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I posted this on another TDI specific site, but I figured I would post it over here too so I could catch some other TDIers opinions :)

I have been thinking about modifying my newly acquired TDI. Diesel is a new thing to me, but I am very capable with conventional gasoline engines. I got rid of my "street" jeep to get this TDI for the sake of fuel economy but the hot-rodder inside of me has a hard time not modifying anything.

So in an attempt to heighten the performance of my Jetta while retaining the economy of it I want to ask if anyone has any experience with a dual stage set up on their car.

I am thinking the use of a dual-stage boost controller with one setting at the factory level and the other setting at a higher lever (dependent upon supporting modifications).

Accompanying the dual-stage boost controller would be a system for supplying the correct amounts of fuel for both boost setting. i.e. a factory fuel map for the factory boost and a tailored fuel map for the higher boost.

I have been doing a bit or reading but so far I have not seen anything specifically for the VW Jetta TDI that would support that? Or is there something and have I missed it? For the sake of my project I would not be against running two ECUs (one with the factory settings, or tailored to run as close to factory as possible with larger injectors, and one ECU with the custom settings) with the supporting wiring to be able to switch back and forth.

Supporting modifications would be ones that I hope (though I may be wrong) would not adversely effect the economy of the car when in factory mode and are as follows:

Better downpipe and exhaust throughout the rest of the car
Larger or more efficient intercooler
Larger injectors (which may have a negative effect on economy I hope proper ECU tuning can work out for the factory mode)

And for the sake of peace of mind, gauges to monitor boost, EGT and other functions that I may need to keep a eye on.

Thoughts? Please correct me if I am wrong in my thinking. I am actually taking this idea from a turbocharged gasoline (capri xr2) car I used to enjoy modifying.
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Discussion Starter #2
Also my car is already running a VR6 clutch and flywheel, though I will be getting a higher performance clutch to follow with other modifications.
 

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All good ideas. Personally I would put the money into: 11mm injection pump, lift pump in fuel tank, larger injectors/turbo+chip tuning in addition to the supporting mods you mentioned.

You could probably do a dual ECU but I have not personally seen it on TDI. The boost setup on TDI is not exactly the same as on older cars. For one thing, my boost controller on another car is set up to let pressure pass the dual stage solenoid in response to its boost sensor (Blitz id-3). Your car moves the N75 solenoid to let vacuum pass in response to boost. I don't know if a conventional boost controller will work on mk4 and newer TDI due to the setup and vacuum can instead of wastegate other than sending it into limp mode. Not saying it won't work but I don't know how.

ECU tuners can set up the ECU to switch the line between vac and pressure for VNT-nonVNT swaps, they would know the details.

Take a look at this article: http://www.myturbodiesel.com/1000q/a4/VNT-wastegate-adjust.htm for some details on how the VNT can works.

Feel free to talk to kermatdi.com, one of the site sponsors, they have a lot of supporting parts in addition to engine tuning. There are many other places to buy parts and get tuned as well.
 

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What is your power goal? Mod to achieve that goal instead of just putting it together. 200 hp? Doable w/stock block. Remember that the engine originally had 90 hp.
 

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Thanks for the input guys. Power goal is 150, I feel that is easily doable based on what I have read.
 

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I posted this on another TDI specific site, but I figured I would post it over here too so I could catch some other TDIers opinions :)

I have been thinking about modifying my newly acquired TDI. Diesel is a new thing to me, but I am very capable with conventional gasoline engines. I got rid of my "street" jeep to get this TDI for the sake of fuel economy but the hot-rodder inside of me has a hard time not modifying anything.

So in an attempt to heighten the performance of my Jetta while retaining the economy of it I want to ask if anyone has any experience with a dual stage set up on their car.

I am thinking the use of a dual-stage boost controller with one setting at the factory level and the other setting at a higher lever (dependent upon supporting modifications).

Accompanying the dual-stage boost controller would be a system for supplying the correct amounts of fuel for both boost setting. i.e. a factory fuel map for the factory boost and a tailored fuel map for the higher boost.

I have been doing a bit or reading but so far I have not seen anything specifically for the VW Jetta TDI that would support that? Or is there something and have I missed it? For the sake of my project I would not be against running two ECUs (one with the factory settings, or tailored to run as close to factory as possible with larger injectors, and one ECU with the custom settings) with the supporting wiring to be able to switch back and forth.

Supporting modifications would be ones that I hope (though I may be wrong) would not adversely effect the economy of the car when in factory mode and are as follows:

Better downpipe and exhaust throughout the rest of the car
Larger or more efficient intercooler
Larger injectors (which may have a negative effect on economy I hope proper ECU tuning can work out for the factory mode)

And for the sake of peace of mind, gauges to monitor boost, EGT and other functions that I may need to keep a eye on.

Thoughts? Please correct me if I am wrong in my thinking. I am actually taking this idea from a turbocharged gasoline (capri xr2) car I used to enjoy modifying.
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First and foremost, stay away from the 2 stage boost controller systems...get the simple boostvalve and set it up yourself for what you are running. you dont need to waste your money on 2 setups...if you want to control your boost levels, just use your right foot on the pedal and your eye on the boost gauge. just ask yourself 1 thing. is the car a race car or a daily driver? mine is a daily driver and want it to be as reliable as possible...im running a hybrid vnt20 with 25psi. egts are low, and everything runs great...i have the power to blow away a BMW M3 with the reliability and fuel economy of a stock tdi motor. When my car was stock, I was getting about 850kms a tank. Now that i have added all these mods (see sig for mods), i have yet to see any loss, if not better, fuel economy...i actually have hit 955kms in 1 tank...i never hit 900km when i was stock. it really is about tuning so make sure you find the right tuner. there are many good ones out there. I say start with a chip, boostvalve and boost gauge and get ready to have a smile on your face. then move from there.
 

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I subscribed because I am interested in some light modding possibly get deeper into as time goes on.
Hey Evil-Diesel I had a question in your signature it says "Precat Exhaust Dump + 0 lambda" what exactly is that? Thanks!

p.s. is it really safe to run that high of boost? You didn't have to lower compression or anything?
 

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I'd advise against a dual setup. Stage 3-5 tunes are some of the most economical tunes availible at cruising speeds. There's no reason to switch to a lower boost map- this will only hurt mpg and defeat the purpose of modifying. Most modifications to increase power will also earn you 1-2mpg each. VNT 17/22 is a very efficient turbo- and in order to keep it clean and healthy you will need to use higher power levels somewhat regularly. With a good tune, IC upgrade, bigger injectors, and gauges.. you'll be set. Turning down the boost just decreases the amount of heat and pressure the turbo can get. This might end up doing more harm than good- a tuner can best decide how to mix fuel and boost with your exact setup.

Good luck, and have fun!
 

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What is your power goal? Mod to achieve that goal instead of just putting it together. 200 hp? Doable w/stock block. Remember that the engine originally had 90 hp.
So what would be the maximum hp/tq that you can apply to the 1.9l? I want to do a serious build with mine but I need to find out what the limitations of the block and headstuds and so forth are?
 

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Hey Evil-Diesel I had a question in your signature it says "Precat Exhaust Dump + 0 lambda" what exactly is that? Thanks!

Its a cutoff from the exhaust system in which i have an electric switch to open and close.
In the pic you can see the pipe that branches off before the cat off the downpipe. that opens up the exhaust to have absolutely no back pressure. I had to move the cat down stream alittle to fit the new piping and electronic motor. The 0 lambda is a O2 sensor delete. so there wont be any cutback of fuel from the ecu if it sees any kind of emssions overload.


(This is all for off-road use)



 

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So what would be the maximum hp/tq that you can apply to the 1.9l? I want to do a serious build with mine but I need to find out what the limitations of the block and headstuds and so forth are?
There is so much involved in answering...

There are lower compression-ratio pistons and high performance rods available that let you push higher psi than head studs alone, gains to be had by modifying the intake manifold, ways to modify head to accept higher valve lift and aftermarket cams (Colt stage 2 for street or tdimeister cam for 11mm racing lift), you can buy or get a custom kit that allows bigger Merc 2260 turbos.

But what you really need is a way to go fast without snapping your axles or destroying your 3rd gear in your 02J transmission. Or maybe you need a European 6-speed meant for a diesel.. those will hold a little more torque but of course they're more expensive when they break.

I know you're looking for exact hp numbers, but those don't exist...
The torque peaks are what will break stuff, and by going to a lower compression ratio and bigger turbocharger you shift the torque peak up... raising the power and increasing redline while allowing torque levels to stay relatively low.

It's always going to be some kind of trade off in drivability vs. maximum power. My opinion is that stock internals are safe up to about 180hp. While adding more power decreases longevity, modified diesels tend to hold up very well under stress- as long as they get good maintenance.
 

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That help a lil bit thanks.... I build turbo cars all the time but they are for hondas and other gas powered motors. I also have a F-350 6.0L Diesel but I know alot more about all the things I can do to that one and how to get power isn't the problem I just don't know what holds up to what better when it come to the VW TDI mototrs and trannys! All the extra insight would be very helpfull. I want to have about a 300-350hp/450-500tq @ the wheels. Obviously custom axles are probably going to have to be in order along with a wellbuilt tranny but what tranny would be the best to work with? U mentioned the 6 speed Euro trans, I could also take another trans for something that can handle a lot more hp and tq and just have a custom bellhousing and adapter plate made to bolt up to tis motor as well if I needed to, Money isn't the question its getting all of the right parts together and working properly that im more concerned with. Then there is the tuning issue? Is there any specific person or shop out there that you would recomend for doing the ustom tuning that would be required for this as well?

Sooo pretty much what Im asking I guess is for someone who knows these cars well enough to help me out while I work on building this. I want to have somthing that not most people see everyday. That being a 300hp Diesel jetta that can lay waste to half of the other cars out there while still getting pretty amazing fuel milage!
 
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