Basal Skull

As you may recall I made an exhaust with a mixing chamber in the middle. https://rennlist.com/forums/showthre...ferrerid=28499
I've been happy with it and it spits fire and such on the track. I've started to wonder though about drawbacks fixing the two sides exhausts together with this type of design. My Ferrari 328 had a crack in the exhaust that I welded back together - apparently a not too uncommon problem with these cars to develop cracks in exhaust parts and manifold. After staring at the exhaust which is a 2 in 1 design, I've come to the conclusion that it may be due to the design that fixes the two sides together without having anything that takes into account the expansion with heat of the exhaust pipe that come together and the stress that this adds to the system.
So I have begun to worry that the exhaust that I built for my car also has this flaw as the two sides come together... As I started to think about this, I can't rationalize a way around it and I've started to take things apart again. I've bought more parts, 2 flexible exhaust couplings that I'm going to add in and I think I have an idea for a small helmholtz type resonator.

Basal Skull

Pics to come of the exhaust.
I have been having some fun with the garage. Although off topic, this is my thread and I'll share about my garage too as it is what lead me to putting my car back on the lift, leading to me taking the car apart again...
How much I can lift my car is limited by the garage door motor on the ceiling. I wanted to get rid of the motor so I put in new garage doors with a roll up design. http://www.smartgarage.ca they are a local company and they did a good job. Now I have improved ceiling clearance and I can lift my car higher on the lift!

Basal Skull

The next thing that unfortunately limits my ceiling height are my lights...
So I researched low profile lights. The lowest profile are in ceiling/recessed lights like I have in the house but those are a lot of work to put in (cutting holes and putting in cans for the lights, parts alone for the fixtures end up being quite a bit, especially if I put in one each meter or so to get even lighting). The lowest profile lights are strips of LEDs. I found a place where I could buy led strips in 10 meter rolls. The highest number of led's I could get is 120 led's per meter. I bought 20 meters of these led's along with power source. It ends up being about 150 watts of led lighting power. When I was trying to figure out how much led's I want to get, seems I grossly underestimated how bright these things are. Depending on the conversion I use, it is somewhere between 600 - over 2000 watts of incandescent lighting. For these led's some say that 20 led's equal 100 watts of incandescent lighting. I have 20 meters of 120 led's per meter - which would equal 120 x 100 watt light bulbs...(was a little worried they were going to be too bright.)

Basal Skull

I had fun crawling around in the ceiling and wiring things up. Did some soldering, using my ohm meter found that I had bad connections which took a while to figure out how to find the bad connection...
It was also fun trying to figure out the best way to string the led's up as it was hard to get them straight.

Basal Skull

I also got to design where to put the led strips up and how long to make each strip. In terms of how to supply the power to them, they can be powered on one end but that sometimes make the end leds less bright, so I powered them in a circular fashion, providing power to both ends of the strips, essentially in a circular fashion and the led's themselves are linked up in parallel, so it seemed to work fine..
I think it was in the movie 'dangerous liaisons?' where John Malkovich was writing a note using Uma Thurman's naked back as a table - the closest I will ever come to that act is using the roof of the Ferrari as the table, to design how I'm putting up the lights.

Basal Skull

The lights are bright, hard to show in pictures, but it is like daylight. I put in more lights around the lift. The color is 400K, similar to daylight. I'll have to see how the shadows are when I'm working, I can change positions of the strips if need be.

Basal Skull

got rid of this mess and got more clearance.

Basal Skull

So the new garage doors and lights allowed me to put the car higher on the lift and find more stuff I must do.

I'm putting two of these in, one on each side. I'm just going to cut and make the upper resonators shorter to fit these. That should take care of any expansion/stress in the system.

OverBoosted28

Very nice, keep us in the loop! :-)

Vince964T

Nice ! Fun to get the small things in place = Satisfaction

Do you know why you get flames with this exhaust ?
I got huge flames with my "silent" exhaust with 2 big mufflers.
With the loud exhaust, muffler delete, no flames.

PiB993

Neat! Good to keep the 993 Turbo forum alive and kicking

Basal Skull

^ Always thinking of stuff I can do...

I think I'm going to lighten the aluminum bumper. Making holes in it I thought might not be good for strength and safety (and the tow eye screws into it). But looking at it, the tow eye actually bolts onto the inside wall (which I would leave intact) and I think I can cut out some metal without sacrificing strength much.
Some guy also hit me (very minor) from behind at a stop light a while back and there are some spider cracks in the paint of the bumper... So I think that means I can modify the bumper as it is no longer pristine. I'm going to make some holes in it for weight reduction and improved air flow and decrease cabin exhaust noise (Tacker said the bumper cover increases noise in the cabin by reflecting the sound?)

Basal Skull

^^ I don't know why you would get more flames with the quieter exhaust.
It is I think unburnt fuel with the ecu trying to protect the engine and running things rich. Maybe the fuel is being 'collected' more or the exhaust flow is such that it can ignite easier with the quieter muffler? I only noticed it on mine in pics and video friends took, usually happens at the end of a straight or when shifting. I think it correlates to coming off the gas after WOT? The throttle body should close when you come off the loud pedal so it should not be getting any more fuel. But maybe the exhaust slows down enough that it can ignite? anyone know?

993Godspeed

Wow, great work man.

Mike J

I know its symmetry, but why not just put the flex on one side, since your issue is having the two sides connected so one flex would solve the issue?

I am not sure if this is really an issue, have you seen any cracks? On my system, the X is "hung" on the standard mounts, so its relatively fixed to the engine. I suspect the cross pipe gets longer as the SS heats up, so that means there is outward pressure on the turbos -> which are also held in place by mounts that can flex a bit, and then the exhaust manifolds themselves. However, unlike your system, I have 200 cell Cats in circuit before the X, and that is attached via ring clamps - but those do not flex a lot either.

Ok, lets do some math. The thermal expansion coefficient of Stainless Steel is approx. 0.0000099 in/deg F, and assuming our maximum temperature is 1200F (its about 1400 at the exhaust port so that is generous), and we have about 20" of pipe on each side, the expansion across the back of car from the centerpoint to the turbo is 0.0000099 * 20" * (1200-70) = 0.22374", so total expansion is 0.44748"

Now the engine itself also expands. Aluminum expansion is 0.0000128 in/deg F, so assuming the span between the turbos is 40", and its all aluminum (which it is not) the total expansion would be 0.0000128 * 40" * (220 - 70) = 0.0768".

That means the exhaust system lengthens approx. 0.37" in width, or 3/8" over the engine expansion.

Someone what to check my math? I could be wrong on the lengths, I am doing this from memory and not measuring the car itself.

Cheers,

Mike