ssswagon

My 383 tune has been tweeked to suit bigger injectors (was 42Lb, now 60Lb on 427, so we can start the engine & check for oil pressure etc.

After that, the consensus seems to be to run the engine in on a dyno under load to prevent the bores from glazing.

The plan seems a bit vague. Is this secret engine builder/tuners business, or is there a common-knowledge best procedure for bedding boosted rings under load on a dyno?

This build will be a daily driver so I'm chasing longevity.
Intercooled 3.3L twinscrew initially ~14Lbs
The Warhawk/Allpro combo with 6 studs should be good for 30Lbs
T56 & 3.73's. Yeeeha!

ssswagon

Must be a secret huh?

Adam98Z

I've heard that should be done on all new engine break ins.

cast iron

if the top rings are chromoly they should be seated under pressure (boost). operating temperature is key as well as some heat cycling for fastners, gaskets, etc.

BigJls1

I was always told rings seat under vacum.

I later comfirmed this when I had a old sbc that had been freshend up, I drove this motor for months with nasty blow by, It was the first time I had an engine where the rings didnt seat. So an old timer told me to get the motor up to temp cruise about 60mph and down shift two gears ( like useing the engine as a brake)untill the truck had slowed to the point where it at idle . I did this three times and no bull the blow by stoped. So the next time I did a motor I would rev it up real slow to high rpm then just let the throttle blades shut quick, basically putting large vacum against the rings.

Websy21

iTrader: (34)

interesting concept

cast iron

vacumn does not affect the rings push against the wall, it is all about BMEP. high cyl pressure force ring to outside of wall, making good wear. high BMEP for a long period of time will cause glazing of the wall.

pressure, short bursts, vary load - no overdrive low RPM wot pulls, and stay at operating temp

BigJls1

I gotta ask what is "it is all about BMEP."

I was also toying with the idea that under hard vacum with the throttle blades closed if the cylinder wall gets a little hotter than normal because there is way less fuel to cool the charge and if that in turn heated the rings to a point where they finaly set.

BigJls1

you know I just read where the big shots that run a belt driven vacum pump on the engine.....why....to increase ring seal hmmmm.

cast iron

that has to do with blow by, not seating rings on a new build. the big shots run very big camshafts that do not create large vacumn that a production car would - thus the pump or using an exhaust pull

please follow this link, it covers the information i convey:
http://www.ntnoa.org/enginebreakin.htm

cast iron

depends on decel enrichment and timing of the efi controller. there is very little cyl pressure (BMEP) so rings will not be pushed towards cyl walls

wall temp is subject of maginitude of wall wetting (decel enrich), AFR, and timing

all are usually kept at safe/minimal levels for longevity

BigJls1

good info