Learn me turbo lag

Knurled wrote:

NordicSaab wrote: In my car I am pulling almost 30# of vacuum at idle. The car does not reach atmosphere pressure (0 PSI) until 3500 rpm. after that , watch out because it's time for baby to eat...

Say what

Yes, but....

So is your post questioning the statement, or something for the magazine.

Because the statement is very questionable, to me.

30# of vacuum is pretty amazing. Beyond a perfect vacuum, since atmospheric pressure is only 14#. Even if you were talking " Hg, that's just over one atm for most of the US. So that's not exactly possible.

And then only getting to atmospheric at 3500rpm- what's wrong with your engine? You should be able to get that ANY rpm. That's WOT w/o boost, which is easy to get all the time.

After that, well, it's conjecture.

anyway...

"Say what" in relation to none of those numbers making any sense...

I forgot where I was, and that "Say what" means a different thing here (it apparently means "Please GRM Gods don't post this to the magazine")

In reply to Knurled: thought that's what you meant.

NordicSaab wrote: In my car I am pulling almost 30# of vacuum at idle. The car does not reach atmosphere pressure (0 PSI) until 3500 rpm. after that , watch out because it's time for baby to eat...

Your boost gauge is broken.

On turbo cars the turbo determines at what RPM the engine produces the most power.

Well, besides the rest of your post... this isn't exactly true. A turbo mostly just inflates the numbers on the powerband that was already there. So, if you have an engine that makes peak torque at 4000 rpm and throw on a turbo, it will probably still make peak torque at 4000 rpm. But it may also make the same torque at 2000 rpm as it made n/a at 4000 rpm.

Turbo lag for me lasts until about 7k rpm in 1st gear........dragging the rear brake does help that, but not a lot.

In reply to yamaha:

Its pretty much impossible to build full boost in 1st and 2nd, not enough load on the engine. To prove my point? Put it in 3rd and go wot under 2k and report back to when there is positive pressure.

Yamaha has a few thousand more rpm to work with on his sport bike ;)

A lot of turbo lag can be caused by low octane gas, knock, anti-knock sensors, and the retarded ignition timing that results.

It's not true turbo lag, but the effect on the car is the same. Terrible off line bogging until the rpms are high enough to get out of the knocking range and allow full ignition advance.

alfadriver wrote:

Knurled wrote:

NordicSaab wrote: In my car I am pulling almost 30# of vacuum at idle. The car does not reach atmosphere pressure (0 PSI) until 3500 rpm. after that , watch out because it's time for baby to eat...

Say what

Yes, but.... So is your post questioning the statement, or something for the magazine. Because the statement is very questionable, to me. 30# of vacuum is pretty amazing. Beyond a perfect vacuum, since atmospheric pressure is only 14#. Even if you were talking " Hg, that's just over one atm for most of the US. So that's not exactly possible. And then only getting to atmospheric at 3500rpm- what's wrong with your engine? You should be able to get that ANY rpm. That's WOT w/o boost, which is easy to get all the time. After that, well, it's conjecture. anyway...

Hmmm... I'm a little confused by the responses here.

Car is a '93 Eagle Talon, 4g63, Holset HX35. at WOT in 3rd gear I hit 42 PSI of boost.

Remember these reading are coming from the charge piping. The turbo is very large and the car at idle pulls a significant amount of air through a very large turbo (inline obstruction) which results in the very large vacuum. This is further aggravated by the lack of any type of IAC.

The turbo takes a very long time to spool and boost does not equal = 0 PSI until about 3500 RPM in first gear... as stated in the post.

Here is info about the car if interested (with a boost log): http://www.dsmtuners.com/threads/holset-hx35w-dyno-stock-head-block-606-awhp.490819/

Also the boost log reading are corroborated by the ECU running on speed density and the Boost gauge with separate sensors.

If you don't have experience with big turbocharges I can understand the skepticism.

Now... Get off my porch.

This is gonna be good...

In reply to NordicSaab:

Two things- you started saying that you have 30# of vacuum. Which is 30psi of vacuum. And that's no physically possible- once you get to 14.7, it does not go lower than that. So if you change your reference to inHg, which is a reasonable mistake, then you are trying to say that your car idles with exactly a perfect vacuum, aka, no air at all. That's not going to happen.

Second thing- 0psi is WOT without boost. So I'm trying to figure out why you can't get just atmospheric pressure when there is no boost- if true, that means that the turbo itself is a big restriction. Again, that makes no physical sense what so ever. So you have something else going on that's a problem- having a restriction that is -2inHg is reasonable, but it's also a restriction. It's also not something to brag about- something else is going on.

I know plenty about car, turbos, and massive turbo lag.

I've seen lag that is terrifying- coming on a 191 mph, and spinning the wheels badly on salt.

alfadriver wrote: In reply to NordicSaab: Two things- you started saying that you have 30# of vacuum. Which is 30psi of vacuum. And that's no physically possible- once you get to 14.7, it does not go lower than that. So if you change your reference to inHg, which is a reasonable mistake, then you are trying to say that your car idles with exactly a perfect vacuum, aka, no air at all. That's not going to happen. Second thing- 0psi is WOT without boost. So I'm trying to figure out why you can't get just atmospheric pressure when there is no boost- if true, that means that the turbo itself is a big restriction. Again, that makes no physical sense what so ever. So you have something else going on that's a problem- having a restriction that is -2inHg is reasonable, but it's also a restriction. It's also not something to brag about- something else is going on. I know plenty about car, turbos, and massive turbo lag. I've seen lag that is terrifying- coming on a 191 mph, and spinning the wheels badly on salt.

I have no idea what you are talking about.

having vacuum does not necessarily mean a lack of air. What that means is the engine is pulling a certain amount of air for the purpose if idling and there is significant amount of obstruction. In this instance multiple feet of charge piping, an intercooler, and a turbocharger. This is the same effect when you suck fluid through a straw. Vacuum is created and is present in the straw, but fluid is being transferred from the basin to the drinker.

I would agree that the car would be operating at 1ATM (14.7 PSI) if it were an NA car without a air tight charge system, but this is not the case. There is 30 PSI of vacuum in the charge system because air is being pulled. There is 14.7 PSI outside the system because of the atmosphere at sea level.

I respect your experience, however, I have facts and logs and personal experience of this car and it's behavior. The car is the highest HP 4g63, HX35 car in the country. I would argue this as proof that what I've done works.

In reply to NordicSaab:

Yes, having a vacuum does mean lack of air- it's exactly what it means. Once you get to -14.7 psi at sea level, there is no air left- not a molecule of nitrogen or oxygen to be found. So you car would not run at -30inHG, as there would be no O2 to combust.

Based on your system, I think you have the wrong sensor calibration. That may also shift your WOT w/o boost condition, too.

I'm not saying that your car does not run, I'm saying that the information that it's giving you doesn't make any sense. That's all.

In reply to alfadriver:

As stated before. 2 separate sensors and 2 separate readouts and both corroborate. remember we are talking about the environment within the charge system.

We may be arguing semantics at this point, either way I'm going to tip my hat and walk away from this one...

In reply to NordicSaab:

No we are arguing physics. If you really think you are drawing a 30inHg vacuum, and the car is still running, well, ok. But it's not. No engine in the world will draw a vacuum more than 1ATM, let alone a car engine that has to operate on the remaining O2 in the intake.

Unless you are living on some other planet where the atmosphere is thicker than it is here on earth. So that a -30 inHg would still be +8 or so absolute.

What you are trying to convince me of is why I always ask people to make sure the numbers they are getting make sense.

That's why I think your calibration is wrong for the sensors. It's interesting to see that in the thread you posted, others questioned the reported numbers, too.

alfadriver wrote: In reply to NordicSaab: No we are arguing physics. If you really think you are drawing a 30inHg vacuum, and the car is still running, well, ok. But it's not. No engine in the world will draw a vacuum more than 1ATM, let alone a car engine that has to operate on the remaining O2 in the intake. Unless you are living on some other planet where the atmosphere is thicker than it is here on earth. So that a -30 inHg would still be +8 or so absolute. What you are trying to convince me of is why I always ask people to make sure the numbers they are getting make sense. That's why I think your calibration is wrong for the sensors. It's interesting to see that in the thread you posted, others questioned the reported numbers, too.

Can we just leave it be? We have destroyed this thread and you an I will not come to a conclusion or agreement.

As stated before 2 separate sensors are providing the same reading. Also, as stated on the other forum, I have a unique setup that works very well. I am providing confirmed facts of the behavior of the system on the car.

You are calling this a physics argument, but you are not providing any support. I have logs. I have sensors. You have here-say. Ultimately this is a silly and sophomoric argument I should not have entertained.

Also, as stated before the vacuum is taking place in the charge system. All cars pull vacuum at idle. The old carburetor guys at one point used vacuum as a tuning mechanism and many still do with good results. Why are you so certain that 30 PSI of vacuum is not reasonable?

Guys. You're arguing the same thing with different units of measurement because Nordic keeps saying psi when he means in/hg.

Trans_Maro wrote: This is gonna be good...

Crud, I'm out of popcorn... BRB

Nathan JansenvanDoorn wrote: Yamaha has a few thousand more rpm to work with on his sport bike ;)

Indeed I do, by 14k in first, it has successfully lit the gt3063 and is making over an extra atmosphere.....granted, the back tire is either a molten blob of rubber or your insides feel like you've just been launched off an aircraft carrier at that point.....

MCarp22 wrote: Guys. You're arguing the same thing with different units of measurement because Nordic keeps saying psi when he means in/hg.

Aw come one, you're screwing up a funny back and forth.

I'm going to say Nordic is correct, he just forgot to mention he's driving about 11 meters under water.

MCarp22 wrote: Guys. You're arguing the same thing with different units of measurement because Nordic keeps saying psi when he means in/hg.

It doesn't even matter... 30in-hg of vacuum doesn't exist anywhere except a hard vacuum in Death Valley. Most engines are good to pull 27" at closed throttle and high RPM.

I still am not wrapping my head around what "doesn't build 0psi boost until 3500" means.

In reply to chiodos:

I can build 4lbs of boost at 7k if the rear rotor is glowing....

MCarp22 wrote: Guys. You're arguing the same thing with different units of measurement because Nordic keeps saying psi when he means in/hg.

30 inHg will not run a car, too- there would be no molecules of O2 to burn. None.

Saab- I get that you have a unique car, and that it make a bunch of power. But there is no way on this earth that you will generate 30psi of vacuum, let alone idle at 30inHg. It's not physically possible. Once you reach 14.7 psi of vacuum, otherwise known as 0psi absolute, there's nothing left to take out.

It's great that your car run, and that whatever voltage the sensors are sending the module are being turned into correct pulse widths and voltages to run the car very, very well.

But no matter how unique your car is, it's not going to go against physics.

So check the calibration of your sensors. Make sure that the outputs make sense. Idle will actually be closer to 22 inHg as there will be enough air to idle. You are reporting information that can't happen, no matter how much you think it can- because you have two sensors that are telling you that it's true.

Vacuum at all is real, is a valuable too, and can easily be used to calibrate fuel injection and carbs. But it's not going to do some things, too. One is be greater than 1ATM of gauge vac.

I'm going to say calibration error... looking at the post, there's no way any engine is going to run at 3" of vacuum at WOT and low engine speed. I don't care what kind of turbo is on it.