Did my boost go up when

[Daniel Young]

I was just wandering if my boost pressure went up when I did a few upgrades and if/or what I can do about fuel cut? Ihave a greddy electronic boost gauge on its way through fedex, so I can't read boost yet. But anyway I added an Injen race division cold air intake and a Apexi 2.5 inch cat-less downpipe with mil eliminator. The engine is definitly running better and my car is faster. The blow off valve is much louder, yet it does want to hesitate in the high revs in 2nd, 3rd, and 4th gears. Fuel cut still doesn't hit until around 7000rpm to 7500rpm. Does anyone have any ideas about boost and how to fix the hesitation? Oh and I have had it flashed at the dealer.

 

[505zoom]

Welcome man, what color did you get?

Check out the search button at the top of the page for your hesitation question, it is quite helpful sometimes.

About the boost, I don't think that a DP and intake will make it actually rise above stock levels. You might have faster spool up times with those mods, but you probably will not see any rise.

 

[Speedplease]

its funny that you say it wont raise the boost with a down pipe. I had a tech mag put out by SCC and they put a down pipe on a stock 91 Talon TSI and it raised the boost by 5psi they actually ended up hitting the fuel cut and had to install a FCD just to run with the down pipe. do you know why it wont raise the boost in our cars?

 

[Dr.Sound]

in our cars the DP will raise the boost maximum 1.5 psi.......no more than that.
mine went up 1 psi with a 2.5 inch DP. it might be a little more with a 3 inch.

intake will not change boost levels.

i dont think u're hitting fuel cut because of the raised boost, it's cause u rev so high. it's not vtec engine, our peak power is not at the redline.

is your car flashed?

 

[speedfrk]

at that rpm it sounds like the rev limiter not the fuel cut.

 

[Micah]

you really shouldn't need to rev that high, these engines produce their torque much lower.

Are you ignoring 4th, and 5th or just trying to hit 140mph in 5th?

 

[Brian MP5T]

The boost is set by the wastegate. The turbo might spool faster but the wastegate will still open at "Max Boost" wherever that may be for your car.

A boost controler can change when the wastegate opens, and thus will allow you to raise the boost.

Later...Brian

 

[505zoom]

its funny that you say it wont raise the boost with a down pipe. I had a tech mag put out by SCC and they put a down pipe on a stock 91 Talon TSI and it raised the boost by 5psi they actually ended up hitting the fuel cut and had to install a FCD just to run with the down pipe. do you know why it wont raise the boost in our cars?

Thats strange. The wastegate is what controls how high you boost. Without changing the way that the wastegate operates, you will not see an actual gain in boost. I'm not AS familiar with the 91 TSI, but +5psi from a DP doesn't sound right to me at all.

Brian is right on here:

The boost is set by the wastegate. The turbo might spool faster but the wastegate will still open at "Max Boost" wherever that may be for your car.

A boost controler can change when the wastegate opens, and thus will allow you to raise the boost.

Later...Brian

 

[Brian MP5T]

DANIEL YOUNG ---

If you would like to research this for yourself or if you are new to the Turbo thing, I would recommend that your first mod be a Book.

Maximum Boost by Corkey Bell. It won't add HP to your car but it will add HP to your understanding of the physics involved in a turbo system and will answer all questions you have.

 

[Daniel Young]

I would still like to know if maybe a s-afc or a similar system might be able to fix the hesitation. I've read in another forum that they don't want to work on the MSP. I also have a fuel pressure reducer i could install, but I figured that since I had it flashed I wouldn't need to install it. Your right it probably is the rev limiter thats hitting, but i still want to get rid of the hesitation, its annoying as hell.

 

[03MSP]

I have always heard that a bigger exhaust will add psi...but it doesn't make sense..now I am confused because Brian pointed out that boost is regulated by the wastegate, which is true, so how do people think DP's raise boost levels??

Every time I learn something on this board, I see just as many other people say the opposite thing.

 

[Dr.Sound]

i will bet money that on MSP downpipe adds 1psi

 

[505zoom]

I have always heard that a bigger exhaust will add psi...but it doesn't make sense..now I am confused because Brian pointed out that boost is regulated by the wastegate, which is true, so how do people think DP's raise boost levels??

Every time I learn something on this board, I see just as many other people say the opposite thing.

Well maybe it could go like 1psi higher as Dr. Sound is suggesting, but I doubt 5psi on any car with a wastegate. And even then, I can only see it SPIKING to a higher psi than it did before, not holding there. Having a less restrictive DP allows the turbo to spool faster which in turn could cause the boost to go slightly higher before the wastegate opens. However, without adjusting it or tricking it with a BC, it will open at the factory preset psi.

My boost spikes a tiny bit more with my mods now, but it has always run maximum 6psi in any gear after the needle settles.

 

[prospeed]

well on my last car witch had alot of mods when i removed the cat i jumped up 12psi over stock with no boost controller. car was also bored 68 thousands,ported intake,portedhead,ported exhaust manifold and a small mitsu tdo4. the wastegate could not flow enough air to regulate boost once i removed the last restriction the cat.

you will not have this problem but i can see a slight increase in boost around 1 psi or so.

 

[tiwing]

If you have a boost controller: Boost will jump when installing a better flowing downpipe. In speaking with the owner of Essential Speed, the PSI on their 03.5 jumped from 10 to 15 after installing a 3" DP ...

If you don't have a boost controller: turbo should spool faster but won't show any increase in boost UNLESS the wastegate can't flow enough air, in which case boost will keep increasing.

 

[Dr.Sound]

no boost controllers and boost went up 1psi on all 4 MSP's that we did that day.

 

[Brian MP5T]

After reading the last many posts, I will say this...

It will spool faster. This is the reason you want a High Flow exhaust system to begin with. This is the Point...

However, the wastegate determines where the turbo stops spooling faster by dumping the extra (Waste) exhaust. If your car makes 5 or whatever more psi of boost after a simple DP install, then I figure the wastegate isn't opening far enough or it is inadequate for the size of the motor that you are running.
The original post was "Did my boost go up?"
I say Not Likely, but it might feel faster because the turbo makes boost faster (Less Lag). Can we at least agree on this? There is so much misinformation on this board.

Later...Brian

 

[505zoom]

After reading the last many posts, I will say this...

It will spool faster. This is the reason you want a High Flow exhaust system to begin with. This is the Point...

However, the wastegate determines where the turbo stops spooling faster by dumping the extra (Waste) exhaust. If your car makes 5 or whatever more psi of boost after a simple DP install, then I figure the wastegate isn't opening far enough or it is inadequate for the size of the motor that you are running.
The original post was "Did my boost go up?"
I say Not Likely, but it might feel faster because the turbo makes boost faster (Less Lag). Can we at least agree on this? There is so much misinformation on this board.

Later...Brian

(werd)

Dr. Sound- You say that the boost went up on 4 cars. I am not doubting this, but I have a question: Was the boost SPIKING 1 psi higher, or was it maintaining 1 psi higher??? I agree with Brian here that unless the wastegate is inadequate for the increased state, there should be no change in when it opens. The wastegate is the number one factor in how much boost your car will maintain.

 

[RX-KEVIN]

I have melted the valve on the external w/g in my RX-7 coming back from OBX cause I was wot for almost an hour or so (speed enforced by aircraft my ass)

 

[Brian MP5T]

I have melted the valve on the external w/g in my RX-7 coming back from OBX cause I was wot for almost an hour or so (speed enforced by aircraft my ass)

Thats a b**** man, I bet it felt really powerful if that valve locked closed.

Later...Brian