WTF? im building mad boost in neutral!?! [Merged 12-7]

[98TsiAWD]

I want to test my pcv valve under boost. Is there anyway I can get the turbo to boost by reving the engine under the hood?

I recently blew out my dipstick, I did a leakage test and my intake valves are sticking open a little so that would mean boost is getting in there when it shouldnt be right? Causing excess crankcase pressure.

My valve cover breather works fine, I pulled the pcv valve, I can blow through it easily, I also pulled the hose that goes from the pcv to the intake. I make sure it and both fittings where not clogged.

So, basically i want to have the engine under boost just for a second to see if the pcv blows off excess crankcase pressure. But being as there is boost in the intake that will keep the pcv from opening wont it? So my intake valves sticking open is what is causing excess crankcase pressure?

 

[truwarrior]

Probably not the best thing for the engine

If you could get dsmlink they have something called antilag which would build boost off the line.

 

[KFT0001]

Stomp on the gas pedal a few times quickly and you'll build up some boost. I can get around 6psi that way.

 

[Defiant]

Seeya in the Engine Problems forum

 

[billdo_83]

I can build 12lbs of boost in neutral.

You need to be near redline because thats when the turbo is spinning fast enough to build boost, not because of some anti-lag switch. I've never heard of that solenoid before

 

[n0va91TSI]

How would it bad to rev it up in neutral? Is there really any posiblity of damage?

 

[EclipseGST-95]

yea blowing a head gasket possibly?

 

[Groomz]

The reason there is no boost in neutral is because there is no load on the motor or very little. The DSMlink and other systems ( MSD ) drop certain cylinders or fire them late to achieve a rev limit at a certain RPM. This also builds boost as the unburnt fuel/air mixture travels into the exhaust manifold and is ignited late, pressurizing the turbine and building boost.

 

[Rx3]

Originally posted by Defiant
Seeya in the Engine Problems forum

:laugh: Should we take bets on when he will post to that section? I say 2 months.....

 

[dave99gst]

 

[Defiant]

Originally posted by Rx3
:laugh: Should we take bets on when he will post to that section? I say 2 months.....

It'll be shortly after the "Best Launch RPM?" post.

 

[Rx3]

Originally posted by Defiant
It'll be shortly after the "Best Launch RPM?" post.

:laugh:

 

[adam355]

And dont the stock bovs leak in nuetral?

 

[billdo_83]

Originally posted by adam355
And dont the stock bovs leak in nuetral?

its possible for them to.

 

[93greentsi]

The reason there is no boost in neutral is because there is no load on the motor or very little.

Right on the dot. If you had the e-brake on and gave it gas and a little bit of clutch you could get it to spool, of course I would not recommend this.

 

[billdo_83]

Originally posted by Groomz
The reason there is no boost in neutral is because there is no load on the motor or very little.

If that is the case then why can i build 12lbs of boost by revving it?
The reason why you dont build as much boost is because only on the throttle for a few seconds.

Autos can braketorque and build boost because they are on the throttle and there is load on the engine.
You can build boost by free revving it in neutral though.

 

[psychlow]

Originally posted by billdo_83
You can build boost by free revving it in neutral though.

Yes, you can, I've done it on a totally stock car. But, it doesn't build boost as easily as it would if the engine had a load on it.

 

[billdo_83]

Originally posted by psychlow
Yes, you can, I've done it on a totally stock car. But, it doesn't build boost as easily as it would if the engine had a load on it.

Agreed

 

[Groomz]

Originally posted by billdo_83
If that is the case then why can i build 12lbs of boost by revving it?
The reason why you dont build as much boost is because only on the throttle for a few seconds.

Autos can braketorque and build boost because they are on the throttle and there is load on the engine.
You can build boost by free revving it in neutral though.

And what happens when you stay on the throttle without a load on the engine? You meet Mr. Rev Limiter. The entire point of being able to build boost at a specific RPM is for consistency. Its much more difficult to stab the throttle the second before the green light flashes. Pulling up to the line and flooring it while getting 12psi at 4000rpm's is much easier and more consistent.

Auto's can build boost because you have the brake on and are loading the motor with the torque converter. Put the slushbox in neutral and rev it up. Same thing happens.

Power delivery is also helped with a stutterbox or 2 step rev limiter as the engine is less likely to bog off the line versus the stab-and-go method. Again, its about consistency and accuracy.

 

[billdo_83]

Originally posted by Groomz
And what happens when you stay on the throttle without a load on the engine? You meet Mr. Rev Limiter. The entire point of being able to build boost at a specific RPM is for consistency. Its much more difficult to stab the throttle the second before the green light flashes. Pulling up to the line and flooring it while getting 12psi at 4000rpm's is much easier and more consistent.

Auto's can build boost because you have the brake on and are loading the motor with the torque converter. Put the slushbox in neutral and rev it up. Same thing happens.

Power delivery is also helped with a stutterbox or 2 step rev limiter as the engine is less likely to bog off the line versus the stab-and-go method. Again, its about consistency and accuracy.

Thats totally correct

I was merely pointing out the fact that its possible to build boost while free revving.

Stutter boxes are a wonderful tool for consistetly launching m/t's.

 

[TSi92]

Originally posted by adam355
And dont the stock bovs leak in nuetral?

They are vacuum actuated. Once vacuum drops to 5hg or so they close and all it takes is to blip the trottle to do that.

 

[ITSME4G63]

Alright, I was at the failed dsm meet yesterday nite in chicago suburbs, sum kid with his red evo said taht he knwos sum guy had has an ems and it lets him build 15lbs boost in neutral so he'll be able to take right of in a race haveing the boost already built-up. I think this is complete bullshti since the our engine wont be able to create anough exhaust gases to spin the exhaust turbine fast enough for the compressor wheel to create that much boost. But if I am wrong, dsm wisemen please enlighten me

 

[DSMJim]

The guy with the EMS will have a two step rev-limiter which allows you to put load on the engine. On my two step at 5500rpm holding I can create 12-15psi of boost to come out of the bucket with, very powerful launches and no bog after the launch ever.

Just incase your not sure what a two step is, ever hear guys launch and the car sounds like its off the rev-limiter? Well it is a revlimiter just not the one at 7500, many EMS and ignition systems like the MSD DIS-2 have the ability to create an extra Revlimiter which you can manually engage, (I use a button) to hold the engine at a particular RPM for launching. I press the button hold the gas right to the floor and it stays at 5500rpm bouncing and boost builds quickly, then I slide the clutch out and let go of the button.

Some stock cars can make boost just by reving them quickly in the upper RPM range, my car would not do that, but I have seen others that will. I think they are few and far between as most guys can not seem to get that to work for them, myself included.

 

[kpt4321]

I just tossed a video up onto my server here at school.

http://users.wpi.edu/~ktarry/files/stutterbox.wmv

At the beginning of the video, you can hear the stutterbox. It allows me to launch with 4-12 psi of boost, depending on what speed I set it to.

 

[candela]

All depends on the car dude. Some can build a few pounds without any aftermarket sutterbox or any other preloading device. Any kind of hindering with the motor revving is going to be drag/load that it will have to overcome. Stutterboxes (ign. related) will usually creat more of a load. The higher the motor revs (higher rpm it is set at) typically the more boost it will be able to generate. Once its generated its easier to maintain (usually builds slowly) with a small load.

That your car kpt?

 

[ViVidTSi]

You can use the E-brake and load it up in first gear {if it'll hold} and launch off that. It isnt that important as high revs and instant load {6000 rpm launch} usually works good enough {and breaks enough parts at that!