Thread: And ANOTHER County Isuzu conversion

Originally Posted by steveG

I've been told I'm breaking the rules by doing things without photos (thanks Rovercare) .... so here's my attempt at rectifying that.



Steve

Hey, what!

Before you install the motor, bung some insulation around the firewall. I just bought 2m of foam/foil from Clark Rubber for $37.00. You can also get pre glued.
Good investment.
Good luck with it, I see your wanted ads- makes you realise whats involved.

BTW, we have twins !!

Thanks DeeJay - sound insulation is definitely on the "todo before the final motor fit" list.
I'm tossing up whether to use the Clark Rubber stuff, or the engine bay insulation from Whitworths Marine which has a has a dense rubber layer in the middle and should stop absorb more noise (but costs more).

Its definitely easier to buy an Isuzu County than to convert one, and at least the same cost if not more to convert. With a conversion you end up doing a whole lot of things at the same time that you wouldn't do straight away if you bought one (eg rodding/replacing radiators, hoses, clutch, gaskets etc). So you end up with more of a known vehicle at the end.
Well that's what I keep trying to convince myself as the dollars flow out and no real visible progress so far

And yes - twins - but your paintwork looks a bit better than mine!

Steve

Originally Posted by steveG

Thanks DeeJay - sound insulation is definitely on the "todo before the final motor fit" list.
I'm tossing up whether to use the Clark Rubber stuff, or the engine bay insulation from Whitworths Marine which has a has a dense rubber layer in the middle and should stop absorb more noise (but costs more).

Steve

Steve,

I would recommend buying proper noise insulation, whether it be from a marine shop or building / industrial supplier. Pyrotek makes noise insulation products and has products intended specifically for engine bays (diesel / heat resistant). The name Sorberflex(?) comes to mind and it is a layer of loaded vinyl (to stop noise transmission), bonded to a thin foam on one side (to dampen vibration in firewall panels) and a layer of "fluff" on the other to absorb noise bouncing around the engine bay. It's not cheap, but works well (if installed correctly). There are similar products by other manufacturers of noise control products as well, but i can't think of the names off the top of my head ( typing this while on the train back home). weight matters in these things - I'd probably go for 4 kg/ sqm vinyl (approx 2.5mm thick from memory) anything more is probably overkill.

Good lock with the swap, I'll be watching with interest.

Cheers

Bojan

Originally Posted by Offender90

Steve,

I would recommend buying proper noise insulation, whether it be from a marine shop or building / industrial supplier. Pyrotek makes noise insulation products and has products intended specifically for engine bays (diesel / heat resistant). The name Sorberflex(?) comes to mind and it is a layer of loaded vinyl (to stop noise transmission), bonded to a thin foam on one side (to dampen vibration in firewall panels) and a layer of "fluff" on the other to absorb noise bouncing around the engine bay. It's not cheap, but works well (if installed correctly). There are similar products by other manufacturers of noise control products as well, but i can't think of the names off the top of my head ( typing this while on the train back home). weight matters in these things - I'd probably go for 4 kg/ sqm vinyl (approx 2.5mm thick from memory) anything more is probably overkill.

Good lock with the swap, I'll be watching with interest.

Cheers

Bojan

I went looking at a few products a while back, including one made for boat engine installations. I was amazed to learn that the various foams and layers will often hold water or other fluids - in other words they are not closed cell. I'm really not keen on lining any part of my car with a sponge. Aside from possible issues with corrosion, the smell would get to be a bit much after a while. I did find one hideously expensive product at a place that installs high powered audio in cars. It might be the way to go if you use it only on the firewall.

Originally Posted by Dave_S

I went looking at a few products a while back, including one made for boat engine installations. I was amazed to learn that the various foams and layers will often hold water or other fluids - in other words they are not closed cell. I'm really not keen on lining any part of my car with a sponge. Aside from possible issues with corrosion, the smell would get to be a bit much after a while. I did find one hideously expensive product at a place that installs high powered audio in cars. It might be the way to go if you use it only on the firewall.

Definitely dont want open cell foam. Had enough of that with the factory insulation in D1 footwells.
This is the Whitworths stuff that I was considering : Whitworths Marine: Engine Sound Insulation Deluxe 800x1370x25mm
Doesn't say whether its open or closed cell though. Was that one of the ones you looked at?

Steve

Originally Posted by Dave_S

I went looking at a few products a while back, including one made for boat engine installations. I was amazed to learn that the various foams and layers will often hold water or other fluids - in other words they are not closed cell. I'm really not keen on lining any part of my car with a sponge. Aside from possible issues with corrosion, the smell would get to be a bit much after a while. I did find one hideously expensive product at a place that installs high powered audio in cars. It might be the way to go if you use it only on the firewall.

Good point Dave,

This could be a problem, especially if the county draws "fresh air" from the engine bay (as mine currently does). However, if attempting to soundproof the engine bay, you have to seal the cabin reasonably well. For me this would also mean fixing my heater box to draw air only from the outside - provided that this has been done, I don't think smell would be a huge concern (especially as the foam would quickly dry in 50 - 80 degree heat from the engine when moving).

The purpose of the acoustic "foam" or "fluff" is to prevent noise buildup within the engine bay by absorbing some of the sound energy bouncing around inside. For acoustic "fluff" to work it has to be open cell - the acoustic absorption is achieved by air being oscillated back and forth through the fibres of the "fluff" / cells of the foam.

So Sorberflex (and other composite materials like it) are a sandwich of thin foam, loaded vinyl and acoustic fluff. The material gets glued to the firewall panels thin foam side first. The purpose of the thin foam is to decouple and dampen vibration in firewall panels. This foam can be closed cell (not sure if it is or not) because it doesn't need to absorb sound energy. The loaded vinyl is to block noise through the material (hence the heavy weight), while the outside is acoustic foam (which has to be open cell), is to absorb reverberant noise within the engine bay.

If you're worried about water ingress into the foam, there are thin impervious linings that can be placed over the open cell acoustic foam. Bradford Acoustituff comes to mind - it is a thin foil that prevents water ingress, yet doesn't significantly degrade acoustic performance. It also has the added benefit of providing good fire rating. I probably wouldn't worry about it myself.

Just my thoughts...

Originally Posted by steveG

Definitely dont want open cell foam. Had enough of that with the factory insulation in D1 footwells.
This is the Whitworths stuff that I was considering : Whitworths Marine: Engine Sound Insulation Deluxe 800x1370x25mm
Doesn't say whether its open or closed cell though. Was that one of the ones you looked at?

Steve

Hi steve - see previous post, the external foam would certainly be open cell. I've just had a look at the product, and it sounds very similar to Sorberflex (same principle, different company). We often use and recommend Pyrotek as they have good product data sheets, and all their products are properly tested to accepted industry standards. There is probably a myriad of other manufacturers producing similar products, however, I would stick with what I know (unless I can get a full acoustic specification sheet for the other material).

Unfortunately, foams are not foams - their acoustic absorption depends on a combination of cell size, foam density and the size of intercell openings, and getting the right combination in manufacture is not easy.

Even more unfortunately, there's no way of telling how acoustic foam performs other than relying on acoustic test data (i.e. the absorption component). Noise transmission on the other hand is mainly controlled by the weight of the loaded vinyl, and is relatively easy to predict performance

I apologise for the technical nature of the post. The message to take away is that acoustic test data is important, and if a manufacturer doesn't provide it, there's usually a good reason why. Sorberflex data sheet attached for reference.

Cheers

Bojan