tazdevl

Break-in periods with cars these days is carry over from cars 20 years and older. Tolerances have tightened up, materials and lubricants have gotten better etc... Brake break-in is another matter and still necessary, but most modern engines do not need a major break-in period.

lobuxracer

iTrader: (2)

OEM pistons are cast not forged. Also, yes, pistons are in a plastic state at full load. Look at my avatar. See the orange glow? What do you suppose the top of the piston looks like at this load? This is also why when I was building bike engines we saw more power from Cosworth pistons than anything else. They chose their alloy based on strength at temperature and nothing else. We typically saw 4% better power with Cosworth.

Pistons are not evenly heated. Their grain structure, even when forged, will undergo significant change as they are initially heated and cooled. This is precisely why I advocate a break-in process that gradually increases load while allowing a 5 minute cooldown period between load sessions. This way the pistons are not thermally shocked in a way that will cause them to lose the shape the manufacturer spent so much time and effort to achieve.

Used pistons require NO break-in, and rings can be broken in with a few short full throttle runs terminated by rapidly closing the throttle to pull oil up past the rings and help remove the metal shavings from initial ring wear.

Bichon

Can you post a full sized version of your avatar? It's hard to see anything on the postage stamp sized one.

SParker1tx

Well with a 350 I could easily have stayed well under 4k RPMs for the first 500 mile but in a 250 its a bit different and you kinda feel like you have to get up to 4K RPM's

clubfoot

OK, I can see what you're saying, we used the same method to break in engines when I was younger, nothing scientific mind you just what my uncle taught me. Still don't see why Lexus didn't use forged pistons to begin with, maybe they don't expect the after market to boost the engines,...who knows. Can't really tell from avatar but is that engine turboed? I've seen the same exhaust colour on a N/A 4.2 Jaguar 6L we stuck in the back of a Morris Marina we built for drag racing.

lobuxracer

iTrader: (2)

Here's the full sized pic. It's from Kistler. They make all kinds of piezo-electric transducers; what interests me are their pressure transducers for engine development. The pic is a V-8 with a single turbo at full boost/full load.

No OEM uses forged pistons for a street car. They make too much noise on start up because their fit has to be looser than cast.

clubfoot

Don't quote me on this but that old 4.2 Jaguar 6L had forged pistons, for sure the new V8 has forged pistons. What made the Cosworth pistons produce more power, was it weight, shape,...?

lobuxracer

iTrader: (2)

Choice of alloy. Where does Jaguar say they are using forged pistons? I can't find it in any of their marketing material.

LexusIS-TL

I always figured break in periods was around 1,000 miles and brakes were 500 miles. I was also told that you need to do the first oil change at 1,000 miles too. Can you guys confirm this? Possibly due to the metal shavings?

Bichon

The break in period in the owners manual is specified as 1,000 kilometers (621 miles), not 1,000 miles.

You aren't going to find anything approaching consensus about break in procedures and oil change intervals on this forum. There are many long threads in the archives debating the merits of various approaches.

Technique

I have a 2005 Jaguar 4.2L V-8 S-type... I could check the manual or other materials if you want... Don't think it would say if the pistons are forged though...

jezza

I strongly doubt Jag was using forged pistons in any of its stock block V8's. That design is ancient.

There are some vehicles that have come from the factory with forged internals, but they're all low production, high performance versions of cars where engine noise isn't an issue with buyers.

The new LS7 in the Vette is an example:

"Within the LS7 block, you'll find a forged-steel crankshaft, forged-steel main-bearing caps, titanium connecting rods, and forged pistons."

Technique

I believe the viper switched to forged internals in like 99 or something...

clubfoot

I just read online that their V8 (supercharged?) uses forged pistons, the 4.2 was along time ago and like I said don't quote me, but from what I remember it may have been forged.

LexusIS-TL

The dealer mentioned oil changes done at every 5,000 miles. Standard on all Toyota vehicles. But that 621 miles of break in period sounds good. I have about 450 miles to go. I'll get to it in no time. Commute too much...