the added heat at the turbo from the cat? That would explain why it would go up after each shift, more heat to the turbo more power.

Just curious

 

[cndctrdj]

Most unfournate, hope you get it resolved quickly.

I don't see how a post turbo exhaust restriction would increase boost. If the turbine slows down so does the compressor and thus its flow/psi. Maybe the added heat at the turbo from the cat? That would explain why it would go up after each shift, more heat to the turbo more power.

Just curious

its actually very simple. boost is a measure of restriction.

so when you have a cat that is no good, the air going into your engine through your turbo and head and .... hits the cat and slows things down. creating.... more back pressure which is measured as boost.

on the stock system your computer will let it spool way up to a designated (16psi stock) to get the correct tq readings. when you have a big exhaust and intake and cams and all this stuff. your car will get to that hp rating at a lot less boost so it will choke the system to keep things in check.

when the car is tuned the safety is taken off and the car is allowed to spool to whatever in most cases 22psi for this car.

now take that 22psi in the car and add way too much back pressure you will see boost rise out of control... kind of a rushed answer but hope it helps a bit.


really what we should all be looking at is cfm pushed by the turbo and what the head and exhaust will flow thats a more accurate way of looking at things but they dont make a cfm gauge that i know of

 

[BNRacing]

It's possible to see more or less depending on altitude and all. Take a data log of it please and send it to datalogs@badnewsracing.net or fill out a ticket at badnewsracing.net/datalogs

 

[Jeraime1741]

Got to get a new boost guage.....when i shift i hear the little needle peg the stopper in the 20 psi boost guage...hehe kinda gives u a tingeling sensation...hehe...ordered full tune so ill be able to let u know how much better it is vs the budget

 

[ras42tbss]

Got to get a new boost guage.....when i shift i hear the little needle peg the stopper in the 20 psi boost guage...hehe kinda gives u a tingeling sensation...hehe...ordered full tune so ill be able to let u know how much better it is vs the budget

not sure where you were going with this....? i don't have the budget tune, so i already know the tune's full potential...

but anyways, i did data log and sent in using BNR's service ticket site. i haven't recieved anything back yet in a week so i'm guessing it's nothing too extreme to worry about. i did flash back to stock though and will leave it like that until i hear further...

 

[JohnT]

yes it is an autometer mechanical gauge and it does set at 0 with the vehicle off. i'm going to data log and send it in just to be sure. when i ordered the tune i was straight piped, not cats or muffler, and specified this, but since it sounded horrible i later threw on a magnaflow muffler and the catted dp back on.

thanks for all the replies though!

Boost creep can be from a few things, but assuming the tune is good, failure of the wastegate acutator or overloading the wastegate are usually the cause (as thats what is responsible for keeping things in check).

I've run into issues with overloading the stock wastegate on a garrett t25 and t28 turbo when running a large free flowing exhaust and no cats. The solution is to port the wastegate itself or move to a divorced external wastegate setup. I wouldn't be shocked at all if it was possible to overload the internal wastegate with free flowing exhaust.