ALH swapped 4runner soundproofing

[BlueCollarBurnout]

I have a 95 4runner with an ALH swap and a larger turbo (GTB1756). She runs great, but the issue I'm having is a tons of noise in the cab coming from the engine bay/turbo. I know diesels are inherently louder engines, but I'm trying to get the noise levels down as much as possible and I'm hoping someone out there might have some insights that will help.

I've already lined the hood with dynamat, and put 3 layers of dynamat inside the cab on the floor. I tried to stretch it as high as I could up the firewall, but there's still a good portion of firewall behind the dash that has no sound deadening on it. Doing all this made a small difference, but it wasn't huge.

What do you think my next steps should be? More deadening on the doors? Inner fenders? Drop the trans and do the tunnel? Thicker walled exhaust? Let me know what you think, I'm all ears!

 

[burpod]

the noise could very well have to do with the tuning - it can make a pretty big difference. since it's got a big turbo, i assume it's tuned? what pump/nozzles are in it as well?

 

[PickleRick]

Sound vibrates, while I have zero issues with my PD diesel vibrating the inside of my 1st gen t4r your ALH likely makes much more torque pulse vibrations.


Your choice of engine mounts may have a lot to do with feeling it inside the cab as well as hearing it.



Id also remove the dash and the engine, clean the fire wall on both sides to cover with the mat if a quiet ride is my goal.

Foam blocks to fill any void under the dash is a method land rover used. Painting cardboard black with a foam backing is another method they used to cap off voids for visual and sound dampening purposes under the dash.

They also used stupid thick foam under the carpets.

Adding mat to all accessable inner door/body skins as well as backs of the door/side panels will also help. Go as far as pulling the headliner and doing the roof.

 

[BlueCollarBurnout]

the noise could very well have to do with the tuning - it can make a pretty big difference. since it's got a big turbo, i assume it's tuned? what pump/nozzles are in it as well?

It is tuned, but I'm working with Malone now to get it revised for the 11mm injection pump recently installed. It has stock injectors too btw (lots of mountain driving, so trying to keep egt low).

 

[BlueCollarBurnout]

Sound vibrates, while I have zero issues with my PD diesel vibrating the inside of my 1st gen t4r your ALH likely makes much more torque pulse vibrations.


Your choice of engine mounts may have a lot to do with feeling it inside the cab as well as hearing it.



Id also remove the dash and the engine, clean the fire wall on both sides to cover with the mat if a quiet ride is my goal.

Foam blocks to fill any void under the dash is a method land rover used. Painting cardboard black with a foam backing is another method they used to cap off voids for visual and sound dampening purposes under the dash.

They also used stupid thick foam under the carpets.

Adding mat to all accessable inner door/body skins as well as backs of the door/side panels will also help. Go as far as pulling the headliner and doing the roof.

Thanks for the info, I've wondered how manufacturers go about insulating some of that sound out of the cab. Currently using hydraulic engine mounts, but most of the noise that's bothersome is turbo noise. I'll just keep plugging away at it piece by piece. Definitely going to have to give that foam a shot. I'll be dropping the trans at some point too, so maybe I'll just pull the engine while I'm at it and go bananas on the tunnel and firewall.

 

[PickleRick]

Your muffler choice will also help with lessening turbo whistle.

7.3 psd owners remove the sound dampening on their charge pipes TO get more of that 6.0 psd turbo whistle sound. A roll of HVAC insulation tape from your local hardware store, tar sticky on the inside and aluminum outside could help make that more suitable to you ears without much effort or expenses.

Or wrap it in the dynamat $$$

 

[burpod]

It is tuned, but I'm working with Malone now to get it revised for the 11mm injection pump recently installed. It has stock injectors too btw (lots of mountain driving, so trying to keep egt low).

can almost guarantee you that tune has too much timing advance (amongst other issues), that its almost counter-intuitively giving you higher EGTs actually as the engine is fighting against itself.... through most of the mid-range of fuel. it's also going to make the engine a lot louder...

bigger injectors + 11mm, if all is right, can actually help lower EGT. those small stock nozzles will require more advance for longer durations than a larger nozzle. the less advance you can use, the better torque you can get and at the same time quiet things down a bit, IMO. just my 2cents

 

[BlueCollarBurnout]

Your muffler choice will also help with lessening turbo whistle.

7.3 psd owners remove the sound dampening on their charge pipes TO get more of that 6.0 psd turbo whistle sound. A roll of HVAC insulation tape from your local hardware store, tar sticky on the inside and aluminum outside could help make that more suitable to you ears without much effort or expenses.

Or wrap it in the dynamat $$$

I never thought of that, that's a good idea. Going to to try that today when I get off work. I'll let you know how it goes

 

[BlueCollarBurnout]

can almost guarantee you that tune has too much timing advance (amongst other issues), that its almost counter-intuitively giving you higher EGTs actually as the engine is fighting against itself.... through most of the mid-range of fuel. it's also going to make the engine a lot louder...

bigger injectors + 11mm, if all is right, can actually help lower EGT. those small stock nozzles will require more advance for longer durations than a larger nozzle. the less advance you can use, the better torque you can get and at the same time quiet things down a bit, IMO. just my 2cents

Bigger injectors are definitely on the table. The 1st engine I had in the truck had the big .260 size injectors. I was dumb and drove it in the mountains a bunch with no egt gauge. Long story short that engine popped and I always figured it was the injectors (maybe falsely). I still have the set of .260's, but I was waiting to order a set of .216's or .226's. I figured those would be a bit more appropriate for my application.

 

[burpod]

.260s + 11mm pump is a lovely combo when done right. i have those in my mk1 swap. drives fabulous with no smoke and low egt they could drive like a dream in a truck like yours if the tuning is done right....