Exhaust systems for Turbo cars.

[Turbo-Brown]

SO! What are people using for their exhaust system when they've turbo'd their cars?

I had a quick measure of the pipes on mine and they're about 44mm OD so probably about 41mm ID.

I have no idea how much they'll flow, guess it's gonna be less than 130bhp worth each but I'd like as little back pressure as possible.

Now for my mates pug turbo we're planning to open up the silencers and weld in some straight through pipe before re-packing the cans, idea being to make a cheap and standard looking system.

What are peoples thoughts on all this?

Cheers!

Alex

[buster]

at the moment i have 6 branch and then straight through pipes to magnex backbox.I did have magnex middle silencer but it developed a crack so i just removed it.
Now the turbo is going on i am just going to weld a Y piece on end of my down pipe and then run 2 pipes to join up with the other 2 pipes which are about in line with the hinged side of the front door shut.So about 2 ,2 foot long pipes to extend forward to the Y piece

[Ant]

Same as Andy really...

Modded 2wd cossie downpipe 1 into 2 into straight section followed with a scorpion rear box.

Burble burble....................

[e30_Turbo]

I suppose I'll be the same then, just got to mate the downpipes with the backbox with some straight through pipes and WOOOOOOOOOSH CHIRP!!

[Andy_magic]

I've got a turbo, manifold, wastgate and downpipe from an E34. Does anyone know if the downpipe needs modding to fit an E30?

[Rowen]

the exhaust on turbo cars should be much larger that those on a NA car, simply to allow the exit of the exhaust gases faster, and you dont what to much back presurre....i would suggest a 2 into 1 pipe, with the exit pipr been 67mm or larger...will post more details tommorrow

[Ant]

I considered the single drain pipe option but 2x 2.5 inches should flow well enough, and survive more than one speed hump

[Jos]

lol ant!

Yeah best exhaust for a turbo is no exhaust at all, so the less restriction you have the better, great idea welding the pipe though the 1st box, I suppose that would be better than beating the crap out of it until all the guts fell out, then putting it back in

[Turbo-Brown]

Fortunately, the standard system looks pretty straight forward with it being pretty much flat except at the front so making one should be <time consuming> childs play.

[Gunni]

below 250hp run a single unrestricted "2.5
for 250-350 run a single "3
for more run either double "2.5 og "3

[320Touring]

the exhaust on turbo cars should be much larger that those on a NA car, simply to allow the exit of the exhaust gases faster, and you dont what to much back presurre

is back pressure not required at low revs to help close the valves??

if so has anyone calculated the minimum back pressure they need?

[Turbo-Brown]

Once gas has passed through the turbo(s), you want as little back pressure as possible.

Once way or t'other, between the turbo and head will exist quite a lot of pressure as the blowers are quite considerable restrictions.

Never heard of back pressure closing the valves, thought that was what the springs were for

[320Touring]

Once gas has passed through the turbo(s), you want as little back pressure as possible.

Once way or t'other, between the turbo and head will exist quite a lot of pressure as the blowers are quite considerable restrictions.

Never heard of back pressure closing the valves, thought that was what the springs were for

true, true about the turbo's

just figuring that backpressure is responsible for low end responsiveness as cars with 'drainpipe' exhausts are notorious for being weedy at low revs???!

could be talking pish

[Turbo-Brown]

I've never really understood the whole back pressure thing.

If you welded a washer into the exhaust system so the gas could only escape through a 10mm hole, you'd have masses of back pressure, but the engine would most likely run like a sack o' shite.

Think what people are really talking about is gas speed. If you can keep this nice and high at low revs, your low end torque should be boosted as the momentum of each 'putt' of gas travelling down the pipe should create a vacuum behind it for the next 'putt' to be sucked out by.

Now obviously to keep the gas speeds high at low engine speeds, you need small diameter pipes and these smaller diameters lead to greater back pressure than larger pipes. However, just talking about back pressure without reference to gas speed can be a bit misleading.

Also, thinking about it, having exhaust gas outside the head pushing back against the valve would make it try to open wouldn't it?

[Turbo-Brown]

Right, had a quote for the pipes to make my system.

Looks like about Ԛ£300 which is quite a lot less than I thought it'd be!

Looks like I'll be making a complete system. That does include for the manifold piping too so by the looks of it, it's gonna work out quite a lot cheaper than buying say a Quicksilver one.

I also have the benefit of a motorsport engineer to help me design it

[lentec]

if i remember right (didnt get a bill )
think i paid
Ԛ£60 for the pipes to make the manifold
Ԛ£20 for the straght 2 1/2"
Ԛ£20 each for the two 45s and the 90
Ԛ£115 for tiger 4" back box
my neighbours love me!!

[lentec]

also this company have good prices
http://www.crazydevelopments.co.uk/Stai ... 0bends.htm