Hey everyone....got a question about my boost level. I’m at the drag strip last night just seeing if I can better my time from this past saturday and the first two runs are going good the boost is where I want it (22psi) and so far so good while launching at about 4500/5000 rpms. For my third run I didn’t adjust the boost level at all (its manual) and this time I launched from 5500/6000 rpms but boost didn’t reach the 22psi, it only reaches about 18psi. So before my 4th run, I turned the boost controller up a little in hopes that it would reach 22psi but on that run nothing happened and the boost level didn’t increase at all while I launched at 5500/6000 rpms. So on the way back from my 4th run, I did a little quick burst and it boosted to 22psi while I was in 2nd gear just to see if it would reach the 22psi. So before my 5th run, I turned down the boost a little to see what it would do and it boosted at about 20psi while launching from 4500/5000rpms. So before my 6th run I turned the boost down a slit bit more and it boosted at about 22psi and I launched from 4500/5000rpms. Also on the way home I left the boost alone and in ever single gear when I was wot it boosted about 24psi.

So my questions are, why would I not boost high enough launching from higher rpms as compared to the lower rpms from a dead stop and why would “turning down the boost” actually increase the boost level on the run? Also, why would I boost at or above the 22psi while on the highway as compared to from a dead stop on the drag strip?

Thanks for the help guys

 

Paul. you need a Retune and check for boost leaks. you should be trapping ATLEAST 112~ even with the 6spd. car doesn't seem to be running at strong as it should. but anyways, the exhaust sounds AWESOME.

 

First off, I would always default to checking for leaks.

That said, I'm not a mechanical engineer, but here's what I've learned from my internet education:

If there is greater load on the engine, it will increase EGTs. Exhaust heat is the energy used to turn the turbine (creating boost). Engine load is not proportional to RPMs, but is dependent on RPMs.

So, an engine under more load will have higher EGTs, which means more energy to spin the turbine, which generally means higher boost.

Also, keep in mind that in higher gears, and engine is working harder to accelerate at a given RPM. This is why its normal to hit higher boost in higher gears.

For your situation:

If you rev the engine to 6k (in neutral) there is no substantial load (which is why the turbo doesn't really spool). When you launch, you're not only starting with reduced load on the engine at 6k (as compared to when you launch at 4k), but the 16G turbo usually peaks around 5500-6000, and then tapers off. So... I don't think there is anything wrong.

My car is tuned for around 23 psi (on a 16g) and I hit about 20-22 psi in 1st and 2nd gears, 3rd gets to 23 psi, 4th and 5th usually hit 24-25 psi.

 

yes i know i need a retune im wokring on tryin to get that set up so this car can run like it should. also i will check for boost leak as soon as i get a chance.

falcon thanks for the info