my aim is to bend rods

[SteveH]

Especially relevant with the dizzy models, as spark hop won't help at all.

[RichLV]

Or X...

[Thuppu]

Still relevant today,

This is why most of us put in H-beam rods.

[Rikki Kitto]

[macspring]

Bump for a good thread.

Still relevant today,

[prj]

It might help if you filled out the country of origin in your profile.

[jay7vee]

ok then with all these. Lets go with facts. I have a stock audi rs2 and want to get as much as i can without changing much. Who you promt me for the program tuning and not getting knock!!

[EspenW]

I had a rod bend a few years back in my UR RR, got a mate to put a bigger turbo on and he decided to road test it... handn't been set up at all, he got about half a mile up the road then it all went pear shapped!!! made right mess of the engine as the bent rod put a big gouge in the cylinder wall... If i knew what i knew now i would have kept the head and crank but instead i binned the lot and put a whole new lump in!!!

Spark hop and the resulting bent rods is a well described phenomenon in the distributor engines. There is a current thread on it.

[EspenW]

From my experience of mapping and tuning various cars, rods don't bend that easily.
The reason why rods bend is not because of a bigger turbo or a lot of torque.
No, the reason is knock.

The rods can take crazy amounts of knock on the stock turbo, but if you install a more powerful unit, that produces more torque, and then have it knock hard, you will instantly make bananas.
When there is preignition in a cylinder, the cylinder pressure spikes insanely. You will never have that much pressure in normal operation.

The reason there is so much talk about bent rods is because people install random chips into their cars, that some random guy says "run great".
As long as you don't do that, there is no reason to change rods up to 400hp.
Your rods will be fine with the K24/7000, the K24/7200, the 2871/K26 and even the 3071/K26.
Only if you go bigger will you need to upgrade your rods.

But this all only holds true, if you get your car mapped properly, so that it does not exhibit constant knock.
For some reason people are okay with paying massive amounts of money for turbos, manifolds etc... but when it comes to mapping their car, they get greedy and later cry over their new made bananas.

Indeed. Very true.
Doubling the boost level will increase the peak cylinder pressure by only approx. 20%.
However, knock can increase cylinder pressure by 1000% in addition to being a shock load.
Run a sensible map/high enough octane and stay completely out of knock, and you can run pretty much any torque level through stock rods, since the peak cylinder pressure (the max compressive gas load the rod sees) is only moderately (20%) affected by boost level. The power and torque gains from increasing boost/flow is that the average cylinder pressure increases greatly. Gains from running alcohol fuel comes from the same phenomenon. Double the boost and you might see 150% more cylinder pressure at 80 degs ATDC, but at peak pressure around 15 degs ATDC, the load is only up by around 20%.
However, raising the boost level without taking proper measures greatly increases the chance of knock, and that is the killer with cylinder pressure spiking to many times the normal peak value in a matter of milliseconds.
Stronger rods is a great insurance against this, but as we see, the problem is the bad, knocking side effect of running high boost/torque at improper octane/setup, and not the boost/torque itself.

[EspenW]

You don't have to upgrade an RS2 to a bigger turbo to bend the rods, just dial in 2.2Bar+ at sub 3500rpm and you'll be well over 600Nm and close to remodelling your internals.

Hmm, I've got 2.2bar at around 3600rpm and around 600nm at the wheels, so 700nm+ at the crank at 3800rpm in 4th and at even lower rpm in 5th and 6th. Everything is straight. The reason can be read in PRJ's excellent comment above.

[prj]

Well, duh...

[m11kyg]

I had a rod bend a few years back in my UR RR, got a mate to put a bigger turbo on and he decided to road test it... handn't been set up at all, he got about half a mile up the road then it all went pear shapped!!! made right mess of the engine as the bent rod put a big gouge in the cylinder wall... If i knew what i knew now i would have kept the head and crank but instead i binned the lot and put a whole new lump in!!!

[david]

From my experience of mapping and tuning various cars, rods don't bend that easily.
The reason why rods bend is not because of a bigger turbo or a lot of torque.
No, the reason is knock.

The rods can take crazy amounts of knock on the stock turbo, but if you install a more powerful unit, that produces more torque, and then have it knock hard, you will instantly make bananas.
When there is preignition in a cylinder, the cylinder pressure spikes insanely. You will never have that much pressure in normal operation.

The reason there is so much talk about bent rods is because people install random chips into their cars, that some random guy says "run great".
As long as you don't do that, there is no reason to change rods up to 400hp.
Your rods will be fine with the K24/7000, the K24/7200, the 2871/K26 and even the 3071/K26.
Only if you go bigger will you need to upgrade your rods.

But this all only holds true, if you get your car mapped properly, so that it does not exhibit constant knock.
For some reason people are okay with paying massive amounts of money for turbos, manifolds etc... but when it comes to mapping their car, they get greedy and later cry over their new made bananas.

Don't put some random generic "RS2 software" into your car. Get your engine mapped by someone who understands motronic and has all the necessary equipment to map it properly.
Or - go standalone and go to a reputable tuner, who will set your car up correctly.

[prj]

From my experience of mapping and tuning various cars, rods don't bend that easily.
The reason why rods bend is not because of a bigger turbo or a lot of torque.
No, the reason is knock.

The rods can take crazy amounts of knock on the stock turbo, but if you install a more powerful unit, that produces more torque, and then have it knock hard, you will instantly make bananas.
When there is preignition in a cylinder, the cylinder pressure spikes insanely. You will never have that much pressure in normal operation.

The reason there is so much talk about bent rods is because people install random chips into their cars, that some random guy says "run great".
As long as you don't do that, there is no reason to change rods up to 400hp.
Your rods will be fine with the K24/7000, the K24/7200, the 2871/K26 and even the 3071/K26.
Only if you go bigger will you need to upgrade your rods.

But this all only holds true, if you get your car mapped properly, so that it does not exhibit constant knock.
For some reason people are okay with paying massive amounts of money for turbos, manifolds etc... but when it comes to mapping their car, they get greedy and later cry over their new made bananas.

Don't put some random generic "RS2 software" into your car. Get your engine mapped by someone who understands motronic and has all the necessary equipment to map it properly.
Or - go standalone and go to a reputable tuner, who will set your car up correctly.

[david]

2.2bar boost is just plane silly,will never map my car past the 2bar mark