Dumb Question, but I gotta ask...

[toniferous2000]

What is it that causes our 3.4 DOHC's to sound so raspy and what is with that rat-a-tat-tat when giving WOT from 1st to second?

i understand what sound you are talking about and i dont think it is all in the exhaust. i use 2.5 aluminized steel and spintech mufflers on my 92 cutty with an auto tranny. i dont get the ratt-a-tat sound between gears, but there is a really unique growling sound from under the hood when accelerating that smooths out as you speed up....sounds almost like the computer is adjusting something and it makes the cams sound like that. i have only heard it on the 3.4 dohc. cant be headers. i have a custom built set of equal length, tuned headers built especially for my car at a performance exhaust shop i trust....and still this sound is heard. and it plainly comes from the engine compartment.
and for those interested, i am trying to get the guy to produce the headers i mentioned....they freed up 18 horsepower in my car.
as for the sound of the 3.4....enjoy it...i think it sounds agressive. sounds even better with the new exhaust.

[IRRebel5150]

Cam design is everything, and you cannot have it all. Sounds like crap at low rpm, but nearly Ferrari-like at 7500 rpm. If you're not happy. Buy Earplugs.

The change in exhaust note, IE, "like crap at idle-3000 rpm" more noticeably at lower speeds as you noted from 1st to second gear, seems to me to be the result of a lot of things already mentioned and a couple of factors in combination with them. Load on the engine at low speed and RPM really magnifies it, I know.

Yes, it is NOT a pushrod engine, thus not limited to the same restrictions on compromise as far as lobe design, ramp, etc. There is a totally different thinking on engines such as this.

Pushrod engines historically, and purposefully, have been noticeably more torquey on the low end but lose their steam rapidly as rpm's get astronomical. DOHC engines have the advantage when coupled with, particularly in this case and actually more the norm these days, 4 valves per cylinder and very generous intake and exhaust ports because no room needs to be reserved for pushrod clearance, for one, and have the capability to reach rpm levels no pushrod engine could ever dream of. Valve float is also nearly a non-issue with this design, which contributes greatly to the high rpm performance. GM engineers did their homework on this.

But with all things, compromise is a necessity. In order to develop horsepower, the engine was designed to come on strong much higher in the rpm range, well within it;s capability, thereby sacrificing the low end torque that pushrod engines live on, but reserving just enough to get a 2 ton vehicle moving.

The exact opposite is true of the pushrod engines. Think about the last time you lined up with a Mustang GT (If you never have, and your TDC is in good shape and hopefully modified, I invite you to do so, it's a load of fun) and he blew your ass off the line breifly only to be eaten alive a few hundred yards later. Many a victim has been embarrassed in front of his girlfriend by yours truly.

The anomoly exhaust sound from being a staggered crank, 60 degree design is also no doubt a small part of it, admittedly less noticeable on the 2.8-3.4 pushrod engines, but I have doubts that this is what you are noticing. This is a V6, first of all, and will never be confused with a V8 by exhaust note. Personally, I ignore it because at least I don't sound like a motorcycle groaning under the weight of a 600 pound rider in a strong headwind like these rice-rocket Civics and Eclipses do. Funny thing though that most of the Toyota V6's are 60 degree design as well though. (Although, admittedly, and reservedly, one of those aforementioned Civics my neighbor owns has beaten me more than I have him, and I have the time slip from when I personally drove it to a 12.46 quarter, so there's nothing wrong with even THAT sound, as much as I despise it).

One thing surprisingly not mentioned was the significantly larger 3" or so Primary exhaust on the 3.4 DOHC vs. the much smaller 2.25" (I Think) or so on the pushrod engines. Truly an example that these engines need to breathe, first of all, and secondly should be a common sense indicator of their ability to move a lot of fumes. At lower RPM's, I would have to beleive a kindof 'expansion chamber' effect would take place, not unlike that on 2-cycle motorcyle engines. I think we all well know what that sounds like given the two-wheeled weedeaters kids are riding everywhere these days.

In all, I wouldn't fret over what it sounds like. It's what the time slip reads and the blank expressions on your friends faces whom you've subjected what the car is capable of is what counts.

[toniferous2000]

Several years ago I had a '92 Cutless that had a particular growl to it. It had the 3.4L dual overhead cam engine. That car could make a turn at a stop light and present torque-steer when the hammer was dropped, followed by a quick acceleration, 6500RPM shift into second that would bark the tires and hit near 110 in just a few hundred yards. I was quite impressed with the performance. It scared me more than once. And the first thing I ever drove was a Super-comp Dragster. I drove it for a year. The repair costs were huge due to the size of the motor and special tools required, but the motor was a KILLER. Fill her up with super-unleaded and add a can of Chemtool and she became a beast with a score to settle. It took a Ford Taurus SHO that had been ridiculously lightened and put on the bottle...by three car lengths in a quarter.
Research revealed that the sound was due to a crack in the airbox. A short-ram intake made the sound louder. I got used to it. Eventually, the tranny gave out...probably due to the power from the motor. It just started to slip in first and then stopped moving altogether. I sold it for 100 bucks, but that motor would have KILLED a small-block chevy in a minute.

[RedZMonte]

Waken up the Zombies with this post... Notice the date "08-25-2004 "

[pocket-rocket]

Waken up the Zombies with this post... Notice the date "08-25-2004 "

Lol, I read the whole thread, saw my post and thought "when did I post this?!?"... then I saw the date, lol.