Discuss here about Yoeddynz's little Imp project...

[shrike]

10 minutes ago, Roman said:

Does a flat six actually have any reason to sound different than a straight six? 

As in, arent they both even firing order? 

Wonder if the "flat six sound" is more "air cooled sound" 

Isn't the main reason for the subie rumble because of unequal length headers?

[Raizer]

19 minutes ago, shrike said:

Isn't the main reason for the subie rumble because of unequal length headers?

Yes, had equal length headers on my old wagon, got rid of the rumble and generally improved the sound.

[BiTurbo228]

7 hours ago, Roman said:

Does a flat six actually have any reason to sound different than a straight six? 

As in, arent they both even firing order? 

Wonder if the "flat six sound" is more "air cooled sound" 

That's my understanding. Flat 6s are essentially just flattened I6s, so there's no fundamental reason they'd sound different.

2v vs 4v has a difference in sound as the valve opening and closing events are more sudden in a 2v giving them a bit more 'bark'.

Silencer design could well make a fair bit of difference. I get the impression the packing in silencers cancels higher-end frequencies better, so it could end up sounding a little raspier with a different design.

You could just put a tin can on a string with some pebbles in it to give it that 911 'clattery' sound at idle   and/or replace the end of the j-pipes with butterfly valves for an open exhaust system as and when you please...

[yoeddynz]

16 hours ago, Roman said:

Does a flat six actually have any reason to sound different than a straight six? 

As in, arent they both even firing order? 

Wonder if the "flat six sound" is more "air cooled sound" 

I don't know why but most flat sixes do certainly have a different sound, including goldwings. I was out cycling a year or two ago and I could hear a distinctive sound of a flat six in the distance behind me and 10 seconds later a gl1500 goldwing past by me. It was just cruising along and had exactly the sound I want at cruise. Its a sort of muffled burble. A sound I have never heard before on any of the inline six powered cars I have owned or driven but my Viva V6 made a similar sound.  Goldwings have twin exhausts but they do have a crossover box between the headers and the tail pipe mufflers. But my Viva just had a single tailpipe.

This video here gives a good idea of the sound I'd like when just cruising. Maybe I just cant hear the burble/rumble from in the car. Mine sound much nicer once its above say 3500.

Or this vid, 6.30min in..

(six carbs for induction doort though)

[Truenotch]

That's a really consistent whistle eh! 

My guess is one of the vac ports in the throttle body is whistling as the flow runs past it. Kinda reminds me of a few 4AGE 20v powered cars that get a whooshy whistle at wide open throttle. 

[yoeddynz]

I was starting to think its something like that too. If it was a simple vacuum leak I reckon it would do the sound at idle with the throttle shut when its at max vac on the engine side.

I also removed the iacv and blanked it off to make sure it wasn't that creating a sound so I know that's not at fault.

There is a thick card gasket I had made for between the TB and the mounting flange. Just a square, one big hole for tb bore and the four holes for the mounting bolts. I wonder if its flapping/whistling where it sits over one of the various bleed ports?

 

[Roman]

 its around the plenum chamber or possibly something funny in the throttle body

This might sound crazy but there isnt something like a lego character stuck in there? 

[tortron]

Just now, Roman said:

 

This might sound crazy but there isnt something like a lego character stuck in there? 

The heads are hollow so kids don't choke on them right. I bet it's just like blowing over the top of a beer bottle

[yoeddynz]

No such issues with my airflow optimised Mandalorians. They have helmets on. Very aero helmets at that..

[Tele29]

Hi, I have the solution to the whistle. Drown it out!

[anglia4]

4 hours ago, yoeddynz said:

I also removed the iacv and blanked it off to make sure it wasn't that creating a sound so I know that's not at fault.

I came here to say that. I have nothing else to add but needed you to know I'm thinking of you.

[HumberSS]

Can you not do the old 'spray a bit of engine start around the place' trick to see if it idles up a little??

[yoeddynz]

I had considered that but its really hard to hold it in a place where the noise shows up unless driving it. 

[HumberSS]

1 hour ago, yoeddynz said:

I had considered that but its really hard to hold it in a place where the noise shows up unless driving it. 

Worth a crack anyway while idling/revving?

[Mof]

Reminds me of a vacuum cleaner noise. What's the black concertina hose, is that your intake? I forget. 

Can you take it for a wee spin with that disconnected? 

Probably not. But hey can't hurt to rule it out 

[yoeddynz]

Yeah I've tried that too. Still there. 

@chris r has messaged me just before and said to recheck my idle bleed screw. He had exactly the same sound. 

Turns out I'm not the only one suffering from whistling Honda throttle bodies.  Loads of threads out there around the world with the same issue.  When I rest my ear against the top of the plenum lid the sound is amplified and does sound like it's coming from the tb. I'm going to have another look at this tomorrow. 

 

[fuzzy-hair-man]

Quote

Although I'm happily getting the last bit of wear out of the old tyres and they always feel super stable and grippy when getting low, like a semi slick, they most likely wont pass another wof test.  They have always worn on the outside which I found odd considering the amount of negative camber. I have always swapped them back to front regularly but they still wore as such. I thought I best check the toe angle. I'd previously done it with string. Not the best way and quite a faff. So I made these measuring jigs up..

Is it the front or rear that wears on the outside? You mentioned swapping them regularly so presumably it's one end? Swing axles have pretty high roll centres so it might be getting some jacking forces on cornering that's actually moving the outside wheel down / into droop on cornering rather than into bump as expected.

[8ball]

Gives off impco gas system vibes that whistle sound.

[DB8-TypeR]

On 16/09/2024 at 20:36, yoeddynz said:

 

Turns out I'm not the only one suffering from whistling Honda throttle bodies.  Loads of threads out there around the world with the same issue. 

 

Yep my integra makes a whistle at certain throttle percentage (quite light) right the way through the rev range. Only really noticeable with an aftermarket intake, original intake with resonator eliminates the noise

[Muncie]

My holden had a squeaky chicken chew toy sound under boost...... 3/4 of a tube of JB Weld grey sealant fixed that. 

+1 for a sharp edge whistling somewhere.