What is the upper hp limit on stock rods?

[EspenW]

Another thing:
Take a look at a typical bent rod. Most of the time it will be seriously bent out of shape. Now, the force required to deform a rod from perfectly straight (as it should be in normal operation) to being bent 20-30 degrees is massive. Much more than the difference from, say, 420nm to 550nm. The look of a rod bent from too much engine torque would be slightly bent out of shape, by a few degrees, barely pushing the material into plastic state. Banana shape from engine torque alone would mean an engine that would have constantly flexed the rods by a large amount, with engine lifespan measured in seconds.

[maRS2]

My RS2 with Map from Mihnea and with turbo boost increased to 2,2bar peak at 3300 rpm by me is pushing 620nm on Maha.
It's like that since 60000km and I'm doing lot of mountain road to go ski using this torque all the time to pass uphill.

some time it's about -10 to 15°C when doing those rallystyle ski trip so I think the limit of RS2 rod are way higher than 500nm.

[S2central.net]

Guess those cold air temps keep you well away from the knock issues which can lead to the stresses of bendy rods.

PAul

[maRS2]

Yes but also drive it hard in our hot summer in south of France.
May be the short intake is helping then to keep intake air temp colder and the good map from Mihnea is doing the other part avoiding knock in summer.

[EspenW]

Very interesting maRS2. 2.2 bar is a lot, what kind of turbo are you running?
Have you logged IAT's (with VagCom or similar).
(I've seen Mihnea mention your car in earlier posts).
This is further indication that our rods can indeed withstand high torque outputs, what kills them are detonation and pre-ignition. Detonation is bad enough, as it dramatically increases pressure in the combustion chamber, but even worse, it can lead to pre-ignition which spells instantly bent rods (and a host of other unpleasant things)
Thus, bending rods at 1.8bar is not a result of the torque developed at 1.8bar, but rather boost induced detonation (and in case of 3B failures, often spark hop induced pre-igntion).
Run good fuel (98 octane or better), keep an eye on boost level (N75 is unstable at anything over 1.7 bar), keep an eye on AFR (wideband sensor should be mandatory at anything over 1.4 bar), and last but not least, run a knock indicator like KnockSense, KnockLite or KnockLink).

[Pirvu Eugen]

Very interesting maRS2. 2.2 bar is a lot, what kind of turbo are you running?
Have you logged IAT's (with VagCom or similar).
(I've seen Mihnea mention your car in earlier posts).
This is further indication that our rods can indeed withstand high torque outputs, what kills them are detonation and pre-ignition. Detonation is bad enough, as it dramatically increases pressure in the combustion chamber, but even worse, it can lead to pre-ignition which spells instantly bent rods (and a host of other unpleasant things)
Thus, bending rods at 1.8bar is not a result of the torque developed at 1.8bar, but rather boost induced detonation (and in case of 3B failures, often spark hop induced pre-igntion).
Run good fuel (98 octane or better), keep an eye on boost level (N75 is unstable at anything over 1.7 bar), keep an eye on AFR (wideband sensor should be mandatory at anything over 1.4 bar), and last but not least, run a knock indicator like KnockSense, KnockLite or KnockLink).

About N75....there is another upgraded option to this?
Thanks!
Eugen

[EspenW]

About N75....there is another upgraded option to this?
Thanks!
Eugen

Rumour has it that there is something new in the works...
In the meantime, there are always electronic boost controllers or mechanical boost controllers. Though MBC's are not popular in this forum, I've found that it works much better than N75 on my car. The N75 would routinely overboost to 2 Bar +, while the Turbotech MBC is steady at 1.8 Bar. I have upgraded it with a ceramic ball, since the steel ball that it is delivered with rusts, sending boost skywards..

[Pirvu Eugen]

And this is direct swap for Motronic?

[EspenW]

And this is direct swap for Motronic?

Yep, just leave the N75 plugged to the harness, so that it won't trip a fault code.
But, if your N75 works fine, without boost spikes, I would use it.

The ECU uses the N75 to reduce boost in case of too high temps, etc.
It is the third safety measure applied by the ECU in case it detects knock:

If knock is detected, first step is to pull timing, if it still knocks, the ECU dumps more fuel. If it still knocks, it uses the N75 to reduce boost .

In other words, you lose the third line of defense if you delete the N75.

[Pirvu Eugen]

Thank You!
Now is clear!
All the best!
Eugen

[S2central.net]

Nice explanation there Espen. Good one...

[maRS2]

Espen: I 'm running Original RS2 turbo with 180000 km on it.
I only run on 98 octane.

If afraid of N75 boost spike you could put a MBC after the N75 to avoid any boost over the desire amount. That way it will let the N75 control anything under boost spike

example: if your max desire boost is 1,8 bar you will set the MBC at 1,85 that way it will only start bleeding if overboost.

[maRS2]

same way you could also increase spool up by puting a Mbc upstream the N75 set at 0,8bar.
because the N75 is never fully close even on the lowest dutycycle and a MBC is.
then every thing over that the N75 will control.

[Pirvu Eugen]

Sorry! But what is an MBC?

[maRS2]

Mechanical boost controler: something like Dawes