Hi Guys,

Firstly, yes I have searched and found some information on the subject.

I have just had a new engine & clutch fitted to my S and it should be ready for collection today. The stealers, as per usual, are stunningly vague on what the run-in should consist of - if anything.

How much of the manufacturer's run-in recommendation is for the whole car - i.e. engine, transmission, clutch, drive train etc?

Does the fact that only the engine & clutch are new change what I should do for the first 600-1000 miles?

Cheers All.

 

600miles do not vtec

Then every 100 you can go 1000rpm more, so at 900 miles you can redline it

 

Sounds familiar
600 miles Ian - I'm working to a 1000!!!!!!

Cool - Vtec earlier, car does feel stonkly quick without vtec

 

You need to bed the rings in, a process which if you don't do it in the first 20 miles, you won't ever do it properly.

Find a stretch of road where, with the engine already warm, you can accelerate hard and then come off the accelerator sharply. Do this a number of times progressively increasing the revs. DO VTEC it, i.e. go over 6,000 rpm - don't necessarily redline it. Remember that the engine will already have been to the redline when it was bench tested.

Don't do this uphill where the engine will be under load. Preferably downhill, but if not that then straight and level.

When you back off the accelerator the back pressure forces the rings against the cylinder wall.

After you've done this change the oil and filter but remember to refill with the oil that Honda use for the running in period. You'll be amazed at how much crud comes out even after 20 odd miles.

After that run it in normally, but again I wouldn't pay too much attention to the no VTEC rule. The best way to run an engine in is to make sure that you are going up and down the rev range, progressively pushing it higher and higher, rather than cruising round at 4,000 rpm or whatever it is they recommend.

 

I'd agree with the welshman but all my experience is with bike engines.

Only one thing to add is make sure the engine is fully warmed up before doing this breaking in stuff. The heat cycling is an important part of the process.

 

So is mine but I apply the same rule to car engines.

People ask "why don't you do what the factory says?"

Well, the manufacturer is always going to come up with as simple as instruction as possible, one that even the dimmest person can just about understand.

Ask an engineer how to bed in an engine and they'll tell you to keep it moving up and down the rev range.

It's important to do this in short bursts only. If you run a new engine in at high revs for a long time the heat build up due to friction can damage the engine.

 

So, you can see where all the confusion comes from

AquilaEagle & Welshman seem to have 2 non-compatible approaches to the same problem.

Which one should I use?!

 

Well you know what I'd say. Any other takers out there?

 

i think you've got that the wrong way round Welshman. Use full throttle when the engine IS under a high load, ie when going up a hill. What you are trying to do is force the piston rings hard against the cylinder walls so that they bed in and seal properly. this happens when cylinder pressures are at their highest ie under full throttle conditions and high engine load. When you lift off the throttle sharply, you actually reduce the pressure on the rings as the cylinder pressures become very low.

This method is one of the internet arguments that has gone on on various car forums for years. The original article relates purely to bike engines and does not take into consideration wear on other components other than piston rings so is highly debateable. It also does not take into accound that if you have replacement engine fitted in your car, the engine comes as a seperate short block and cylinder head so has not been bench tested.

Either way, you can take a balance approach and meet the honda recommended method and the ring bed in method. Don't vtec for the first 600 miles, but do use full throttle when the engine is under load in the first 20 or so miles. That way you bed the rings in, but you're not revving the engine madly.

 

The bench run in standard we use is probably closer to AE's method. I don't have the standard to hand but from memory it's start at idle and no load for a few minutes then progressively up thr RPM and engiene load until you're at max RPM and Wide open throttle. It steps up in engine load in about 12 steps and the whole process takes 1 hour (equivalent to about 1000miles).

That's for a mass production engine which doesn't have to be as accurate as a prototype engine. For those we do a similar test but scaled up to 8 hours to get more consistent results.

The aim is to allow any surface imperfections to wear off before the rings pass over them at high load.

A service part short block will not have any sort of run in on it at all I would have thought (ours definately don't). Also whilst not entirely sure of Hondas test methods i think it highly unlikely the engine is run in on a loaded test bed due to the installation time. We test every engine we build but only in no load conditions. They do however test the vehicle on a rolling road all the way up the gearbox at full rpm but again that's no load.

On a secondary note, if you test as per the manufacturers recommendation then they've no comeback at a later date if something did go wrong