My Ti exhaust project

[ALEX P]

I really like the exhaust on my car, it's a nice cheap simple set up that works well but it does have a few limitations which have been bugging me.

It's a fairly modified 964 3.6 running some reasonably priced 1.75" dia headers going into a 14" Magnaflow rear box. It sounds great if a little on the noisy side, particularly on a long run so I did have to make up some inserts which work in reducing the db level but if you are going to restrict the outlet with a bung like this then sometimes I think I may as well have made it out of smaller dia tube in the first place!

964 Engine rebuild questions





Some of the things I've grown a little bit tired of are:

1. There's no heat - I'm getting old and soft and would like to use the car in the winter more.
2. The headers sit a bit too low so meet the ground on too many occasions!
3. I'd like the option of less noise or drone on longer journeys.

So I've been messing around with making a new exhaust. As always this will be done on a shoestring budget!!

I'm going to use a pair of 993 heat exchangers with flipped flanges but the ones I've sourced have at least one knackered heater box so I'll probably end up stripping them back to bear headers like the 993 cup cars had (see below) then make up some sort of baked bean tin arrangement to get some heat out of them. I am a bit worried about dropping primary tube dia from 1.75" bore to 1.5" bore and I know it will need to be remapped but I guess if it was good enough for the 993 factory cup cars.....

The aim at the end of it is to end up with something vaguely resembling some of the arrangements below:

993 Factory Cup setup



Lovely looking Supersprint setup



Kline-Innovation exhaust (lottery winning stuff!)

[ALEX P]

Originally I was looking at the possibility of modifying a set of GT3 headers but for now I've taken the easy 993 route.

997 GT3 Cup Exhaust Headers

So far I've cut the ti exhaust I sourced down & reduced the length of the boxes so they fit around the back of the car, tacked the ends back on and made up a 'X' pipe which will lead to the 993 heat exchangers. I'm also looking to incorporate and electric valve into the 'X' section to give the option of fully silenced through to straight through.








Does anyone have photos of heater boxes that have been retrofitted to give me some inspiration? I remember reading about someone who made removable ones but can't remember where.

[ALEX P]

I would like to point out that I have got no idea whether this will work or not but it's kind of a fun project!

This is a basic layout of how it will be configured:

[RWebb]

how hard is it to weld titanium?

[HawgRyder]

If you place a cross section of metal (looks like an X) in the system...it will mke it quieter.
It might take a couple of tries to get the correct placement.
What it does...the straightens out the flow in the pipe.
OR...perhaps making the flow "spin" might also help (putting the "X" in the pipe with a twist to the pieces).
Also...I have had sucess with making mufflers that separate the flow as it enters the muffler...then diverting it back so the 2 flows crash together in the middle (seems to tune out higher frequencies).
If I can get my CAD working...Iwill post some designs I have used over the years.
Bob

[Elombard]

Where did the Ti exhaust come from? How does the weight compare to your old set up?

Cool project!

[eastbay]

Originally Posted by Elombard

Where did the Ti exhaust come from?

sure look like C5 Z06 corvette to me

[ALEX P]

Originally Posted by RWebb

how hard is it to weld titanium?

Confession time - For me very difficult. I'm not a great welder but luckily a friend of mine is an excellent welder so I do all the cutting, trimming, & forming and he does the welding.

So far any welds are just tacked together so no problem but I believe to do a really nice job he'll purge it so cap the ends off and fill it with argon.

Same friend made my previous Magnaflow and a very nice nose mounted oil cooler and ducting along with a few other bits

Originally Posted by HawgRyder

If you place a cross section of metal (looks like an X) in the system...it will mke it quieter.
It might take a couple of tries to get the correct placement.
What it does...the straightens out the flow in the pipe.
OR...perhaps making the flow "spin" might also help (putting the "X" in the pipe with a twist to the pieces).
Also...I have had sucess with making mufflers that separate the flow as it enters the muffler...then diverting it back so the 2 flows crash together in the middle (seems to tune out higher frequencies).
If I can get my CAD working...Iwill post some designs I have used over the years.
Bob

Thanks Bob, I'd be interested to hear more - Is it almost like a propeller to twist the flow of exhaust gas?

Originally Posted by Elombard

Where did the Ti exhaust come from? How does the weight compare to your old set up?

Cool project!

The old Magnaflow isn't really very heavy so I don't know how much weight differential there will end up being but I'm hoping it will be quite a lot quieter. I'll weigh it all when it's a bit further on.

It probably didn't help that I used fairly heavy gauge Stainless tube with the Magnaflow setup, it's like lifting lead next to the titanium pipe. Hopefully that doesn't mean I'll end up with extra resonance.

Originally Posted by eastbay

sure look like C5 Z06 corvette to me

Good spot that man! It was from a C5 Z06.

Not that common in the UK but found a chap selling one that had been cut in half so cheap and perfect for me.

This is what the internal layout looks like:

[ClickClickBoom]

Originally Posted by RWebb

how hard is it to weld titanium?

Easier than steel, welds like artwork.

[ALEX P]

Well, I highly rate my friends welding, whether it's art or not I dunno

Had the X pipe welded up, shortened the boxes for a good fit and had a quick trial fit. It's quite close to the bumper but it doesn't sit low like my magnaflow so hopefully some of my grounding issues will go away.

I also jumped on the lathe and knocked up a couple of bosses for the lambda. Now I've got to try to figure out the best place to put them - Is there an optimal place?

[RWebb]

I've always heard that Ti was hard to work with -- maybe they meant the bending & forming of it

[ClickClickBoom]

Originally Posted by RWebb

I've always heard that Ti was hard to work with -- maybe they meant the bending & forming of it

Machines and cuts like stainless, tough stuff. Slow blade speed, high pressure, lots of coolant.

[Kraftwerk]

I like this kind of stuff, custom muffler, fabbed from a Corvette bit makes it even better!

Yep, ti is way harder to cut. I didn't know it was any easier to weld though. Thats good to know.

[RWebb]

please weigh it and the Ti muffler when you have it fabbed - a lighter exhaust system would really help these cars a lot

[ALEX P]

Sorry, I forgot to say - I did stick it on a very rough old inaccurate pair of hanging scales - The Magnaflow setup weighs around 9 - 9.5kg and new new one 5 - 5.5kg so far however this will go up as there is more welding to do on the boxes as the ends are just tacked on, it will need a fixing bracket and I've got to machine up the flanges and oval the pipe to mate to the 993 h/e.

I am looking to incorporate a flange onto the 'X' pipe so that I can add a sound valve like the one shown below but I want to hear it before doing the work so the plan is to get the flanges sorted and connect them up to the heat exchangers & fire it up without finishing the outlet / tailpipes just to give an indication. If it's nice and quiet (as I hope) then it's time to play around with the valve idea. If it's really noisy then it will be back to the old drawing board!

[Jaskas]

What i have noticed with several exhaust valves, both electric and vacuum operated that they have tendency to start leaking after a while. My next exhaust won't have any valves, although the idea is great.

[ALEX P]

Hey Jaskas, Jevvy pointed me towards you as you had already incorporated a valve onto an exhaust system. I looked for ages and I found your video clip but no thread so didn't really see how you did it.

I guess the thing is with the way I'm looking at doing this is that if it breaks, leaks etc then it can either be replaced or just put a blanking plate there instead.

I can't really see how it would leak unless it's not closing properly - If it's got a load of crap all over it I guess it can always be removed and cleaned.

Have you got any photos of your setup?

[Elombard]

What is your plan for tail pipes? 2 out the center? Interested to see how you configure the tail pipes. It would be nice to enlarge one outlet and just block off the other but might mess up the muffler sound deadening characteristics.

I got to go ask my local muffler shop if they can weld Ti :-0

[ALEX P]

Originally Posted by Elombard

What is your plan for tail pipes? 2 out the center? Interested to see how you configure the tail pipes. It would be nice to enlarge one outlet and just block off the other but might mess up the muffler sound deadening characteristics.

I got to go ask my local muffler shop if they can weld Ti :-0

I've got 4 tailpipes but they've all got the 1.75" dia pipe on them so provided the exhaust is fairly quiet and I do incorporate the valve what I plan to do is cut the small pipes off and replace it with the 2.5" pipe something like this:








Then incorporate a flange onto the 'X' pipe and the tailpipes with the valve in the middle. The muffler outlets will then have to blend into the tailpipes. Something like the photo below.

I haven't decided whether to trim the muffler pipes back and weld on a 90 degree pipe or just trim them back as if they enter the tail pipe fairly perpendicular then it may knock a little more noise off.

First step before any of the valve stuff is to get the flanges knocked up and start it with the tailpipes as they are just to get an idea of how loud or hopefully quiet it is.

[ALEX P]

I'm thinking of taking a bit of a U-turn on the Corvette silencers. There is quite a lot of work to do welding up the ends back on as they need a full bead all the way round the ends externally and around the end face which is all time and money (titanium welding rods are $$$).

The other reason is I recently bought a very nice silencer from a 997. The problem with this is that because I want heat I'm going to to stick with the 993 heat exchangers which exit facing towards each other and the 997 silencer is quite wide with the inlets and outlets on the end faces.

Because of this I may have to rob the 'X' pipe I made for the Corvette silencers to make an adaptor pipe a little bit like the Bischoff catalytic converter.



I've sketched up roughly what it will have to look like although I would really like to 'straighten out' some of it. The 993 flanges are at the water cutters so I've got a couple of weeks to figure it out but I also need to get prices for the 180 degree bends as I don't have enough pipe to make this. If they work out at silly money maybe the Corvette boxes and 'X' pipe can go on hold and I'll have to look out for some short headers to go directly into the sides of the silencer and weld a tin round hem for heat.