Breaking in engines on LPG 3

[cheguitarra]

Please forgive me if this is an unchallenging question, but i'm an electrical engineer looking to give my automotive pride and joy a new berth of life!

I have converted my Suzuki Sierra (known as a Samurai in other parts of the world) to run straight LPG and all has been running swimmingly for the last two years. But alas, time has come to rebuild.

On the side I have a G16A (1600cc 8v engine) I plan to rebuild to stock specs (unless specified otherwise), i'm running an Impco CA100 propane mixer, and the dizzy timing has been re-curved to suit the LPG fuel. I'm concerned that I may have issues seating in the rings of a freshly rebuilt motor on LPG, being a dry fuel i'm not sure if I need to take precautions during the breaking in process, or if I should avoid an LPG break in all together.

Whilst i'm aware of the general breaking in process, LPG information is extremely limited and any tips that can be forwarded my way would be greatly appreciated. I love my ride and it's my first and only car.

Thanks in advance for any pointers

 

[FoMoCoMoFo]

The "secret" to the modern engine is, as you and others have said,
Modern machining, round bores correctly finished etc.

That said, for break in purposes, I would run conventional oil until the first oil change.

And, in case it hasn't been said enough already;
Do raise the compression.

 

[cheguitarra]

OK - block, cam and head go in for machining on monday, i'm getting excited.


Would you recommend any particular oil for breaking in? I was told by my car club to use a standard oil along with a zinc additive like ZDDP in the initial oil fill.

 

[patprimmer]

Interesting concept.

Gas fuels will not allow the rings to seat because the oil lubricates the bores to well by having no wash down.

Use extra anti wear additive while to improve lubrication while the rings seat.

I would just use a good detergent single grade lightweight oil for the first hour or so, making sure it got plenty of short full load pulls to increasing rpm with a good cool dawn period between pulls. Like a 3 second pull and a 30 sec cool down then a 5 second pull, 30 sec cool down etc etc.

When rings are bedded, change oil and filter. Use a good full synthetic and enjoy.


Regards
Pat
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[turbocohen]

TRW sells a plasma ceramic top ring that is the cats meow for LP or NG. Finish the bore and lightly scrub it with panty hose over the stone while squirting old style dexron into the bore.. works like a charm and momma will not notice them missing.

Start off with 0w-20 for initial break in for about an hour of mild driving then switch over to 5w-40LL and gradually increase loads over approx 500 miles. Keep revs high enough to prevent lugging buy well below redline for the first 500 miles.. gradually work revs up. Do not add ZDDP to good oil, it is like putting steak sauce on a good peice of meat that was cooked properly.. 5w-40LL has superior chemistry that replaces grandpas zddp. A lot of additives oems boost are there to protect from early abuse, condensation and corrosive acid buildup from long term storage prior to sale. Also wrap a flexible magnet around the filter for the first hour and open the filter with a can opener before removing the magnet.. sort of a low budget tattle tale

Ditto modifying the exh valveguide and using Full Synthetic from the first run.. I have yet to see any real world problem with breakin using light synthetic oils during initial breakin.. The oems use it but the additive package is altered. As for the heads, add 10% to the width of the cut (not ground) intake valve face and 20% to the exhaust. If you have not done so consider stellite seats.

 

[franzh]

To add my humble opinion, if your machine shop is simply honing the existing bores to deglaze them, then you can almost guarantee the rings will never seat, but then, they probably wouldnt seat properly on a liquid fuel engine. A good boring with straight cylinder walls, and a quality honing to original ring manufacturer specs and you shouldnt have any oil consumption problems. Most of the above posts are right on target with the exception of the old, old, really old school of pouring Bon Ami through the carburetor throat, or coat the pistons with a mixture of Bon Ami and oil. If you value the life of your engine, dont do it. Not that long ago, I would settle for a slightly rougher cylinder wall finish but modern rings have solved that problem.

Turbo hits it right on with the valve seat widths, wider seats absorb valve heat quicker and prevents valve burn in.

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[MikeCaruso]

Guys,
You can use John Deere engine Breakin oil if you think you have a ring to cylinder wall issue. It has fixed many fresh rebuilt engines which had a gasoline wash of the cylinder walls and were using 1 qt of oil in 200 miles. switched to J/D oil and now uses 1 qt maybe in 3000 miles. This oil works great and also protects flattappet type camshafts. No I do not work for John Deere I work at

http://www.aera.org

I hope this will help someone.
Regards,
Mike