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Backfires and rev limiters. Login/Join 
"Member"
Picture of cas
posted
So I'm sitting here surfing Sig Forum and I hear what might possibly be gun shots. The sound and cadence wasn't right for fireworks. Is it gun shots? No, I don't think so. Or is someone beating on something? As it comes closer I realize it's an intentionally backfiring car. Every stop sign another string.

A few minutes later I'm hearing someone torturing their car, bouncing off the rev limiter. Not 2 or 3 times, more like 20 or 25. Then a few seconds later I hear it again. This keeps going for several minutes. Good lord dude, what are you trying to do to your engine? It was almost painful to listen to. (not audibly but mechanically) I guess they think it sounds cool?

These latest automotive trends are rather confusing.


_____________________________________________________
Sliced bread, the greatest thing since the 1911.

 
Posts: 21501 | Location: 18th & Fairfax  | Registered: May 17, 2003Reply With QuoteReport This Post
Three Generations
of Service
Picture of PHPaul
posted Hide Post
I feel ya.

Then there's the morons that intentionally burn the tires off the rims while simultaneously holding the engine against the rev limiter and trying to melt down the exhaust system.

And what really makes my head hurt is that it's NOT some kid in a $500 junker, it's usually cars/bikes that cost more than my house!




Be careful when following the masses. Sometimes the M is silent.
 
Posts: 15635 | Location: Downeast Maine | Registered: March 10, 2010Reply With QuoteReport This Post
A Grateful American
Picture of sigmonkey
posted Hide Post
quote:
Originally posted by cas:...I guess they think it sounds cool?

These latest automotive trends are rather confusing.


Yes x2.

I was working with a friend on a procharger and methods to make it as quiet as possible, a sleeper is not a good sleeper if it is talking in it's sleep.

So, naturally I do little googling to see what other's have discovered that are effective or a waste of time, and was surprised at the number of wankers that want as much whine and loudest waste dump as possible.

I understand the "scene" and the likes/dislikes of things change with time, and I am a "to each his own" kind of guy, but damn, son, I say, I SAY, what the hell's in that paste you been eatin', boy?




"the meaning of life, is to give life meaning" Ani Yehudi אני יהודי Le'olam lo shuv לעולם לא שוב!
 
Posts: 44689 | Location: ...... I am thrice divorced, and I live in a van DOWN BY THE RIVER!!! (in Arkansas) | Registered: December 20, 2008Reply With QuoteReport This Post
Member
posted Hide Post
Hey, go easy here.

The guys making all this noise cannot hear it over the sound of their own insecurity. Big Grin
 
Posts: 4979 | Registered: April 20, 2010Reply With QuoteReport This Post
Member
Picture of P250UA5
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The 'backfiring' is common on some high performance cars. Mercedes AMG, Jag FType, and a few others.

In some cases it sounds good, but in a neighborhood, I'd be annoyed too.




The Enemy's gate is down.
 
Posts: 16278 | Location: Spring, TX | Registered: July 11, 2011Reply With QuoteReport This Post
Dances With
Tornados
posted Hide Post
quote:
Originally posted by sigmonkey:
quote:
Originally posted by cas:...I guess they think it sounds cool?

These latest automotive trends are rather confusing.


Yes x2.

I was working with a friend on a procharger and methods to make it as quiet as possible, a sleeper is not a good sleeper if it is talking in it's sleep.

So, naturally I do little googling to see what other's have discovered that are effective or a waste of time, and was surprised at the number of wankers that want as much whine and loudest waste dump as possible.

I understand the "scene" and the likes/dislikes of things change with time, and I am a "to each his own" kind of guy, but damn, son, I say, I SAY, what the hell's in that paste you been eatin', boy?


UH, you didn't post the FogHorn LegHorn effect.
 
Posts: 12063 | Location: Near Hooker Oklahoma, closer to Slapout Oklahoma | Registered: October 26, 2009Reply With QuoteReport This Post
Member
posted Hide Post
quote:
Originally posted by P250UA5:
The 'backfiring' is common on some high performance cars. Mercedes AMG, Jag FType, and a few others.

In some cases it sounds good, but in a neighborhood, I'd be annoyed too.


Yes, some AMG's do it when paddle shifting them. They retard timing, throttle, or something briefly as the transmission shifts.
 
Posts: 21428 | Registered: June 12, 2005Reply With QuoteReport This Post
Inject yourself!
posted Hide Post
I bet he’s not talking about AMGs. Maybe.


It’s usually the Honda/Mazda ricers around here doing that. Slow and Upset types.




Do not send me to a heaven where there are no dogs.
Step Up or Stand Aside: Support the Troops !
Expectations are premeditated disappointments.
 
Posts: 8404 | Location: West | Registered: November 26, 2002Reply With QuoteReport This Post
Member
Picture of Prefontaine
posted Hide Post
It may be unburnt fuel in the exhaust track. It crackles and pops.



What am I doing? I'm talking to an empty telephone
 
Posts: 13128 | Location: Down South | Registered: January 16, 2010Reply With QuoteReport This Post
Purveyor of
Fine Avatars
Picture of Orguss
posted Hide Post
What cas is describing is called anti-lag or 2-step backfire. It's a deliberate attempt to get a turbocharged motor to backfire rapidly by bouncing the tach off the rev limiter.


https://youtu.be/GOMYum7WJgU



"I'm yet another resource-consuming kid in an overpopulated planet raised to an alarming extent by Hollywood and Madison Avenue, poised with my cynical and alienated peers to take over the world when you're old and weak!" - Calvin, "Calvin & Hobbes"
 
Posts: 18123 | Location: Sonoma County, CA | Registered: April 09, 2004Reply With QuoteReport This Post
A Grateful American
Picture of sigmonkey
posted Hide Post
quote:
Originally posted by OKCGene:
quote:
Originally posted by sigmonkey:
quote:
Originally posted by cas:...I guess they think it sounds cool?

These latest automotive trends are rather confusing.


Yes x2.

I was working with a friend on a procharger and methods to make it as quiet as possible, a sleeper is not a good sleeper if it is talking in it's sleep.

So, naturally I do little googling to see what other's have discovered that are effective or a waste of time, and was surprised at the number of wankers that want as much whine and loudest waste dump as possible.

I understand the "scene" and the likes/dislikes of things change with time, and I am a "to each his own" kind of guy, but damn, son, I say, I SAY, what the hell's in that paste you been eatin', boy?


UH, you didn't post the FogHorn LegHorn effect.


It's implied. Big Grin




"the meaning of life, is to give life meaning" Ani Yehudi אני יהודי Le'olam lo shuv לעולם לא שוב!
 
Posts: 44689 | Location: ...... I am thrice divorced, and I live in a van DOWN BY THE RIVER!!! (in Arkansas) | Registered: December 20, 2008Reply With QuoteReport This Post
Ammoholic
Picture of Skins2881
posted Hide Post
I will have to admit I love the sound of properly done exhaust and a blow off valve. Drone, or pissing off neighbors - uncool.



Jesse

Sic Semper Tyrannis
 
Posts: 21336 | Location: Loudoun County, Virginia | Registered: December 27, 2014Reply With QuoteReport This Post
A Grateful American
Picture of sigmonkey
posted Hide Post
Being from the "olde days", any "after fire" is typically an indication of several things, incorrect timing, leaking exhaust, too rich AFR, burnt, sticking exhaust valves or valve float due to valve spring binding, and none of them good or proper operation of engine.

In some cases, with circle track/spring style/outlaw cars, which are tuned to a point that some of the things above are "OK" because the performance gain is worth the "bad tuning", but most street/strip and straight line cars, it is indicative of poor performance.

And to me, it is like fingernail on chalkboard.

And most of the people doing it on the street, do it for the noise, not because they are squeezing every bit of performance out of their vehicle.




"the meaning of life, is to give life meaning" Ani Yehudi אני יהודי Le'olam lo shuv לעולם לא שוב!
 
Posts: 44689 | Location: ...... I am thrice divorced, and I live in a van DOWN BY THE RIVER!!! (in Arkansas) | Registered: December 20, 2008Reply With QuoteReport This Post
Nullus Anxietas
Picture of ensigmatic
posted Hide Post
This ^^^^^



"America is at that awkward stage. It's too late to work within the system,,,, but too early to shoot the bastards." -- Claire Wolfe
"If we let things terrify us, life will not be worth living." -- Seneca the Younger, Roman Stoic philosopher
 
Posts: 26031 | Location: S.E. Michigan | Registered: January 06, 2008Reply With QuoteReport This Post
אַרְיֵה
Picture of V-Tail
posted Hide Post
True story: The year was 1957. All was right with the world. My friend Gino and I had graduated from the Navy's Guided Missile School and we were attached to a Guided Missile Squadron based at NAS Chincoteage VA. Gino and I were both from the NYC area, and we car-pooled to spend some weekends at home, taking turns driving. I had a piece of shit 1950 Studebaker, Gino belonged to a hot-rod club (the Golden Wheels) and had a customized 1951 Mercury, that he was very proud of.

Our route from the DelMarVa peninsula took us over the Delaware Memorial Bridge and the NJ turnpike. A momentary ignition failure (loose ignition switch) in the Studebaker while coming down from the apex of the bridge led me to the discovery that if unburned fuel was allowed to accumulate in the exhaust system and then the ignition was switched back on, I would be rewarded with a really impressive backfire. Needless to say, this was pretty hilarious to a 19-year old, and it became a ritual to be observed on every trip home.

The trip after I discovered this delightful pastime, it was Gino's turn to drive his beloved Mercury. Coming down the bridge, I badgered him into trying the backfire trick. He left it in gear, turned the ignition off, and let the unburned fuel / air mixture accumulate in the exhaust. Near the bottom of the slope, he turned the ignition back on and we were rewarded with the mother of all backfires. I'm pretty sure that parts of the mufflers are still circling the Earth in low orbit. For the rest of the trip, instead of listening to the burble of dual glass-packs, we were rewarded with an ear-shattering roar that rivaled a gang of Harley riders with straight pipes at full throttle. We had not one, not two, but three separate "conversations" with patrol cops in two different states. That might have been the start of my hearing loss.



הרחפת שלי מלאה בצלופחים
 
Posts: 31699 | Location: Central Florida, Orlando area | Registered: January 03, 2010Reply With QuoteReport This Post
Don't Panic
Picture of joel9507
posted Hide Post
I agree with the 'blackboard-scatching' contingent.

Too much of a Mech E to be infatuated with the audio evidence of mechanical systems being abused.
 
Posts: 15235 | Location: North Carolina | Registered: October 15, 2007Reply With QuoteReport This Post
Member
Picture of Perception
posted Hide Post
As Orguss said, what you're hearing is a either a two step or anti lag system. A two step lets you set a low rev limiter for launching, and anti lag dumps fuel into the exhaust to keep a turbo spooled. Both sound ridiculous, but they do actually serve a purpose. Hell, the new Hyundai Velosters come like that from the factory.




"The people hate the lizards and the lizards rule the people."
"Odd," said Arthur, "I thought you said it was a democracy."
"I did," said Ford, "it is."
"So," said Arthur, hoping he wasn't sounding ridiculously obtuse, "why don't the people get rid of the lizards?"
"It honestly doesn't occur to them. They've all got the vote, so they all pretty much assume that the government they've voted in more or less approximates the government they want."
"You mean they actually vote for the lizards."
"Oh yes," said Ford with a shrug, "of course."
"But," said Arthur, going for the big one again, "why?"
"Because if they didn't vote for a lizard, then the wrong lizard might get in."
 
Posts: 3608 | Location: Two blocks from the Center of the Universe | Registered: December 30, 2004Reply With QuoteReport This Post
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