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Amaru

By Amaru,
in Engines & Forced Induction

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Amaru Veteran

Amaru

Posted
  • Author
Posted (edited)

The car was tuned correctly when it first was built (when it did alot of km's as well being a daily driver then). The problem crept up when I added on parts that would alter the AFR's and never got it retuned properly, just patch up jobs here and there, and as an end result it ran stupidly rich on boost. The AFR's on boost were low 11's, and for one small part of the map dipped into the high 10's. Aside from that, cruise was never worse than 14.0:1. Im going to stop being a slacker and get it properly tuned (map wiped and start from scratch) when its back together.

Ferni, dont run octane booster, it does the same thing :unsure:

Edited by Amaru
chops Experienced

chops

Posted
Posted

Slightly off topic, but does water injection help to keep pistons clean?

I know in an old engine that I blew a head gasket on years ago, the one cylinder where water entered had a very clean piston, whereas the others were all carboned.

RB30-POWER Mentor

RB30-POWER

Posted
Posted

Yeah if your careful, you can suck small amount of water in with manifold vacuum (use a few revs for a while) and it will clean the pistons more then you would think it would.

Otherwise get something like suburu upper cylinder cleaner, designed specifically for this purpose (highly recommended by many people) and works better then water alone.

  • 4 months later...
amosite Proficient

amosite

Posted
Posted

old topic, I know.

When you pull an engine down, the condition of the bore can not be determined by hone marks. Its a common misconception!

The way manufacturers hone their engines, you will see hone marks at over 200,000klm. Im sure some people with that sort of mileage will strongly agree.

The only way to determine the condition of the bore is by measuring it at several different levels as this give you a much better idea of the distortion of the bore. You will often find more wear in the middle of the bore then at the top 1/4 and bottom 1/4. Not only wear but distortion where the bore is oval- this leaks compression as the piston powers through the combustion phase and as it reaches Bottom of the bore.

On some of the better engines, you will often find that bores are machined, honed and measured with a dummy head fitted to account for block distortion when the head is torqued up. Its mainly used on more serious engines as the results of a few thou and insignificant on a road engine.

Lastly, excessive carbon on the top of the piston is unlikely to cause pre ignition on boost. If your mixtures are consistently running that rich on boost- The amount of fuel that the engine is seeing keeps the combustion temps low enough so that the carbon wont cause pre ignition. Im not saying that it is good to run AFR's this rich, im just saying it is safer. I personally would rather run 11.5 AFR on boost then 12:1 on a track day. Yes, the leaner mixture will make up for some power, maybe 5% difference at this level but at 11.5 the engine will run cooler, combustion will be cooler and there is less chance of melting engine internals when your running full throttle for 10-15 min stints 5-6 times in a day.IMO I would rather drop 5% power but be sure to drive the car home.

williamsf1 Mentor

williamsf1

Posted
Posted

hmmmm the run in should be done on a dyno and do NOT baby it... 50km on mineral run in oil at 5-7k revs loading it up!

just warm the oil up to the 90c mark with a warm up idle and roll on the dyno first....

drop the oil after the 50km on the dyno, and then repeat with semi syn. oil for another 50km medium to high revs/ load....

then your top wack oil i.e 300v or castrol 10w/60

no more run in required and will have an engine with more power and long life!

yes Im sure there will be controversy over this but it is true :blink:

rob82 Mentor

rob82

Posted
Posted (edited)
hmmmm the run in should be done on a dyno and do NOT baby it... 50km on mineral run in oil at 5-7k revs loading it up!

just warm the oil up to the 90c mark with a warm up idle and roll on the dyno first....

drop the oil after the 50km on the dyno, and then repeat with semi syn. oil for another 50km medium to high revs/ load....

then your top wack oil i.e 300v or castrol 10w/60

no more run in required and will have an engine with more power and long life!

yes Im sure there will be C over this but it is true :dry:

I'm with you on this one maybe not right up to 7k at first though. I usually put 20kw load on and accellerate through to 3/4 of the rev limter max and then decel, then reapeat about 5 times and then double the load and do the same thing and then double the load again. If you engine isn't run in, in the first 500k's then it will probably never be run in. I'm sure this will get some controversy as well!!!

Edited by rob82

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