Engine Compression

[mk1 Andi]

Hello,
due to engine problems i checked the compression today.
I think 18 bar on each cylinder is a little too high 

What compression range does a standart K20A N/A (220) have?
Thanks for your help

Cheers Andi

[8407jeff]

The standard compression ratio from the factory was 11.5 to one.  This equates to about 215-225 psi on a gauge.  Mine engine registers 218-220 psi across all pistons.

[John Scherrer]

A typical K20A pressure is ~210 psi (pounds per sq inch)

1 bar (atmospheric pressure at sea level) = 14.5 psi

So 210 divided by 14.5 = 14 bar

[mk1 Andi]

So i have about 260psi.

Is that 'normal'?
How could it be that high?

On the previouse setup it had 260psi PLUS supercharger.. 
Its a wonder that the engine didnt blow up!?

[John Scherrer]

Has someone fitted different cams, shaved the cylinder head or could the pistons/heads be covered in excessive carbon deposits?

Didn't you say it was running very rich and smoking like a diesel .. ?
May be excessive carbon build up ?

Was the engine warm when tested, did you measure 'dry' or did you use any added oil ?

[mk1 Andi]

Unfortunately i can't tell if any modifications inside the engine was made.

Could carbon build up result the high compression? If there is less displacement due to carbon build up, this is also there when the fresh air gets sucked in the head, so the compression should stay the same, or am i wrong??

Today i fitted new spark plugs and after ten minutes running at idle they where black again.....

The water temp was about 50degrees when i tested compression and i measured dry!

I tested it because i built in the N/A intake.....

[mk1 Andi]

....and the idle is pretty poor and under 2000rpm the engine has spark failure/misfire!
Over 2000 everything is ok!
The exhaust is still smoking (short) when i open the throttle body fast!

And when idle-ing and then full throttle it quick goes to 700 idle an sputters (strange word)  short, then the rpm are going up as normal!

[K20A2]

Sorry to say but I am afraid, that -supercharger or not- you actually may have to do a remap, especially with regards to your high compression and provided that the data are correct. 

[lemmy01]

If you don't have changed the big injektor's to stock size the engine run's rich as before.
Thats the reason it missfire on low rpm.
If you change the injektors allready take a look on the fuel pressure,maybe the previous owner rised the pressure.
It's also possible that you have a smal leak in the piping to the map sensor.So ecu see not enough vac on idle or low rpm.

[mk1 Andi]

I already changed the injector to the std ones!
It has a fuel pressure regulator and i have tried from 14psi to 45 psi. No change of idle or the smoking...
But it has a bigget fuel pump (300l per minute) could that cause the rich problem even if i regulate the pressure as stock?

And my map sensor has no pipe at all. Its just screwed in the top of the throttle body. 

Today i cleaned the Idle air controll valve but have to wait for the new gasket. I dont think that this was the problem....

What else could cause the rich running?

[lemmy01]

Fuelpump has no effect if you be able to lower the pressure.
It's curios that lowering the pressure has no effect on the idle (smoke/too rich)
You must set the fuel pressure without vak pipe connected to the regulator.You know?

Take a look in the Honda manual what pressure is stock and use that value.

[mk1 Andi]

Nope, i didn`t know that i have to take the Vak pipe off the regulator! 

Today i was at the Honda Workshop near me and they told me that 3 bar (42psi) would be ok!
On monday i will take the Throttle Body to Honda and let them measure out if the TPS works right (i changed it yesterday) and is in the right position!

[lemmy01]

I look in the manual 48psi so 3bar is ok.

the regulator lower and rise the pressure relative to the manifold pressure.
That means that if the engine idle and the vak pipe connected you have much less than 48 psi fuel pressure.
The pressure should be 48psi without vac or pressure (hose disconnected).

[mk1 Andi]

Thanks, so i will try that when i have the new IACV gasket! 

What manual do you have to look at such data?

[lemmy01]

Any Honda service manual with your engine.
Maybe this: http://downloads.hondatech.info/Auto/Manuals/RSX/Ab0VE.Acura%20RSX%20(02-03)%20Service%20Manual.zip