Stainless Steel Silencer for Subaru Powered T25

[mshaw1980]

Hello

I am going to make myself a new subaru exhaust from stainless steel as the mild steel one I knocked together (pictures below) is on its last legs due to rust. I will be increasing the exhaust size slightly from 1.75 inch to 2 inch pipe. I know that it wont make much difference in terms of power but it should help a bit however I am unsure what to replace the existing T25 silencer with? Is the T25 silencer very restrictive to the subaru engine? If it is I would look to change it as I do feel my van struggles more than it should in terms of acceIeration. Seems to just about make it to 70mph (although I dont drive it at that speed very often).Anyway I digress. The T25 silencer seems to do a decent job of keeping the engine noise to an acceptable level. It also looks 'right' at the back of the van because it is so long. Most generic stainless steel silencers are tiny in comparison and I dont want it to be stupidly loud which I am worried will be the case if I go down that route. Any suggestions would be appreciated. Thanks

[silverbullet]

FWIW going up in diameter will make it louder. Been there! You wont gain any power because the system is so short there is very little back pressure anyway.
Even going up to 1.75" (45mm) will give it a beefy note, any bigger and it will really drone.
Loud exhausts are fun for about 10 minutes, thwn you wish you had gone smaller.
Maybe try and get a secondhand VWSpeedshop exhaust? Its so quiet, stainless silencer made by Phoenix and has a standard 3-bolt collector flange.

[mshaw1980]

Thanks

I dont mind if I have the vw flange to connect to the silencer. In fact it would probably be better replaced with the exhaust sliding in to the silencer as I always found that area eventually started blowing due to the round seal inside being compressed and no longer sealing. If what you say is right though in terms of low back pressure due to short length I may stick with a VW silencer but in stainless steel. Unfortunately I have already bought the 2 inch bits to increase my pipe size from 1.75 so too late now. Just have to see how it goes.

[slowcoach]

Hi ho,
We can perhaps share notes- I have 2" pipes, and don't experience any lack of power, having had it over 90mph on one short lived,unwise and not to be repeated occasion some years back. It will roar up to the 8k rpm cut out if you have the nerve (not in 5th!). Any gear over 3.2k is definitely when the engine starts to push the bus forward hardest.

My pipe layout is different, and has a 2in-2out silencer. The noise however is too loud now, having blown all its wadding/wrapping out of the silencer :-\ when it was new however it was a great and tolerable and lovely sound. Now it's a bit obnoxious, mainly from outside the bus as fir any droning, that's been kerbed by paying attention to the intake and running a snorkel up the d pillar.

I'm looking for a baffled, rather than just wadding type silencer. I believe that the shortness of pipes and useable high rpm of the Subaru's create too high a temperature for the wadding. Do you know what's inside the big vw silencer you're running?

I was on my way to longlife for a new silencer to suit when covid kicked off and it's droped off my list.

[silverbullet]

My reckoning is that the reason why systems like the Speedshop are so quiet, despite the small silencer, is because the primaries are long (as well as being of near-equal length) and not too large in diameter which helps to dissipate the pressure waves before they arrive at the collector, so the silencer has less "work" to do.
Not very scientific language, but I can think of other well-known Subaru exhausts that used to be available were horrendously loud as well as other inline systems that were also very noisy.
All had very short primaries as well as overall system length.

[rollercoaster]

I'm no expert but it does look a bit like one of your manifolds isnt going to flow very well,
and when I had a subaru the exhaust was too loud, so do your best for quiet..

[silverbullet]

John Lucas aka "J P" made a lovely equal length manifold for the Subaru in his syncro pickup.

Might be worth a look if you can find the pics, or try a pm?

[mshaw1980]

Hi rollercoaster. Thee Subaru manifolds in my photo were cut off from the original Subaru exhaust so there is no way I could have done better than the manufacturer. I just had to shape the exhaust in the best way I could to fit around the engine sump and RJES engine support bar.

Slowcoach I was worried that a baffled rather than wadding silencer would be too loud. I laugh now at all those kids driving base model fords etc with stupid loud exhausts. I may have liked that breifly when I was 18 but not at 40. Just a nice bus that pulls well and sounds a bit subaru but not 'boy racer' loud. Not asking a lot am I?

Silverbullet. Dont Kennedy Engineering in the US make their subaru vanagon systems in the same layout as mine? Too be honest, I am not an expert welder in terms of getting the 'stack of dimes' look and also need to use off the shelf bits to cobble something together so if JP's manifold requires complex cuts of pipe to weld together in a beautiful ornate way then that is definitely not for me.

By the sounds of it I may need to stick with the VW silencer as based on Silverbullet's info on the reverberation on a short exhaust system then I do need a decent silencer even if that means reducing the power a bit.

I actually changed my coolant temp sensor yesterday as was having random 'no starts' in cold or damp weather. And seems a bit more pokey so that may have been my issue with it being a bit down on power, running rich.

I see just kampers sell a stainless t25 silencer. Any thoughts on that??

[300CE]

Might be worth sending a message to Matt Brighton as he put a Ford Focus exhaust on his Subaru and pretty sure he wasn’t looking for crazy sound:

[mshaw1980]

Thanks 300. Dont particularly like the look of that if I am honest. Too 'glitzy' and also low too. I like the look of the original silencer really. Funny really me talking about originality when it is subaru powered

[300CE]

No worries mate - Dependent on budget, you could also contact Longlife exhausts as they’ll be able to make something up to your spec.

Also a stainless system on eBay at the mo:

https://www.ebay.co.uk/itm/284159229047

Or new silencer:

https://www.ebay.co.uk/itm/203263974481

[silverbullet]

Slight aside but worth mentioning, all the post-1990 SA buses with inline engines including the Golf-engined 1.8 Volksiebus have an exhaust that runs forward from the engine to a double-pass silencer under the floor, then back the same way to a smaller silencer under the nsr lamp.
This was done to achieve some system length and thus get the exhaust nice and quiet, as well as avoiding the requirement for a long silencer squeezed behind the longer 5-cylinder engines.

[bmakins]

Apologies for commenting on an old thread, just wondering what silencer/pipe diameter you went with in the end, and how does it sound?

[mshaw1980]

I had one made in stainless steel by a seller on ebay. Gave them the dimensions and they made it up for me. Was about £100 including delivery. Works great and still sounds like a Subaru but not stupidly loud.

[M4tt_1]

I had same requirements, didn't want anything loud so went custom and very happy with it.