Boost pressure and throttle input?

[TurbochargedRiot]

Quick question regarding boost and throttle position.

Obviously, throttle position and RPM play a big factor when it comes to an engine and turbocharger producing boost pressure.

When in first gear, you can easily bring this specific engine up to redline using very little throttle pressure, pretty much utilizing the engine as naturally aspirated, no boost pressure required to travel the entire RPM range.

My question is, when driving in normal everyday situations, how much throttle input is required for the engine to create/utilize boost? More specifically, when do you see your FiST making boost? 1/8 throttle? 1/4 throttle? 1/2 throttle? What psi do most of you see in normal city driving?

Also, what RPM do most of you see boost coming in at? With a small turbo, boost is more easily made at lower RPM due to a small turbine but what I’ve heard from others, the fun seems to get going around 3,000 RPM.

Thanks!

 

[zanethan]

There is no simply answer to your question as it all depends on a multitude of factors. The ECU is programmed to hit specific HP and torque numbers, once it does it will divert boost in order to not exceed those numbers. Therefore everyday will yield different results due to different weather conditions (and possibly altitude changes if you're traveling).

Additionally, boost is limited in 1st and 2nd to help preserve the life of your driveline and clutch. So you might need 1/2 throttle input in first to build boost but only 1/4 in second.

So with all that being said my final answer is that it depends. I typically see boost in first if I go a touch past 1/2 throttle. 2nd gives boost a little earlier and 4th-6th allow boost to be built by just tapping the throttle. You're results may vary though.

 

[TurbochargedRiot]

Thanks Zanethan for the in-depth reply, I appreciate it very much.

In your opinion, what is a safe RPM to begin utilizing boost? With a turbocharged engine and higher compression ratios, lugging becomes more serious and can cause damage easier than with a non-turbo engine. So, while driving, what would you say is a safe RPM to be considered non lugging? 2,500 rpm? Higher?

Cheers!

 

[zanethan]

2500 should be ok. I prefer the 3000-3500 range in I'm going to floor it though.

 

[TurbochargedRiot]

Thanks for the reply, sounds good.

Lastly, I have about 2,800 miles on my FiST. Would you say that the engine is now broken in enough to allow for more spirited driving?

I've always held back on the throttle since I wanted to get enough miles on the engine before driving harder than normal. Am I good to go at this mileage?

Happy 4th to everyone!

 

[zanethan]

Different people have different opinions on the proper break in procedure for our cars. Some people baby it until 10,000 miles others drive them like they stole them right off the lot. There doesn't seem to be any correlation between how it's broken in and reliability. I would think that 2,800 miles is enough assuming its cone through its first oil change though.

 

[TurbochargedRiot]

Yep, definitely got the break-in oil out of the engine pretty quick once I took ownership.

I figured that 2,800 was adequate enough for more spirited driving. Not redline, mind you. Lol

Cheers!