What causes rasp!
What causes rasp! 
04-12-2006, 03:11 PM
#4
Originally Posted by JDP
LS1s cause rasp. cats and mufflers hide it
thats what i always thought
thats what i always thought
Originally Posted by GuitsBoy
I hear that the blat blat blat rasp sound is from unequal length pipes in the Y pipe.
04-12-2006, 03:20 PM
#5
Originally Posted by jmm98LS1
Nope....listen to any decent dual setup, mufflers or not. No rasp.
That's the right answer, as well as the design in the y-merge. I had absolutely terrible rasp from 2200-2500rpm with my macs/crappy ory. New setup is pacesetters/custom duals/1 chamber flows and there's nothing but purty music to be heard now!
That's the right answer, as well as the design in the y-merge. I had absolutely terrible rasp from 2200-2500rpm with my macs/crappy ory. New setup is pacesetters/custom duals/1 chamber flows and there's nothing but purty music to be heard now!
04-12-2006, 04:42 PM
#6
Originally Posted by ROCNDAV
Pics and sound clips?
04-12-2006, 09:37 PM
#7
Tech Resident
i always figured the potential rasp of LS1's are due to aluminum blocks. it just seems to me cars with aluminum blocks have higher-pitched, racy sound while cast iron blocks have deeper, guttsier sound, but not very race-like. for example, corvettes (aluminum) scream at WOT while big trucks (iron) sound like thunder but don't have that race car sound. i suppose it's because aluminum blocks put less load on the engine due to their lighter weight.
the ability of the LS1 to "scream" gives it a greater chance of rasp - it's a higher pitched motor and higher frequencies are always more prone to rasp.
i guess cats take the rasp out because their restriction regulates the airflow in the tubes.
i've always wondered how they make a harley motorcycle engine so very deep whereas a honda civic whose engine is much MUCH larger than that of a motorcycle is so high pitched...it has to do with the amount of air in your exhaust tubing, its evenness and its velocity. i guess cats are like a built in regulation device.
sound and potential rasp also has to do A LOT with cylinder firing order. why are lamborghini's so high pitched? they have a straight firing order. 1-2-3-4-5-6-7-8-9-10-11-12. i'm sure they would rasp too with the proper exhaust setup, even with their 12 cylinders.
on the other hand, mustang motors are deep. i'm not sure of their firing order but i know IMO 5.0 mustangs are some of the best sounding cars ever produced-and their heads flow like sheit-i've never heard one rasp, ever. two of my friends have them, catbacks, no cats, ORY...0 rasp. their sound blows away the LS1's...too bad they're like driving a matchbox with doors.
the ability of the LS1 to "scream" gives it a greater chance of rasp - it's a higher pitched motor and higher frequencies are always more prone to rasp.
i guess cats take the rasp out because their restriction regulates the airflow in the tubes.
i've always wondered how they make a harley motorcycle engine so very deep whereas a honda civic whose engine is much MUCH larger than that of a motorcycle is so high pitched...it has to do with the amount of air in your exhaust tubing, its evenness and its velocity. i guess cats are like a built in regulation device.
sound and potential rasp also has to do A LOT with cylinder firing order. why are lamborghini's so high pitched? they have a straight firing order. 1-2-3-4-5-6-7-8-9-10-11-12. i'm sure they would rasp too with the proper exhaust setup, even with their 12 cylinders.
on the other hand, mustang motors are deep. i'm not sure of their firing order but i know IMO 5.0 mustangs are some of the best sounding cars ever produced-and their heads flow like sheit-i've never heard one rasp, ever. two of my friends have them, catbacks, no cats, ORY...0 rasp. their sound blows away the LS1's...too bad they're like driving a matchbox with doors.
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04-13-2006, 12:05 AM
#8
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Originally Posted by jmm98LS1
that is sick. I just made a thread regarding gmmg "vs" true duals. +1 for duals. 
04-13-2006, 07:01 AM
#10
I think there are two different definitions of rasp here, and Im not certain which one of them if correct.
One issues is the blat blat blat sound that comes in a mid throttle level between 1800 and 2800 rpm. Sounds like an old pickup with straight pipes. I believe this is caused by the unequal length pipes.
The other issues is simply a less refined exhaust note. Almost sounds like whitenoise (static) overtones, or like scraping sandpaper togather. This is believe is just nature of the beast, however I believe sharp edges, hard corners, and other irregularities can contribute to ir.
One issues is the blat blat blat sound that comes in a mid throttle level between 1800 and 2800 rpm. Sounds like an old pickup with straight pipes. I believe this is caused by the unequal length pipes.
The other issues is simply a less refined exhaust note. Almost sounds like whitenoise (static) overtones, or like scraping sandpaper togather. This is believe is just nature of the beast, however I believe sharp edges, hard corners, and other irregularities can contribute to ir.
04-13-2006, 09:17 AM
#12
Originally Posted by rgaynor85
yeah that true dual with flowmasters sounds awsome, i wonder how loud that is in person compared to say a hooker catback
. It probably wouldn't be as bad if it wasn't dumped under the car, but I love it! The only catback that will come even close to being this loud is a loudmouth behind longtubes/ory. 
04-13-2006, 09:46 AM
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to bad i like it but i cant have a car that loud..., what power u putting down with that asa cam, i love the idle how hard was it to get to idle with that 110lsa
04-13-2006, 11:30 AM
#15
Originally Posted by pdanrichey
I love how you don't let the car warm up before you rev the crap out of it. It sounds freaking sweet though. What's up with the SES light?
I had been out driving for 45 mins before I took that vid. Oil temp was 190 degrees, water temp was 180. SES light is on because I'm tuning the car in speed density mode (no MAF sensor) so I have the MAF turned off which throws an SES light.
Originally Posted by rgaynor85
to bad i like it but i cant have a car that loud..., what power u putting down with that asa cam, i love the idle how hard was it to get to idle with that 110lsa
04-13-2006, 07:16 PM
#17
Originally Posted by pdanrichey
I was just looking at the temp gauge on your console..it wasn't far above the first degree mark...mine always runs just under the 210 mark. No biggie.
04-13-2006, 08:56 PM
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"it just seems to me cars with aluminum blocks have higher-pitched, racy sound while cast iron blocks have deeper, guttsier sound"
I'm no expert...I can only comment on what I've actually heard, and I have to agree with the above comment. I've owned, modded, driven, & raced both LT1 & LS1 F-Bodies. I firmly believe that the LS1 is MUCH pickier about exhaust component choices than the LT1, if you're after that rrrrrumble sound.
You could slap a system on an LT1 made out of empty creamed corn cans welded together, and it would still sound good. The selection of components for the LS1 is not only trickier, but is much more limited if you're looking for that nice, deep rumble.
There are just 2 long-tube/cat-back combinations I've heard that had that nice rumble. Both had Kooks headers, but one had a stainless Magnaflow cat-back, and the other one had a Spin-Tech. As high a quality piece as they are, to my ear, nothing sounds more "crackly" or "raspy" than a Borla on an LS1. That's my experience, anyway.
I'm no expert...I can only comment on what I've actually heard, and I have to agree with the above comment. I've owned, modded, driven, & raced both LT1 & LS1 F-Bodies. I firmly believe that the LS1 is MUCH pickier about exhaust component choices than the LT1, if you're after that rrrrrumble sound.
You could slap a system on an LT1 made out of empty creamed corn cans welded together, and it would still sound good. The selection of components for the LS1 is not only trickier, but is much more limited if you're looking for that nice, deep rumble.
There are just 2 long-tube/cat-back combinations I've heard that had that nice rumble. Both had Kooks headers, but one had a stainless Magnaflow cat-back, and the other one had a Spin-Tech. As high a quality piece as they are, to my ear, nothing sounds more "crackly" or "raspy" than a Borla on an LS1. That's my experience, anyway.
04-14-2006, 08:41 AM
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yeah i agree, i dont mind the high pitched sound that makes it sound like a racecar with BITE! similar to cobras also i think, but its just that blappy noise and **** thats sound horrble i dunno maybe its just me but my friends alllove my flowmaster sound and think im crazy for wanting soething diffrent.