400 Hp

[A80Avant]

i will agree to that but not entirely. Having constantly boost pressures of 1.9 or above for overboosting, etc, is a significant stress to the engine, combustion chamber, gaskets piston rings, drivetrain, etc no matter how well built it is. So yes, if boost is lower and mapped properly, it should last longer than the same engine with higher boost and again mapped properly.

[prj]

i will agree to that but not entirely. Having constantly boost pressures of 1.9 or above for overboosting, etc, is a significant stress to the engine, combustion chamber, gaskets piston rings, drivetrain, etc no matter how well built it is. So yes, if boost is lower and mapped properly, it should last longer than the same engine with higher boost and again mapped properly.

Disagree completely:

1. Having a single event of knock in any cylinder is ten times as stressful. Have a look at difference in PCP between normal operation and knock. Boost does not wear piston rings nor the combustion chamber. Detonation and mileage does.
2. Over a long period of time there will be no really noticeable difference between running 1.9 or 1.3 peak, because 99% of the time the engine is operating you are nowhere near that.

[GazzaG60]

I like the safeguard of rods and new shells but as many say its not essential. a good set of head bolts should suffice. this is mainly due to the fact that 400 may easily turn into 500.

its in the mapping as prj stated and others as to whether it will be good or not.

[A80Avant]

Disagree completely:

1. Having a single event of knock in any cylinder is ten times as stressful. Have a look at difference in PCP between normal operation and knock. Boost does not wear piston rings nor the combustion chamber. Detonation and mileage does.
2. Over a long period of time there will be no really noticeable difference between running 1.9 or 1.3 peak, because 99% of the time the engine is operating you are nowhere near that.

That's ok. We know that almost half the things you post you come back on a later date and take back anyway so believe what you must. My post we clear. I said same proper map which means knock free. (which even yourself cannot guarentee but that's a completely different story.)

[Rusty]

Play nicely kids.

[|CL|NIKI]

Custom head bolts are advice - my opinion. I've never got curve cylinder head or burned/broken head gasket using oem bolts.

[prj]

That's ok. We know that almost half the things you post you come back on a later date and take back anyway so believe what you must. My post we clear. I said same proper map which means knock free.

Makes absolutely no practical difference. Again. Boost does not wear rings, bores or cause wear on the engine...
It's a common myth. Just like the myth that torque bends rods.

Or maybe you would like to describe exactly how a higher cylinder filling in 1% of cases (if not less) is going to cause more engine wear?
You are trying to split hairs over something like 0.1% if even that, when 99% is how much mileage you do, and how hard you drive the car, meaning how many revs the engine makes during said mileage.

Example - camshaft tensioners and chains completely shot on my RS4 after 190 000km.
On a V8 Audi A8 they easily last 400 000km. Why? Because my RS4's engine has done double the revolutions going through that 190 000km.
Same thing with piston ring wear. What predominantly kills rings and bores is cold start where fuel flushes the oil out of the bores as well as high revs and lots of mileage.

In fact, I would dare to say that a car at higher boost could wear the engine less, if the user can use a lower gear instead of having to rev the engine unnecessarily.

(which even yourself cannot guarentee but that's a completely different story.)

No one can if the customer puts **** fuel in, that's why the car has an octane it's rated for.

[A80Avant]

Or your precious knock sensors fail or are torqued wrong or ... or...

A lot of parameters. I had no pitting or knock signs and my rings we worn after 100k kms so not because of mapping. Is that considered normal wear? If so then why do race engines require frequent rebuilds and report suggests so as well as other respected engine builders? Is it because of knock? Or maybe extreme tuning which also includes high boost?

Anyway, big chapter. But I always take what you say with a big pintch of salt. I'm bordering to hypertension!

[prj]

Or your precious knock sensors fail or are torqued wrong or ... or...

Happens extremely rarely. You might as well say if the fuel pump fails and tapers pressure and so on.

A lot of parameters. I had no pitting or knock signs and my rings we worn after 100k kms so not because of mapping.

Pitting means really heavy knock. If there is light knock you predominantly see accelerated ring wear.

Is that considered normal wear?

Depends on how the car is driven. Can be considered normal for ones, not normal for others.
It also depends on the quality of the rebuild, how often the car is cold started, how much ring gap you run, how you drive the car, how the rings bedded in and so on. Not to mention mechanical lifters, which will need adjustment etc...

If so then why do race engines require frequent rebuilds and report suggests so as well as other respected engine builders? Is it because of knock? Or maybe extreme tuning which also includes high boost?

Neither. Race engines require frequent rebuilds because they run more gap on everything - rings, shells and so on.
Plus, the race engine is just that - a race engine. It has a very hard life. The race engine can easily make more revolutions to run 20 000km than a normal car will make in 100 000km. Also, at higher revs the engine wears more.
Boost has nothing to do with it here at all, as a naturally aspirated race engine also is frequently rebuilt.

I don't know why you are so obsessed with boost - it's just cylinder filling, really does not do as much as you'd like to think for engine life compared to the other factors that are much more important. You really think running 20% more cylinder filling at 4000 rpm is worse for wear than revving the nuts off the engine at 7000 rpm?

[Rocco]

Peter K told me that i will need open my race engine every 10K kms.....

that´s all he said.

[quattrostyle]

Not going to argue with any of the above. But why were my NA 10V engines in perfect order after 300.000+ kms and why were the 3 S2 engines I opened up at about 200.000 kms worn and in need of a rebore?
The 10V engines I took the head of were 2 KV (2.2) and 1 JS (2.0) engine.

Sure a 20VT revs higher than a 10V but as mentioned above not constantly and the gearboxes on the 10V engine rev about 4.000 rpm on the highway at 120 km/h. A S2 will rev lower than that.

[prj]

Not going to argue with any of the above. But why were my NA 10V engines in perfect order after 300.000+ kms and why were the 3 S2 engines I opened up at about 200.000 kms worn and in need of a rebore?
The 10V engines I took the head of were 2 KV (2.2) and 1 JS (2.0) engine.

Compare the same engines between each other
Turbo engine with turbo engine. N/A engine with N/A engine. Too many reasons really, but one of them being the turbine housing choking the exhaust flow and causing higher temperatures. That is also why you can find 7A heads with no cracks and most AAN heads have cracks.

That said, I have seen a few AAN engines myself at 200 000+ km and mostly the problem were the valve steam seals, and the bores were still OK.
Are you sure it was 200 000, and not clocked?
Again, it all depends on driving pattern. And I guess you did not own the car from new, so you never know how the first owners took care of the car.

I don't see much point in anecdotal "evidence".

[djh]

Play nicely kids.

Thats like expecting jeremy kyle guests to know proper english and have a full compliment of teeth.

[rynaqui]

Thats like expecting jeremy kyle guests to know proper english and have a full compliment of teeth.

[A80Avant]

And your evidence is coming from your years of experience as a mechanic as well..

Anyway as always there is an answer for everything from prj so anything else is a waste is our forwards and backwards finger movement