What's a safe redline for a 2.2 with stock components?

[RobFrost]

What's a relatively safe redline for a 2.2 with stock (counterweighted) crank, valves, springs etc.?

I'm assuming here the cam, compression, fuelling etc. are set up to keep pulling to whatever range it needs to go to. At what point to things start flying off, not getting the oil they need, hitting each other, or making their exit from the case?

I think the first "protective" improvement needed to the engine, is extra cooling in the form of say piston oil squirters if not already in place, maybe a later oil pump too. At what point are the stock crank, valvetrain and other bits not up to the job?

[Sam]

There are so many variables here.

Is the engine built?

If so the usual test is to hold the revs at 6000 for 20 seconds, then increase it by 100rpm, hold it for 20 seconds, increase it by 100 rpm, hold it for 20 seconds etc etc.

When it blows up you’ll have established the safe limit was the one before that point.

[RobFrost]

There are so many variables here.

Is the engine built?

If so the usual test is to hold the revs at 6000 for 20 seconds, then increase it by 100rpm, hold it for 20 seconds, increase it by 100 rpm, hold it for 20 seconds etc etc.

When it blows up you’ll have established the safe limit was the one before that point.

ok i'll let you know how I get on.

I think Mike Champion said he thinks the stock T crank is ok up to 7,200. So I assume the counterweighted crank will go a little higher. S redline is 7,200 and I think the main thing I don't have there is the nitrided con rods.

[Lightweight_911]

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I don't think you need to worry about exceeding the safe rev limit with the relatively mild modifications you're planning.

A std 2.2S has a redline at 7300rpm but peak power is developed well below 7k - around 6500rpm from memory - so, other than shifting into the wrong gear (eg 3rd instead of 5th) when really caning it, it's unlikely to be a problem.


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