biturbo?

Has anyone made a biturbo mk4 jetta? if so whats the power difference, and economy difference?

titantdi said:

Has anyone made a biturbo mk4 jetta?

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I don't think so.

if so whats the power difference

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You can get a lot of pressure with a single turbo, with only four cylinders and such a low revving engine two turbos isn't very practical. Power would most likely be about the same as if you were to use a single aftermarket turbo, but really it comes down to what you've done to your ECU. Turbos just do what they're told.

and economy difference?

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Turbos aren't rated by what kind of MPG hit you'll take after installing, this is likely due to the fact that it depends largely on how you drive. If you drive the same as you did before the turbo upgrade, mileage should not make a noticeable change.

titantdi said:

Has anyone made a biturbo mk4 jetta? if so whats the power difference, and economy difference?

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If you want a bi-turbo setup get yourself a high performace audi with AWD thats built to handle the added power.

There wouldn't be any power difference unless you are overfueling before adding the extra turbo, thereby adding extra air to burn your excess fuel, and usually you will drop a little mileage with the extra turbo.

The main purpose of inline twin-turbos is reduced lag, but since we already have VNT turbos... it would be money spent for nothing.

Buy new bmw 2 liter twinturbo.. 218hp

The turbo is the least of your worries.

The new generation diesels have different combustion bowl designs, 7/8/9 hole Piezo common rail injectors operating at 1800 bar anbd injecting 5 or more injections per combustion stroke and that is just the tip of the iceberg.

Adding more boost does not magically cause more fuel to burn. Each pistons combustion bowl has a unique design to work with the intended fuel quantity and boost pressure. You can within reason increase fuel and boost but the side affect is lower actual efficiency since the fuel/air is outside it's optimum range for the bowl design.


Designed with a race inspired lower compression bowl for extreme boost including both single and staged turbo applications.


DB

The OEM high performance diesel world is moving towards engines having two staged fixed-geometry turbochargers in place of a single variable-geometry turbo. Small turbo operates at low engine revs, then the big one takes over (and the small one is bypassed) at high engine revs, and there is a changeover period where they are both in series.

BMW already has this in production (335d / 535d). Mercedes will have this on their new 4-cylinder diesel. Ford 6.4 Powerstroke - for all its issues - is something like this although in that case one of the turbos is a variable-geometry design.

The OEM's are moving towards this because emission constraints are driving them towards having some degree of EGR under *all* operating conditions including full load and including just off idle. If you want the engine to have any torque for pulling away from idle at all, you have to generate boost (with the air and EGR mixture) right off idle. A turbo small enough to do that, even with variable geometry, isn't going to be able to flow enough to generate the power at higher revs that the market demands. Solution, two staged turbochargers.

And yes, I know the upcoming 2009 Jetta has dual EGR and only one single VNT turbo ... but it doesn't make as much power as the dual-staged-turbo BMW and Mercedes 4-cylinder offerings, and we don't yet know how it's going to be at pulling away from a standstill off idle. 'Course, the price tag has an effect, too.

I haven't seen any bolt-on biturbo commercially available, but I'm sure some of the more knowledgeable members will chime in.

If you didn't see this thread

http://forums.tdiclub.com/showthread.php?t=214694

it might be useful. There seems to be a sequential turbo available from the guys mentioned there, but it's for the MKV. Stingray also mentions that you could do a custom setup in 2 weeks, and I seem to recall seeing some people post that they were at least thinking of making one...

Does anyone know of any cars that actually have this setup running?

thanks for all the help and info guys! i was just wondering with all these new biturbo engines from mercedes and bmw if you could make the same with a vdub. since im in high school and i dont have much money does anybody have any ideas that i could use on my jet?

So you're building a small turbine engine with a turbo as base, or do i see this wrong?

i think you see it wrong, i was asking whether it would be really a cost efficient idea to add a second turbo to a stock tdi.

titantdi said:

i think you see it wrong, i was asking whether it would be really a cost efficient idea to add a second turbo to a stock tdi.

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Nopers.

What is your goal? More MPG, more power?

i was hoping with the biturbo it would give a large power enhancement without hurting the mpg too much.

its a idea i had thought might work. but after looking at the stats these guys have told me it wouldnt be cost effective for the little power you get.

Power doesn't come for free.

Look into chiptuning and bigger nozzles for your current engine and turbo. Once you exhausted that, go with a bigger turbo.

Typically one doesnt do two turbos for added power...that is simply a caveat. One does twins primarily to increase the area under the curve as it were.....or more simply, the useable powerband. There is no turbo that will give you all the air delivery necessay to make maximum power and efficiency over the whole rev range. With twins, you can get much closer to this ideal. In theory, one would have the max useable power possible at all times....along with the max efficiency possible at all times. Drive easy? get mileage. Drive krazy? get power! And even better than that, no peaks and valleys. A good strong pull right till redline. The only reduction in power due to tuning to decrease torque at high rpm.

It really isnt cheap...igf you are handy....and have a bunch of time, you can make it cheap. But otherwise, it is pricey. But so are 6 speeds..... and how many have those?

Another benefit of a twin-turbo setup that nobody's touched on would be the decrease in stress on the turbos to provide a comparable amount of boost of a larger turbo. If you're running 2 vnt15's right in their ideal boost range of 14-18 psi, you're getting much more boost flowing into the engine without peaking the turbo's to the point where you're shortening their lifespan.

Excellent point Ed...thanks!

Ed's TDI said:

Another benefit of a twin-turbo setup that nobody's touched on would be the decrease in stress on the turbos to provide a comparable amount of boost of a larger turbo and more. If you're running 2 vnt15's right in their ideal boost range of 14-18 psi, you're getting much more boost flowing into the engine without peaking the turbo's to the point where you're shortening their lifespan.

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Very good point ED

LA@JSPerformance.ca said:

Very good point ED

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Make sure you tell Jose that I manage to absorb some of the stuff we discuss in the shop!!

Ed's TDI said:

Another benefit of a twin-turbo setup that nobody's touched on would be the decrease in stress on the turbos to provide a comparable amount of boost of a larger turbo. If you're running 2 vnt15's right in their ideal boost range of 14-18 psi, you're getting much more boost flowing into the engine without peaking the turbo's to the point where you're shortening their lifespan.

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Not true

In your example the turbo's will not provide ANY amount of usable flow or boost.

Define stress? A turbo running at 18psi of boost and 1650F will last forever and never fail. Increase boost pressure slightly or temperature 10F and failure is imminent within a very predictable time frame.

Also in your example the engine simply cannot feet the required flow to drive the turbine's of the two turbos. The turbo's would never spool up even if the engine is redlined.

Compound turbo charging goes WAY WAY WAY back to world war II, it's nothing new. Aircraft would use various combinations of "Compound supercharging" to provide suffient air to piston engines at very high altitudes which were not possible with single turbo or supercharger applications. If you oversimplify the concept, one of the compressors provided pressure/flow up to one altitude, the second kicked in which was designed to work in the higher thinner atmosphere and supplemented the first to trick it into thinking it was still at sea-level or it's maximum designed altitude.

In the case of cars one turbo is undersized to provide boost and pressure at very low engine rpms and output sufficient to improve emssions and engine response. The second comes on line when the first can no longer operate with the higher flow rates associated with engine rpms and output (gas flow/pressure).

Again getting back to basics, more air or boost alone does not increase power of a diesel engine, it simply works with the fuel system and combustion bowl so as to provide clean combustion.

What others don't seem to understand is that these turbo systems are designed to work with VERY specific aspects of the engine they are bolted onto. You simply CANNOT bolt a compound turbo to an engine and expect it to work if at all. It is simply one of a dozen or more ingredients that combine to make the combination which provides the most power and lowest emissions while delivering on fuel economy.

If you want a compound turbo set up then you need:
-Cross flow head
-4 valves per cylinder
-CR injection 7-9 holes ideally
-Pieze actuation
-Bosch 17 series EDC control
-Digital flow control of the turbo
-Design specific combustion bowl
-Digitally controlled Tumble flap to regulate the swirl at all rpm ranges of the incoming air charge regardless of flow, pressure, engine rpm
-Flow specific intercooling
-Custom compressor design (x2)
-Custom turbine wheel design (x2)

My advice is it would be cheaper to move to Germany and buy a BMW than it would be to waste your time trying to get an oudated motor to come close to a state of the art engines performance.

Gotta go to 4 1 Oh...
DB

When they tricked the small turbo, how did the big turbo do that? It never exceded the small turbo's max psi, yes! MRCHILL hit the nail on the head. twins make it a very efficient sytem to go fast.

Drivbiwire said:

...
If you want a compound turbo set up then you need:
-Cross flow head
-4 valves per cylinder
-CR injection 7-9 holes ideally
-Pieze actuation
-Bosch 17 series EDC control
-Digital flow control of the turbo
-Design specific combustion bowl
-Digitally controlled Tumble flap to regulate the swirl at all rpm ranges of the incoming air charge regardless of flow, pressure, engine rpm
-Flow specific intercooling
-Custom compressor design (x2)
-Custom turbine wheel design (x2)

My advice is it would be cheaper to move to Germany and buy a BMW than it would be to waste your time trying to get an oudated motor to come close to a state of the art engines performance.

Gotta go to 4 1 Oh...
DB

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Wow if this is the case some one better tell the 12V cummins guys...

-Cross flow head (yup they got this one)
-4 valves per cylinder (nope)
-CR injection 7-9 holes ideally (nope)
-Pieze actuation (nope)
-Bosch 17 series EDC control (nope)
-Digital flow control of the turbo (nope)
-Design specific combustion bowl (specific too compounds, nope as well)
-Digitally controlled Tumble flap to regulate the swirl at all rpm ranges of the incoming air charge regardless of flow, pressure, engine rpm (still nope)
-Flow specific intercooling (i know of at least two setups that have no intercooling at all)
-Custom compressor design (x2) (one stock turbo, one stock to another vehical)
-Custom turbine wheel design (x2) (same as above)

So one out of eleven and yet there are thousands of working examples including ones that make 220whp/L+, which would be a 440whp+ in a tdi...

So I'm gonna have to call BS on those requirments...

dvst8r said:

Wow if this is the case some one better tell the 12V cummins guys...
So one out of eleven and yet there are thousands of working examples including ones that make 220whp/L+, which would be a 440whp+ in a tdi...

So I'm gonna have to call BS on those requirments...

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Well if you want to compare apples to watermelons then I have a CF6 that makes 130,000hp...whats your point.

Lets get back to what is required to make a 1.9L diesel run a compound turbo system. The fact is it will require VERY specific custom designed components.

220whp per liter would translate into a car that smokes like a tire fire and is not streetable nor reliable enough to use as a daily driver, let's not even bring up the issue of passing emissions.

BMW is pushing the 130hp per liter while meeting emissions. If you want to garage hack a motor to make power, by all means install a 1.8T and run nitro.

A standard TDI simply cannot drive a compound system without extensive modifications which would result in an engine that you started with.

DB

dvst8r said:

Wow if this is the case some one better tell the 12V cummins guys...

-Cross flow head (yup they got this one)
-4 valves per cylinder (nope) Do your cylinders have 480cc of total displacement? So how do you plan on flowing enough volume to drive dual turbo's???
-CR injection 7-9 holes ideally (nope) Does your Cummins rev to 5100 rpm? Didn't think so! Does your Cummins have to insure perfect distribution of that fuel with multiple injections at 5,000 rpm while working with fuel pressures of 1800 bar?
-Pieze actuation (nope) Does your cummins inject 5 injections per 3miliseconds to achieve the rpms required to produce power from a 1.9L engine while remaining in the ball park for emissions reasons?
-Bosch 17 series EDC control (nope) Again design dictates massive processing power to drive multi stage injection, digital control of the engine systems, and prevent the turbo's from outflowing the motor during transitions in flow and compressor rpms which would exceed 280,000 rpms in the compound applications in the smaller turbo.
-Digital flow control of the turbo (nope) Does your turbo spin at 280,000-300,000 rpms, didn't think so!
-Design specific combustion bowl (specific too compounds, nope as well) The 1.9TDI would require lowered compression to accomodate higher levels of cylinder pressure during combustion. Also the engine would require richer combustion. This would require radical changes in bowl design to achieve fuel air ratios approaching 14.7:1 (vs 33:1 in current TDI engines). The bowl works with the multi hole nozzles to achieve a high level of fuel dispersion and distribution within the bowl to insure optimum combustion characteristics.
-Digitally controlled Tumble flap to regulate the swirl at all rpm ranges of the incoming air charge regardless of flow, pressure, engine rpm (still nope) given the wide rpm range flow characteristics change from one extreme to another. In order to accomodate the strict requirements of bowl swirl and velocity accross an rpm range of nearly 4,000 rpm you MUST vary the incoming air charge to maintain a stable bowl flow pattern to insure dispersion of fuel and prevent melting of the pistons.
-Flow specific intercooling (i know of at least two setups that have no intercooling at all) give the operating temperatures of the TDI intercooling is mandatory to prevent the TIT's from vaporizing the single crystal alloy of the turbine wheel (KP series). Already the temps of the turbines have to endure 1040C without fatigue or failure. factor in richcer combustion and the temps rise to levels that will require extremely efficient intercooling to lower the combustion temps entering the turbo.
-Custom compressor design (x2) (one stock turbo, one stock to another vehical)News flash it does not exist for the TDI in this flow range (yet).
-Custom turbine wheel design (x2) (same as above) What kind of turbine are you thinking that can produce 1bar of boost at low power and flow from a 1.9L engine below 2000 rpms?

So one out of eleven and yet there are thousands of working examples including ones that make 220whp/L+, which would be a 440whp+ in a tdi...

So I'm gonna have to call BS on those requirments...

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DB

You make that sound incredibly complex and unique, Pete. Lets not forget that one can buy this technology in a run-of-the-mill Peugeot, Citroen, or even Ford!

Drivbiwire said:

-CR injection 7-9 holes ideally (nope) Does your Cummins rev to 5100 rpm? Didn't think so! Does your Cummins have to insure perfect distribution of that fuel with multiple injections at 5,000 rpm while working with fuel pressures of 1800 bar?

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You have never seen a Cummins revv to 5000rpm? You are really missing out. That is like your little TDI revving to nearly 9,000rpm!
Here are some 4,000rpm examples:
http://www.youtube.com/watch?v=vJkIOEFxb2w
http://www.youtube.com/watch?v=3JN5F3zGh0o

Some race trucks (especially sled pulling) are getting into the 5000-6000rpm range!

http://www.srdieselconcepts.com/Dodge_Cummins-12.html
1994-1998 12 Valve Cummins 5000 RPM Governor Springs
If you don't already know what these do, then you should not buy them.
5000 RPM's is not for your grocery getter

http://www.atsdiesel.com/ATSWebsite/ProductsDodge/Mechanical.asp
GDI4000 Part Description
Governor Spring Kit, 4000 RPM - 1994-98 Dodge 5.9L 12-Valve Cummins

-Digital flow control of the turbo (nope) Does your turbo spin at 280,000-300,000 rpms, didn't think so!

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Does your turbo flow 3000cfm at 75+psi of boost, didn't think so!

There is no need to make it overly complex. Stock AHU GT15 and something in the balpark of HX 30 would make one impressive vehicle for a spirited daily driving. The cost would be minimal. Then if you have the green then you could go a bit wilder with the turbos like using something like GT2871R as the LP unit. Even if its not that good turbo for small displacement diesel on its own it would be a good unit for ~300hp compound. Then for a HP turbo I would get something with a bit larger wheels. Maybe a hybrid made in the stock turbo housings

titantdi said:

Has anyone made a biturbo mk4 jetta? if so whats the power difference, and economy difference?

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The OP was asking about power and fuel economy not about building a Frankenstien car that can pull a sled and rev to 9000 rpm.

As I stated to hit his goals of a streetable vehicle that delivers decent power and economy all of my statements stand.

DB