Cylinder Pressure?

[marcus]

I just had Compression Test done,

Cyl 1) 11.1/2Bar ;)

Cyl 2) 11 Bar

Cyl 3) 11 Bar

Cyl 4) 11 Bar

Cyl 5) 10 Bar ;)

Cyl 6) 11 Bar

What "Bar" should all the Cyl be at on the IS ;)

Any one know!!

[star a]

between 9.8 & 12.5bar

[Monster-Mat]

within 15% of each other,

thats a perfectly good reading

[Gord]

Marcus i got

cyl 1 = 12 bar

cyl 2 = 12 bar

cyl 3 = 4 bar

cyl 4 = 12 bar

cyl 5 = 12 bar

cyl 6 = 12 bar

as you can see number 3 is very low :duh:

[Rob]

assuming that the following is correct and following boyles law and assuming that the temperature remains constant ( if compression is done slowly)

unswept cylinder volume: 333cm3 ( 1998 /6 = 333)

compression ratio 10:1

if the original volume is 333cm3 and the pressure is 14.503psi ( atmospheric pressure) with a compression ratio of 10:1 the swept volume would be 33.3cm3 therefore the pressure will be 145 psi or 10 bar

but going on previous replies the following may be true:

1:either the equipment is not calibrated

2:the test was done quickly causing the gas to expand resulting in higher pressures

3: the figures above are incorrect

if it was done quickly it isnt a bad thing as it still shows that there is a difference between the cylinders. u would only get 10bar under lab conditions anyway

[Zee007]

assuming that the following is correct and  following boyles law and assuming that the temperature remains constant ( if compression is done slowly)

unswept cylinder volume: 333cm3 ( 1998 /6 = 333)

compression ratio 10:1

if the original volume is 333cm3 and the pressure is 14.503psi ( atmospheric pressure)  with a compression ratio of 10:1 the swept volume would be 33.3cm3 therefore the pressure will be  145 psi or 10 bar

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That'll be crystal clear then Rob......

[Rob]

perfectly clear mate

[Mr Morse]

assuming that the following is correct and  following boyles law and assuming that the temperature remains constant ( if compression is done slowly)

unswept cylinder volume: 333cm3 ( 1998 /6 = 333)

compression ratio 10:1

if the original volume is 333cm3 and the pressure is 14.503psi ( atmospheric pressure)  with a compression ratio of 10:1 the swept volume would be 33.3cm3 therefore the pressure will be  145 psi or 10 bar

but going on previous replies the following  may be true:

1:either the equipment is not calibrated

2:the test was done quickly causing the gas to expand resulting in higher pressures

3: the figures above are incorrect

if it was done quickly it isnt a bad thing as it still shows that there is a difference between the cylinders.  u would only get 10bar under lab conditions anyway

←

Did you teach physics in a previous life?

[Rob]

come on mike u should know this off by heart!

[Gord]

assuming that the following is correct and  following boyles law and assuming that the temperature remains constant ( if compression is done slowly)

unswept cylinder volume: 333cm3 ( 1998 /6 = 333)

compression ratio 10:1

if the original volume is 333cm3 and the pressure is 14.503psi ( atmospheric pressure)  with a compression ratio of 10:1 the swept volume would be 33.3cm3 therefore the pressure will be  145 psi or 10 bar

but going on previous replies the following  may be true:

1:either the equipment is not calibrated

2:the test was done quickly causing the gas to expand resulting in higher pressures

3: the figures above are incorrect

if it was done quickly it isnt a bad thing as it still shows that there is a difference between the cylinders.  u would only get 10bar under lab conditions anyway

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Right rob :duh: im with you on that what wrong with my number 3 cyl then

[PhoneDrome]

From enginecheck before S/C fitting (done 118.000km):

[Rob]

Right rob  :duh: im with you on that    what wrong with my number 3 cyl then 

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u have a leak!

[PhoneDrome]

u have a leak!

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No. 5?

For me its perfect :)

But I miss 7 and 8 :(

[Rob]

sorry andi - that was for Gord.!

[marcus]

Thanks for that guys............so my cyl are ok then

[MacRS200]

Like Rob says you got a leak Gord. Could be piston rings, valves, head gasket or cylinder bore wear. Any one is bad news, my money is in a sticky valve though as all the other cylinders have had the same strokes.

[Rob]

Andi - number 5 is very slightly down compared to the others but its a perfectly good reading

[SpOcK]

I tested mine and the result was:

Cyl 1) ~4 Bar

Cyl 2) ~12.5 Bar

Cyl 3) ~12.5 Bar

Cyl 4) ~12.5 Bar

Cyl 5) ~12.5 Bar

Cyl 6) ~12.5 Bar

I don't remember the actual readings, but all the others except Cyl 1, were over 12 Bar. I have a supposed piston ring failure in Cyl 1. I haven't opened the engine yet, so I can't be 100% sure of true nature of the failure. But what I do know, is that the leak is from the chamber to the "downstairs", not "upstairs".

The car won't idle normally unless you don't let the rpm fall below ~1500rpm. But during cruising it's ok.

I had noticed the had idle before, but I thought it was due to bad spark plugs or coil pack, or smth, so I didn't know it only ran 5 cyls when I went to the dyno last time...

So we did the dyno runs with only 5 cyls, and thus the engine being only "1,65 Litre"... I was a little confused about the lower output compared to my previous dyno run, but after I found out that it did run only on 5 cyls, the figures seemed quite impressive, after all: ~260hp / 320Nm!!!!! ;)

[Gord]

Like Rob says you got a leak Gord. Could be piston rings, valves, head gasket or cylinder bore wear. Any one is bad news, my money is in a sticky valve though as all the other cylinders have had the same strokes.

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Its in lexus at the mo having engine strip :duh: the car was using/burning oil too :duh: (no smoke that you can see) i will have to see what wrong, i think valve to. :o

[RoadRash]

I tested mine and the result was:

Cyl 1) ~4 Bar

Cyl 2) ~12.5 Bar

Cyl 3) ~12.5 Bar

Cyl 4) ~12.5 Bar

Cyl 5) ~12.5 Bar

Cyl 6) ~12.5 Bar

I don't remember the actual readings, but all the others except Cyl 1, were over 12 Bar. I have a supposed piston ring failure in Cyl 1. I haven't opened the engine yet, so I can't be 100% sure of true nature of the failure. But what I do know, is that the leak is from the chamber to the "downstairs", not "upstairs".

The car won't idle normally unless you don't let the rpm fall below ~1500rpm. But during cruising it's ok.

I had noticed the had idle before, but I thought it was due to bad spark plugs or coil pack, or smth, so I didn't know it only ran 5 cyls when I went to the dyno last time...

So we did the dyno runs with only 5 cyls, and thus the engine being only "1,65 Litre"... I was a little confused about the lower output compared to my previous dyno run, but after I found out that it did run only on 5 cyls, the figures seemed quite impressive, after all: ~260hp / 320Nm!!!!!    ;)

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And I suggest that you did it in the wrong gear again, as before in 4th. ;)

[marcus]

I tested mine and the result was:

Cyl 1) ~4 Bar

Cyl 2) ~12.5 Bar

Cyl 3) ~12.5 Bar

Cyl 4) ~12.5 Bar

Cyl 5) ~12.5 Bar

Cyl 6) ~12.5 Bar

I don't remember the actual readings, but all the others except Cyl 1, were over 12 Bar. I have a supposed piston ring failure in Cyl 1. I haven't opened the engine yet, so I can't be 100% sure of true nature of the failure. But what I do know, is that the leak is from the chamber to the "downstairs", not "upstairs".

The car won't idle normally unless you don't let the rpm fall below ~1500rpm. But during cruising it's ok.

I had noticed the had idle before, but I thought it was due to bad spark plugs or coil pack, or smth, so I didn't know it only ran 5 cyls when I went to the dyno last time...

So we did the dyno runs with only 5 cyls, and thus the engine being only "1,65 Litre"... I was a little confused about the lower output compared to my previous dyno run, but after I found out that it did run only on 5 cyls, the figures seemed quite impressive, after all: ~260hp / 320Nm!!!!!    ;)

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And I suggest that you did it in the wrong gear again, as before in 4th. ;)

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A bit Off Topic!! but i was just thinking that Spock get your guy to do the Dyno run in the right gear "ie" 5th gear!! then come back and let us know what your BHP is :winky:

[SpOcK]

And I suggest that you did it in the wrong gear again, as before in 4th. ;)

I had a chat with my dyno guy about this, and he said that on Dyno Dynamics' dyno it doesn't matter on which gear the dynoing is done, beause it is not a conventional inertia dyno. Dyno Dynamics calulates the power loss individually on every gear, and compensates accordingly. Last time I was on dyno (5 cyls) we did a few runs on 5th for a comparison, and the result was about +/- 2 bhp vs. the run on 4th. So it doesn't matter on whih gear the dynoing is done on the Dyno Dynamics' rolling road. Let me check if I can find the result receipt from that run, and I'll post it for you to see...

It's not always blak and white, you see...

[RoadRash]

Every tuner who knows his job will say to run the this gear which is closest to 1:1.

And the 5th is 1:1. :)

And if we check the calculation form of stock HP * added boost = new HP

Then we have 155 * (1+0,70)=263,50BHP

But I believe in 1/4 mile times and not only sheet of papers. :)

Our 30 years old crappy dyno jet here said 225BHP and I ate a WRX STi for breakfast and sticked on a Carrera 4's a**.

So I doubt dyno sheets sometimes.

[SpOcK]

Every tuner who knows his job will say to run the this gear which is closest to 1:1.

And the 5th is 1:1.  :)

I say this again. In Dyno Dynamics' dyno iiit dooooeesn'ttt maaaattteeeeer, as the dyno measures the drive line power losses specific to used gear.

And if we check the calculation form of stock HP * added boost = new HP

Then we have 155 * (1+0,70)=263,50BHP 

Your point here is? ^^That's exactly what I got. With only 5 cyls.

But I believe in 1/4 mile times and not only sheet of papers.  :)

I agree on that. But as I don't have even the original lsd, I've not wanted to go to the strip, as the launch from stand still is somewhat painful... I've done 400m only once, and then my 60feet time was a very poor ~2.5sec because of the wheelspin and the rear end "bouncing". 1/4mile time was ~14.5sec.

Looky HERE for my last dyno slip, for which I asked to do few runs also on 5th gear!

The green line is for comparison, and from the first time I was there, when my engine still ran on all 6 cyls... (you can see the boost rise much more earlier)

All three other lines are from last time, and were done on 5th gear with only 5 cyls running (which I didn't know back then, it came clear just later).

The differences between those three other lines are because we tried different A/F mixtures and ignition timings.

SO: on Dyno Dynamics' the gear used to do the run doesn't matter.

[Gord]

I tested mine and the result was:

Cyl 1) ~4 Bar

Cyl 2) ~12.5 Bar

Cyl 3) ~12.5 Bar

Cyl 4) ~12.5 Bar

Cyl 5) ~12.5 Bar

Cyl 6) ~12.5 Bar

I don't remember the actual readings, but all the others except Cyl 1, were over 12 Bar. I have a supposed piston ring failure in Cyl 1. I haven't opened the engine yet, so I can't be 100% sure of true nature of the failure. But what I do know, is that the leak is from the chamber to the "downstairs", not "upstairs".

The car won't idle normally unless you don't let the rpm fall below ~1500rpm. But during cruising it's ok.

I had noticed the had idle before, but I thought it was due to bad spark plugs or coil pack, or smth, so I didn't know it only ran 5 cyls when I went to the dyno last time...

So we did the dyno runs with only 5 cyls, and thus the engine being only "1,65 Litre"... I was a little confused about the lower output compared to my previous dyno run, but after I found out that it did run only on 5 cyls, the figures seemed quite impressive, after all: ~260hp / 320Nm!!!!!    ;)

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Same as mine (cyl pressure's) :o and just had word, that mine is piston :o hope you get sorted mate.