Exhaust note/tone on the Barra - Page 3

Bossxr8 · 10-04-2018, 02:27 PM

Quote:

Originally Posted by solarite_guy

This is interesting how the information is surfacing.

Maybe I got it wrong but I was positive I had heard either a programmer or tuner say that all the turbo vct tables were zeroed out.

Maybe it was just a myth.

I'm surprised it took so long for all the vct tables to be cracked, considering there are gains to be made in this area, and all with some keystrokes and time.

**solarite_guy** · 15-04-2018, 10:01 AM

Then how does it all work together with some hard parts and SW tuning to make some hp and hot rod sound?

We know a hot rod rumble is created when Lobe Separation Angles (LSAs) are closed up. This can be done by either advancing the intake lobe or regarding the exhaust lobe or doing both at the same time.

We know doing any of the above will increase overlap, which, depending on rpm (and if that rpm is in range or not of being in sync with the the induction and exhaust at the same time) can add or subtract power as well.

Everything is relative.

Something else covered. Many cam designers consider the closing point of the intake lobe as the single most important of all cam measurements. Did we ask why? The intake valve closing point plus valve and seat dimensions, port dimensions and flow characteristics, and cylinder displacement are key components to understand the inherent rpm of max hp of the engine.

The sooner the intake valve closes, the lower in the RPM range that max hp will tend to happen. Likewise the later the intake valve closes, the higher in the RPM range max hp will tend to happen.

If we stop right here for a minute, while there are still plenty of tricks up our sleeves we can now take 3 physically identical engines and have 3 entirely different running engines.

1. We can program an engine with a lot of fixed overlap(Close LSAs) which will sound and act raucous. Not much tq and power in the lower RPM ranges. Strong mid-range. Good for the weekend hot rod cruises and able to light of the tyres with the right components in the power train. Not really driveable on a daily basis though.

2. How about programing the LSA's way wide. Smooth idle. Burns little fuel at cruising speeds. Also, soft down low, BUT lacks the mid-range punch. In fact now punch anywhere, yet if wound out will make more power than the 1st engine.

3. Hey, I have an idea, Why don't we toss aside the whole concept of overlap. Instead, let's take some time to understand the ideal intake valve closing points for this particular engine across the entire operating RPM range this particular engine will operate in 3 possible operating scenarios.

Heavy load, full throttle (balls to the wall - trivia question: Without using google, who knows what balls to the wall means?)

Intermediate loads and throttle

Light cruising

Then, why not do something similar for the exhaust side?

The overlap value will be whatever it is for every possible LSA for any given condition and throttle setting and so will the LSAs.

I think this would be a good running engine. Even a Coyote or Miami have room to improve the factory valve timing maps.

But, the glass is only half full at this point. Current phaser technology hand cuffs us.

Talk about that later.

Maka · 15-04-2018, 10:24 AM

"Balls to the wall" meaning SG? Ive no idea actually, is it related to wfo (wound flat out)? I haven't googled yet either mate lol!

cheers, Maka

Mercury Bullet · 15-04-2018, 10:29 AM

Quote:

Originally Posted by Maka

"Balls to the wall" meaning SG? Ive no idea actually, is it related to wfo (wound flat out)? I haven't googled yet either mate lol!

cheers, Maka

Same same.

Surprised you've never heard of balls to the wall maka.

**solarite_guy** · 15-04-2018, 10:31 AM

It's aircraft related.

Let's wait a little longer.

**solarite_guy** · 15-04-2018, 10:33 AM

Quote:

Originally Posted by Mercury Bullet

Same same.

Surprised you've never heard of balls to the wall maka.

I think a throttleman would know this.

Maka · 15-04-2018, 10:35 AM

Quote:

Originally Posted by Mercury Bullet

Same same.

Surprised you've never heard of balls to the wall maka.

Ive heard it a few times before MB, i just assumed it was another saying for "pedal to the metal" lol, the clichés are starting to flow now lol!

cheers, Maka

**solarite_guy** · 15-04-2018, 11:51 AM

Quote:

Originally Posted by Maka

Ive heard it a few times before MB, i just assumed it was another saying for "pedal to the metal" lol, the clichés are starting to flow now lol!

cheers, Maka

Maka,

You are on the trail. Just searching for the words. Those 2 white balls. Those are the pilots throttles. When they are jammed all the way forward, that is balls to the wall.

Alright, then later we will give thought to how some SW tuning and newly engineered cam phasers cam make it possible to really put a new engines balls to the wall.

arronm · 15-04-2018, 12:04 PM

Balls to the wall = full throttle..

Maka · 15-04-2018, 01:12 PM

Quote:

Originally Posted by solarite_guy

Maka,

You are on the trail. Just searching for the words. Those 2 white balls. Those are the pilots throttles. When they are jammed all the way forward, that is balls to the wall.

image

Alright, then later we will give thought to how some SW tuning and newly engineered cam phasers cam make it possible to really put a new engines balls to the wall.

Awesome stuff, thanks for the info SG!!

cheers, Maka