breaking in an OBD II engine with no exhaust?

Captain Ledd · Aug 14, 2010

Couldn't find a spot in any of the other forums since this pertains to a Jeep, technically.

Helping a friend put a 4.7L stroker I6 into his jeep. The donor harness and electronics are all from a 2000 XJ. Along with alot of other things.

Would it damage the engine during the initial break in not running any exhaust? His current exhaust is crumbling (literally) and we plan on getting a entire new one, and his doesn't have any kind of emissions anything on it currently.

I'm worried that the computer compensating for the lack of sensors and CAT, will more easily damage the new components.

Anyone have experience with this?

I'm really hoping I don't have to assemble the engine, install it, and then drag it to the exhaust shop, drag it back, re-lube stuff, and then break it in.

Explorin94 · Aug 14, 2010

For what he just spent on that stroker and what could happen to it without any exhaust.....I wouldn't. Them stroker engines are expensive to build and that would be a shame it he would have to tear it back apart due to a burnt valve or piston. I would wait for the exhaust before any type of break-in procedure. Starting it and seeing if it runs periodically is fine, but I wouldn't chance it.

feellnfroggy · Aug 14, 2010

The onyl thing not having the exhaust is gonna do is throw off his emission and make him run rich. For properly running motors everyone says drive it easy for however many miles......BS. How you break it in is how its gonna drive its best. Saleen and Honda motorsports break in their performance motors at about 9grand (motorcycle engines) and redline(saleen motors) for about 3 hrs. If you drive like a demon, then break it in like a demon, if you baby it all the time, then baby it on break in.

Something about not being broke in, and running rich makes me think of slightly lower oil flow and easy cylinder wall wash. An expert will have to chime in but maybe a lower weight oil for better flow and you might be alright without the exhaust, unless you have a handhel tuner that you can tune it for the lack of sensor reading from o2 and prevent it from running rich. If you have the tuner then you can break it in without exhaust just fine.,

adsm08 · Aug 14, 2010

it won't run very well with no exahust and no sensors. I'd avoid it. It's worth waiting for the exhaust.

breaking in an OBD II engine with no exhaust?

Captain Ledd

15+ Year Member

Explorin94

15+ Year Member

feellnfroggy

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adsm08

Senior Master Grease Monkey

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