Aftermarket Exhausts?

[Guff]

Originally Posted by Gardus

I wouldn't go for Titanium on the headers, do you have any idea what happens to Ti at 600+ °C?

Realibility is more important than weight in that department, also it's all weight under the engine, it's so low that it doesn't affect much the whole dynamics of the car.

Titanium's melting point is at 1668 C, sooooo I'm not sure what you're on about....

[Gardus@Supersprint]

I doesn't melt but it starts to absorb oxygen, and at the temperatures close to the head it gets very fragile so the welds on the flange and the primary pipes tend to crack.

[Dimman]

Originally Posted by Gardus

I doesn't melt but it starts to absorb oxygen, and at the temperatures close to the head it gets very fragile so the welds on the flange and the primary pipes tend to crack.

That doesn't seem to be a problem on bike headers. Nor on certain old F1 cars (AAR 'timag').

I've had some Ti deliberately improperly welded without back purging to test the popular belief that it will suck up O2 and N2 out of the air and create a completely brittle and fragile weld area. Not entirely the case.

We will be looking to experiment with something a bit more serious in the future but believe a lot of the talk is to scare noobs safe and proper design and production will easily work around this. Keep in mind that poorly manufacturer 304 headers will also frequently crack at the same spot.

[chewyv]

I'll be making my own as well. I'm thinking, convert to a single exit. Did anyone else see the picture of the under carriage? I'm not sure if the picture was taken at a bad angle or what, but I hope there wont be any clearance issues.

[Gardus@Supersprint]

For what I've seen the rear muffler has to be either very small or mounted trasversally.

It looks like the 350z rear muffler.

The car is very small and lightly build and it's NA, so I think it'll drone if you go too thin with the pipe walls or if the muffler is too small.

Back to the Titanium issue, bike Ti headers are not very popular on road bikes, also the temperature is much lower usually than car headers due to the air flow.
On old F1 cars they had titanium exhaust systems for the qualifying laps but they switched to steel for the race!
Now they use inconel which combines the lightness of TI and no crack issue at high temperatures.
As with SS, also with TI there are a lot of different alloys, when you see a cheap-ish Ti system usually the material quality is very low.

[Dimman]

Originally Posted by Gardus

For what I've seen the rear muffler has to be either very small or mounted trasversally.

It looks like the 350z rear muffler.

The car is very small and lightly build and it's NA, so I think it'll drone if you go too thin with the pipe walls or if the muffler is too small.

Back to the Titanium issue, bike Ti headers are not very popular on road bikes, also the temperature is much lower usually than car headers due to the air flow.
On old F1 cars they had titanium exhaust systems for the qualifying laps but they switched to steel for the race!
Now they use inconel which combines the lightness of TI and no crack issue at high temperatures.
As with SS, also with TI there are a lot of different alloys, when you see a cheap-ish Ti system usually the material quality is very low.

We'll see. The Dan Gurney TiMag car didn't switch off theirs and still has its original headers on in historic racing afaik.

Bike airflow wouldn't be an issue as the gas absorbsion would be on the inside of the tube. There are some other issues that may be causing the cracking. The expansion difference (same issue as with SS as Ti expands just a bit less than SS) and the rate of heat conductivity. Ti transfers heat very slowly and aluminum rather quickly so coupled with different expansion rates cracks are possible but again SS has similar issues. But Ti has superior high temp relative strength and fatigue resistance.

Getting to the different alloys is interesting. Grade 2 commercially pure has been recommended for exhausts. But what a lot of people don't realize is CP2 isn't very strong. It's about between 6061-T6 aluminum and 1018 mild steel strength-wise. People automatically equate Ti with almost magical strength. Not the case. So on the more stressed headers they may be under built for the loads.

We will be experimenting with CP2 for exhaust piping which should have no gas absorbsion issues. Then we will be evaluating its suitability for headers in seamless and welded tube forms with concern for mechanical stresses and corrosion against 321SS.
We will also be comparing CP2's performance in headers to the much stronger Ti 3Al 2.5V seamless tubing. Plus a few more tricks...

[illmatic]

Prova center exit with diffuser

[whitejdm]

Originally Posted by illmatic

Prova center exit with diffuser

YES...
That also looks like a nice diffuser if you want to do a single exit exhaust on one side and just mesh or cover the front outlet.

[Gardus@Supersprint]

Is it ABS or glassfibre?

[Draco-REX]

Originally Posted by illmatic

Prova center exit with diffuser

Oh my... That's just too cool. I just wish the can was smaller.

2K-3K though...

[JohnnyR]

What? No "Kazuma" exhaust from TRD? Loved that on my Celica GT-S.

[Slartibartfast]

http://performancedrive.com.au/prova...ack-edition-1/

http://performancedrive.com.au/wp-co...-Edition-2.jpg




Forgive me if this was already posted. I came across these in a search for the Prova exhaust installed.

[OrbitalEllipses]

That doesn't look very good mounted or perhaps it's the angle. I like the idea, but I'm not sure on that execution.

[whitejdm]

Originally Posted by OrbitalEllipses

That doesn't look very good mounted or perhaps it's the angle. I like the idea, but I'm not sure on that execution.

Yup the more I look at it on the car the more I'm turned off a bit (maybe it's just the car itself that bugs me). I'm sure there will be tons of different options for a diffuser, but I'm really wanting to go with a single exit of some kind so hopefully someone will make something that fits the bill.