16g to 14b temporarily

[Calan]

Just upgraded to 650cc FIC's and about to install Walbro 255 that have, followed by an APR (probably the Import Evolution kit). Car is running pretty well, but still needs some tuning.

One problem I still have is boost creep. I'm running a stock 16G (I believe) with a new manual boost controller, and can't lower the boost. Just sits at 15-18psi, causing some knock if I'm not careful.

Anyway, I'm gonna pull the 16g and have it ported and thoroughly checked out. Would there be any issues with temporarily bolting a 14b back up to it while the 16g is out?

Would I actually like the 14b better for goofing around town from light to light?

Thanks as always!

 

[spyderturbo007]

Would there be any issues with temporarily bolting a 14b back up to it while the 16g is out?

Nope, you will just be flowing less air at the same boost level as you were with the 16g. The ECU will see that lower airflow and adjust fuel delivery as needed. You might have to richen things up a little since the 14b isn't as efficient at the same boost level as the 16g. This will lead to intake charges that are hotter than they were with the 16g. Just keep an eye on your knock, but with the cold weather, you should be fine.

 

[b00st3d]

You are chasing the wrong problem if you are porting the turbo to try to stop boost creep. While porting the wastegate may help a little, you will see better results porting the o2 housing, boost creep is caused by backpressure. Free up the flow, no more creep.

 

[Calan]

Boost creep update...

It was being caused by a home-made hack on the actuator control arm, which was basically useless until enough pressure built up. (who knows... 19-21 psi?)

Removed that mess and added an MBC to the vacuum side of the actuator, and it's butter. Can dial in boost nicely now, and it stays where I put it (12psi for now) with only a very minor spike (+1-2 psi) every now and then.

Now if I can just get this new knock sensor installed after while and get rid of the phantom knock....

 

[turbolaserawd]

Nope, you will just be flowing less air at the same boost level as you were with the 16g. The ECU will see that lower airflow and adjust fuel delivery as needed. You might have to richen things up a little since the 14b isn't as efficient at the same boost level as the 16g. This will lead to intake charges that are hotter than they were with the 16g. Just keep an eye on your knock, but with the cold weather, you should be fine.

So your saying that if I had a 14b on my car and ran it at 15psi there would be less air flowing than running my 16g at 15psi? If so how's that? Because 15 pounds per square inch is 15 pounds per square inch, I dont see how you could get more air flow while still running the same psi. I dont want to run more than 18 psi on my car and was looking to swap my 16g with a ported 14b seeing as how the 16g would just be carrying extra wait since I wont be using its potential and the 14b is smaller, but i don't want to sacrifice too much performance if that's going to be the case.

 

[spyderturbo007]

I'm glad to see you are thinking, but this can get very complicated, very fast. I am talking about flow, not pressure. But in a nutshell, the 16g will flow more air, at the same pressure and at a higher efficiency, than the 14b. Did you ever take a look at a compressor map? Also, do some reading on volumetric efficiency and take a quick look at the ideal gas law equation (PV=nRT). That should help.

Check out the 14b's here and the 16g's here.

You will notice that at the same pressure ratio, the 16 will outflow the 14b by 5cfm.

 

[turbolaserawd]

I'm glad to see you are thinking, but this can get very complicated, very fast. I am talking about flow, not pressure. But in a nutshell, the 16g will flow more air, at the same pressure and at a higher efficiency, than the 14b. Did you ever take a look at a compressor map? Also, do some reading on volumetric efficiency and take a quick look at the ideal gas law equation (PV=nRT). That should help.

Check out the 14b's here and the 16g's here.

You will notice that at the same pressure ratio, the 16 will outflow the 14b by 5cfm.

I looked up volumetric efficiency on wikipedia, it said it refered to the efficiency in which an engine can move the charge in and out of the cylinders. I'm not sure if I read it in this forum or not but I heard the 16g charge temp. is cooler than the charge temp. of a 14b at the same psi. Cold air is denser than hot air therefore the charge from the 16g, being colder, contains more air molecules making it move "more air" into the engine while remaining at the same psi. Is this what your refering too? (The links you posted didn't work for me.)

 

[spyderturbo007]

I think I know what your getting at, I just turned 16 in dec. and am just getting into dsm's and all this stuff so try not to get too agrivated with me.

Sorry if my post came across that way.......It wasn't my intention.

(The links you posted didn't work for me.)

Try this, go to www.stealth316.com and click "Enter Framed Version". Then click on "Technical" on the upper left menu. Under the heading of "Long Notes" you will see a section entitled "Compressor flow maps". Have a look at that if you get a chance.