From a 700hp Cummins to a TDI

I learned what i know of diesels on a truck i built from stock, an all mechanical 12v ppump cummins. It was extensively modified but with no electrical worries and a simple design, everything was pretty straightforward.

I realized the money pit it became, and was going to be, and sold it. I picked up a 5speed 00 TDI last week and have started with maintenence.

Im enjoying the mpg a lot. I know it wont be as fast as my truck was, but I'd to be close as possible while preserving reliability and economy.

I search the net and this forum extensively. I have a few unanswered questions.

1) what is the effective powerband with this vnt turbo? Max effective boost/power level? My truck stock started defueling before 2800rpm, until fueling mods of course. I can hear this turbo spool well til 2k rpm then power and noise disappears. Is this just what 90hp fueling feels like? Is it due to stock tune? Is the turbo just higher pitched at rpm and thus inaudible.. or is it done singing already with so many rpm left?

2) what are the hp limits of the 10mm pump vs 11mm? Straightforward swap? Need retuned?

3) the FAQ states never to exceed 18psi boost on a stock engine without lowering compression. This can only be done w internals, yes? Head gasket?

4) can nozzles be swapped without a tune for a short time or longer? The FAQ stated the ecu doesnt know output at the injector, only fueling through the pump, so it seems fine but want to double check

Will have more questions that i cant find through searching. Thanks

1. This turbo is stock set to about 13.5psi from factory, which comes pretty fast and stays there till 4000rpm. It can handle about 18-18.5 psi sustained max. IMO the turbo is good for about 150-160hp crank (120-130whp). Dirty wastegate vanes may keep it from boosting to the proper level. Turbo is very audible with a catalytic delete.

2. 10mm pump can be good till about 200hp provided that you do nozzle swaps. The pump itself maybe fuels enough to 130-140hp crank, before you have to change nozzles to be able to get more fueling out of it. Some tweaks may be made to injection duration to get a bit more fuel. To change to 11mm pump, you HAVE to have a tune specific to that pump, as the voltage conversion is different.

3. Stock engine can take more than 18psi. The FAQ is very conservative.

4. Most common nozzles are the Bosio PP520's if you're aiming at long term minor to moderate tune. Others have put Race520, and tuned later. Obviously more smoke, your stock clutch will slip real soon with a tune.


To know more about the stock tune see http://forums.tdiclub.com/showthread.php?t=375099


17-18psi out of the stock turbo, with 50mg of fuel/stroke up from ~38 stock (plus the 5-10mg extra from my PP520 nozzles), and tweaking with other maps makes the car much more driveable, with 0-60's in the 7 seconds. Calculated power at crank 150hp, 260-280 ft-lbs of torque. Up from the 90hp / 172 ft-lbs torque. Haven't dynoed it, because I don't care for the expense. But it keeps up to a 2003 Honda Civic Si up to 90mph.

IIRC, that whole 18 psi thing was pertaining to the 1Z, which is a 96-97 Passat/Jetta 3 engine. Some people saw stress risers develop in the pistons. But, that was also a long time ago. There are numerous people running those engines with VNT turbos these days and well in excess of 18 psi.

The general rule I use is that ~30psi or so will kill a stock head gasket without head studs. Be careful of too much timing advance or you'll blow the head gasket or bend the rods due to the cylinder pressure. There are many instances of 200hp or more at the wheels on a stock shortblock.

I don't recall off-hand what the speed limit is of the 11mm pump, but since they came on the automatic cars I wouldn't worry too much about it. A lot of people spin the 12mm pump heads faster than that, but it seems to cause some sort of cavitation. I wouldn't be surprised if it's an issue with the vane pump not delivering enough fuel at that point which would also explain why they sometimes seize and break.

You can swap nozzles without retuning, but as to whether it is safe will depend on your nozzle choice. If your goals involve big power then it might be better to wait and do both at once assuming you don't want to buy more than one set of nozzles.

Thanks for the quick and thorough response.

I do have an open downpipe at the moment and the turbo is definitely audible at idle and up to 2k, then nothing and power falls off with the noise

I have to clean the EGR and intake for sure, and will check the wastegate vanes if I get to pulling the turbo out. Will some egt clean it up?

Undecided on 10mm vs 11pump. Is 350$ a good price for a used 11mm w unknown miles and are there any castings or ways to identify one vs a 10mm?

I went from a superbike to a truck that had damn near the same pull. After timing belt etc and clutch ill probably jump to the race520s right away. Need for speed here. Reliable speed on a reasonable budget

What rpm can the 10mm and 11mm pumps effectively fuel to? In mechanical trucks a few springs almost doubled the effective powerband, though power fell off towards redline it was sometimes worth holding a gear

Well I'm not sure if I worded my phrasing correctly regarding wastegate. The VNT15 turbo has vanes that direct the flow on the exhaust turbine to produce more boost, or less boost. It is a vacuum line leading to an actuator on the turbo from an electric valve (named N75) which is completely controlled by the ECU. It helps the turbo keep to the boost targets, and prevent boost spikes. It is the only way the ECU controls boost.

The vanes themselves in the turbo can get clogged with the soot from the exhaust, making them move much slower, or get stuck.

TheBullRoars said:

Thanks for the quick and thorough response.

I do have an open downpipe at the moment and the turbo is definitely audible at idle and up to 2k, then nothing and power falls off with the noise

I have to clean the EGR and intake for sure, and will check the wastegate vanes if I get to pulling the turbo out. Will some egt clean it up?

Undecided on 10mm vs 11pump. Is 350$ a good price for a used 11mm w unknown miles and are there any castings or ways to identify one vs a 10mm?

I went from a superbike to a truck that had damn near the same pull. After timing belt etc and clutch ill probably jump to the race520s right away. Need for speed here. Reliable speed on a reasonable budget

What rpm can the 10mm and 11mm pumps effectively fuel to? In mechanical trucks a few springs almost doubled the effective powerband, though power fell off towards redline it was sometimes worth holding a gear

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The turbo is a VNT so I wouldn't mess with the actuator unless something is wrong with it. The part numbers on the front of the pump can identify if it's 10 or 11mm. $350 wouldn't be a bad deal for a good used one, but it also isn't the place I'd start with modifications.

The powerband of the engine really has little to do with the pump. The engine just doesn't flow particularly well at high RPM. So, unless you want to get into a cam and porting I wouldn't worry too much there. Usually you won't see a horsepower peak past around 4200 RPM.

Informative.

Are there tuning issues switching to a non VNT turbo?

I have faint ideas of a stock vnt in a compound setup

TheBullRoars said:

Informative.

Are there tuning issues switching to a non VNT turbo?

I have faint ideas of a stock vnt in a compound setup

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It can and has been done. In both cases.

Step 1. Get VCDS and make sure the VNT mechanism is actually working properly. Step 2, you can add injectors, clutch, and a tune, and nearly double wheel horsepower on otherwise stock hardware and also gain fuel economy.

Enabled said:

1... Dirty wastegate vanes...

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not a wastegate

The FAQ on the home page is very out dated, running ~50psi on "stock" compression(stock for a PD130/150). As you get around 26-30psi, you'll have to start upgrading things depending on who's doing the tuning.

Mine is VGT in compounds - save yourself the headache and go wastegate only. 100% mechanical controlled gates.

Pumps and nozzles can be swapped without a tune, but you'll want a tune, it makes it all run so much better together.

JFettig said:

not a wastegate

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Enabled said:

Well I'm not sure if I worded my phrasing correctly regarding wastegate.

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Yes, correction noted. In fact, completely wrong word choice. I had thought VNT was a style of wastegate, but research shows that it's not.

TheBullRoars said:

I learned what i know of diesels on a truck i built from stock, an all mechanical 12v ppump cummins. It was extensively modified but with no electrical worries and a simple design, everything was pretty straightforward.

I realized the money pit it became, and was going to be, and sold it. I picked up a 5speed 00 TDI last week and have started with maintenence.

Click to expand...

I have a 12v cummins toy hauler at probably 250 hp SBC clutch,exhaust brake,etc.My dailly driver Jetta tdi is at 200 hp.You made the right choice going hot rod TDI VS cummins.Seems that there are many diesel truck guys that swap their diesel truck for a TDI.

I run staged VNT's (1749va and 2256v) on my Jetta,I'll soon make a video of both boost gauges in action.

I have 7 Mk4 TDIs. Tune is the best investment and most fun. I have one with 11mm pump, 205 nozzles, VR6 clutch and stage 2 tune. It is quick and can slip clutch whenever I want. Have done tunes on stock engines for friends, right away they think they have a race car. Im building another with 11mm pump,232 nozzles(764) stage 3 tune and hybrid turbo from UK. Should make 175+hp

Hmm what is your hp goal? Might help. I think you can do more to They's injection pumps. Bigger injectors sure more fuel more power, the Hammer mode I don't know what to think of this other then it fools the tps a bit timing is still done mechanical they advance is still spring controlled . I took one apart a day ago to see what's in there for giggles I'm like this pump is gen 1 Cummins pump. Lol so I might see what the difference is in cam face plates for more lift for better injection pressures. But iv killed enough of your thread and I wounder what the are changing with a tune. I don't want to bust any bubbles just trying to learn but being a ag tec some stuff make me go hmmm.

I guess i dont know how much hp i want because of no frame of reference. I guess being FWD and 5spd i wont be winning any drag races but to trap 120-130mph in a hypothetical 1/4 mile would be great. Looks like big nozzles will be the first step, then tune and clutch. Would only like to buy nozzles once. Undecided on size

andy2 said:

I have a 12v cummins toy hauler at probably 250 hp SBC clutch,exhaust brake,etc.My dailly driver Jetta tdi is at 200 hp.You made the right choice going hot rod TDI VS cummins.Seems that there are many diesel truck guys that swap their diesel truck for a TDI.

I run staged VNT's (1749va and 2256v) on my Jetta,I'll soon make a video of both boost gauges in action.

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My choice to.switch from the truck was more for economical and practical purposes. I do a lot of driving, and the traffic is hellish here. All highway, but 50/50 stop n go. Was just too much weight and power to move around all day every day and it was getting up in miles.

Im not convinced a hot rod tdi can even compare to a hot rod monster in any way except mpg and handling.but if i can get close for my daily ride ill be happy

TheBullRoars said:

but to trap 120-130mph in a hypothetical 1/4 mile would be great.

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Indeed. That would be the fastest tdi in history.
Good luck.

From an expectations standpoint, take everything your cummins did and divide by 3. A 230 HP ALH is possible, but takes some $ to do it. If you do it on a stock bottom end, it'll either not last very long (bent rods/cracked pistons/blown head gaskets) or will drive so poorly because the power is at such a high RPM to keep PCPs down that you'll hate the car.

The threshold is ~180 HP/300 ft-lbf in my opinion. If you stay under that, you can have a very reliable daily driver with bolt on parts (Turbo/pump/nozzles/tune/clutch/etc) for under $5k.

From 180-200 HP / 300-350 ft-lbf you're on borrowed time with stock internals, but some have done it

200+/350+ you're into rods/pistons/head work/cam/custom manifolds for turbo(s)/LSD in trans/etc plus all the above items and you're in the $10-15k range pretty quick.

I'd suggest finding a GTG to attend and driving a couple various setups to get a feel for where you want to go. These cars are generally not regarded as fast on a dragstrip, but they're quick and fun as a daily driver.

KERMA said:

Indeed. That would be the fastest tdi in history.
Good luck.

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we did 140+ MPH well over a year ago?

This is a bit more recent

https://www.youtube.com/watch?v=mj0wSE4LHOU&list=UU0094mZa12f2cA3_NPzNwlw

not a daily like this guy is speaking
he wants it in his mk4, not a 1800 lb shoebox
talking about stop and go traffic, etc

This is a daily - http://youtu.be/o7s_9HU0lUU
Drove it to the track and back. 11.08s @ 129mph

Drives it every day

Or this one http://youtu.be/KtN936P8ygY

11.75s @ 123.04mph

It does 120 miles each day

How about a money back guarantee if he doesn't achieve the same thing in his Mk4 daily that he drives for fuel economy, grocery getter? that is the common frame of reference.

Maybe you can get him one of those little spanish shoeboxes for import too?

full interior, 3500 lb, A/c and heat, ALH with rotary injection pump, 8v head, 50 mpg, no slicks, all season tires that last 50k miles, drive in snow and 100+ heat every day to work, radio, open diff, etc

We aren't talking about a race car that you "drive to the track" (just to say "we drove it to the track") but a real car that is in common, within reach with reasonable effort and a budget. Or maybe I am mistaken.

Another potentially good thread ruined

I don't see many seat cupras or skoda fabias on the streets in these parts.

I do hear from a lot of people who get lured in by fantastic claims on the forums, who end up disappointed when their dreams of glory aren't met. After years of back and forth and tinkering and it's never "right".

this is precisely the kind of "money pit" the OP is hoping to avoid. if I read the intent of his first post correctly.

"Can" it be done? of course. But is it what he is asking for?

I'm just saying the 130 mph goal is not doable within the parameters he stated.

We have 100's of tuned cars that once finished we only see for the 8-10K services.

Idiot shops wrecking peoples cars does happen often and more so with crappy tuners but thats not the hardware's fault

Then maybe he should make an appointment at your shop in England.

And does that mean 100's of tuned cars that do 130 mph traps, or 100's of cars in a more reasonable (expectations) and achievable (practically) state of tune? I would guess the latter.

Mid 90's traps and low 15/high 14 sec is reasonable to expect for an ALH that doesn't break every year, on a reasonable budget. That's plenty on fun especially compared to stock 18 sec@72 mph or something. The difference is dramatic and totally transforms the car. (but it doesn't satifsy the epeen crowd I guess)

No problem. Would be nice to make a post without you following and trolling once in a while.

Also, keep editing your posts after I reply

Are you two done?

My point is, and was, 130 mph traps is not a reasonable expectation for a "normal" mk4 ALH that's not a science project. At that point it's purpose is as a "hobby" instead of transportation. (maybe saying it like "fastest tdi in history" was a bit overly simplistic, my bad, consider the context of the thread please)

If I read it correctly, the guy wants a reliable economical car, that's considerably more fun than what he has now, not a money pit. (He had a trick that was a money pit and sold it for the tdi, IOW he has "been there done that")

there's a place for "car as a hobby" but I get the impression that's NOT what this guy wants.