just wondering what people's opinions are i have a new bottom end going on the car soon - the head and cams are already run in so don't need to worry about them but the rings, bearings etc are all new and never run - was wondering people's opinions on how is best to run them in...
I took it relatively easy for the first 500 miles then gradually worked up to taking it to the limit. For the record a new car is 1000 miles for run in period.
Just use the car as you would normally but dont leave the car ticking over if you dont need to and make sure the mixture is ok. Over fuelling can cause problems later, change the oil and filter at 500 miles apart from that give it some stick.
Have you ever seen people bedding in race engines with vim? Sit it at 8000rpm and feed vim into the intake...seems to work....but not advisable on a road engine!
Don't rev over 3 grand for the first 600 miles, then build up gradually till about 1000 miles. Also try not to make the engine work to hard in that first 600 miles. Between 2000 and 3000 rpm is the ideal engine speed. Revving the tits off it sraight away is a bad idea as all the tolerances will be out until things have worn in a bit, so treat it gentle.
I was quite hard on mine TBH, & mixture of hard/gentle driving! My car felt loose & like it wanted to be revved though, although a friend had a rebuilt ABF on his 16v & said it was tighter than a ducks rear for 1000 miles!! You should be able to gauge it from the feel of the car!
'RIDE' magazine did a test a few years back. They took 3 high performance bikes, and got 2 of each. 1 of each was run in as the manufacturer said. the other was riden hard from the off. They did a strip down and power tests etc after to see which way was best. Sadly i never got the final part of the test! [:^(]
I did 100 miles with my brand new vag block and then took it to the 'ring. It had done a few miles by the time it got there though. I would let it rev quite high but not use full throttle if you know what i mean
Sorry to do an Altern8 style bump, but this is interesting regarding running in. http://www.mototuneusa.com/break_in_secrets.htm
I've seen that page, and that's exactly how I do mine (unless there is a new cam in as well). If you build the engine carefully and get all your bearing clearances right, there is very little to be "run in", just the rings. I drive mine hard, as normal, straight away, and always end up with a nice free engine with great compression numbers....... One thing I hate though is people who just chuck in new rings without any honing at all - nice way to build a bollox engine.
Haven't even got the bits yet to build the thing and I'm already thinking about running it in Makes sense what he says about the combustion gas pressure forcing the rings into the bores tho.
Exactly - I mean you line up the rings so the gaps are equally spaced, because your rebore is never totally round. So if you rag it from day one, your rings will shape to the bore due to the outwards pressure, and stay where you put them. Otherwise as I see it you are just "wasting" the honing process, because you aren't getting enough pressure between rings and bore to "cut" the rings to shape. Just slowly wearing away the nice abrasive, sharp, honed crosshatch which you put there in the first place to "cut" your rings!
I have to agree with second coming. I've always heard from fairly respectable sources(old mans racing friends and his engine builder)that you want to get the rings seated to the bores and the bearings shouldn't have to bed or wear in at all, they dont actually touch anything if done right. On order to seat rings 4th or 5th gear pulls from 2-5000 rpm are ideal, lots of cylinder pressure forces the rings out so they match the bore perfectly and result in nice high compression values. After that drive it as normal. Don't forget to change oil after the first 100 miles. Start with mineral or running in oil and then move to your oil of choice. Most of the swarf will have been found after that time and needs removing. After that there should be another 500 or so before the next change and then revert to regular intervals. The oil is all important. Dexter, you said that your head has been run before, if you want to bed a new head in let it run a constant revs so there is much less load but the friction surfaces in the head(cams lifters etc.) get a nice finish to them. This is advice I have been told and has worked for me, the only time I've ever had a problem with bedding in was when I didnt build the engine and took advice from a fairly reputable VW specialist and it went horribly pear shaped. They said keep it under 2500 rpm for the first 1000 miles then 3500 rpm for the second 1000 and so on. Took forever and resulted in a spun big end. Compression wasn't great when we took it apart either, so the ring seal was pretty poor anyway.
Lol..... lots of old threads coming up these days! But aye, if you get your bearing clearances right, then the rings are all you really need to worry about. I've mentioned it before, but bearings vary in tolerances a fair bit - so buy 2 or 3 sets, plastigage them, then mix and match them till you get the clearance you want on each journal. Then return them to GSF or wherever after a clean, and say they weren't the size marked on the box, get your cash back.......
Haha, I'm well on the ball me! Nice tip with the bearings, i've never had too many problems to be honest. Worth knowing though.
I just like all my clearances to be bang on (I'm a Mechanical Engineer, and a bit of a tribology nerd!), so you don't get the overheating you sometimes get with new bearings which are a touch tight. That way you can rag it for far longer before it needs to cool down!
Cheers for the advice Jimmy but sadly it may be about two years too late... well for me anyway! In the end i changed the oil at 50 miles, 100 miles, 250 miles, 500 miles - each time putting in the cheapest mineral oil i could find. Only changed the filter at 250 and 500 - since oil filters work better the older they are. Stuck below about 3500-4000 for the first 250 miles, but using half- 2/3 throttle in short blasts, after 250 miles i gradually increased the revs and throttle up to the 500 point and then started driving it *normally* I did keep the MFA on oil temp the whole time to make sure i wasn't overheating anything. That engine made 180bhp and 155lbft on soft cams so i'm happy it bedded in pretty nicely
The running in process is a lot easier with the tighter tolerances manufacturers achieve now. Couple of things though: Don't labour a motor in a high gear with low revs- the bearing won't like it, don't be too gentle as you'll glaze the bores and don't uses max revs either. So normal road driving with the odd burst of speed through the gears should do the trick. Barkstar
