Cruising And Engine Damage?

[AidZ1488]

Being aware of engine revs and engine damage, I have a question regarding cruising:

If I were to cruise at a moderately high speed, say, 90mph (on a private road of course) for an extended period of time (...an hour?) would this cause engine damage?

The reason I ask is because generally gear-chaging RPM tends to be around 2500 - 3000 RPM for me, so maintaining e.g. 3500 RPM or 4000 RPM for an extended period of time might not be good for the engine.

On the other hand, it's half-way to redline (ish) so nowhere near maximum capacity; the oil has been changed, I've ran an engine cleaner recently, and the wheels balanced and aligned, plus checked air filter (it's clean) and cleaned the MAF sensor. Plus I use Shell petrol to try and 'give it the good stuff' for the sake of engine maintenance and wear (not bothered about performance boost or MPG increase or other placebo benefits of Shell - I'm aware it's a whole discussion by itself!)

So, this is my dillemma. I know it's not good to maintain high(ish) revs, but does it actually cause harm?

I've tried searching but couldn't find anything, if my search skills are lacking please point me in the right direction.

Thank you.

[RUToyota]

These engines LOVE revs.!..cannot see how it could do any actual harm to a WELL MAINTAINED engine.!.

I can't imagine a scenario where I'd want to be running at 4k revs for too long. ...I'd find an hour would be very tiresome.!

Neil

[alan333]

My Dad always told me that holding revs above 4500 for long periods wasn't good for an engine, but that was in the early 80's. I'd say you'll be fine...and if you're not, then the engine was probably needing recon anyway.

[Konrad C]

Late to the party, but think about this.

There are a lot of cars (mainly) that are geared to roughly 21mph per 1000rpm. That means that at the 70 the engine is at 3300rpm. Some car have even lower gearing so are doing about 3500rpm. Think of cars with only 4 gears and standard gearing. They will be at 4000 rpm.

The engines are better now so mid to high rpm (4500), should not be so damaging. Good oil with regular changes is a must!

[AidZ1488]

Suspected as much :)

Thanks all!

[AidZ1488]

So, a follow-up question - what about tyre pressure?

Recommended is 32psi under 100mph and 39psi if over 100mph. Would it hurt to inflate my tyres to e.g. 35psi and maintain them at that pressure?

Would this cause problems or structural damage during town driving?

Is there an increased chance of puncture or tyre wall damage?

What are the negatives?

I suspect it would be better to leave my tyres at e.g. 34 or 35psi to assist with the faster speed driving, rather than 32psi for day-to-day but then (possibly) underinflated for high speed driving.

[armoredfist2002]

If you over inflate your tyres your only running on the centre of the tyre not the whole width of the tyre, so less grip, faster tyre wear and problems with steering, if you underinflate your tyres you'll wear them out faster and use more fuel, they also heat up faster so more chance of damaging the tyre.

As the contact patch on the road is so small it's a balancing act between tyre life, handling & fuel efficiency.

39PSI would be the rating if you were on parts of the autobahn in Germany all the time where you can travel over 100mph for a length of time, if your doing that speeds on UK roads then your just stupid, plus as far as I know over 100mph and it's an instant ban, so say goodbye to driving your celica for over 12 months.

Your better off sticking to manufacturer recommendations they're there for a reason.