Talon12bp

i have a friend that gets 4 psi in 1st gear, 6 psi in 2nd and 8 psi in 3rd, where it pulls hardest.
Is this typical of turbocharged hondas? or cars in general.
i thought you would get Full boost once the RPMs were in the turbo's range and i thought it didn't matter what gear u were in.

If the gears are short, can 1st gear only give a certain amount of boost. and then later gears result in more boost since more time is spent in those later gears?
I dunno, its just odd how my friends turbo LS civic. boosts 4 psi in 1st, and 8 in 3rd.
someone explain?
Thanks,
Bryan

RedTegLS

I just had mine out for the first time this afternoon. Almost 9psi every gear.

stierhund

yeah does seem odd, but maybe its because w/the motor under more load and the taller gears it causes the turbo to take longer in higher gears and produce more boost (plus the fact that after a shift there is still an addition of pressure in the manifold to add on)

Bailhatch

I have a d16z6 w/ little t25. my boost builds up to about 5.5K in every gear then drops one or 2 by redline

1st 7max
2nd 8
3rd 9
4th 9-9.5
5th 9.5

It's cool though, it's just traction control for my massive WHP YO!! i figure about 390ish you know straight junkyard gangsta powa!

kpt4321

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by stierhund &raquo;</TD></TR><TR><TD CLASS="quote">(plus the fact that after a shift there is still an addition of pressure in the manifold to add on)</TD></TR></TABLE>

Dumbest thing EVAR. No.

First gear may be a little lower because it is so short, but from then on, any variation beyond a fraction of a PSI is not right. A difference of 1 psi from second to fifth might be reasonable.

stierhund

take this for example, if in first gear your wastegate stays open through the entire gear, and then when u shift to second it closes in order to put all pressure on the turbine... in that case there is no pressure to add to when u goto second

first gear is a shorter gear, and because of that it doesnt have enough time to produce enough airflow... so the impeller does not produce as many cfms as it would compared in a taller gear under more load

do u not see what I said?

quikB18B

Something is wrong with your friends car

I get the same consistent psi in every gear, granted 1st is short, i get full boost at 4100 and it repeats same psi in every gear.

Only times ive seen that big of change is in the bigger hp guys who run the gear dependant boost controllers.

I can see maybe a guage reading low in 1st gear if you spin like crazy and hit the rev limiter and shift, but the other gears should be the saem if not very close.

Kwuaymaikrup

What turbo is he running? I have heard of cars not reachig full boost until 3rd gear. I beleive it has to do with the fact that there is less load on the engine in the lower gears. Just my .02

-Ryan

kpt4321

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by stierhund &raquo;</TD></TR><TR><TD CLASS="quote">take this for example, if in first gear your wastegate stays open through the entire gear, and then when u shift to second it closes in order to put all pressure on the turbine... in that case there is no pressure to add to when u goto second</TD></TR></TABLE>


Ok, what is your point? What is this crap about "adding" pressure?

The wastegate is open when you are at full boost, and a little below that. When you lift to shift, boost drops, so the wastegate closes. That's about as advanced as "spark plugs make sparks." However, you fail to say anything meaningful.

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote &raquo;</TD></TR><TR><TD CLASS="quote">
first gear is a shorter gear, and because of that it doesnt have enough time to produce enough airflow... so the impeller does not produce as many cfms as it would compared in a taller gear under more load
</TD></TR></TABLE>

Shut it with trying to be technical. No more of this impeller CFM ****.

First is to short, that there is not a lot of engine loading, and thus not a lot of exhaust gas volume. It also is so short that you may not have time to build full boost.

stierhund

dude, its not my problem... u attacked a point and are busy pounding me like u know me... its not my fault if u cant understand what im sayin... if a word as simple as "adding" makes no sense then im sorry I cant find a way to make u understand

and u dont have to explain how a wastegate opens to me... I was using an example that isnt really possible w/air pressure wastegates, I was saying it to clarify my original point

and thanks for clarifying the last quote, u are such a genius

have a good one

Chillinit

does ur friend have a boost controller??

kpt4321

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by stierhund &raquo;</TD></TR><TR><TD CLASS="quote">dude, its not my problem... u attacked a point and are busy pounding me like u know me... its not my fault if u cant understand what im sayin... if a word as simple as "adding" makes no sense then im sorry I cant find a way to make u understand</TD></TR></TABLE>


WTF? No, it doesn't make any sense, because you haven't explained it yet. Maybe if you could stop freaking out and sit down and type up a coherent sentence explaining what you are trying to say, we could figure it out.

What do you mean, adding? Explain it.

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote &raquo;</TD></TR><TR><TD CLASS="quote">
and u dont have to explain how a wastegate opens to me... I was using an example that isnt really possible w/air pressure wastegates, I was saying it to clarify my original point

and thanks for clarifying the last quote, u are such a genius

have a good one</TD></TR></TABLE>

WTF again? "Isn't possible with air pressure wastegates"? That is the only kind of wastegate there is, what are you talking about.

You said that the wastegate would be open at WOT, and then would be closed when you shifted. That is all correct, but how it bears any relevance, nobody knows.

Of course the wastegate is open when the boost is up, and closed when the boost is not all the way up. What does that have to do with anything?

sporkcrx

kpt4321 &gt; stierhund

stierhund

I need to stop freakin out? you are the one who came at me first

by adding I mean there is already positive pressure that was produced in the previous gear, so that makes sense that the fella who brought up this topic was seing more boost in higher gears from a 1st gear start

there are electronic wastegates that are activated by set pressure transducers, I was making an example with the wastegate, what I said does not happen unless u use an electronic wastegate and dont want to boost in first or whatever gear, what it has to do with anything is that I was making an example

am I still not making sense to u?

im not tryin to freak out, sorry if I came out that way, but u coulda picked a better way to ask me a question

avex

what's an electronic wastegate?

Lucky_Smurf

Sounds like a bad problem. It's not that unusual to not hit full boost in first gear until later rpms or not at all. Some engine will actually out accellerate a turbo. Causing you to approach redline before max boost is built. However this doesn't sound like the case with your friend. I'd get him to check all his vacum lines and check his boost controller. Try adjusting it and see what he gets. Also try each gear several times before shifting to see if the response is the same. Pull in 2nd back it off pull again. Is it the same? Do the same in third now, does it still jump?

ekb18c

It all depends on the size of the turbo. He may not hit full boost on all gears if the turbo is a big sucker.

kpt4321

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by stierhund &raquo;</TD></TR><TR><TD CLASS="quote">
by adding I mean there is already positive pressure that was produced in the previous gear, so that makes sense that the fella who brought up this topic was seing more boost in higher gears from a 1st gear start
</TD></TR></TABLE>

Wrong. First of all, there is not positive pressure if you lift to shift. Second of all, if there was, it doesn't just "add" on to your boost pressure. Do you have any knowledge of basic chemistry/physics? If not, I would be happy to explain this to you.


<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote &raquo;</TD></TR><TR><TD CLASS="quote">
there are electronic wastegates that are activated by set pressure transducers, I was making an example with the wastegate, what I said does not happen unless u use an electronic wastegate and dont want to boost in first or whatever gear, what it has to do with anything is that I was making an example</TD></TR></TABLE>


Electronic wastegates?

Making an example of what?

Even with air pressure wastegates, what you said is true. However, it still doesn't have any relevenace to the discussion at hand. The wastegate opens at full boost, and closes when boost drops. Yes. So?

stierhund

When you shift and the throttle plate closes, then opens not all the pressure is removed by the blow off valve. I am sure most ppl try to shift quick when they are gunning it. How does it not add? Is it not pushing a flow of air on top of a already active force of air that has barely been purged? If you dont understand what I am saying then fine.

I explained what electronic wastegates are. Its an electric valve in the same positions as a wastegate would be however it is not opened until a pressure transducer closes the switch.

I was saying that if u had one and used it to keep pressure off the turbine then that would make a shift to the next gear have to build up completely from a vacuum.

I agree w/others saying its the size of the turbo. The fact that an engine does not rev as high as it needs, and doesnt output as much exhaust (displacement) would make it hard to gain boost unless the impeller already had force going.

kpt4321

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by stierhund &raquo;</TD></TR><TR><TD CLASS="quote">When you shift and the throttle plate closes, then opens not all the pressure is removed by the blow off valve. I am sure most ppl try to shift quick when they are gunning it. How does it not add? Is it not pushing a flow of air on top of a already active force of air that has barely been purged? If you dont understand what I am saying then fine.</TD></TR></TABLE>


Well, thank you prove answering my question; you really do have no knowledge of thermodynamics, or even basic chemistry.

Pressure is caused when you have a lot of stuff crammed into a small area (or, more generally, when stuff hits other stuff). In a car with a turbo, that pressure is caused when the turbo throws more are at the motor than it can injest. The air will stack up, and pressure is created (it's a bit more complex than this, but...). Now, when you shift, the airflow drops off, so pressure drops. When you get back on the gas, if there is a little pressure left, that means that there is a little air left packed into the intake system. When the turbo starts jamming stuff into the intake manifold, it will just have to jum a little less because of the stuff that is "left over."

A wastegate works by opening when the desired pressure pushes down on a membrane and moves the actuator. If you set this to 8 psi, it will open and limit boost to 8 psi every time, regardless. It doesn't know anything about "adding" or "leftovers," it just knows that it has a force of 8 psi pushing down on it.

Pressure does not add, ever.


<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote &raquo;</TD></TR><TR><TD CLASS="quote">
I explained what electronic wastegates are. Its an electric valve in the same positions as a wastegate would be however it is not opened until a pressure transducer closes the switch.</TD></TR></TABLE>

1: Does ANYONE on here use one of these? No, so therefore who cares.
2: Was it relevant to the question? No.

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote &raquo;</TD></TR><TR><TD CLASS="quote">
I was saying that if u had one and used it to keep pressure off the turbine then that would make a shift to the next gear have to build up completely from a vacuum.</TD></TR></TABLE>

If you don't shift fast, then you always have a vacuum. Most people don't shift fast enough to keep the car out of vacuum, even if you shift really fast, when you close the throttle plate a vacuum happens almost instanteneously.

Going by your theory of pressure adding, what happens if someone running 8 psi shifts without lifting? They keep 8 psi the whole time, would the 8 more psi in the next gear add on and ive you 16 psi? Ummm, no.


<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote &raquo;</TD></TR><TR><TD CLASS="quote">
I agree w/others saying its the size of the turbo. The fact that an engine does not rev as high as it needs, and doesnt output as much exhaust (displacement) would make it hard to gain boost unless the impeller already had force going.</TD></TR></TABLE>

Nope. Let it be known now, that IT IS NOT THE SIZE OF THE TURBO.

If the car was laggy in just first gear, then it could be because the turbo was too big and he was not getting to full boost. However, he specificially said that the boost increases in EVERY gear! That can't be lag, unless he has a turbo the size of a barn and he can't even get full boost after 20 seconds in fourth gear.

The problem UNDOUBEDLY lies within the boost control system, either the boost controller, the boost controller's setup and source, the wastegate, or the wastegate entrance or exit area.

stierhund

Are u think headed enough to think that when I say add I mean take the 8 psi the shift was made at, and add the capable output of the turbo afterwards?
You are trying your hardest to completely ignore what I am saying.

You cant add pressure... WTF?

Then what makes it harder for a turbine to turn? When you turn your air compressor at home off and come back the next day and plug it up because it leaked a little.... is that not "adding"?

Me talking about the electronic wastegate was relevant to the case, I was using it as an example to make you see what I was saying.

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote &raquo;</TD></TR><TR><TD CLASS="quote">...when you close the throttle plate a vacuum happens almost instanteneously.</TD></TR></TABLE>

how does the vacuum happen so instantaneously with a plate completely closed, and the only way the engine can get air is by pulling it past the IACV, and the plate bypass. Doesnt make much sense to say it would happen that quick? It is being channeled away from the intake manifold, and then the surge that was caused by that opens the BOV.

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote &raquo;</TD></TR><TR><TD CLASS="quote">If the car was laggy in just first gear, then it could be because the turbo was too big and he was not getting to full boost. However, he specificially said that the boost increases in EVERY gear! That can't be lag, unless he has a turbo the size of a barn and he can't even get full boost after 20 seconds in fourth gear.</TD></TR></TABLE>

Of course its gonna increase in every gear, but thats because the turbo is being worked more under the cars moving load and time. And its because the first few gears of load werent enough to give the turbo time to create pressure.

I dont see how the problem lies in his boost controls. That doesnt sound very likely that it would increase in every gear for any reason other than the increased time because of each gears load.

kpt4321

You said that, for example if you had 2 psi left after the shift, plus 6 psi that the turbo was making, would be 8 psi.

I said that, what if you had 6 psi left after the shift, which is entirely possible if you don't lift. Would you get 12 psi? NO!

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote &raquo;</TD></TR><TR><TD CLASS="quote">
You cant add pressure... WTF?</TD></TR></TABLE>

If you have a can that has 4 psi of air pressure in it, and a can that has 6 psi of air pressure in it, and you connect the two cans, they are not going to add together and make 10 psi. They they form an equilibrium around 5 psi in both cans.

Not only that, but you fail to comprehend that boost is a CONTROLLED pressure! The wastegate controls boost based on manifold pressure, so it's ALWAYS going to end up at or near the same peak! If it goes higher, the wastegate opens more, and the boost goes down.

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote &raquo;</TD></TR><TR><TD CLASS="quote">
Then what makes it harder for a turbine to turn? When you turn your air compressor at home off and come back the next day and plug it up because it leaked a little.... is that not "adding"?</TD></TR></TABLE>

First of all, a compressor at home is different, because it is a closed system.

However, let's think about this. The compressor is not outputting a set pressure! It is just shooting air molecules into the tank, and as the number of air molecules increases, the pressure increases. The compressor is not "blowing" a certain psi, it is just blowing air.

Let's say that you set the compressor's motor to shut off at 8 psi (which is very similar to what a turbo does with a wastegate). You fill the tank, it goes to 8 psi, and then the pump shuts off. You come out the next morning, and the pressure is down to 6 psi. So you turn the pump pack on, it goes up to 8 psi, and shuts off again. The pressures do not "add," the compressor just has to do less work because they is some pressure remaining in the tank from the day before.


<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote &raquo;</TD></TR><TR><TD CLASS="quote">
how does the vacuum happen so instantaneously with a plate completely closed, and the only way the engine can get air is by pulling it past the IACV, and the plate bypass. Doesnt make much sense to say it would happen that quick? It is being channeled away from the intake manifold, and then the surge that was caused by that opens the BOV.</TD></TR></TABLE>

If a 1.8 liter motor is spinning at 6000 rpm, and you shut the throttle plate, what happens? You have 90 liters of motor trying to fill with air EVERY SECOND! What happens when you try to pull 90 liters of air per second through the plate bypass and the IACV? You get a manifold vacuum really ******* fast.

Have you ever owned a turbo car, or any car with a manifold vacuum gauge for that matter? Go out and floor it, and then lift off the gas completely, all at once. The manifold drops into vacuum almost instantaneously, ANYONE with a vacuum gauge can assert to this.


<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote &raquo;</TD></TR><TR><TD CLASS="quote">
Of course its gonna increase in every gear, but thats because the turbo is being worked more under the cars moving load and time. And its because the first few gears of load werent enough to give the turbo time to create pressure.</TD></TR></TABLE>

So you are saying that a full third gear pull isn't long enough for a turbo to create the desired pressure? What you just described was a turbo that lagged to redline and took more than 6 or 8 seconds to reach full boost at over 5000 rpm. NOBODY has a turbo like this. You get full boost within half second at WOT, and by 4000 rpm.

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote &raquo;</TD></TR><TR><TD CLASS="quote">
I dont see how the problem lies in his boost controls. That doesnt sound very likely that it would increase in every gear for any reason other than the increased time because of each gears load.</TD></TR></TABLE>

Boost does not just go up and up as time goes on!!

Boost jumps up to the value you have set in the boost controller, and then the wastegate keeps it there until you lift.

You you ever even owned or ridden in a turbo car and watched the boost gauge? It doesn't take much time for boost to build.

****, I'm sure you could find a video of a boost gauge somewhere.