Engine Run In/break In Query

[Kinkstaah]

Hi Folks, and especially those in the know.

Dumb question time

About to have yet another freshly rebuilt engine to do a run in on.

However, before it felt the need to be rebuilt, it was an 8.2:1 CR running E85 (but has flex capability)

It will now be 9.01:1.

My questions are:

1) Conventional wisdom (google) says that washing bores down is usually due to too much fuel and rah rah rah. Given E85 is using 30% more fuel pretty much all the time, would be swapping back to 98 pretty much vital or does E85 do magic to ensure this is a non issue?

2) With the CR increase, would I need to be dropping timing in the area that is OFF boost. If so, how much? Can I just drop a blanket -X degrees and "she'll be right mate" or is this epically stupid?

I've been advised that the way to do the run in (by the guys building engine) is 500 or so kms of easy, off boost, varied driving but not too much load (i.e, pretty much off boost) just to get it all rotating.

Then dump oil, and 500kms or so on 'some' load. In this case, sort of half throttle, 3-5 psi, up hills, a little bit but no crazy WOT 30PSI "load"

Then drop the oil again and tune. They however weren't really sure on 1) and 2) above.

Thoughts?

Surely someone has had to run in an engine which has more comp ratio after a rebuild and thought "hhmmmm..."

[Piggaz]

Read this

http://www.mototuneusa.com/break_in_secrets.htm

Go to your preferred tuner and make sure it's timing and fuel is right on a dyno.

[Kinkstaah]

I have read that in the past...

Fuel won't be an issue as the car has a (correctly working) wideband. Timing obviously need a dyno.

I'll obviously at least check things on the dyno. I don't know how much difference 8.2 to 9.0 CR will result in.

Does anyone?

That link almost insinuates first turn of the key is on a Dyno then immediately do a 400RWKW power pull.

But I've also read people build engines and then "run them in" on the way to the drag strip in the morning and then go do passes at 175mph.

I'm just looking for some info. The tuner may very well say "Hmmm, I'm not sure either?" therefore I was curious if anyone had done it and their results of doing so.. if available.

[MutatedHero]

The Nissan GTR is run in with one warmup lap and then full speed ahead the following laps straight of the assembly line. When the costumer gets the car it can be driven on a race track right away.

Edited February 26, 2015 by MutatedHero

[scotty nm35]

The 4 door's back on the road Greg? Nice.

Definitely need some boost to bed the rings imo, but any good tuner will have done this many times and have their own ideas on it surely. Remember, you only get one good shot at fileing those rings to match the bore.

Don't be surprised if the engine spews oil from every seal in the process, my Evo engine was leaking everywhere before the rings bed, as the blowby was crazy. Seen that a few times too.

[GTRPSI]

You need light boost for bed in.

When the bores are new, the hone leaves a finish thats rough and creates a lot of initial wear AND heat.

So start with lower RPM, low boost, load up the engine with Accel, keep RPM's lowish, progressivly increasing load and RPM as the peaks of the hone get worn off.

And as importantly to accel and give it some power, decel is just as important as it pulls the crap off the bores.

So dont pussy foot it, but dont start off with crazy load and RPM, progressivily increase the load and RPM.

Also you need your mixtures to be right, regardless of if its E85 or 98, too lean, too much heat in a cylinder thats already getting hot from bedding in, too rich washes off the oil thats lubing your rings which are going through a hard time and need oil to cool them during the high friction phase.

[GTSBoy]

The real problem with the need to bed rings on load when confronted with an untuned engine is not having the time available to get the fuelling and timing right to allow you to run it on load. If your engine is at least basically the same as before, sans the compression boost, then it is likely that your fuel map will be perfectly fine for enough load to bed it and run it in a bit. The timing is another matter. I would pull a few degrees out pretty much everywhere. You can't really hurt it by doing so - it will just make less power and you don't care about that. It would be most important to soften the timing in the boost transition area where it may well have been quite aggressive if your previous tuner was trying to get you the best response possible.

As to the question of E85 washing the walls.....just because it uses ~30% more doesn't make it more likely to wash the walls. If the mixtures are right then the fuel will burn, provided it's actually firing!

[Kinkstaah]

I won't be too worried about the fuel, it has a wideband controller and a gauge and I'm familiar enough with the Haltech that I can change fuel maps on the fly to get it happy.

Main problem was as GTSboy has mentioned, the time it takes to get the timing right.... is critical time to make sure the engine is being run in at all.

It's on E85, so pinging was never a problem. I don't know how 'much' timing to pull to accompany 8.2 to 9 CR. I can easily just pull -X degrees everywhere and then go for a drive, my main concern was pulling too much, could affect how the run in is actually done. Can confirm I don't care about power during the run in.

The 'problem' is the previous engine kind of made 350RWKW at 4000rpm. If you're trying to "Load it up" in a high gear at medium RPM then there's a good chance that uh, it's kind of party time in those cells..... with a different CR. The characteristics of the engine meant 5-10 psi happened quite a lot while just cruising around at 30-50% throttle at 2-3k rpm. You could argue that that's pretty ideal for running an engine in.

If E85 isn't a big deal, or doesn't cause any crazy problems for bedding an engine in, then that's a great piece of news for me, because it may only need 'minimal' adjustment to account for the extra CR, which isn't that much, I'm not going from 8.2 to 13.5 or anything of that nature.

[GTSBoy]

Just pull a few degrees. It won't stop you from being able to run it with enough load to bed the rings. It also won't likely ping, as you say, even if you should have pulled more, because E85.

Set the boost as low as you can and set the boost controller to not keep the wastegate closed agressively.

[jay-rod]

Very First start always run at a constant ~2500 for about 15 minutes as to get the oil "everywhere" so to speak.

Dump the oil, put new in.

Just drive it normally for around like you say 500km, normally meaning every day driving.

Essentially the break in process is to prove that no tolerances are incorrect

in theory a proper engine rebuild should need 0 break in time and should be able to be run 100% after first start after 2500 idle process.

But nothing is perfect in this world.

That said, im not sure about the e85 affecting this process, and im not sure there is enough evidence out in the world to convince anyone aswell.

Edited February 27, 2015 by jay-rod

[GTSBoy]

Very First start always run at a constant ~2500 for about 15 minutes as to get the oil "everywhere" so to speak.

I think you'll find a very large number of people will tell you that running an engine at a constant speed is going to cause worse ring bed in than almost any other option (except idling it).

[zebra]

Mmmm...you do that on cast iron cams to be them in. not pistons rings.

[jay-rod]

I think you'll find a very large number of people will tell you that running an engine at a constant speed is going to cause worse ring bed in than almost any other option (except idling it).

Interesting, i mean ~2500 with no load by the way, not moving.

If you were to have a to rich fuel map, that would cause wash in on the cylinder walls correct?

And that would be easy mistake to do with 85 ?

Edited February 27, 2015 by jay-rod

[GTSBoy]

That would be very bad.

You need lots of cylinder pressure acting on the rings to make them shape up to the bore wall and knock all the high spots off. If you don't (ie idle it or hold it at a constant speed, or even just drive it around really gently) then the rings will glaze up and you'll not get a good seal. Then you start chucking Bon-Ami down the carb (if you're living in the 70s).

[jay-rod]

Well i will throw that out of my head then, not sure why i thought otherwise.

I assumed the short period was not long enough to cause that on the rings.

More so for a fresh engine with "dry" internals to get the break in oil to get to those locations it wouldn't normally be on a first topup.

[GTSBoy]

On a dry engine you just use lots of assembly lube and you crank it without ignition and fuel until you get good oil pressure, then try to start it.

[jay-rod]

If i could edit my post i would to remove my suggestion but it wont let me

[GTSBoy]

Sad. But ultimately doesn't matter. You could beg a mod to delete the whole conversation. In the long run though you learned something that may save an engine that you're starting up for the first time, and the conversation might be more convincing (to some future reader) presented as it is rather than just a blanket statement saying "Do X because you have to".

[Ben C34]

Just claim your kid brother or idiot mate used your login.

Happy to help....

And I'll just add for reference, when cranking engine to build oil pressure remove plugs to remove load from bearings and pull fuel pump fuse.

[jay-rod]

I just wanted to test you guys make sure your on the ball