Exhaust Sound - What are you hearing?
04-24-2006, 02:11 PM
#22
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Patrick, I'm with you - but most people have no idea what a spintron is, let alone heard a engine on one. We (Dart Machine) have one - and yes for a empty motor WITH extra holes (for high speed cameras) in it - it is amazingly loud. It does sound JUST LIKE a real running motor.
04-24-2006, 02:38 PM
#23
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I'm glad I posted this thought. I knew some of the sound was exhaust gas
leaving the chamber, but I didn't know it was such a majority.
Now that I think about it, engine brakes on a truck...that's essentially cutting
the ignition correct? Similar sound coming from the exhaust.
leaving the chamber, but I didn't know it was such a majority.
Now that I think about it, engine brakes on a truck...that's essentially cutting
the ignition correct? Similar sound coming from the exhaust.
04-25-2006, 07:12 AM
#26
It takes power to compress the air. Normally the engine gets some of that power back on the power stroke as the high pressure air presses back down on the piston, even without combustion. But when the air is released right after being compressed all that energy goes right out the exhaust without pushing the piston back down. It basically turns the engine into an air compressor that is powered by the momentum of the truck.
04-25-2006, 07:55 AM
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But when the air is released right after being compressed
Thanks.
Last edited by Adrenaline_Z; 04-25-2006 at 11:08 AM.
04-28-2006, 01:32 PM
#28
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One thing I have noticed (at an idle) is that most engines with abnormally high compression, mainly drag race engines, have an almost squeaky exhaust sound. It is almost a chirp coming out of the pipe as so much air is pumped in, it escapes rapidly.
If you dont believe me, go to an NMCA race or equal, and listen to one of the "big" nitrous motors, and you'll more than likely hear the "squeak" or "chirp" at an idle.
If you dont believe me, go to an NMCA race or equal, and listen to one of the "big" nitrous motors, and you'll more than likely hear the "squeak" or "chirp" at an idle.
04-30-2006, 12:07 AM
#29
Originally Posted by The Alchemist
Yeah, to continue the discussion of 'explosion' vs. 'burn' listen to a top fuel (80:20 Nitromethan : Methanol) compared to a gasser. The nitromethane burns at a much higher rate and sounds more like an explosion than a burn.
The greatest thing I've ever heard is the first time I was standing in the pits and a top fuel funny car started up doing his morning tuning session. The sound is intoxicating much less the vapors that burn your eyes and lungs.
The greatest thing I've ever heard is the first time I was standing in the pits and a top fuel funny car started up doing his morning tuning session. The sound is intoxicating much less the vapors that burn your eyes and lungs.
05-01-2006, 08:03 PM
#31
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I just went to my 5th-ish NHRA event (at Bristol, Thunder Valley) this past weekend and our seats in the stands were basically right in line with the angle the exhaust was coming out of the zoomies. I hadn't noticed it before but on some cars when they were idling before coming back up to the line you could distinctly hear one cylinder have a EXPLOSION coming out of it. They're loud as hell at idle anyway but this was a distinct POP coming out of several different cars almost to the point of having to hold your hears before they even took off. I just thought it was an interesting observation.
After I noticed this I started listening to every Fuel car at idle. Some were (relatively) quite whereas others sounded like they would come apart at any second. I know this didn't add any real merit to the discussion but I love reading ANYTHING on nitro cars. Just makes me wonder what all was different in the timing and rest of the setup to make them act like this. Guess we will never know cause those boys aren't letting their secrets out anytime soon haha.
After I noticed this I started listening to every Fuel car at idle. Some were (relatively) quite whereas others sounded like they would come apart at any second. I know this didn't add any real merit to the discussion but I love reading ANYTHING on nitro cars. Just makes me wonder what all was different in the timing and rest of the setup to make them act like this. Guess we will never know cause those boys aren't letting their secrets out anytime soon haha.
05-01-2006, 10:25 PM
#32
Well, this may or may not be true, but I've read in the past that fueler motors ingest so much nitro that the dual plugs are an absolute necessity. If one charge of fuel doesn't fire, the hydraulic pressure in that cylinder either lifts the head or bends a rod, which is what we see when they are running on 7 cylinders. The exhaust pressure out of the zoomies is great enough that when they lose a cylinder, you'll see the car move a couple feet toward that side.
Also, if you weren't aware, a fuel motor spins an average of 7500 rpm down the track. But since the run is so short, the engine only turns about 900 revolutions from start to finish.
Also, if you weren't aware, a fuel motor spins an average of 7500 rpm down the track. But since the run is so short, the engine only turns about 900 revolutions from start to finish.
05-06-2006, 09:18 AM
#33
Originally Posted by Malihoochie
Patrick, I'm with you - but most people have no idea what a spintron is, let alone heard a engine on one. We (Dart Machine) have one - and yes for a empty motor WITH extra holes (for high speed cameras) in it - it is amazingly loud. It does sound JUST LIKE a real running motor.
I guess this now explains why you can be going down the road and turn the engine off and the sound never changes!
05-06-2006, 09:29 AM
#34
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Originally Posted by The Alchemist
Yeah, to continue the discussion of 'explosion' vs. 'burn' listen to a top fuel (80:20 Nitromethan : Methanol) compared to a gasser. The nitromethane burns at a much higher rate and sounds more like an explosion than a burn.
The greatest thing I've ever heard is the first time I was standing in the pits and a top fuel funny car started up doing his morning tuning session. The sound is intoxicating much less the vapors that burn your eyes and lungs.
The greatest thing I've ever heard is the first time I was standing in the pits and a top fuel funny car started up doing his morning tuning session. The sound is intoxicating much less the vapors that burn your eyes and lungs.
Man, when those things fire up at the line, it's crazy. I have a buddy that lives 6 miles from there and his windows rattle everytime they run.
As they streak past yer seat, it's like a frikin' hurricane. I love it!!!!!!!
Even my non-gearhead girlfriend has a new favorite sound after the Nationals
05-07-2006, 03:29 PM
#35
Originally Posted by hammertime
Well, this may or may not be true, but I've read in the past that fueler motors ingest so much nitro that the dual plugs are an absolute necessity. If one charge of fuel doesn't fire, the hydraulic pressure in that cylinder either lifts the head or bends a rod, which is what we see when they are running on 7 cylinders. .
They found pieces of block 200yards away. I think i'll stick with street engines. 
05-07-2006, 09:57 PM
#36
Spintrons are cool we just got one at our engine shop and you cant hardly tell the difference between an engine dyno and the Spintron which is just valvetrain....untill something breaks.. When you watch a race on tv and theres an in car shot what your hearing is primarly valvetrain...
05-08-2006, 04:26 PM
#37
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Originally Posted by hammertime
You are half way there. A V8 has two cylinders that fire consecutively on both banks. On an LS1, it is split at the end-beginning of the firing order.
1-8-7-2-6-5-4-3
It is easier to see on a Gen I/II SBC, as it is buried in the firing order, not at the end.
1-8-4-3-6-5-7-2
1-8-7-2-6-5-4-3
It is easier to see on a Gen I/II SBC, as it is buried in the firing order, not at the end.
1-8-4-3-6-5-7-2
05-09-2006, 01:41 PM
#38
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Also LS1s have the same fire order that Ford has used for some time. Although Ford numbers their cylinders different so it doesn't look the same, but it really is.
06-01-2006, 01:00 PM
#39
Originally Posted by 67RSCamaroVette
I was looking at a nitromethane donovan blocked race engine (for a big cigarette boat) in the bodyshop my car is in, and the owner told me the exact same thing you just said. He said every time you shut the engine down, you have to bump the engine backwards by hand to pump all the extra nitro out. He said he got lazy once, ran the engine for about 10 seconds, killed it, and just walked away.. the next time he bumped the starter, it fired and blew the back end of the engine off, enough to rip a gaping foot-wide hole in the side of the boat. They found pieces of block 200yards away. I think i'll stick with street engines.
They found pieces of block 200yards away. I think i'll stick with street engines.
06-01-2006, 01:12 PM
#40
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Originally Posted by hammertime
Also, if you weren't aware, a fuel motor spins an average of 7500 rpm down the track. But since the run is so short, the engine only turns about 900 revolutions from start to finish.