AFN Tuning: Limit High RPM?

Hi there,

Is it practically feasible to modify the AFN engine in such a way that the power increase only occurs above 3000 rpm? I'm aiming for roughly 92 kW as a target. However, the torque should not increase significantly within the range up to 3000 rpm. Additionally, I would like to extend the usable RPM range to 4500 rpm, meaning that the torque curve should not decrease after 4500 rpm.
I know that the efficiency of a TDI engine tends to drop at higher RPMs, but my request is based on real-world considerations.
What needs to be done to teach a TDI engine to run smoothly at higher RPMs? Or is that simply not possible?

Regards,
Jens.

Counter-question: Why would you want to do that?

For more top speed, I would recommend either a longer gear ratio for the rear axle or higher gears.

Quote:

Counter question: Why would you want to do this? For more top speed, I would rather recommend a longer gear ratio for the rear axle or higher gears.

Okay, so I guess I have to tell more about the background...
Okay, so the AFN engine is pushing a 2400 kg T3 Syncro, and those standard 235 Nm of torque are really working hard to do it. The vehicle's gearing is set up such that at the AFN's rated RPM (4150 rpm), you can reach approximately 135 km/h. Those 81 kW might potentially allow for a slightly higher top speed (meaning the overall gear ratio would be a bit too short), but I don't really want that.
Unfortunately, the T3 Syncro only has 4 road-legal gears in the transmission, and there's no way to change that . In my opinion, the gear ratios are currently pretty optimal, and I can't do anything more about it. I definitely don't want to increase the overall gearing (which would require a different axle ratio or larger tires), because the vehicle needs to remain off-road capable. The current gearing is already borderline. I simply want more power in extreme situations (overtaking maneuvers, or sand or mountain passes off-road). At the same time, the transmission is actually undersized. Based on experiences with various transmission failures after TDI conversions, it's precisely the high torques at low RPMs that are deadly. Therefore, I don't need an increase in torque in the lower RPM range. At the same time, shifting the rated speed upwards would compensate for a wider gear spread in the transmission (which, of course, cannot be changed).
That's all I have to say on this matter.

Regards,
Jens.

Regarding your original question: it should be feasible.

Best regards, Rudi.

Hi, is it practically possible to modify the AFN engine in such a way that the power increase only occurs above 3000 rpm?

Yes, of course, that is possible.

It all depends on what kind of modifications you were thinking about.

In a modified chip, it would definitely be possible to achieve such a performance curve, and the desired 14% power increase should also be achievable. However, you'll need to find someone who can create a chip specifically tailored to your requirements, rather than just using copy-and-paste methods. This shouldn't be too difficult with AFN and other large online platforms.

Another option would be larger nozzles, which, according to Ulf, primarily affect the higher RPM range, but are likely to only provide an 11% increase in power (e.g., a .216 size instead of a .205 size).

A speed-dependent controlled 10-cent tuning might also meet your requirements (although it would likely require a Russ setting with P=4%).

What kind of modification (or what level of cost) were you thinking of? (Of course, it's clear that it should always be as inexpensive as possible ).

Regards,
Private.

EDIT: It seems Rudi was about a minute faster...

Hello,

Based on your description, the original AFN engine in your case should theoretically be able to rev up to 4500 RPM without any issues. Mine does too (with a 5-speed manual transmission). The fuel injection amount isn't significantly reduced at those higher RPMs. With that rear panel you installed, the 81 kW should also allow for speeds of around 160 km/h. Did you install the original dual-mass flywheel?

Best regards,
Christian.

@Private
The nozzles are likely to provide a yield of slightly more than 5%. The diameter is either .205 or .216.
and the amount should be proportional to the area.

@Jens
I consider everything except for tuning the fuel and ignition maps to be amateurish or makeshift work.

Best regards, Rudi.

216-size [items] provide 11% more surface area.

216 squared divided by 205 squared equals 1.11.

Okay, please provide the German text you would like me to translate into English. I will only provide the translation.

@Rudi:
, I have corrected it above as requested...

I also believe that adjusting the engine mapping is the most elegant method. On the other hand, some people strongly resist using a chip tuning device, which is why I listed all the possible options.

Regards,
Private.

Quote:

In a modified chip, it would definitely be possible to achieve such a performance curve, and the desired 14% power increase should also be achievable. However, you'll need to find someone who can create a chip specifically tailored to your requirements, rather than just using copy-and-paste methods. This shouldn't be too difficult with AFN and other large online platforms.

Hi there.
I once called several well-known tuning companies and asked them this question. The answers I received were either completely irrelevant, ranging from "yes, we have a test bench" to "just buy our chip." In any case, I didn't get the impression that any of them were even remotely interested in seriously addressing the issue. And to be honest, I'm not willing to pay for 10 hours of engineering time just to figure out the program.

Quote:

Another option would be to use larger nozzles (e.g., .216 instead of .205).

I had also considered that option, but the costs are incredibly high. The TDI engine currently has about 140,000 km (of which 100,000 km were in a T3), so new injectors aren't necessarily needed yet.

Quote:

A speed-dependent controlled 10-cent tuning might also meet your requirements (although it would likely result in a pitch of 4 cents).

The principle is clear to me, but how do you make it speed-dependent?

I understand that things cost money, but I don't want to spend more than 300 euros on it.

Thank you and best regards.
Jens.

Hi Christian,

Quote:

Based on your description, the original engine's RPM should theoretically be able to reach up to 4500 without any issues in your case.

Yes, it revs up to 4500 rpm. However, the power output noticeably decreases after that.

Quote:

With your wardrobe system, the 81 kW should be sufficient for approximately 160 amps.

Don't be fooled, those 81 kW engines definitely can't achieve more than 140 to 145 km/h. The aerodynamic drag from the four driven wheels, large tires (225/75R16), and a height of 2.85 meters simply won't allow it.

Quote:

Did you install the original dual-mass flywheel?

Yes, but after 20,000 km it was completely worn out. The clutch doesn't work well with the T3 gearbox, and it really doesn't like off-road driving! Many clutches have been ruined in T3 Syncros due to off-roading, and even those who modify vehicles for profit no longer install them.
"I'm currently using a heavy, conventional flywheel from the AAZ engine. It also feels very pleasant to drive because the long transmission input shaft from the T3 gearbox (designed for inline engine mounting) provides good damping. The strong torsion springs in the clutch disc also seem to work well. I would definitely say that the dual-mass flywheel didn't run much smoother."

Regards,
Jens.

Quote:

I also believe that adjusting the engine mapping is the most elegant method. On the other hand, some people strongly resist using a chip tuning device, which is why I have listed all possible options.

Hi there.
Who performs such a specific engine mapping adjustment? Do you happen to have any contacts who do that?
"I don't mind changing the chip. I wouldn't care about the TÜV (German technical inspection) either. The engine in the T3 is a non-original engine, so neither a regular inspector nor a steam boiler inspector would be familiar with it. You can never tell from the outside whether it has 81 or 90 kW of power. And anyway, the top speed is limited to about 145 km/h due to the gearbox, regardless of how powerful the engine might be."

Regards,
Jens.

Who does such a specific engine mapping adjustment? Do you happen to have a contact for that?
I'll send you more details tomorrow via private message. I don't want to publicly promote specific individuals here.

I understand the principle (of the 10-cent method), but how do you make it speed-dependent?
My initial thought is to use a frequency-to-voltage converter that transforms the speed signal into a voltage proportional to the speed. This voltage could then be used to control a 10-cent relay, so that it only activates at higher voltages (i.e., higher speeds).

But I believe that the solution using chip tuning is the most sensible one.

Regards,
Private.

Jens 16syncro wrote:

Quote: A speed-dependent controlled 10-cent tuning might also meet your requirements (although it would likely result in a pitch of 4 cents). The principle is clear to me, but how do you make it speed-dependent?

With the diode trick... the plus nozzle for the 111 kW 5-cylinder engine should provide good extra power, especially in the higher RPM range, even without chip tuning - and with a potentiometer in the 10c, it could even be adjustable, instead of always having to re-chip until you find the optimal solution.

Yes, using diodes.
Take a look at 10 cent tuning.
Then you simply connect two of them in series to create a resistor that works in either direction, as you can see.

-> ->
<--<<
and then apply the 10-cent tuning later.


or in two stages.

Okay, so we have a 10-cent tuning using one diode to increase the resistance in series, but in parallel with a 10-cent tuning using two diodes to decrease the resistance in series.

In every direction!!!

++++ Better fuel injectors and then it'll really take off.

good luck

Contact me; I know someone who had the same thing happen to them.

Greetings.
Daniel.