That's why to increase the HP on the TDI engine is not newsworthy. To increase the HP on a 52 HP engine is big news
Exactly 
Actually, I don't think that is a true nor a fair statement in many ways and it comes down to efficiency factors...
This is probably true...you have to work harder on an IDI motor to get the fueling "tune" quite right to start giving you usable power. Your right in saying in some ways that comparing a TDI to an IDI motor is apples and oranges because there are several variables and design differences between the two that would allow you to have an accurate comparison.
i.e.
-One is direct injection....one is not
This will play a huge role in the power output just from a shear design factor. With the indirect injected engine think about how much potential energy is lost through the injection/combustion method alone. Many TDI guys that have switched from IDI to TDI remark about engine temperatures, etc. and how they seem to be "cooler" on the TDI. That is because on the DI motors everything is happening right in the combustion chamber. There is less heat transfer through the head and since the power stroke of the motor is applied directly through the combustion chamber itself....all contained in one area....there is less chance of a loss for power vs. the indirect means (fuel combusts in prechamber, power flows down the blast ramp, then create the power stroke, etc. to push the pistons, yada yada yada
)
The DI engine simply make more use of the energy that they have with less ending up with less waste through the head through simple efficiency means. For one...
Two...
If I were to take a 9mm pump head, use the TDI camplate, etc. and put it on the TDI engine. I'm going to be getting fairly close back to an IDI motors output. Especially if we are talking about a TD or even...and SDI motor. They exist...look at the numbers out there for them in stock form. Efficiency differences between the two motors will always probably allow the DI motor to have a bit of an edge since it makes use of its energy more efficiently with less waste and power is applied more directly. But then you have to figure in that TDI's do come with a differently designed camplate (profiles between DI and IDI are different) and a larger pump head/rotor assembly as well. Even the european SDI motors I believe ran 10mm pump heads.
I'd be interested to see what the dyno plots of a TDI motor with a 9mm pump head and a stock TDI camplate correctly matched to the motor would provide. I'm going to bet...you'd see close to stock IDI TD numbers and the same if you were using the DI motor without the turbo, etc. making it essentially....an NA motor.
So then you move into fueling considerations and the fatal flaw in a few of the above comments. A TDI motor can be just as easily "overfueled" as a IDI motor can and not have the power output to show for that. However, do to design you won't see the "brick wall" in very little power gain in the TDI as much as you would see it in the IDI motor. You can subtly add power to the 52hp motor and gain hp without increasing smoke too much...you can do that a bit more on the TDI motor comparatively. One is going to always be "better" at handling that increase in fueling because of shear design (as mentioned above) which lends to using the fuel more efficiently, creating the power more efficiently and wasting less energy through heat loss because of these efficiency (and other) factors. Eventually there is a trade off and design will harm you and just create "more smoke".
You can be careless though in overfueling and lose the efficiency and potential power of the TDI motor quite easily as well. This is more visible with some of the mTDI builds that are occuring these days just based on how some pumps are being built/designed without taking in some key differences (especially when many are used IDI pumps as a base). Camplates alone (sounding like broken record) aren't the answer. The eTDI versions ECM will correct many of these flaws to the best of its ability...so its harder to see on electronic cars. I could go into more of the DI loosing efficiency through improper pump design, crappy nozzles with nasty spray patterns, etc. but thats for the TDI forum sometime down the road.
Prothe...yes, that is of course correct (re: the bosch manual)...as a matter of fact, its almost a direct quote I think .
I think you need to look at the IDI vs. DI camplates again as there are other factors beyond just the slope of the curve that are different between the two different profiles of camplates. Not sure where/what this comment means or is going with anything "Yes, I have installed a AAZ camplate on a 9mm pump" The point being....? There is a direct correlation between the "slope of the curve" as you call it, injection duration and injection pressures to begin with. Though different between IDI and TDI (DI motors needing more of course...as their camplates show) you make it sound as if on the DI motors that this is mystical and its something that only happens on the DI motors...with this comment...
"As far as AAZ camplates are concerned, it's the slope of the curve will affect injection duration. But with the TDI, the steeper slope of the camplate also helps generate higher pressures needed"Camplate design between IDI and DI motors share this function and are directly correlated between both motors. 'slope height' and the 'length of slope' play the same part in both motors injection duration/creating injection pressures, etc. but are respectively different between the two different motor designs. In other words, the slope on the IDI camplate as well helps "generate" the pressures needed for the IDI motor too. Its not a function of the DI motor alone (to keep info clear...because thats not the way your comment reads).
Making "lots o' hp" on a 52hp motor would be great and is newsworthy. I have to wonder if your comparing to lumps though such as the TDI vs. an IDI motor....at what cost does the power increase come at? The effiency of these motors is going to differ no matter what the power level or how much fuel you throw at them based on the design alone in many ways. It simply will take "that much more" to get the IDI there vs. the DI for that reason. There has to be a trade off somewhere. Almost makes me wish I had an IDI motor to still mess around with.
Joe
Topic: Dynoed my NA Golf with a Giles pump!! Dyno POSTED (Read 36943 times)
