m3gtdriver

I own this '71 Opel A Commodore Coupe since 1984. I restored and modified her during 2,5 year and still drive her around.

We also did 4 seasons dragracing/sprint on 1/8 mile tracks but it showed that the 3.0L fuel injected straight six with stickshift wasn't fast enough for the V8 autotrans cars.

I wanted a Chevy V8 in it but they had the oilpump mounted on the rear crankshaft bearingcap. When installed in the car, the center link between the pitman arm and idler link had to go through the oilpump, which ofcourse isn't possible. I know that there are some guys who install the V8 forward and up but that's not how I prefer to install any engine, specially not a big heavy V8.

Now I'm again looking for a V8 conversion because of the new Generations of Chevy V8's with their front mounted oilpump and 6speed autotrans. Seemed a very nice combination untill I discovered that the new gen engines don't make that typical raw V8 sound anymore because of the revised firing order.
I'm not racing my Commodore anymore so I don't really need 500HP but I DO WANT that typical V8 sound. So now I want to find out if camshafts are made so you can have the old firing order in the new gen engines and are there negative side effects, if doing so?
Are there people that performed a modification like that??
Or, would switching to a 180 degree headerset only, help to restore the sound??

I hope someone can shed some light on this subject.

thunderstruck507

iTrader: (18)

You can get close enough with proper exhaust and an aftermarket cam. Most people (even car people) have no clue mine is late model engine swapped or EFI until I tell them.

You need longtube headers, 3" duals with either no cross over or at most an H pipe, and a cam with some overlap. From there have the ECM programmed for an idle in the 700-850 range depending on cam size. Muffler choice will determine more about the sound than anything.

I don't have a good idle video of the car as it is with the new larger cam but here is an older one, still not the best representation of how it sounds in person:

Midnight02

iTrader: (8)

It's a combination of a number of things that make that "raw V8 sound", however most would attest that a cam swap and a free-flowing exhaust (long tube headers, off-road y-pipe or true duals, catback) will get you pretty close to the sound of the good 'ole days.

I also added an electric cutout in the intermediate pipe. By cracking that open 30-40%, it supplies additional volume to the exhaust note without getting a ton of rasp. I'll try to get you an idle clip when I get home this evening, however here's a good idea of what it sounds like on the track.....

RPM WS6

iTrader: (3)

This is excellent and correct advice.

If you are looking for the "old" V8 sound from an LSx, first rule is to definitely avoid a Y-pipe and really even an X pipe, as these produce a higher pitched, more "modern" exhaust note. As stated above, you'll want straight duals or an H-pipe at most.

I'm sure this goes without saying, but obviously you must not use any sort of cat converter either, as this has a noticeable mellowing and smoothing effect on any exhaust system which leaves it sounding far more modern than old systems without emission controls.

m3gtdriver

Because of the build year of my car, I don't have to comply to any emission requirement
My exhaust will be open with one muffler per side and NO cats.
I listened to both videos and then to a video of an 350 V8 and it's a lot different still.
I thought, maybe the modern V8's have a flat crank but that's not the case so the only thing that's different is the firing order, right?

RPM WS6

iTrader: (3)

I agree, you won't get an LSx to sound exactly like an old iron SBC, but, as stated above, muffler and exhaust pipe configuration will play a big role in this so unless the videos you are comparing are of identical exhaust setups, it's still not a 100% fair comparasion. Also, video quality might not be the same, so it's really best to compare in person.

It's more than just the firing order that's different. There are also several cylinder head differences and exhaust port/location differences.

thunderstruck507

iTrader: (18)

The video of my car is not entirely accurate as to how it sounds in person. The video will not capture how deep the tone is as well as other nuances.

I had the same exhaust before with a 350 sbc and other than sounding a little raspy in the mid range now and overall getting a little angrier there wasn't much change. It definitely sounds more gnarly with the ls1 than it did with the 350 in person.

m3gtdriver

I still have the idea that the old 350 sbc have a more irregular sound compared to the civilized sounding LSx. Maybe it's also due to the intake manifold plus the fact that the old sbc fire twice in each bank (per 720 degrees crank rotation) before going to the other side. That's why I thought that going to a 180 degree header setup should bring back that same sound.
Some years ago when I visited the States I also went to some NASCAR races and I could easily hear the difference between the 4into1 header cars and the 180 degree header cars. The 180 degree header cars sounded with a higher pitch and that's not what I would prefer for my car.
I think I have to think it over again or maybe search a bit more about different cams that change the firing order.

BTW, Thunderstruck507, your chevelle looks really mean, nice car.

m3gtdriver

I reviewed the rumble sound problem again last weekend, made some drawings and excel sheets and came to the conclusion that it's not the firing order itself that makes the different sound between the old SBC and the modern Chevy's.
Nor is it the firing in the same bank after each other that's responsible for it.
Both V8 configurations eventually have the same firing-pulses in the exhaust pipes, L-R-L-L-R-L-R-R.
Putting it on paper made it all clear to me, if you write down the firing-order per bank of both configurations (whether you hear the firing in the left or right exhaust pipe, with normal 4into1 headers) and slide the lists next to each other, you'll find the same rhythm. What's different, is which cylinder fires exactly but will that be the cause of the old V8 rumble??

RPM WS6

iTrader: (3)

Again, cylinder head/port design and location are all different, as well as intake manifold design. They are different engines, beyond just the firing order.

If you've ever heard an old Oldsmobile V8 engine with stock head castings, they have a very distinctive sound. This is due, in part, to siamesed center exhaust ports with a recessed divider. Often, when performance work is done to Olds heads (or with aftermarket performance castings), this divider is made flush to the header flange surface - better isolating the exhaust ports. The difference in exhaust note from this one simple change is noticeable to anyone that is familiar with Olds engines.

What does all that have to do with LSx vs. SBC? Just the fact that, even on the exact same engine (meaning the Olds example above), exhaust note can change noticeably with cylinder head/port changes, and that's even with the same initial head. LSx vs. SBC heads are considerably different, so I'm sure this has a great deal to do with any differences in exhaust note (assuming similar exhaust system, cam overlap and state of tune.)

m3gtdriver

I think I know what you mean. Probably it's best to stick with long tube headers going into a big diameter exhaust pipes with H-pipe and only one muffler at each side in front of the rear axle and the pipes exiting at the rear bumper.
Thanks for the help everyone.

falcon_morris

This is an old thread, but the answer is still not complete. I believe the "rumble" that you are seeking, we called it a scramble back in the late 60's is a function of the Carb. The carb is hunting back and forth from the idle circuit to the run circuit. The sound is very irregular and literally shakes the car a bit with a large overlap cam.
If you have this condition on an old time motor and don't like it (there might be a couple out there) a small hole can be drilled in the throttle blades and it will go away.

All the other answers are also contributing factors, but cam overlap and carb seem to be key.

I was always baffled by how all the really fast cars would start right up, until I got my first really good ignition system.

RPM WS6

iTrader: (3)

This doesn't cause a lopey/choppy idle specifically, just an overly rich poor quality idle. The throttle blades should never be open far enough to expose the transfer slot at idle more than .020-.040". As you mentioned, holes can be drilled in the throttle plates if more air is needed at idle.

Having said that, even with a properly setup and tuned carb, you can and will still get that lopey/choppy idle with a high overlap cam, you don't need to have the carb tuned wrong to get this. Conversely, you won't get that same sound if you have a mild/stock cam and simply tune the carb poorly by opening the throttle blades too far and/or running the idle overly rich.

Mercier

iTrader: (15)

Here's a clip that I think gets pretty close. This is LS2 (6.0L aluminum V8) with 2.5" run-of-the-mill aluminized pipe, no crossover, 40-series Flowmasters("2-chambers" - YES I still call them that ), and even with 1-5/8" shorty headers since I can't find long tubes to fit my application. 222/228/112 cam. Also I couldn't put the exhaust out the back because of space around the factory fuel tank. I think with long tubes, exhaust straight out the back it would be even more in the direction you guys are referring to. Fuel injection and improved head design has smoothed things out a little but there is not reason you can't get old-school sound IMO. I do still have a little more tuning to do but that's a fairly steady 800RPM idle. Might bump it down to 700-750 to make it sound a little meaner.

You need to listen to this on some decent speakers with a little bass to them to get the full effect..sounds like crap on a phone. The second video is from a slight angle so you can get more of an idea how much different the sound is straight out of the pipe. You get more of that sound waves bouncing off of metal effect(which i personally like)

RPM WS6

iTrader: (3)

^ Those above videos sound fantastic, among the best sounding Gen IIIs/Gen IVs I've ever heard IMO. I'm another BIG fan of the sound of old 40-series Flowmasters and true duals with no crossover (I have the same exhaust setup on my Nova).

Very nice!

Mercier

iTrader: (15)

Thanks! I considered going ultra-modern with x-pipe, stainless, and some fancy mufflers and make something that you *would not* expect to sound like that in a Jeep...but then mid-life crisis kicked in and I had to have my 2-chambers! They're cheap, age well, and can take a beating without much drama.

roninsonic

iTrader: (3)

My car don't sound modern


At the track (all you can hear is my car)



cold idle:



Hot idle:




Here's what it looks like under the car... Nothing special.

Mercier

iTrader: (15)

Sounds nice.

A little too close to open headers for my palate. But I've always liked a little tailpipe to smooth things out. Dumps are cool in their own right but I like to be able to at least hear the radio turned all the way up at a stoplight!

Actually probably not as bad in a Camaro..I've had a few fox bodies with dumps and they were livable. I don't want to imagine LTs and dumps in a Jeep with the top and doors off. I think passengers would have symptoms of shell shock.

roninsonic

iTrader: (3)

Believe it or not, I can hear music just fine, the only thing the exhaust affected was washing out the bass. One 10" W6 and a Fosgate 400-2 solved that.

I can carry on a conversation with bluetooth via my head unit no problems. In-car isn't that bad. Don't get me wrong, you can DEFINITELY hear it at all times, but I still jam out and listen to music while cruising with no problems.

Mercier

iTrader: (15)

I guess that's what doors and a roof will do for you.

I'm going to find a sound bar from a later Jeep and hack it in. Figure if it's 3" from your ear you'll probably hear at least some of it.