I know the basics, exhaust, cam and cubes, and i know firing order has a little bit to do with it. but what else can be done to make an engine sound bad? will heads or compression ratio change the sound? also, i know on old engines you can do the 4&7 firing order swap, does that make a difference? can you change the firing order on a newer engine like an ls1? also, as far as cubes goes, soundwise is there a preference between boring or stroking? for exhaust, does it sound better with or without a crossover? any input would be appreciated. thanks

 

High compression engines have a distinctly different sound, kinda raspy. A tight/narrow lobe separation angle on your cam will give it the rumpeta-choppeta sound I think you're looking for due to dilution of intake charge by exhaust gasses. I personally don't think there's any better sound on the planet (mechanically speaking) than a healthy high compression big block with a long duration solid roller cam. My ears perk up and heart beats a bit faster every time I hear one idle. HTH

 

does a high compression make the sound any deepr, or just raspy?im assuming its a good kind of raspy. and do heads make a difference? and i definately like a nice lope to the idle. thanks
btw, does any one know where i can get sound files comparing high compression sound to low compression sound? thanks

 

Horse Power makes all the difference. If you biuld a motor to make power it will sound "bad" The more Horse Power a motor makes the more the pillars of heaven will shake and that gets everyones attention. Open the exhaust up, port out the heads, get a nice lopey cam and up the compression...an internal combustion engine is all about moving air... the more air you move the louder she'll roar.

 

thanks for the help, but theres still a little bit left to be answered. is there a preference between boring or stroking? and does exhaust sound better with or without a crossover? thanks

 

There are advantages/disadvantages to both stroking and boring. The main reason that stroking is more popular is that (in most engines) you can gain more displacement than with just boring. Exhaust sound is a matter of personal preference but, based upon your original post, I think you are looking for a "rougher" sound rather than a "smoother" sound so you'd be happier without a crossover, which will smooth the sound some.

As far as making an engine "sound bad", there are lot's of ways, including actually building a "bad" engine. The "bad" sound of a race engine is typically a combination of lots over overlap and an exhaust system that lets the natural sounds of combustion be heard. Keep in mind that the reason the race engine sounds so "bad" at idle is because it's running really crappy at that rpm.

 

ok guys thanks a lot, but(theres always a but)as far as the crossover goes, I know on C5s that if you keep the original h-pipe, than u get loud popping sounds on deceleration which i don't care for, it sounds like a backfire. would this happen without a crossover, or is it jsut because its an h-pipe?it doesnt do it with the x-pipe. also, is there a difference soundwise between 2 engines of the same cubes, but one is bored and one is stroked?I understand how a stroked engine is more for torque and a bored engine is more for hp, but I'm jsut curious about the sound right now. btw, u guys are great, thanks for the help.

 

The "Bacfire or Popping" you don't like is the combination of a fairly rich mixture, combined with a lower exhaust pressure. This lower pressure causes extra flow through the exhaust valves, letting fresh mixture in the hot exhaust. This causes the nice pop in decellerating. A properly mounted cross over will help equalize the variances in the exhaust pressure that cause this and "silence" the popping by minimizing the amount of fresh mix drawn into the hot exhaust system during deceleration. The down side is that they don't work just during deceleration so an X- or H- pipe will even out the exhaust note and hide the "bad" sound you are looking for.
As far as Bore vs. Stroke.... Again it's an air pump..more air is moved "freely" the more power and more bad the engine will sound. Higher compression "hits harder" so the exhaust note is usually more raspy... Back to Bore vs. Stroke though: Closer the ratio of Bore to stroke usually makes it easier to rev up the motor which will help in the race car "crack of the throttle sound" as you romp on it.

 

unplug a spark plug wire-i guarantee it will sound bad!

 

I've got a 12:1 427 with Hooker headers and side pipes. The 246/254 @ .050" duration of the cam does give a lope to the idle. Regarding noise, there is a sharp note made with every firing of the cylinders causing a sonic vibration that you can feel throughout the car, throughout your whole body.

Cruising down the highway at 2500 - 3000rpm reminds me of WWII warbirds at air shows when they do their stately passes over the crowd. It is actually about the same rpm. (2000rpm with V12 Merlin = 3000rpm V8). When I put my foot into it and run up to my 7000 redline it sounds as good as any race car I have ever heard. To say it screams is a bit of an understatement.

High compression gives an engine a certain "bite" to its sound. There are drawbacks like gas availability, but its demanding, high strung personality are hard for me to pass up.

Chuck

 

2 will really do it

 

I want a 427