Hi all
I'm building my chassis right now and have made my tunnel nice an wide , 210mm inside to be exact and planned to run my exaust through it and out
the back instead of out the side like normal locosts. Does anyone know of any reasons why that might not be ok for the SVA before i go too far?
I mean most normal cars have the exhaust through the tunnel and out the back right! so it must be ok 
Although it's wide will it fit with the prop in there aswell??
You would need some serious heat protection and also it would be close to the fuel and brake lines and wiring.
I'm not sure it would be looked upon that well at SVA.
Rich.
Are you going to have the bottom of the tunnel open? If it will be closed then the heat build-up could be impressive! Most production cars run their
exhausts along grooves in the floor, open to the air.
Standard disclaimer: these views are purely conjecture and not based on personal experience... 
Mind you - my exhaust get bleeding 'ot after a run - you can feed the radiated heat a few feet away.
David
[Edited on 10/2/05 by David Jenkins]
yes,
The tunnel is open to the world at the bottom and also the exhaust is planned to sit half in and half out the bottom of the chassis this is because
it has to go below the gearbox mount which sits about 2" up from the botom of the chassis.
Cheers Mike.
[Edited on 10/2/05 by quattromike]
the Dodge Viper exhaust gets so hot it glows red. They have very expensive sils to box it in without melting. Enclosed exhausts are much better IMO. I'd rather have one myself, but be careful how you do it.
Most main exhaust pipes (excluding cat & associated down pipes Which tend to be stainless and run about 200 degrees hotter) tend to run, in open
air, at just below visible red temperature, which I beleive is about the 600 degree mark, when an engine is on full song at motor way speeds. This is
why it is possible to wrap a steak in foil and cook it by securing it to your exhaust , then going for a long drive.
For these reason it is not a good Idea to place the exhaust IN the tunnel.
Unless you have a vented top on the tunnel with hinges and a clip fastening system you will not be able to tell when your steak is done, so it's not a good idea.
It wouldn't matter how well you insulated it I guarentee that it you went fo a 'sprited' drive then got out and left it a few minutes
you would leave the skin of your hand on the tunnel when you got back in it. The heat would soak up into the structure when left and you arm, hand,
thigh frequently touchs the tunnel when driving and getting in or out
- Alan
quote:
Originally posted by jollygreengiant
For these reason it is not a good Idea to place the exhaust IN the tunnel.
I wouldn't do it.
I have dealt a bit with GT racing cars with enclosed and semi-enclosed exhausts and they are a complete pain in the ar5e!
For one, it will make tunnel acces more difficult than it already is on a seven, and for that reason alone i wouldn't do it, but it will also get
very hot, as has been said, and may be likely to cook the grease in the front UJ of the prop, depending on how close it is to the exhaust.
quote:
I'm building my chassis right now and have made my tunnel nice an wide , 210mm inside to be exact
Don't Westfield run the exhausts on some of their V8 powered cars down the tunnel?
Sam
I like the idea of exhaust enclosed from the aero point of view. Would be nice to duct a bit of air down the tunel to keep things cool and use some exhaust wrap in places where you dont want heat or maybe whole length.
Personally i like the idea. Only reservation is that the cars are small and space is tight.
On my car ive put the floor straight across the bottom of the tunnel. An idea for central exhaust may be to recess the central part of the floor into
the lower tunnel area by approx 70mm thereby creating an open bottomed exhaust tunnel (ie std tunnel is split into two with false floor - exhaust
below, prop above). The prop could then go above this new floor section in the standard tunnel.
Inside the exhaust tunnel heat proof reflective material could line it and protect prop from drying out and excessive heat into cockpit.
Tricky areas - getting the exhaust to go from manifold to the underneath of tunnel without being to low.
Access to gearbox etc for oil changing / clutch changing.
Exhaust routing thro back under diff / fuel tank.
What about creating a shallow exhaust tunnel in the passenger footwell floor. If it is no higher than std seat runners it should result in the pass
seat being much higher than normal. Instant seat warmer!
Alternatively modify the side of the chassis and make the box run up the inside of the 'sill' area. This way it will be just inboard of the
normal external position. Rear routing will need to be carefully thought out tho'.
I must admit that I like the idea as well - I worry about people coming into contact with the exposed hot pipework after a run.
David
[Edited on 11/2/05 by David Jenkins]
Well i think it's fair to say there's been a bit of a mixed reaction on this subject but this only encourages me even more to do it.
I've commited to it now so i will carry on and prey that it'll be a sucsess 
.
Mike.
P.S. cheers for all responsess so far .
Bring the exhaust outlet out to one side, as if its directly behind the car, the exhaust fumes will be swept up in the turbulence and swirl around
the area of your head. Which is not the best you can do for your health.
OK, it wont be that bad, but it could be.
Its not the best idea.. I did this on my Landrover, and it filled the vehicle with fumes. Bring it out at the side..
The plan was to take it right down the middle then split it behind the diff and have two back boxes out from the middle to each side and out and mabey
have the back boxes low enough so you can see them from behind to add a bit of bling . or it was suggested that from the 4-2-1 manifold just
have the 4-2 part and take a smaller pipe down each side of the tunnel and then out along the back again, but i'm not sure about that idea
because i'm not sure what it's gonna do for my engine power / torque.
cherrs Mike.
you are right, it won't help the engine performance doing that with the 4-2-1.
You just need to bear in mind the heat output of the pipes. On a leading manufacturers GT car, the heat was severe enough to burn the paint off
anywhere near the exhaust, and melt the insulation off wiring a 1.5 feet away from the tunnel!
Having said that, most road cars dont suffer from that problem, but they are not operated at such high powers for so long, and have a less enclosed
tunnel.
I've seen a Rover 800 burnt out becase the cat was mising its heat shield and the sound proofing in the interior started to burn . The air going through the tunnel is already pretty hot without adding to it.
This is what i had i mind:-
Rescued attachment TUNNEL.jpg
Take a look at the underside of your quattro, and see the exhaust heat shields, particularly at the opening of the tunnel. A bit of curved ally isnt going to be upto the job
I agree with what your saying ,so do you think if i added some heatproof material to the cover will it help ?
Rescued attachment TUNNEL2.jpg
I cannot see how you can fit the exhaust, heat shield and the other gubbins into such a small space, I struggled with just the prop, fuel pipes,
wiring etc
Rescued attachment Tunnel Clearance Exhaust.jpg
Mike,
From your photo archive it looks you're going IRS of some description (w/bones or de dion).
Bear in mind your ex pipe will need to go round diff, fuel tank, w/bones (or de dion tube) and any other gubbins that may need to be in there (battery
perhaps?).
I like the idea, but think you'll find it far too much aggro. Don't forget, you'll also have to get it into tunnel and front end too!
With a dirty great b/housing in the way.
You may be better going for something like 3 or 4" x 1" box tube and running it under car.
As for comments about the Viper, Top Gear managed to set the exhaust "tunnel" alight. And that's a major motor manufacturer.
Good luck
ATB
Simon
I'm quite interested in how folk have done V8 exhausts in their 7's.
Your normal V8 exhaust system has a crossover pipe between the two bank exhausts about 5 or 6 feet away from the engine and this apparently releases
quite a lot of power!
Obviously this is impossible in a 7 with a bank exhaust on each side.
In my mazda I couldn't do the crossover pipe thing, so I paired cylinders an a 3/5 beat (best of a bad job) i.e. 1&5 3&7 2&4 and
6&8
Has anyone got a reference for exhaust tuning on V8s? (and not the flat plane exotics)
On yeah - re: this thread - with the exhaust in the tunnel of a v8 you can easily do the crossover pipe to make the exhaust work better.
Cheers
Bob
Hi all, first off thanks for the good advice comming in,
and to marks question: I have made the tunnel alot wider in my chasis measuring 210mm inside at the top and 240mm at the bottom sloping over to the
pasengers side at the bottom and still have 550mm in the cockpit for the seat, so it leaves some room spare in the tunnel.
i was planning to take the exhaust low enough to pass under the diff and then split it to each side with 2 small back boxes then out at each side.
then hopefully plum the fuel tank it above somewhere. ther is still along way to go in planning and building the chasis alone but i'll get
there
Mike.
i Think the idea is a nice one..
Donkervoort does it to.....
BUT they also do other stuff different then we do, so i think that if you want to change the exhaust layout you need to change more..(fuel
tank??)..
also the heat amount is impressive....
just think 35degrees and you ar e stuck in traffic jam?? the heat build up is high..
very high.. if i was you and you want it then do it, but choose another route for the fuel and electrics etc...maybe in another sperratute tube or
something....
the heat is the one to beat..
and while driving it will be ok....
TKS
p.s my bike exhaust pipe near the head after just starting lets say 3min. are hotter then 350degrees...
20cm away my device can measure it again 320degrees...
and you cant see it they are...
but i think you need a good isolation method....soo in fact i will go for a double floored tunnel if you get what i mean..??
on the first bottom you put prop and electrics and fuel then you put a floor and there you put the exhaust..
and the brakes you put away but still on the bottom of your car...or also near the electrics..
TKS
quote:
Originally posted by tks
just think 35degrees and you ar e stuck in traffic jam??
TKS
