how to tell if your boosting...correctly

[1Gina2G]

Here's a real noob question. I've been wondering this for a while, I've yet to drive a dsm yet, or any turbocharged/supercharged car for that matter. I've been taking the last 2 years putting this car together from scratch, trying to make a reliable daily driving setup, with the basic mods.

I always see people explaining how they'll be driving, or cruising casually, and then they WOT and get into boost. Just trying to understand, when the car is usually supposed to start boosting? How can you tell if the car ISN'T building any boost?

I have a working aftermarket boost gauge, and some other gauges as well

 

[Calan]

I'm not sure I understand your question. If I'm reading that correctly, then the answer would be:

When the vac/boost gauge goes above 0.0 psi, you're building boost.

 

[PrimerPLus]

Your turbo starts to build boost when you are into gear and press on the throttle. The rpms will determine when you are into full boost. Different turbos build full boost at different rpm ranges. On my evo 3 16g, you can hear that sucker sucking in air inside the cabin. It is a pretty awesome sound if I do say so myself. Also you will feel that car pull, it's an awesome feeling. But there are bigger turbos being used than the one I have.
People saying they get into boost usually means they are WOT and have reached their boost levels, what ever that might be.

What turbo are you using?

 

[Calan]

The rpms will determine when you are into full boost.

...as well as the gear you are in, load on the engine, timing, AFR, throttle position, and many other factors.

 

[PrimerPLus]

Ah yes, that is very true.

 

[4G63_fiend]

Turbo size has A LOT to do with it! As well as the amount of air the engine is capable of moving. The quicker/more air pushed thru the engine, the more/faster boost the turbo will push. Smaller turbos spool quicker than larger ones. On the other hand a small turbo may fall off during high RPM's due to its capacity, while larger ones will keep making power. As long as your boost gauge is connected to your intake manifold it will display your boost levels accuratly. If you connect it before the manifold and there is a boost leak downstream, it will not display the boost the engine is seeing correctly.

 

[1Gina2G]

Well I have a boost / vaccum gauge it says. Should be normal to have boost AND vaccum on the same gauge right? So far I've just done 1 30 minute run just idleing/breaking in the engine, and the boost gauge just goes up to 10-12psi or so, thought it was coincidental since I have my wastegate line run directly to the intercooler piping, with a 14B from a 1G. Do these readings sound normal, for vaccum?

I guess what I'm wondering is, how I should know if I'm building boost correctly, of course driving off right after a boost leak test. Should I be able to hear the turbo? Is it more the forced air sound or the turbo whistle? both?

How do people know when they arent building boost under a load, or at WOT?

 

[4G63_fiend]

Well I have a boost / vaccum gauge it says. Should be normal to have boost AND vaccum on the same gauge right? So far I've just done 1 30 minute run just idleing/breaking in the engine, and the boost gauge just goes up to 10-12psi or so, thought it was coincidental since I have my wastegate line run directly to the intercooler piping, with a 14B from a 1G. Do these readings sound normal, for vaccum?

I guess what I'm wondering is, how I should know if I'm building boost correctly, of course driving off right after a boost leak test. Should I be able to here the turbo? Is it more the forced air sound or the turbo whistle? both?

How do people know when they arent building boost under a load, or at WOT?

What are your supporting mods? Do you have link? You should hear the turbo and feel it pull HARD once it starts to spool. Where is the gauge connected?

 

[PrimerPLus]

If you are idleing you will see in Hg not psi.
What boost gauge are you using?

 

[Calan]

How do people know when they arent building boost under a load, or at WOT?

Uhhhh... by looking at a boost gauge.

 

[oneslowwdsm]

Yeah load is another thing.. If you have a bigger turbo do NOT put full load on it say in 5th gear at 60mph, make sure you are in the correct RPM range for full boost because if you don't, then this happens: (notice the 2 small at the bottom)

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[PrimerPLus]

Was that fun?

 

[4G63_fiend]

So I get your question but is the reason your asking because the car isn't pulling when it spools?

 

[1Gina2G]

So I get your question but is the reason your asking because the car isn't pulling when it spools?

No I'm more just trying to gather information before I take it out for the very first drive down the road, just a matter of fixing a cupple small oil leaks and then the insurance is just a phone call away. I've only got the engine running right now, did the 30 minute break-in like I was saying, and checked the timing, holds the idle perfect after adjusting the BISS and the SAS on the throttlebody

I can't belive it didn't occur to me about the gauges being the reason, just wanted to make sure there wasn't anything else that was obvious that I'd be missing. Sometimes I look at things to hard

Also worried about 'running into a brick wall' there seems to be alot of threads on here about that happening for both new & factory builds. Right now I'm just thankull that the engine idles perfect by itself AND the fact that my gas is burning at a PERFECT 14.7 at idle or slightly high revs.

 

[oneslowwdsm]

Was that fun?

Tons of fun that motor was completely obliterated. Addition to the two small holes in the front, there was a huge chunk missing on the back in the same area. Stock 7-bolt on a 20g on 25lbs. Tell you the truth idk what I was thinking that night, I was trying to build boost slowly but then it suddenly jumped.

Right now I'm just thankull that the engine idles perfect by itself AND the fact that my gas is burning at a PERFECT 14.7 at idle or slightly high revs.

Your wideband should be jumping a little bit, maybe 14.7-15ish.. I think your wideband isn't working I've never seen one perfectly steady.

 

[hotrodssnova]

With 441 tech posts, you should know what boost feels like.

 

[1Gina2G]

The wideband does bounce around 14.7, from the low 13's to the 15s or so like you were saying, always goes to 22.0 for regular air with just the ignition on. Also forgot to mention up there, that I just updated my profile for my mods

With 441 tech posts, you should know what boost feels like.

Didn't even read any of my posts, I haven't even moved this car around besides pushing it around the driveway. Completley new rebuild. Most of my posts are questions, so it wouldn't matter if I had 1000 posts like anyone else, doesn't mean anything.

 

[undefined0000]

You know you're boosting when it feels like your car is slow, then you get sent back in your seat and next thing you know, your pants are gooey.

 

[hotrodssnova]

You should move that wideband sensor to either the stock location and wire it up to the ecu for nb operation, or weld a bung in the down pipe and run it there. Installing it after the flex pipe will give you false readings when the flex starts to leak. When the wb starts showing a lean condition, you start to get freaked out, well I do, and wonder whats going on. If you mount it BEFORE the flex pipe, you take that scenario out of the picture. I only tell you this so when it happens, you will know where to look. I had 2 widebands hooked up at the same time, one in the stock location, one 3" passed the flex. Brand new flex, and the one after the flex was almost 1 point off at idle, leaner, then the one in stock location. At cruise, both ran identical. just thought you would want to know.

 

[arabeclipse]

You know you're in boost when your gauge is not reading in inches mercury. Vacuum is the air the engine is taking in without any help from the turbo. When your gauge beings to read 0psi then you are entering boost. At that point, your car will pull harder even if your right foot didn't push much harder on the gas pedal. You should feel a harder pull when you're in boost, depending on what gear and rpm range you are in. Oh, and the type of turbo you have. The larger the turbo, the longer it takes for it to fully spool.

Example: you will not feel a pull if you're doing 45 in 5th gear and put the pedal to the floor. If you're doing 45 in 3rd gear and you floor it, you WILL feel it.

 

[Calan]

So far I've just done 1 30 minute run just idleing/breaking in the engine

I just saw this, but...

I hope you did some spirited acceleration under load, followed by engine braking/deceleration during that 30 minutes, and not just letting the car idle.

 

[1Gina2G]

i haven't put it under a load yet but i took the engine to the 2-3k range just sitting there, was told.this was all that was needed to fully break in the rings.
was going to do another 20 minute run, and then drive it if there's no more leaks.

 

[BogusSVO]

You need to load the rings to get seat right.

The 20-30 mins between 2000-2500 RPMs is a flat tappet camshaft break in method. Not the method needed for a 4G engine.

Read the "Motorman" break in method.

 

[gsxeclipse97]

Well it would seem in an na if your stepped in the gas and had a boost gauge it would read more vacuum not moving towards the positive pressure side of the needle. Like when going 60 and you let off the gas and it drops to 25hg. Even though your nt techinally in boost range yet the turbo is still forcing more airy than your engine would normally take in on its own.