Rb20 With Low Compression + Rattling Noise

[dan.1337]

The other day when coming out of my work carpark, my car (r32, rb20det) lost all compression and moved like a slug.

I dropped it off at my mechanic who has just informed me that it has extremely low compression and a rattling noise in the engine. This means that it isn't combusting fuel properly and well...just not going.

I think that I have two options now:

1. Strip down the engine and find out what's going on

2. Replace the engine

Would anyone have any suggestions in what could have happened? Or any other options I might have?

Thanks.

[GTshortie]

Option 1: Would mean labour costs plus rebuild if your intending to keep the RB20 and add forgies

Option 2: Replace it with a second hand RB25DET or another RB20 if your tight on funds, make sure you get a leak down and compression test on them before purchase.

i'll personally prefer a cheap RB25 and wack it in there.,

[Simon-S14]

Were you giving it stick at the time of coming out the car park? Generally speaking motors just dont die and lose compression like that unless they have detonated (cracked ring lands, bottom end bearing and various other things could be damaged) or your oil pump has died causing bearings to run dry and spin.

If the motor is stuffed, i'd look into replacing it with an Rb25 (minus the box) and take it from there, you can get them for around 2200 with ecu and loom + all bolt ons.

[MANWHORE]

I like GT shortie's second option.

Rb20s are cheap as chips (<1k). Rb25, more.

If I were to blow my engine, that's the option i'd be taking. Sure, building an engine will make a stronger engine, but they cost a lot. The stock one will take a good whack of power if you look after it.

[dan.1337]

i'll look into swapping to another rb20. i've already got all the supporting systems for it and it'll probably be an easier swap without having to worry as much about wiring etc.

are compression and leakdown tests able to be conducted on an engine not in a car?

[Beer Baron]

by all means put in a second hand RB20, BUT make sure you figure out why the first one went bang so you don't do it to the new one (ie, dud fuel pump? bad tune? broken injectors?...)

[dan.1337]

well, everything was given the twice over and it came back to the engine itself. the fuel pump, injectors and tune were apparantely retested and still running a stoich mixture but the engine is just losing compression somewhere. there is also a worrying rattle inside the engine somewhere which sounds like a loose bearing.

[Rekin]

you can purchase rb20's for around $400~

Roy purchased a 2nd hand rb20 from wrecker and is running 260kw no worries haha

[dan.1337]

  Rekin said:

you can purchase rb20's for around $400~

Roy purchased a 2nd hand rb20 from wrecker and is running 260kw no worries haha

thanks, but would u konw whick wrecker he got it from?

[GTS4WD]

For the price of a 25..

you can get a 20.. and some nice mods..

Better off spending money on a 20 and mods..

see if you can repair the 20 and sell to make a little bit of money for more mods..

[Beer Baron]

  dan.1337 said:

well, everything was given the twice over and it came back to the engine itself. the fuel pump, injectors and tune were apparantely retested and still running a stoich mixture but the engine is just losing compression somewhere. there is also a worrying rattle inside the engine somewhere which sounds like a loose bearing.

well it shouldn't be running a stoichiometric AFR anywhere except at cruise (light throttle, low load) if it's running stoich anywhere else then you have big problems.

anyway, I would do your best to pin point exactly what killed the motor as it wont be much funning fitting a new one then going through it all again.

[dan.1337]

it's running stoich at low load and off boost and a tad rich on boost. not sure of the exact afr's tho.

would it be worth paying for the motor to be stripped down to find out what's wrong before going further?

[FordyR31]

If they just tested ur fuel pump by adding power and not running in a motor it doesnt mean too much.. Could have been leaning out under boost and running to lean for a while. GTS4WD U could get another with some mods, to catch up to a 25 and then some. Or u could just get the 25 and the base right there for some really good potential. All comes down to how much cash u wanna spend. Spend ur cash now on a 25 and get better results later with mods or spend the same amount on a 20 with mods and have more power than a stock 25 with lower gains for all the mods u do in the future.

Liam