Hi everyone, just thought I would post this since reading Tdiclub.com where people have been saying that they have wasted 1.8Ts and VR6s with their modded tdi's.

My question is: how is a tdi more tunable power wise than an idi engine? I have heard that some guys run their tdi's in excess of 130bhp. Why is a standard tdi 90bhp whereas a standard idi is 74bhp (but a 1.9sdi and 1.9D are same power, in Europe anyway) What makes a tdi more powerfull?? electronics? If so why do they opt to have mechanical pumps to increase performance? Is it direct injection? but then why is an 1.9sdi same power as a 1.9idi?? :roll:

If anyone could clear it up for Ill be very thankfull! :lol:

I would say that a TDI has more potential because of the electronics.

More precision for boost, fuel and timing results in more torque.

Forget about power, all you need is torque. :twisted:

"All you need is love" from the Beetles, remix by DJ Rammstein:

[All you need is torque, ta da la la la
All you need is torque, ta da la la la
All you need is torque, torque.....torque....torque is all you need.... :wink: ]

Sorry, had that song in my head for a long time... :lol:

Yes, (back on topic), electronics makes you the master of your engine performance.

You can increase these parameter until the engine can take no more.

300 lb-ft of torque is easily attainable with a rotary pump TDI, even more with a PD.

Lets see.

Your goal is 300 lb-ft for a start with a rotary pump TDI:
You will need:

Bosch 216 (203) with the biggest damn nozzles you can find (>.230mm)

Rocketchip 3.1.

There you go.

Total cost, less than 1G CAD.

Now try to do that with an IDI.

The cost vs benefit vs torque isn't the same.

PD's are supposedly even easier to tune...

We aren't talking yet about big pumps, big intercoolers, bigger turbo or dual turbo....

I don't mean to offence anybody by my statements, they are facts of things I've seen done.

Never said IDI tuning was cheap and easy, only that it was possible. TDI's have excellent aftermarket support compared to the IDI, that helps. We're kind of on our own...

On another note, after running the numbers, our swedish friend either put his golf on a serious diet or it is making nearly 200hp. Thats what it takes to get a ~2800pound golf TD down the track in 15.07 seconds... Anybody heard of another VW diesel, other than TDIRS, that's faster?

Juicy stuff.

Isn't the stock boost on TDI's at 12 and spikes at 14. :idea:

From the '99-'03 Golf bentley manual, section "Turbocharger and Intercooler" page 21-3, under heading "Turbo boost pressure, checking", for the A4 platform 90-hp TDI, it gives 10.15 - 17.4 psi gauge boost pressure as the specification for the engine.  I think that the ECU reduces the boost pressure at high altitudes below 16 psi, to prevent turbocharger overspeeding (at least the A3/B4 TDI's setup without the variable vanes does that.)

I have an SAE paper describing the boost pressure characteristics of the A3/B4 TDI engine; I will see if I can dig it up, but from memory I remember boost pressure at reasonable altitudes was 16 psi or maybe even more than that.

BTW European cars are not measured at the crank but at the wheel. :roll:

Actually I think all car manufacturs quote crank hp (I could be wrong, but I would be surprised if they didn't.)  Now that's not saying that sometimes their quotations are more conservative than others, and might end up being close to the actual measured wheel horpower.

My point was that with less money you can get more torque (who cares about hp).

Actually for performance-tuning purposes, I care mostly about how tall (peak hp) and how wide the hp plot vs RPMs looks like.  My objective for performance tuning a race motor is not really focused on peak torque, unless my focus is on increasing the beefiness of the powerband into the lower rpms.  Case in point: if you have lots of peak torque but not a lot of peak hp, the engine isn't going to perform very well at any RPM, although it will be turning at a low rpm when it is performing as well as it can.  To me a motor developing 100hp from 2000-4000 rpm is equivalent performance-wise to a motor developing 100hp from 4000-8000rpm.  Even though the lower-revving motor would have a much higher peak torque rating, they both put out 100hp through a 200% change in engine RPM.  What's important is to have a meaty (high and wide) usable powerband, not so much exactly where it is placed.  For a street driver, particularly automatic transmission, arguably having the powerband be really meaty right off of idle might improve driveability.

If you were to slap on a TDI variable-vane turbo giving peak boost pressure of 16'ish psi at 1900 engine rpm onto an IDI motor, that would give an IDI combustion chamber TD a HUGE boost in peak torque, and would make it very close to the TDI (probably a bit less due to the reduced efficiency of the IDI), although the IDI would have capability of developing a beefy powerband much higher into the RPM range than a DI motor would.

Also you cannot make the timing vary on IDI's like TDI's do with a chip.

Yes you can, although granted not just by changing the software, or chip.  Like other alterations of the mechanical governor mechanism, the timing control can be altering by changing spring rate and preload and hydraulic pressure.  Some might actually prefer this "hand-on" approach to tuning due to the reliability and simplicity of the system.  Personally, I would love to adapt a TDI electronic control mechanism onto an IDI motor and optimize all parameters... I think it could be optimized easier than with the mechanical controls.  But given enough time... you could optimize the parameters mechanically (like many people do with carburators).  I do think that they might never be quite as sophisticated as the electronic controls though.

In summary, TDI's are sort of extreme in that for a given displacement and boost pressure (say, atmospheric pressure: SDI), they maximize fuel consumption, but develop the least max power.  Gas motors are on the other hand extreme in that they develop the most power (assuming they aren't detonating from too much boost pressure, which makes them poor candidates for turbocharging) but the worst fuel consumption.  And IDIs fall somewhere in between - better peak power (and broader powerband) than the TDI for a given displacement and boost pressure, but less than the gas motor; also better fuel consumption than the gas motor, but worse than the TDI.

i would definately say that teh tdi has more potential..first its direct injection no prechamber to mess up..i've had them lossen up in the head and either allout or crack...much much better multiple layer metal head gasket on the tdi ..much tuffer headgasket i've blown tons of 1.6l TD idi head gaskets i even blew one out the side of the head from pressure... and teh TDI has MANY AFTERMARKET FUEL INJECTOR NOZZLES AVAILABLE!!!!! what injectors are avail for the idi? i know only of the stock GTD 1.6L replacements, or the 1.9L idi stock replacements..so not much to pick from in fueling on the idi....and the bigger stroke o the 1.9L crank with the nice pistons later tdis have larger brass trunion inserts and metal support rings for the top ring land etc.. the td idi has nothing besides graphol coating etc..... guys swap the mechanical pump on tdi for swaps into older cars for simplicity.. it would be nice to tune the electronic your self but not possible chip or custom chip tuning is only outlet for tdi electronics... alos the tdi starts much better in the cold...this winteri had 10-20 below far. and the tdi started  un plugged left out side for 5 days all winter...in oswego ny....no idi vw i've ever seen would start like that unaided....oh well tdi or me unless for goofy projetcs ..i've got tons of them..
later
Deo
\x/ hillfolk

Hey Deo - a MLS 1.9lTD head gasket works great on a 1.6lTD.  I ran one for my last headgasket and it worked great... just had to plug the hole for the extra oil return that was not there on the solid lifter 1.6lTD.  It would be a direct bolt-in type swap on a hydraulic head 1.6l or 1.9lTD.  But then again, I've never had a problem with the stock head gasket that wasn't overheating related (not counting propane detonation  :? ), but I've not run more than 14 psi boost pressure either so I'm not exactly pushing the cylinder pressure envelope.

I agree with you that the combustion chamber design of the TDI allows better cold starting than an IDI.

As for high flow injectors, it's sort of a chicken and egg problem.  No one's built a monster IDI TD yet that requires large injectors, so we aren't aware of them besides those options you listed and Gile's increased pintle travel modification.  If none of those worked, I'd think it would just be an interesting, but solvable problem to find a larger injector.  I'd bet even a stock injector would pass plenty of fuel if coupled to a high-lift 12mm pump plunger!  Or, there is the whole CAV pump thing (sold on some VW diesels in the UK) to explore... IMO fuel injection is the area that we seem to be innovating the quickest in the aftermarket performance modification world of VW IDI Diesels, I wouldn't rule out the IDI motor because we haven't fully pushed the fuel injection boundaries!

A very high boost IDI might hold up better and put lesses stresses on the bottom end of a TDI due to the combustion pressure rise being controlled better by the swirl chamber port.  The piston with more of a flat top may also be more structurally sound than the TDI piston with the deep swirl pockets.  Anyway, that's my 2c at least...

i have no clue how i posted 2 times but sorry :?:  

today has been a weird day, time to go relax.