Porsche 928 Episode 94 - Exhausting times

[@OB928]

I had a “Y” pipe installed and kept the single pipe all the way back to a Magnaflow single in/dual out rear muffler. Sounds good and seemed to wake it up a bit.

[@MrToddgibbs]

Thanks David, useful info. So you only had front original silencer and new rear ?

[@frankirvine316]

Hi Todd, Your doing a great job and no doubt (Quite Exhausting) but you’re tenacity is 👍 great With my car when I had a refresh with gaskets etc15yrs ago,I got talked into Eurospec camshafts,and I got headers etc It made the car boogie,especially being a manual I have the headers,ceramic coated and would bolt straight on to your car Todd😅 Currently it is 3” from front to back with a single at the back with 3” outlet Nicely done and you can get the twin outlet and will be looking at that The 6.0 is getting a stage 2 camshaft And Stainless long tube headers etc My health issues are slowing me down,so winter it be under way✅ Best Regards Todd Frank

[@MrToddgibbs]

Good to hear from you Frank, and sorry the health is still a problem :(. Exhaust sounds good (pun intended!) creating this was great fun - I didnt replace my headers but probably should have done. If you ever want to part with yours let me know :) I’ve literally just got the car back in the road after a rear suspension rebuild…… that was tricky! Take care and taking for checking in :)

[@redkenj]

Maybe if you get some cheap plastic pipe of a suitable diameter and a roll of gaffer tape. You could cut, splice and tape pieces together to create a model of what you intend to make. It would highlight issues (i.e. bends, places were the exhaust will need to be away from lines etc.). Just a thought

[@MrToddgibbs]

Oh Redkenj, you spoilt my surprise :) I have a load of 2” pipe here to mock it up. I’ll see if I can do it

[@mowdra]

I say that if you are going to all the trouble, and it is not much more, make it the best it can be.

[@MrToddgibbs]

Thanks Mowdra.

[@anthonygordon14]

Hi Todd, electrics are such an important aspect of 928 rejuvenation. Especially on later models as the electrics/electronics became even more intense and sophisticated. Have you cleaned up as many of the many earth points as possible? This makes a big difference also :-). There is normally a resonator at the rear section and looks like it has been previously replaced by a straight-through. Noting that the engine is simply an air pump - optimising the breathing is always a good thing to do and exhaust is a big factor here. Might be worth tapping into some exhaust houses and especially those that may have done some work on 928 exhausts previously. Of course, it is also about the sound you are also seeking the standard rear muffler is a big part of keeping things quite. Good luck :-). Cheers Tony

[@MrToddgibbs]

Thanks Tony. Yes all earths are clean and sound. Exhaust companies aren’t keen to advise, and just want to slap £1000 on for their labour. I should be ok as I’m basically copying other stainless systems out there already :)

[@alanstewart9120]

Hi Todd, I greatly respect your enthusiasm, to tackle these old cars. I would recommend the stock system approach, as you do not want this to be an open ended engineering project. You have tackled such challenging project elements, time to let Porsche team solution prevail. Yes, you can develop a one off solution, that is almost good. But why bother when this problem has already been solved. Exhaust noise is a subjective analysis, with some liking more noise, I like fairly quiet, as this is a road car for long trips. (this can be solved like the new Corvettes, with bypass electronics, for noise on demand) save your energy for problems that have current solutions, like the alternator, with web belt, versus v belt. And maybe the electric fans versus belt drive fans. I have a CIS car, and debating going to at least LH or LZH. Always a slippery slope, key here is feed back info to know what is going on in the engine, with electronic injectors easier to determine operational performance. So far I have avoided the desire for aftermarket fuel/spark management, but i have several 928 cars, actually 7, 79- 87 and would like a common solution, as Porsche had major revisions every two years. Obviously, the 32V cars, are a class of there own. When I look at the wiring issues, of 35 year old cars, it suddenly seems smarter to upgrade all to a common platform, similar to current EFI cars, with OBD2 feedback. The fuel dampers were an elegant, expensive, solution solved, partially, by sequential injector firing. ( for fuel pressure excursions) My main point is to take on problems, not already solved. And there are plenty of those.

[@MrToddgibbs]

Hi Alan, thanks for your comment and advice. I don't disagree with your logic. Im fighting the temptation to try something adventurous vs playing safe. But managing the risk / cost at the same time. More importantly - how on earth have you managed to get 7 928s?! :)

[@davidwebster5258]

Hi Todd, If I was you I'd stick with the single system,simpler and more straightforward with a big weight saving over the twin system.Those big pumpkin rear mufflers are pretty heavy, I replaced mine with a smaller inline muffler which tucks up where the pumpkin was and then connected stainless twin tips in place of the originals. Just my two cents worth,keep up the good work. 😊

[@MrToddgibbs]

Hi David. Did you keep the front box and remove the middle as well? So you ended up with a 2-box system? How does it sound ?

[@davidwebster5258]

That's exactly what I did, replaced the front muffler with a smaller s/s one and did the same with the rear one. Sounds louder than the original, more muscelly but then this is probably the last v8 I'll ever own so l want it to sound like one.😊

[@MrToddgibbs]

@@davidwebster5258 just what I’m thinking

[@johnmcdonnell81]

My vote goes to an X pipe and stick with a single pipe which you could always go up from 2.5''/67mm to 2.75''/70mm. Ideally in stainless. I'm unsure what your plans are for the boxes but if you are considering deleting the back box I'd be very inclined to fit a resonator (middle box) back were the original was removed by someone. Regardless of what I say, it might be a case of do it and see what it's like and maybe do it again! Still, you're a better man than me and many other's as I'd would be off to the exhaust specialist while possibly paying over the odds.

[@MrToddgibbs]

Hi john, thanks for the thoughts. Is there any advantage in fitting an x-pipe if I then channel the gases into a single pipe? I am planning to put a resonator where the middle box was, deleting the back one.

[@johnmcdonnell81]

@@MrToddgibbs Hi there Todd. That's a bloody good point. No, would be the answer, I'd hadn't got my thinking hat on when I mentioned it. From my research twenty years ago the X pipe was and I still think is a popular modification (the Yanks fit it to their V8's car's a lot). So, as you originally suggested two 2''/52mm pipes all the way back after the X pipe. May be two 2.25/57mm... Did you check what the likes of 928 Spares/ Paul Anderson etc offers as guide? Yep, I reckon you're on the money refitting a central resonator when deleting the back box. You should weigh that box for a bit of fun, wouldn't be surprised if it's 6 kilos/13 lb or more.

[@MrToddgibbs]

Thanks John, yes will weight the beast for a bit of fun :)

[@Morrisonspouch]

Hope you are doing well Todd. Had a break on my 928, about to get going again. All the best

[@MrToddgibbs]

Hey Luke! Yes I’m well thanks. Battling through the many issues with the exhaust. Should be ok now but need to wait for a few parts to arrive

[@eoinosullivan2636]

X pipes, use the Venturi effect to pull exhaust gas from the opposing side of V8 bank. If you don't have access to pipe benders, pipe notcher (even though you can notch by hand) and haven't much experience with stainless steel welding, I think you'll spend a lot of time and effort and possibly end up with results you may be unhappy with. I think you should look for a premade system, or take the car to a good exhaust fabricator and have them fit a stainless twin-pipe system to a nice back box.

[@MrToddgibbs]

Thanks Eoin, so it’s worth fitting an x-pipe even if it outputs into a single pipe? I know it would be safer getting one built, but where is the fun in that ? :)

[@eoinosullivan2636]

@@MrToddgibbs Hi Todd. Most X pipe setups go to a double and most I've seen on 928s go to a double pipe. I'm sure there must be plenty of images on Google and forums that would give you an idea of what way to route. I certainly don't want to spoil your fun 😊

[@MrToddgibbs]

Yes I’ve worked out the route and design. Just need to decide if it will be worth it and doable

[@mcr1photo]

I say go for it.

[@MrToddgibbs]

I like the enthusiasm :)

[@mcr1photo]

@@MrToddgibbs Gotta get your money’s worth from that welder.

[@redkenj]

Another great project and a difficult decision to get it right. I would try and follow what the Porsche engineers designed originally, given the time they would have spent getting it right. The car is already missing the centre box (and currently sounds great). However, if you now remove the rear box and just have pipes running from the front box basically straight out the tail pipes you might find it too loud for comfort (but it would sound great). Hopefully someone can advise the best solution

[@MrToddgibbs]

Agreed Porsche knew what they were doing but they also were concerned about loudness. My requirements are slightly different :)

[@PeacefulPathways926]

So if like me, you aren't creating a museum piece and don't plan on racing the car or putting on 000's of kms every month- lay beads on the front 'silencer with the horns' as you call it. Then run single pipe back (with the necessary angles) to the rear of the car. Remove the pumpkin (obviously keep it and store it though for the day you want a museum ready car ;) ) put on a Borla or equivalent single muffler - single in/single out. Terminate the whole shebang with dual exhaust tip off to the side as in the factory. I am almost at this stage just need to get the final dual exhaust tip sorted out as the PO decided on a straight terminating single wide tip.

[@MrToddgibbs]

So that’s the other argument I am battling internally, Jarrod. I can make something very decent for less effort and money that will be perfectly good enough. Just need to balance the desire to always push vs sensible

[@MD-318]

It'll be a good mini project making your own exhaust. Stainless is susceptible to cracking over time along the welds but you can always re-weld where you need to.

[@MrToddgibbs]

yeah thats what I thought! :)

[@MD-318]

@@MrToddgibbs I used to weld stainless adaptors for motorcycles, so have a bit of experience tig welding them, no idea on gas flow and what works best though, unfortunately other than keep an eye on how lumpy the penetration is at the back of the weld

[@neildonaldsonlotusexcelresto]

Brilliant that you are taking on this kind of job, Todd. I am no exhaust expert, but my two cents worth, is try to keep the design as close to the original as possible. You inspire me to think that no job on a car is a big deal. Cheers!

[@MrToddgibbs]

Hi Neil, thanks! I am leaning towards the simplier single system to be honest. Not only will it be cheaper, it will also be less welding, definitely fit and still sound decent if I skip that final silencer. Thanks for your input though :)

[@anthonygordon14]

X-pipes are very good improvement. I would also go stainless steel as this will last forever :-). Cheers Tony

[@MrToddgibbs]

Thanks Tony. I am tempted, just need to make sure I can create it all.

[@G928...]

Hi Todd, to help with different ways of doing this. Have you looked at the part supplier sites with diagrams of the different systems used on 928's over the years. The UK 928 S2 had a dual system as did the S4. Just an idea for inspiration of layout. Personally I use rose passion because I live in France, but the others suppliers and Porsche dealers no doubt have similar online parts diagrams. FYI personally think my single pipe system sounds good, but a twin would deffo give it a different sound.

[@MrToddgibbs]

Thanks g, yes I have studied a few aftermarket 928 systems. To be honest, given the route it needs to take, there are very few options. I think I am leaning towards the single system though…. (I also use RosePassion a lot:) ). Thanks for watching :)

[@sammm700]

Probably a bit late to the party on this although I am catching up, but have you seen HomeBuiltByJeff and the exhausts fabrication he's done for his Porsche, Datsun etc?

[@MrToddgibbs]

Hi Martin, oh I haven't seen his channel, will go look now. Thanks!

[@TTjustTT]

Which one do you like better?

[@MrToddgibbs]

Good question! Half of me says do the whole thing, it will last longer. The other half says it’s my first exhaust, so the least to make sure I can do it. So I don’t know