best way to remove rasp
I haven't read through this whole thread but I think most rasp is caused by a loose or vibrating exhaust system. It resonates at such a frequency that the resulting sound output is rasp.
Poly motor mounts help and/or eliminate most of it. I've experienced it even after installing the mounts when my muffler/exit pipe on the driver's side was just about to fall off the hanger. The result of it being less secure was more play and movement and I heard more rasp. Just my observation.
Poly motor mounts help and/or eliminate most of it. I've experienced it even after installing the mounts when my muffler/exit pipe on the driver's side was just about to fall off the hanger. The result of it being less secure was more play and movement and I heard more rasp. Just my observation.
Originally Posted by BigDaddyBry
I haven't read through this whole thread but I think most rasp is caused by a loose or vibrating exhaust system. It resonates at such a frequency that the resulting sound output is rasp.
Poly motor mounts help and/or eliminate most of it. I've experienced it even after installing the mounts when my muffler/exit pipe on the driver's side was just about to fall off the hanger. The result of it being less secure was more play and movement and I heard more rasp. Just my observation.
Poly motor mounts help and/or eliminate most of it. I've experienced it even after installing the mounts when my muffler/exit pipe on the driver's side was just about to fall off the hanger. The result of it being less secure was more play and movement and I heard more rasp. Just my observation.
Originally Posted by ChocoTaco369
a couple things. eliminating the y-pipe will take away a lot of the rasp because the sides of the y-pipe are unequal. the exhaust gases travel further from one side of the motor to the other, then meet at an imperfect merge. both these things mean that the y-pipe itself creates a lot of rasp. going to true duals will get rid of that component of the rasp since it doesn't take gases from the cylinders traveling at unequal length and shove them into an imperfect merge in a single piece of pipe.
also, a lot of the rasp is caused by the LS1 itself. the LS1 has a wacky firing order. the LS1's firing order is, i believe, 1-8-7-2-6-5-4-3. the order that the cylinder's fire in causes rasp. going to true duals will only take into account 4 cylinders per each pipe instead of all 8 cylinders going into 1 single pipe. since only 4 cylinders are being taken into account, that will cut down on some of the rasp, also.
true duals aren't perfect. sweet thunders are kinda raspy IMO, but true duals in general are the best chance you'll get at limiting rasp on the LS1. it may not be gone 100%, but it's certainly less raspy than anything a y-pipe setup can get you.
wow, i did not write that so well
excuse my awful grammar, i can't think so well right now 
also, a lot of the rasp is caused by the LS1 itself. the LS1 has a wacky firing order. the LS1's firing order is, i believe, 1-8-7-2-6-5-4-3. the order that the cylinder's fire in causes rasp. going to true duals will only take into account 4 cylinders per each pipe instead of all 8 cylinders going into 1 single pipe. since only 4 cylinders are being taken into account, that will cut down on some of the rasp, also.
true duals aren't perfect. sweet thunders are kinda raspy IMO, but true duals in general are the best chance you'll get at limiting rasp on the LS1. it may not be gone 100%, but it's certainly less raspy than anything a y-pipe setup can get you.
wow, i did not write that so well
excuse my awful grammar, i can't think so well right now Thats awsome man. Now there is a great excuse for me to get a true dual system.. That and the ( my exhuast is hanging waaay too low and Im scraping issue, should be enough for me)
But why doesnt the LT1 sound raspy, even though it has the same Y pipe setup.. It cant only be the firing order difference.
Originally Posted by Ace$nyper
I am pretty drunk and you still sound dumber then a rock found in a oxens poop.
You didn't hear what you wanted to and throw a hissy fit? **** YOU are you nine?
The only person crying is you, wanta talk race cars? I had a BBF T-bird before my 2nd nut dropped. You are the ******* ricer ***** that give LS1s a bad name.
So many times you can't even back you reasoning and still stick too it like your ******* Moses himself holding all 10 damned commandants. You are a tool who can't pioneer **** and rides the bandwagon of fat misinformantion on this site.
Wanta "own" choco and post how balla and right you are? How about this mr I own a race car? Dnyo your car with cats then with out show this 54908645908605 HP differnce you seem to claim.
No Child left behind has failed you are the poster child for it.
You didn't hear what you wanted to and throw a hissy fit? **** YOU are you nine?
The only person crying is you, wanta talk race cars? I had a BBF T-bird before my 2nd nut dropped. You are the ******* ricer ***** that give LS1s a bad name.
So many times you can't even back you reasoning and still stick too it like your ******* Moses himself holding all 10 damned commandants. You are a tool who can't pioneer **** and rides the bandwagon of fat misinformantion on this site.
Wanta "own" choco and post how balla and right you are? How about this mr I own a race car? Dnyo your car with cats then with out show this 54908645908605 HP differnce you seem to claim.
No Child left behind has failed you are the poster child for it.
you dam douche bag who the hell are you calling me a ricer, I dont gave a **** if you have a funny car Im not a dam ricer I tear ricers apart and suck ther pait off and those ugly *** body kits. If yoy read the thread I havent said one dam word about any hp difference you tool bag I just said I dont mine the rasp. You dam right I own a race car and my ls1 IS NO ******* RACER LS1 IS "BUILT BY GOD" I'd rather buy cats just to beat the hell out of you with them, No child left behind is a ******* mistake and joke just like you douche bag.
TECH Fanatic
Joined: May 2005
Posts: 1,135
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From: The 'Burgh, PA
Originally Posted by blacksskid07
you dam douche bag who the hell are you calling me a ricer, I dont gave a **** if you have a funny car Im not a dam ricer I tear ricers apart and suck ther pait off and those ugly *** body kits. If yoy read the thread I havent said one dam word about any hp difference you tool bag I just said I dont mine the rasp. You dam right I own a race car and my ls1 IS NO ******* RACER LS1 IS "BUILT BY GOD" I'd rather buy cats just to beat the hell out of you with them, No child left behind is a ******* mistake and joke just like you douche bag.
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Tech Resident
Joined: Jan 2006
Posts: 5,117
Likes: 3
From: Philly
Originally Posted by LSGunZ28
Thats awsome man. Now there is a great excuse for me to get a true dual system.. That and the ( my exhuast is hanging waaay too low and Im scraping issue, should be enough for me)
But why doesnt the LT1 sound raspy, even though it has the same Y pipe setup.. It cant only be the firing order difference.
But why doesnt the LT1 sound raspy, even though it has the same Y pipe setup.. It cant only be the firing order difference.
firing order plays one of the biggest roles in sound of all, my man. ever wonder why a ferrari and a lambo sound so high pitched, even with a V8 or big V12? it's because their cylinders fire in order. they fire 1-2-3-4-5-6-7-8 or 1-2-3-4-5-6-7-8-9-10-11-12. firing order plays one of the biggest roles of all in sound. why do you think mustangs sound so alike?
Originally Posted by blacksskid07
you dam douche bag who the hell are you calling me a ricer, I dont gave a **** if you have a funny car Im not a dam ricer I tear ricers apart and suck ther pait off and those ugly *** body kits. If yoy read the thread I havent said one dam word about any hp difference you tool bag I just said I dont mine the rasp. You dam right I own a race car and my ls1 IS NO ******* RACER LS1 IS "BUILT BY GOD" I'd rather buy cats just to beat the hell out of you with them, No child left behind is a ******* mistake and joke just like you douche bag.
Originally Posted by slp#3130
i only drive my car once a week, so really can't remember what it sounds like 
On The Tree
Joined: Aug 2006
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From: OKLAHOMA
Originally Posted by jimmypop13
well now that i'm thinkin about it, he MAY have a cutout. Damn that sure would make A LOT of difference. What I said could be pointless. GO DRIVE YOUR CAR....NOW!!!
Originally Posted by ChocoTaco369
firing order plays a big role in it. also, the LT1 has an iron block, which plays a HUGE rule in the sound, not to mention another 4 cubic inches than the LS1 has, though that probably has little effect. the iron block produces a much less raspy tone since it's so much denser and thicker than the LS1's lightweight, soda can block. that's not saying you can't make an aluminum block sound good or not be raspy, but it's harder to do. the LT1's iron block produces a deeper tone while the LS1 produces a more high-pitched, race-like tone, and these high pitched tones are more susceptible to rasp than the deep iron tone the LT1 produces.
firing order plays one of the biggest roles in sound of all, my man. ever wonder why a ferrari and a lambo sound so high pitched, even with a V8 or big V12? it's because their cylinders fire in order. they fire 1-2-3-4-5-6-7-8 or 1-2-3-4-5-6-7-8-9-10-11-12. firing order plays one of the biggest roles of all in sound. why do you think mustangs sound so alike?
firing order plays one of the biggest roles in sound of all, my man. ever wonder why a ferrari and a lambo sound so high pitched, even with a V8 or big V12? it's because their cylinders fire in order. they fire 1-2-3-4-5-6-7-8 or 1-2-3-4-5-6-7-8-9-10-11-12. firing order plays one of the biggest roles of all in sound. why do you think mustangs sound so alike?
Lol, they( Ferrai and Lamborghini) dont fire in that order!!!
Im not sure the block material has to do with the sound so much...
The firing order maybe...
The Y pipe is believeable as well.
But the firing order you gave for the v12 is ridiculous
1-2-3-4-5-6-7-8-9-10-11-12
Lol and rip the crank in half.
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Joined: Jan 2006
Posts: 5,117
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From: Philly
Originally Posted by LSGunZ28
-----------------------------------------------------------
Lol, they( Ferrai and Lamborghini) dont fire in that order!!!
Im not sure the block material has to do with the sound so much...
The firing order maybe...
The Y pipe is believeable as well.
But the firing order you gave for the v12 is ridiculous
1-2-3-4-5-6-7-8-9-10-11-12
Lol and rip the crank in half.
Lol, they( Ferrai and Lamborghini) dont fire in that order!!!
Im not sure the block material has to do with the sound so much...
The firing order maybe...
The Y pipe is believeable as well.
But the firing order you gave for the v12 is ridiculous
1-2-3-4-5-6-7-8-9-10-11-12
Lol and rip the crank in half.
i'm trying to picture this.
say these are the cylinders:
7 8
5 6
3 4
1 2
now here's how they fire:
4 6
2 8
3 5
1 7
i think. i think.
that's more like how a ferrari would fire. something along those line.
ferrari's use a flat crank V8. nothing's gonna rip off.
Originally Posted by ChocoTaco369
i'm looking at it upside down. a ferrari would actually fire 1 - 5 - 3 - 7 - 4 - 8 - 2 - 6
i'm trying to picture this.
say these are the cylinders:
7 8
5 6
3 4
1 2
now here's how they fire:
4 6
2 8
3 5
1 7
i think. i think.
that's more like how a ferrari would fire. something along those line.
ferrari's use a flat crank V8. nothing's gonna rip off.
i'm trying to picture this.
say these are the cylinders:
7 8
5 6
3 4
1 2
now here's how they fire:
4 6
2 8
3 5
1 7
i think. i think.
that's more like how a ferrari would fire. something along those line.
ferrari's use a flat crank V8. nothing's gonna rip off.
dude before you go on any further... are you sure, you know what you are saying?
if this was an inline 4
1-2-3-4
and it fired
1-2-3-4
the crank would twist in half.
wtf is a flat crank? wtf?!?!?!
Tech Resident
Joined: Jan 2006
Posts: 5,117
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From: Philly
Originally Posted by LSGunZ28
dude before you go on any further... are you sure, you know what you are saying?
if this was an inline 4
1-2-3-4
and it fired
1-2-3-4
the crank would twist in half.
wtf is a flat crank? wtf?!?!?!
if this was an inline 4
1-2-3-4
and it fired
1-2-3-4
the crank would twist in half.
wtf is a flat crank? wtf?!?!?!
There are two classic types of V8s which differ by crankshaft:
* The cross-plane V8 is the typical V8 configuration used in American road cars. Each crank pin (of four) is at a 90° angle from the previous, so that viewed from the end the crankshaft forms a cross. The cross-plane can achieve very good balance but requires heavy counterweights on the crankshaft. This makes the cross-plane V8 a slow-revving engine that cannot speed up or slow down very quickly compared to other designs, because of the greater rotating mass. While the firing of the cross-plane V8 is regular overall, the firing of each bank is LRLLRLRR; this leads to the need to connect exhaust pipes between the two banks to design an optimal exhaust system. This complex and encumbering exhaust system has been a major problem for single-seater racing car designers.
* The flat-plane V8 design has crank pins at 180°. They are imperfectly balanced and thus produce vibrations unless balance shafts are used, with a counter rotating pair flanking the crankshaft to counter 2nd order vibration transverse to the crankshaft centerline. As it does not require counterweights, the crankshaft has less mass and thus inertia, allowing higher rpm and quicker acceleration. The design was popularized in modern racing with the Coventry Climax 1.5 L V8 which evolved from a cross-plane to a flat-plane configuration. Flat-plane V8s on road cars come from Ferrari (the Dino), Lotus (the Esprit V8), and TVR (the Speed Eight). This design is popular in racing engines, the most famous example being the Cosworth DFV.
* The cross-plane V8 is the typical V8 configuration used in American road cars. Each crank pin (of four) is at a 90° angle from the previous, so that viewed from the end the crankshaft forms a cross. The cross-plane can achieve very good balance but requires heavy counterweights on the crankshaft. This makes the cross-plane V8 a slow-revving engine that cannot speed up or slow down very quickly compared to other designs, because of the greater rotating mass. While the firing of the cross-plane V8 is regular overall, the firing of each bank is LRLLRLRR; this leads to the need to connect exhaust pipes between the two banks to design an optimal exhaust system. This complex and encumbering exhaust system has been a major problem for single-seater racing car designers.
* The flat-plane V8 design has crank pins at 180°. They are imperfectly balanced and thus produce vibrations unless balance shafts are used, with a counter rotating pair flanking the crankshaft to counter 2nd order vibration transverse to the crankshaft centerline. As it does not require counterweights, the crankshaft has less mass and thus inertia, allowing higher rpm and quicker acceleration. The design was popularized in modern racing with the Coventry Climax 1.5 L V8 which evolved from a cross-plane to a flat-plane configuration. Flat-plane V8s on road cars come from Ferrari (the Dino), Lotus (the Esprit V8), and TVR (the Speed Eight). This design is popular in racing engines, the most famous example being the Cosworth DFV.
Last edited by ChocoTaco369; Jan 18, 2007 at 09:38 PM.
Tech Resident
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Posts: 5,117
Likes: 3
From: Philly
here's another example. we'll take the 2001 Ferrari 456M GT. its firing order is 1-7-5-11-3-9-6-12-2-8-4-10. on the engine, it would look like this:
11 12
9 10
7 8
5 6
3 4
1 2
so that means the cylinders would fire in this order:
4 8
6 12
2 10
5 7
3 11
1 9
notice how the whole left side of the engine fires before the whole right side of the engine? that is this "straight firing order" i'm speaking of. the whole left side fires before even one cylinder on the right side. this is what makes a ferrari sound like a mean V6 they're so high pitched...IMO, they sound like trash unless they're going WOT. a ferrari revving it up crusing at 15 mph...my car sounds a lot better. at WOT...well, the ferrari sounds pretty darn mean 
http://en.wikipedia.org/wiki/Firing_order
11 12
9 10
7 8
5 6
3 4
1 2
so that means the cylinders would fire in this order:
4 8
6 12
2 10
5 7
3 11
1 9
notice how the whole left side of the engine fires before the whole right side of the engine? that is this "straight firing order" i'm speaking of. the whole left side fires before even one cylinder on the right side. this is what makes a ferrari sound like a mean V6
they're so high pitched...IMO, they sound like trash unless they're going WOT. a ferrari revving it up crusing at 15 mph...my car sounds a lot better. at WOT...well, the ferrari sounds pretty darn mean http://en.wikipedia.org/wiki/Firing_order
