garnet92

A little background: I’ve been one of the CL’ers Bit**ing most about the L-Tuned droning resonance at about 2K rpms. I considered replacing the system with something else – I like the LT sound but hate the drone – but ended up changing my driving style instead.

I don’t hear it as much lately since I e-shift almost 100% and I usually start in 2 and click to 3 when I’m ready – same with the 3-4 shift. Keeping the rpm’s up above the 2K mark avoids the drone and has the additional benefit of pushing me back into the seat every time my lead foot drops. Sure, it plays hell with gas mileage – but it’s worth it. The torque converter just compounded the g-force and I’ve already gone on record as to how much better the overall drivability of the car improved with the TC. But I just stumbled on another benefit of the TC.

Today I noticed the ABSENCE of the drone????? No BS – it hasn’t vanished completely but it’s not nearly as noticeable. I noticed its absence on the way home at rush hour. I took a different route and was forced to drive like a sane citizen (I couldn’t haul a$$ from one light to the next). As soon as I noticed – I made it a point of turning off audio and leaving it in “5” for the remainder of the drive home. It’s mostly start-stop from light to light and traffic is heavy. The drone is seriously reduced. I don’t know how noticeable it would be if I wasn’t aware of it.

Now combustion engine/transmission technology isn’t my area of expertise – but we know that a higher stall speed converter changes the relationship between the engine and tranny. It never occurred to me that increasing the stall speed of the converter could yield another hidden benefit – that of almost eliminating the dreaded “drone”.

Anybody else with LT or Borla and TC noticed this???

Mr Johnson

This may sound wacky but... What was the weather like? I've noticed a dramatic change in the amount of resonance depending on both temperature and humidty.

DaveGS4

iTrader: (2)

Hmmm... Garnet very interesting observation.

I got my Borla and TC put on at the same time, and I've never had a droning issue. Never thought to connect the two.

Manaray

From my experience with all the exhausts I've had on my cars (including the current APEXi WS system and the Veilside Ti system), the exhaust gets quieter after you've had them on for a while but then it will eventually get louder.

I'm not a expert on this either but I think it's because the packing loosens up a bit which abosorbs more sound but then once the packing is shot, it will get louder (this may take years though).

I could be way off base but this has been the case with every system I've had on every car...even my Veilside Ti's which are loud as hell (sounds DAMN mean though!) because I took off my resonators have quited down a bit. The MEAN droning (you think the L-Tuned is bad, multiply that by like 1000x and you'll have what I had) has calmed down. I still need resonators (which should fix it completely) but it's much better than before.

I have spoken with my buddy who is a motorcycle expert (in every respect) and he said the same thing about motorcycle exhaust...both are combustion engines (hell, some motorcycles have larger engines than some cars!) so I would assume the same theory applies.

LexusRules

Sound changes a lot, In canada when winter comes my PE is much louder than in the summer on a hot humid day.

regarding the TC / Stall speed / Droning. my guess is that the tc is a stall ~3000 right? drone is at 2000? as long as teh drone is below the TC release the TC should cause the car to make a nicer sound.. if you ever rev your car to 2000 you'd notice theres no drone, or i hope not. Just a nice vroom.

The reason i think that the drone goes away is because the TC acts like a clutch, and as it slips more it allows less load on the engine but more momentum.. maybe like spinning tires? im not sure exactly how the TC works either yet.. basically the higher stall speed allows the engine to work at a way so the noise it produces isn't a "lugging" that produces droning.. does this make sence?

JacobT

Garnet,

I've noticed that after I got my TC installed. That's another reason I told you "can't live without it".

With the stock TC, at cruise speed and 2000 rpm, if you give a little more gas, the tranny keep in the same gear but more load on the engine. This is where the drone comes from. With the higher stall TC, you give some more gas, due to the higher slippage rate, the tranny will downshift and rmp jumps to 3000. The drone will never happen

Have you noticed the car shifts more agressive with high stall TC?

garnet92

Alex – the stall speed is 2800 and yes, your thoughts are similar to mine.

I know that the higher stall speed allows the engine-side turbine to get to higher rpms (in my case, about 500-600 more) before pumping enough energy to the stator to actually move the car. The stator is the output of the TC unit (and input to the transmission). So, like you say, the engine doesn’t labor as much to move the car. Makes sense to me.

Anyway – it could be that we’re all partly right – the weather/humidity could have an effect although the weather was pretty much the same for a couple of weeks before the TC install – cool and rainy. As far as the “burning in” of the packing material – that could also have an effect – the LTs have been on for almost a year now – but only yesterday noticed the lack of resonance?? Perhaps all played a part??

And Jacob – I should have asked you for a detailed list of TC benefits – I didn’t know that “”drone reduction” was included at no extra cost? That alone is worth a couple of hundred of the price to me! So you also noticed the same thing? And yes, it does seem to shift more positively.

Whatever the reason, the GS is getting better and better.

whitels

I wonder if anyone has played with changing resonator size to fine tune their exhaust sound. It plays a role in the sound frequency generated by the exhaust. Bigger means quieter, smaller means louder. With the L-tuned drone, perhaps changing to a slightly bigger or smaller generator would alter the 2K rpm drone. I'm betting on the slightly larger resonator.