How do I make a GM LS-based motor sound like one of these?

tuna55 wrote:

Javelin wrote: Most of the engines were also a very large bore with a short stroke. Built for high-RPMS and run through straight exhaust sidepipes.

I know I am picking nits here, but I don't believe short stroke = high RPM potential. I think that large bore = high RPM potential and that most classes have a CID limit. I doubt that stroke contributes much to sound. I am not sure if that's what you were saying or not. For one example, IHRA mountain motors have crazy high RPM potential, easily cresting 8 grand, and their strokes are over 5.5".

Pretty sure you're wrong.

One of the limiting factors for engine speed is piston speed. Piston speed is lower in a short stroke engine, so it can spin faster.

Not LS but SBC courtesy of Andrew Nelson:

Competing elsewhere:
http://www.youtube.com/watch?v=YXnbl4vFB-E

http://www.youtube.com/watch?v=2kGjMHFfAdA

and at the challenge:
http://www.youtube.com/watch?v=m_-IaXoLXUU&feature=channel&list=UL

180 degree headers for a Chevy, circle track ones, Dave posted the video of the sound.

Tuna55, shorter stroke engines can rev higher easier than long stroke ones can (Ferrari, Lambo, etc run short stroke engines), but you can still turn a long stroke engine pretty high, it just puts alot of stress on the rotating parts. IHRA peeps are building the biggest motors and the most power they can, so they do run long strokes. They do run for shorter times so they can get away with it. Pretty sure their engines wouldn't last long at the 24 hours of LeMans.

DILYSI Dave wrote: Randy has 180 headers and a 7# clutch and flywheel assembly on his Camaro. It sounds unholy. http://www.youtube.com/watch?v=wnck2ITynk0&feature=youtu.be

Holy E36 M3 that sounds cool! What engine is he running? Any videos of that at speed??

MrJoshua wrote: Not LS but SBC courtesy of Andrew Nelson:

Damn. You're right. I forgot that Andy's gorgeous headers turn an SBC into such a glorious sounding motor. Interesting.

This one is fun too:

http://www.myspace.com/video/the-phantom/road-race-corvette-on-drag-strip/4289688

IIRC that has LG longtubes and is a displacement limited motor. Something like 302 cubic inches?

ITB's with velocity stacks help a lot for a more exotic sound.

dyintorace wrote:

DILYSI Dave wrote: Randy has 180 headers and a 7# clutch and flywheel assembly on his Camaro. It sounds unholy. http://www.youtube.com/watch?v=wnck2ITynk0&feature=youtu.be

Holy E36 M3 that sounds cool! What engine is he running? Any videos of that at speed??

No videos at speed yet. Engine is a 377 SBC with Z28 crossram. I had it in a 67 El Camino with normal headers before and it sounded like a regular SBC with a big cam. 180 degree headers changed the sound alot.

DILYSI Dave wrote:

tuna55 wrote:

Javelin wrote: Most of the engines were also a very large bore with a short stroke. Built for high-RPMS and run through straight exhaust sidepipes.

I know I am picking nits here, but I don't believe short stroke = high RPM potential. I think that large bore = high RPM potential and that most classes have a CID limit. I doubt that stroke contributes much to sound. I am not sure if that's what you were saying or not. For one example, IHRA mountain motors have crazy high RPM potential, easily cresting 8 grand, and their strokes are over 5.5".

Pretty sure you're wrong. One of the limiting factors for engine speed is piston speed. Piston speed is lower in a short stroke engine, so it can spin faster.

Ding ding ding! What Dave said.

81cpcamaro wrote: No videos at speed yet. Engine is a 377 SBC with Z28 crossram. I had it in a 67 El Camino with normal headers before and it sounded like a regular SBC with a big cam. 180 degree headers changed the sound alot.

Very interesting! It sounds wicked with those headers on there! Not knowing much about SBCs, is there a performance advantage to the 180 degree headers as opposed to more traditional headers?

Cool car BTW!

SupraWes wrote: ITB's with velocity stacks help a lot for a more exotic sound.

Carbs will sound a whole lot similar for some reason

Keith wrote: Seems to me a flat plane crank for an LS motor would cost about the same as a custom stroker crank for an LS motor. You might want a different cam, too

Depends on if you want forged or billet. Billet would probably be billet no matter what, but forgings would require a different die set. For a one-off crank? Billet.

Cams... apparently aren't that expensive. There's a guy putting LS3 (I think) heads on a stroked 351W and said that the camshaft for it will cost just as much as any other billet cam. Ford valve order is reversed so a standard core won't work. The fun part looks like it's going to be the intake manifold, since Chevy and Ford have opposite leading banks.

Here's a similar question: how do I get a Chevy to sound like the old Boss 302 winding out to 9000 rpm like I heard at the Mitty?

Why not just build a Boss 302? The parts aren't that hard to come by, as long as you're not looking for actual 1969/1970 parts. Heck, modern aftermarket 8.2-deck blocks are way better anyway, and so are the aftermarket Cleveland heads.

Javelin wrote:

DILYSI Dave wrote: One of the limiting factors for engine speed is piston speed. Piston speed is lower in a short stroke engine, so it can spin faster.

Ding ding ding! What Dave said.

The limiting factor at the scary-edge forms of racing isn't the bottom end, it's the valvetrain. When I was a kid, everyone said to never run valvesprings more than X away from coil bind. Now, the thinking is, run as close to coil bind as you dare, since slamming the spring solid instantly negates any harmonics in the spring

Big cubes need big valves and big lift numbers to make big power, this means scary loads on the valvetrain.

Bigger bores do at least mean more room for larger valves and/or less bore shrouding for more actual flow, but at some point you run out of room for more bore. Didja know that they're making "small block Chevy" engines with big-block bore centers now?

One thing that kinda shocked me was that Pro Stock engines are really getting tiny. 500 cubes from engines with sub-9" deck heights. Getting the intake manifold geometry correct is way more important than rod length. I know some people who would have fits if they learned about that. "b-b-but... rod length!"

Knurled wrote:

Javelin wrote:

DILYSI Dave wrote: One of the limiting factors for engine speed is piston speed. Piston speed is lower in a short stroke engine, so it can spin faster.

Ding ding ding! What Dave said.

The limiting factor at the scary-edge forms of racing isn't the bottom end, it's the valvetrain. When I was a kid, everyone said to never run valvesprings more than X away from coil bind. Now, the thinking is, run as close to coil bind as you dare, since slamming the spring solid instantly negates any harmonics in the spring Big cubes need big valves and big lift numbers to make big power, this means scary loads on the valvetrain. Bigger bores do at least mean more room for larger valves and/or less bore shrouding for more actual flow, but at some point you run out of room for more bore. Didja know that they're making "small block Chevy" engines with big-block bore centers now? One thing that kinda shocked me was that Pro Stock engines are really getting tiny. 500 cubes from engines with sub-9" deck heights. Getting the intake manifold geometry correct is way more important than rod length. I know some people who would have *fits* if they learned about that. "b-b-but... rod length!"

ding ding ding!

off topic, we'll table this for later.

tuna55 wrote:

Knurled wrote:

Javelin wrote:

DILYSI Dave wrote: One of the limiting factors for engine speed is piston speed. Piston speed is lower in a short stroke engine, so it can spin faster.

Ding ding ding! What Dave said.

The limiting factor at the scary-edge forms of racing isn't the bottom end, it's the valvetrain. When I was a kid, everyone said to never run valvesprings more than X away from coil bind. Now, the thinking is, run as close to coil bind as you dare, since slamming the spring solid instantly negates any harmonics in the spring Big cubes need big valves and big lift numbers to make big power, this means scary loads on the valvetrain. Bigger bores do at least mean more room for larger valves and/or less bore shrouding for more actual flow, but at some point you run out of room for more bore. Didja know that they're making "small block Chevy" engines with big-block bore centers now? One thing that kinda shocked me was that Pro Stock engines are really getting tiny. 500 cubes from engines with sub-9" deck heights. Getting the intake manifold geometry correct is way more important than rod length. I know some people who would have *fits* if they learned about that. "b-b-but... rod length!"

ding ding ding! off topic, we'll table this for later.

I've a hunch that there isn't one aspect that's always the limiting factor.

MG Bryan wrote: I've a hunch that there isn't one aspect that's always the limiting factor.

You mean, there isn't a single all-encompassing stumbling block on the road to higher RPM?

Knurled wrote:

Here's a similar question: how do I get a Chevy to sound like the old Boss 302 winding out to 9000 rpm like I heard at the Mitty?

Why not just build a Boss 302? The parts aren't that hard to come by, as long as you're not looking for actual 1969/1970 parts. Heck, modern aftermarket 8.2-deck blocks are way better anyway, and so are the aftermarket Cleveland heads.

'cuz I like the packaging of the LS motor better and there's already one in my car