will performance exhuast over rev the turbo?

[gsrtype1]

someone told me that less backpressure helps the turbo spool faster.... byt this will over rev the turbo and ruin the turbo?!!!!is this spike and boost creep?? is this true???!!!(friday)

 

[knowledge007]

what...never heard of any of that. There is no way you will ruin the turbo, but yes you will be able to rev a little higher than normal. Trust me, your turbo will thankyou for widening the asshole....(boom05)

 

[SwampAss]

It's called boost creep. The air capacity is too great to make it through the waste gate and instead goes through the turbo. It slowly raises your boost as revs climb. Esp in higher gears.

edit: This is a general term. I don't know if it applies to the MS3 with a turbo back/CAI.

 

[gsrtype1]

some guy that used to work at an exhuast shop said that guys with big desiel turbo trucks would take off there mufflers for more power and would over rev the turbo and in 5 to 10 thousand miles the turbo housong was ruined

 

[knowledge007]

Well that could be caused by a few things... But first, we do not run deisel which you already know. Second, taking off the mufflers really doesn't give you any hp. Just makes the sound a bit different. Only way you are going to gain hp with an exhaust is by widenening the diameter and getting rid of your cats and or replacing cats with high flows. Other wise its pointless. Third of all, only way you are going to melt away housings and seals is if you do not COOL THE TURBO DOWN. Meaning you must let the turbo cool after after hard pulls before shutting off the engine.

 

[gsrtype1]

thanks for the info!, i like the sound of cpe so much im saving for the catback, and i always!! wait for atleast 20 seconds before shutting off the engine to let the turbo cool down

 

[gsrtype1]

swampass cool stickers on your hood!!!! those oz wheels are sweet too

 

[matsuda]

someone told me that less backpressure helps the turbo spool faster.... byt this will over rev the turbo and ruin the turbo?!!!!is this spike and boost creep?? is this true???!!!(friday)

Yes, less backpressure will cause the turbo to spool faster.

Since the ECU is controlling the boost pressure, lowering the backpressure without changing the wastegate control parameters may cause the turbo to "overspin" and shorten its life considerably.

 

[gsrtype1]

so how come no one talks about this?????????!!!!!!!!!!!.

 

[SwampAss]

so how come no one talks about this?????????!!!!!!!!!!!.

It may not be an issue with the current set ups for the MS3. Boost creep is no big secret. I am wagering that people who are putting out turbo back exhausts are designing them with this in mind. If they sold exhaust systems that grenaded turbos, they wouldn't be selling them for long.

 

[dread]

just don't get anything bigger than a 3" diameter and you will be fine.

 

[Scott]

It may not be an issue with the current set ups for the MS3. Boost creep is no big secret. I am wagering that people who are putting out turbo back exhausts are designing them with this in mind. If they sold exhaust systems that grenaded turbos, they wouldn't be selling them for long.

AEM sold their little add-on mid-pipe filter to prevent the CAI from sucking up water. This little unit was known to fall apart and get sucked into the engine, causing severe damage in many cases. AEM KNEW THIS and did nothing for almost 2 years.

And that is only ONE example. Aftermarket companies, and even car companies CONSTANTLY sell parts that they know are of poor quality, yet continue to sell them anyway. Why? Because it's all about making the $$$. In the case of a larger diameter exhaust causing boost creep to prematurely fry a turbo housing, it's not an overnight thing. It merely speeds up the process of a turbo's aging process. If your turbo gives way after 2 or 3 years of having the exhaust on, when most people are getting 5 or 6 years out of a turbo, you're more likely to think you had a bad turbo. Odds are, you won't rationalize that the exhaust had anything to do with it.

 

[justa4banger]

WHOA.............. Where i the **** do you guys come up with this garbage?

Boost creep is caused by the wastegate hole not being an adequate size for the turbo. boost creep happens when you run a bigger turbo with a small wastegate or with a small internal gate. For instance my 50 trim turbo won't hold lower than 15psi in 1-3 gears, in 4th it goes to 18psi. WHY because the internal gate is only 28mm in diameter and it can't bleed enough air to slow the turbo. So the exhaust keeps spooling the turbo. If i ran a 40mm tial external gate i could control the turbo down low.

THERE IS NO WAY IN HELL YOU CAN HAVE BOOST CREEP WITH THE MS3's SETUP. the turbo is too damn small besides a manufacturer wouldn't install a turbo that could possibly hurt the engine.

next i don't care if you run a 5" DP off the turbo............. theres no overspeeding it UNLESS you raise the boost to say 24psi and runs the revs above 7k with a 5" dp , since the turbo is able to breath easier you might overspin the turbo, MIGHT. If you can read a compressor map, you'll notice most maps also have a rpm scale across the top of the map. higher pressure ratios require more RPM.
just adding a cat back exhaust or even a turboback exhaust in 4" diamter or 3" won't hurt anything PERIOD...

Yes, less backpressure will cause the turbo to spool faster. (TRUE STATEMENT)

Since the ECU is controlling the boost pressure, lowering the backpressure without changing the wastegate control parameters may cause the turbo to "overspin" and shorten its life considerably. (FALSE STATEMENT)

The wastegate gate parameters are easy, keep the boost at these levels, 15.6 psi or what ever in each gear. the ECU says i want 10 psi in first the solenoid controls the wastegate according to how much pressure is in the intake, VIA map sensor or whatever MAzda has. I don't care if you run a GT-40 turbo off the back of the MS3 motor, IF the wastegate is ADEQUATE to control boost pressures down low, then the solenoid controling the actuator will work as advertised in conjunction with the ECU. It will maintain 15 psi or what ever the ECU requires.
Now with that comment made, say you did instal a gt-40 turbo (In theroy) and tried to drive the car around and get the same power level as stock. It would only need maybe 10-12 psi to get the same output as the stock turbo. WHY? because of the volume of air........ the bummer is the tubo wouldn't come on to boost til 5k +.

Long story short, Added turbo back or cat back exhaust to the tock turbo and keeping the turbo at stock levels of boost , will not hurt anything.


For the record not trying to slam anyone, but there seems to be alot of guessing on what turbo's really do and how everything works with them. Just trying to set the reocrd straight.

 

[justa4banger]

Well i'm not going to change my post, but i guess it sounds kind of harsh... either way i just want to share my knowledge. i have learned the HARD way.
My SVO has has 3 full exhaust systems installed, 3 turbo's (first 2 times were the same turbo), 3 different exhaust manifolds, 2 different intakes, 2 sets of injectors and i have rebuilt everything ATLEAST twice........... name it i have tried it (except meth injection thats next). Not cause it needed it, mainly for improvements. I went from making a measly 230whp and 320 trq at 20 psi to making 324 whp and 380wtrq on 25 psi. they say general rule of thumb is 10 hp per psi, so how did i get almost 20 per? worked on making the engine more efficient and better flow.

 

[matsuda]

WHOA.............. Where i the **** do you guys come up with this garbage?

[misc. garbage truncated]

The wastegate gate parameters are easy, keep the boost at these levels, 15.6 psi or what ever in each gear. the ECU says i want 10 psi in first the solenoid controls the wastegate according to how much pressure is in the intake, VIA map sensor or whatever MAzda has. I don't care if you run a GT-40 turbo off the back of the MS3 motor, IF the wastegate is ADEQUATE to control boost pressures down low, then the solenoid controling the actuator will work as advertised in conjunction with the ECU. It will maintain 15 psi or what ever the ECU requires. WRONG

Just trying to set the reocrd straight.

Please don't spread misinformation based on your total ignorance. You obviously have no experience or background in closed loop control system theory or operation.

On the MS3, the ECU controls the boost pressure in a closed loop system. Do you really think that the ECU waits until the target boost pressure is reached before it starts to close the WGA solenoid valve? (lol2) That is not how a closed loop system operates. There are MANY parameters used by the ECU to control the action of the wastegate. The target boost setting is only one of them.

Here is an example (courtesy of Cobb Tuning) of what happens when exhaust back pressure is reduced without adjusting the WGA control parameters:

CAUTION!!! DO NOT RUN ANY Stage1 CALIBRATION WITH ANY TYPE OF HIGHER FLOWING DOWNPIPE OR TURBO-BACK EXHAUST ON YOUR 2007 WRX. THE Stage1 CALIBRATION HAS VERY HIGH WASTEGATE DUTY CYCLE SETTINGS TO TRY AND BRING BOOST ON AT LOWER RPMS WHEN USING THE
MORE RESTRICTIVE, STOCK EXHAUST SYSTEM. THESE SETTINGS WILL INDUCE SEVERE BOOST SPIKING AND WILL OVERSHOOT THE SPECIFIED BOOST TARGETS CAUSING BOOST SEARCHING. THESE BOOST SPIKES CAN CAUSE ENGINE DAMAGE. IF YOU HAVE A HIGHER FLOWING DOWNPIPE OR TURBOBACK EXHAUST SYSTEM ON YOUR 2007 WRX, PLEASE REFLASH THE APPROPRIATE Stage2 CALIBRATIONS.

Note: SEVERE BOOST SPIKING AND OVERSHOOT as a direct result of reducing the backpressure
This is exactly what I warned the OP about when the exhaust backpressure is reduced. Of course the MS3 is not a WRX but it uses a virtually identical closed loop system to control the boost pressure.

The MS3 ECU also uses somewhat aggressive parameters for wastegate control to get fast spooling. I have logged boost "spikes" of 3 PSI over the target boost setting on a MS3 with just a testpipe. The overshoot would potentially be much greater with a full turbo back system or an open downpipe.

You can always learn something new, right?

 

[matsuda]

so how come no one talks about this?????????!!!!!!!!!!!.

Because very few people understand the operation of the ECU and the wastegate control system.

 

[TheMAN]

regardless of all the technicalities no one in this thread seems to care about, the only time you're going to "over rev" the turbo is if you have the wastegate shut close (like welded shut if you're stupid enough, or your wastegate actuator just jammed/broke)... and guess what? your engine will blow before the turbo does!

 

[matsuda]

regardless of all the technicalities no one in this thread seems to care about...

I would like to think that not everyone prefers to remain ignorant. Some people really do care about how things actually work. How about yourself?

 

[iracemine]

subin for more info.

 

[justa4banger]

I do stand corrected and i do understand why the Wastgate would be affected. Mainly due the aggressive tuning of the solenoid control to bring in boost as fast as possible, with free flowing exhaust the turbo would reach its optimum sooner causing the boost spikes.

Makes sense.

i don't have these issues with my old car. set the boost on the gauge and just drive. i do get variation depending on the gear, but no more than 1-2 psi 1-5th gears.

this could be controlled by bypassing the solenoid with a MBC, though i dunno how the car would react with that idea......... Would definetely fix the boost spikes.