Engine note change/drone when in 6th gear

[LikeMike]

Originally was going to put a double H pipe or single X pipe but the stock exhaust sounds great 1st to 5th gear. However on the 6th gear, the engine note goes really low and starts having a very deep drone. I don't think this is from RPMs as it occurs at 50+ mph. Need to know if this is normal.

Car Conditions:
- In sport exhaust mode when in 6th gear
- Premium gas
- Fully stock, 700A
-200 miles old
- No lights

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[murick]

I believe I heard some droning when the engine/trans was still cold, but it was present on the other gears too. I will look into it more at the next opportunity. At 50+ mph in the 6th gear, you were around 1.500+ RPM?

 

[shogun32]

there are resonance frequencies between 1400-1800 rpm. The solution is to always stay above 2000. 6th gear shouldn't be used below 65MPH. I don't bother to use it till over 70.

 

[RocketGuy3]

I have noticed some drone, but I don't think it's anymore drone than on other loud, aftermarket exhausts I've had on other cars... Of course, the nice thing about this one is you can always just put it into quiet mode if it bothers you, heh (and I usually do for road trips).

 

[RocketGuy3]

there are resonance frequencies between 1400-1800 rpm. The solution is to always stay above 2000. 6th gear shouldn't be used below 65MPH. I don't bother to use it till over 70.

Wow. I'm using it by ~40 unless I'm goosing it. Haven't noticed any drone quite that bothersome even in "race" mode, and the gas savings of course are nice.

 

[JOKER M1]

Yeah 6th seems like an overdrive gear

 

[JDM_WAAAT]

Yeah 6th seems like an overdrive gear

There is no "seems like". 6th is a huge overdrive. You can use 6th gear at 40 mph if you want, so long as you use it correctly. It's not for acceleration unless you're going 60-65+, but even then you should probably downshift to 5th. Doing so sounds better anyway.

 

[Rhyanski]

Mach 1 supplement (Edition 2020) says the recommended gears for economy driving.
6th is huge overdrive

And yeah, running 6th on 43-45 MPH goes around 1500RPM, which is quite low. I just add throttle not to go below 45mph while just cruising like Miss Daisy..., but for takeovers or acceleration always downshift to at least 5th, which sets me around 2500-2800rpm.

 

[Charlemagne]

running 6th on 43-45 MPH goes around 1500RPM, which is quite low.

Pretty normal for constant 35 mph speed in the city, it goes even to 1300 rpm with 10R80 in 7th gear at 30-35 mph in Drive mode (Sport sticks to 6th around 1800-2000 rpm at minimum). Never heard any weird sounds or resonation at this rpm, the engine is barely noticable at this speed and rpm. I don't think it hurts it at all. Obviously downshift is needed for accelerating.

I keep it tame within city limits and step on it when I'm out

 

[Magnetic Stang]

Aren't 5th and 6th gears basically over drive gears? 6th gear at 40 seems crazy to me. Even 6th gear at 50 seems crazy unless you're on flat ground.

 

[Dfeeds]

Aren't 5th and 6th gears basically over drive gears? 6th gear at 40 seems crazy to me. Even 6th gear at 50 seems crazy unless you're on flat ground.

The Mach 1's 5th is its 1:1 so not necessarily the OD like the 2018+ GT.

That low hum might be you lugging the engine. My car absolutely hates 6th gear below 60 mph and any attempt to accelerate, below that speed, just gives me this awful deep humming sound (.62 to .63 so our 6th gear ratios are practically identical). It's not the same sound I hear when cruising below 2k in other gears, but the engine also doesn't have to work as hard to accelerate with higher gears.

Fwiw, I can still squeeze out 27 mpg keeping the rpms around 2100. Cruising around 1800 actually gets worse mpg, because I need more throttle, unless I'm cruising on a slight decline.

 

[LikeMike]

The Mach 1's 5th is its 1:1 so not necessarily the OD like the 2018+ GT.

That low hum might be you lugging the engine. My car absolutely hates 6th gear below 60 mph and any attempt to accelerate, below that speed, just gives me this awful deep humming sound (.62 to .63 so our 6th gear ratios are practically identical). It's not the same sound I hear when cruising below 2k in other gears, but the engine also doesn't have to work as hard to accelerate with higher gears.

Fwiw, I can still squeeze out 27 mpg keeping the rpms around 2100. Cruising around 1800 actually gets worse mpg, because I need more throttle, unless I'm cruising on a slight decline.

I will look at the RPMs more in detail later. I would agree with others that it puts me around 1500-2000 whereas the other gears I am around 2000-3000. Though I've gone below 2000 several times. I may just be noticing that quick trips below 2000 sounds different that being there consistently. But you best described the sound, it is like a low pitched diesel drum/hum that gets worse trying to unsuccessfully accelerate lol. Also first time owning a manual. Having driven a manual Honda, the Mach 1 is by far the easiest someone can drive a manual with.

 

[JDM_WAAAT]

Aren't 5th and 6th gears basically over drive gears? 6th gear at 40 seems crazy to me. Even 6th gear at 50 seems crazy unless you're on flat ground.

Again, there's no "basically" to this.

5th is 1:1 (not overdrive)
6th is 0.63 (quite an overdrive)

 

[shogun32]

Also first time owning a manual. Having driven a manual Honda

then you should be well aware of how to wring a motor's neck. Just because it's a V8 doesn't mean you don't rev the snot (well if 4-5k is 'snot') out of it. The meaty part of the power starts at 3500. If you're going to just stay under 3000, should'a bought the 4-banger.

 

[Dfeeds]

I will look at the RPMs more in detail later. I would agree with others that it puts me around 1500-2000 whereas the other gears I am around 2000-3000. Though I've gone below 2000 several times. I may just be noticing that quick trips below 2000 sounds different that being there consistently. But you best described the sound, it is like a low pitched diesel drum/hum that gets worse trying to unsuccessfully accelerate lol. Also first time owning a manual. Having driven a manual Honda, the Mach 1 is by far the easiest someone can drive a manual with.

Each gear is progressively harder for the engine to spin. So cruising under 2k in 5th isn't going to be the same as 6th. 6th gear is very tall and really labors the engine, hence the lack of any acceleration and the sound you hear.

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