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#30 by regcheeseman on 24 Dec, 2008 03:39
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If you can weld (you should have had enough practice with ROV716Y) then make one, this was my first...
Mis-mash of bit's and pieces
180 degree 2.5" bend from powerflow
2.5" flexi from Ashley
manifold bracket from standard downpipe
90 deg and conector hacked from ecort cossy downpipe
All in the bits were £80 - so still pretty expensive
All stainless, but I wont bother polishing it.
They got better....and cost me £13 for the flexi
A later one
I've made 6 like this and they sold real quick, unfortunately I've changed job and lost the access to TIG and free stainless pipe.
You'll need a 180 degree mandrel bend and a 90 deg bend, I can tell you how to cut them if you fancy making your own. -
#31 by carrizog60 on 24 Dec, 2008 03:58
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i would like to know as i am planning on doind it myself.
do i reaaly need a 180degree?
hard to find around here...
also does any stainless work?
i have a friend that works on a shop that makes house stuff in stainless and he gave me a 3 mt long pipe for free...
will it work or do i need some special one? -
#32 by molgrips on 24 Dec, 2008 04:09
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Quote
but all that torque makes it much quicker than a gas engine with the same power
It'd feel quicker, not be quicker. Power is power, and is the bottom line. -
#33 by rov716y on 24 Dec, 2008 04:15
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Quote from: "regcheeseman"
If you can weld (you should have had enough practice with ROV716Y) then make one, this was my first...
Mis-mash of bit's and pieces
180 degree 2.5" bend from powerflow
2.5" flexi from Ashley
manifold bracket from standard downpipe
90 deg and conector hacked from ecort cossy downpipe
All in the bits were £80 - so still pretty expensive
All stainless, but I wont bother polishing it.
They got better....and cost me £13 for the flexi
A later one
I've made 6 like this and they sold real quick, unfortunately I've changed job and lost the access to TIG and free stainless pipe.
You'll need a 180 degree mandrel bend and a 90 deg bend, I can tell you how to cut them if you fancy making your own.
i dont have access to any kind od stainless steel welder.
i did weld the mk3 mild steel downpipe into the mk1 mild steel downpipe to mate them together,
all i need it to get it as far back as a where a gti sytem would start them buy an after market gti system. -
#34 by TurboJ on 24 Dec, 2008 14:51
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Quote from: "molgrips"Quote
but all that torque makes it much quicker than a gas engine with the same power
It'd feel quicker, not be quicker. Power is power, and is the bottom line.
Sorry, but that's not entirely true. You see, torque and power are just two sides of the same thing and you can actually calculate power if you know torque.
Let's say you have two engines.
Engine 1: 2.0 litre N/A gas. 100 hp and 170 Nm of torque.
Engine 2: 2.0 litre turbodiesel. 100 hp and 260 Nm torque.
The gas engine would make max. power around 5500 rpm, and max torque around 3000 rpm. The TD would make max power at 4500 rpm and max torque between 2000 and 3000 rpm roughly.
There is no question whatsover that the TD will be quicker (just compare any similar-hp gas and diesel equivalents and you'll see that).
Acceleration (especially overtaking) will be VASTLY quicker.
Top speed may be around the same for the both because at max rpm they will have equal power. Maximum power actually tells you little about a car's performance. All it tells you is how much torque you have AT HIGH RPM. Peak power helps little if another engine makes twice the accelerative force 80% of the rev range.
Power is nothing if you have no torque. Then again, torque will still make you go quickly with a moderately low max power. The reason why a TD will have lower max power, is because it has lower max revs - simple as that. With a TD, however, you will have much more torque over all the revs that you use - this is why the performance is stronger than hp would make you expect. Heck, this is why we frive TDs in the first place!!
Enzo Ferrari put it simply: "Horsepower sell cars, torque wins races".
I don't consider myself an expert, but I'd trust il Commendatore
In any case, merry christmas!! -
#35 by TurboJ on 24 Dec, 2008 14:58
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Quote from: "carrizog60"
when building a full system do we need the fex joint like the one that 935 racer was selling?or that isnt needed?
in original form it doesent have...
Everybody tells me you need one.
I believe on the stock exhaust, the flex is provided by the flange between the cast downpipe and the first section of exhaust pipe. And even if it doesn't flex much, the cast elbow isn't going to crack under load, so it can 'force' the rest of the system to move about. And allow the flange connector to flex ever so slightly.
If you have a thin-walled normal exhaust tube connected to the turbo and no flex piece, changes are it will crack in time. -
#36 by Tony2ltr on 01 Jan, 2009 12:50
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my 2 cents, I hope no one minds:
HP=RPM X Torque/5252 One is a mathematical function of the other. This is why Hp and torque on a dyno sheet should always show HP and Torqu crossing at 5,252 RPM, unless the scales have been graphically shifted.
Torque is the amount of power per combustion stroke.
At peak torque, an engine is at high volumetric efficiency, making the most out of every breath of air, this also tends to coincide with lower fuel consumption.
Hp is the substitution of more combustion strokes over time, it is an accumulation of torque at a given RPM, how much total power that is accumulating at a given rpm. It is like the way a 2 stroke makes more power than a 4 stroke, it totals more power per time than a 4 stroker at the same RPM, but each power stroke makes much less torque than a 4 stroke does each stroke, but because you have two power strokes in the same period of time, it will deliver more power at the same rpm(as long as each power stroke of the two stroke equals more than half of the torque than each power stroke from the 4 stroker machine, which it better, or it is a piece of crap).
Does this help?
-Tony -
#37 by regcheeseman on 20 Jan, 2009 14:54
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i dont have access to any kind od stainless steel welder.
You have a mig don't you? You can mig stainless easy with stainless wire.
Would probably last better in mild steel anyway. -
#38 by Baxter on 20 Jan, 2009 15:45
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Quote from: "rov716y"
just rang around everywhere for a mk1 1.6td turbo pipe and nowhere can get one just refere me to custom places.
I have a new passenger performance one at the workshop I didn't use.
01484 664 017
I post daily. -
#39 by Tony2ltr on 20 Jan, 2009 18:54
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I made the whole 3" stainless exhaust on my turbo cosworth vega with stainless wire in my lincoln 100 mig. it welds really nice actually, you have to use a bit more argon in your mix if I am not mistaken, No straight CO2 unless you want a perforated bead.
BTW, I have been driving my 1.6 jetta (engine in avatar) for about two weeks now, running 25 pounds of boost. It is a crop duster under load but MAN THE PULL!
-Tony -
#40 by GEE-BEE on 20 Jan, 2009 18:56
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Techtonics.com
they will make you a complete 2'5 system -
#41 by arb on 21 Jan, 2009 10:25
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Quote from: "Tony2ltr"
I made the whole 3" stainless exhaust on my turbo cosworth vega with stainless wire in my lincoln 100 mig. it welds really nice actually, you have to use a bit more argon in your mix if I am not mistaken, No straight CO2 unless you want a perforated bead.
BTW, I have been driving my 1.6 jetta (engine in avatar) for about two weeks now, running 25 pounds of boost. It is a crop duster under load but MAN THE PULL!
-Tony
Yes, get a flex joint. I paid $23 for mine from http://autozone.com
Before I sold my MIG to get my TIG, I welded S.S. just fine. My gas shop sold me a mix for this - 25% CO2 / 75% Argon. The mix gave great penitration and a good bead on the S.S. (with S.S. wire of course.) You'll need to crank up the amps a bit more than mild steel. -
#42 by Tony2ltr on 21 Jan, 2009 19:22
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Yep, I think that is the mix that the gas shop sold to me as well.
Stargon usually has a bit of notrogen in it as well for mild steel.
is the stock downpipe really that restrictive?
-Tony -
#43 by regcheeseman on 22 Jan, 2009 04:51
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Mix is known over here as cogarQuote
is the stock downpipe really that restrictive?
to any form of tuning - yes -
#44 by Tony2ltr on 23 Jan, 2009 05:14
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So at 25 psi boost like I am currently running, I would see a drastic improvement on performance? I would imagine that a large downpipe tapering to a slightly smaller tailpipe would be best.
? And of course, double wall pipe or heat wrapped downpipe/exhaust would improve flow.
On another note, I have a theory about Fuel pumps for performance our turbo diesels.
I may start another thread on it, but I have some to a realization about fueling. Fueling drives exhaust boost levels, but on a turbo IP, fueling follows boost. This is great for clean exhaust turbo cars, but it inhibits performance. I have had great luck so far with the NA pump, but it is really smokey under initial acceleration.