DC2R Compression test

[ewendc2r]

ummm, no.

you seem confused.

the low number above on the Honda Manual = the "minimum"

it could mean the "minimum required to get the engine to fire"

it could mean *minimum* anything!

importantly - see how the re is no "service limit" listed?

i guess they believe that their mechanics are smart enough to know when a rebuild is required?

Exactly though, if it is the minimum and therefore there is a maximum (i.e new condition) compression reading. Are you saying that the drop in cylinder compression does not negatively impact efficient combustion/power production?

[B.ITR.00]

compression pressure doesn't have as much of a effect on power as people think, its more to do with correct compression ratio for the fuel's octane rating your using.. ie AUDM has lower compression ratio to JDM due to Australia's lower octane....dc2r set for 95ron JDM for 100ron,, increasing compression will gain more power as turbo/super charging dose but significant amount of it will be lost due to pumping losses and friction and whats left is the power gain

honda give a variable in there Manuel due to tolerances of the engine ei longest block with largest cylinder head volume, shortest conrod, shortest piston this might seem small but that's why they make pressure a variable. because no 2 motors are the same (and umm a b18c with 135psi i think its dusted lol)

i've also read that when Honda engineers design there engines they have to for fill a basic service life of 250,000km's or 15years its on world Honda http://world.honda.com/history/chall...e/text/01.html

[tinkerbell]

Are you saying that the drop in cylinder compression does not negatively impact efficient combustion/power production?

no.

as i said:

it could mean the "minimum required to get the engine to fire

[ewendc2r]

Tinkerbell --- As above it seems the the correlation between Power & Compression is a hyperbolic curve in that the gradient for loss of power is significantly higher at lower compression vs higher compression .. Therefore there is obviously a loss of power as compression drops. With such a significant threshold there WILL be a drop in power, however as B.ITR said, at that threshold the power differential may be quite small. Having said that, there are cars with worn rings / valve seals etc that still run with SIGNIFICANTLY less power than when new. Obviously with worn rings etc compression test will be low. Then when the engine is reconditioned (even honed / new rings) power is back up. Why?

Because the engine now develops better compression. It is more efficient.

THEREFORE.

An engine at 130psi vs 270psi will have a difference in power.

My initial point is that how much different / loss of power is there, I would think at least 10-15% of the potential power delivery then power loss becoming more and more apparent as the graph falls away towards 0psi (or whatever point at which the engine is able to fire / run / idle).

[tinkerbell]

My initial point is that how much different / loss of power is there, I would think at least 10-15% of the potential power delivery then power loss becoming more and more apparent as the graph falls away towards 0psi (or whatever point at which the engine is able to fire / run / idle).

you can't make a "point" that is a question...

it is very confusing if you try to do that..

do you have a point to make? or are you asking a question?

here are some facts:

compression is required for the a/f mix to create power, if it is not compressed enough, it won't explode very well.

compression is also required to "suck" the a/f in and "blow" the burnt a/f out...

so compression is vital for an engine to make power and obviously affects how much power in total is made.

if you want to determine the relationship between compression and power, you could test it, or infer it.

but i would concur with your idea that it is not an arithmetic relationship...

[ewendc2r]

My god .. Symantecs. In any case the relationship is definitely arithmetic, but not linear. Now thats irony. I understand it all perfectly, I was contradicting someone said earlier in the thread about no loss of power within threshold (esp. 130psi - 270psi).

you can't make a "point" that is a question...

it is very confusing if you try to do that..

do you have a point to make? or are you asking a question?

here are some facts:

compression is required for the a/f mix to create power, if it is not compressed enough, it won't explode very well.

compression is also required to "suck" the a/f in and "blow" the burnt a/f out...

so compression is vital for an engine to make power and obviously affects how much power in total is made.

if you want to determine the relationship between compression and power, you could test it, or infer it.

but i would concur with your idea that it is not an arithmetic relationship...

[tinkerbell]

My god .. Symantecs.

yes, and proper use of words.

In any case the relationship is definitely arithmetic, but not linear.

huh?

http://en.wikipedia.org/wiki/Arithmetic_progression

arithmetic = linear

http://en.wikipedia.org/wiki/Geometric_progression

geometric = non-linear e.g. as you said - hyperbolic curve

Now thats irony.

it certainly is!

I understand it all perfectly, I was contradicting someone said earlier in the thread about no loss of power within threshold (esp. 130psi - 270psi).

hmmm, no that person said:

compression pressure doesn't have as much of a effect on power as people think

which is true.

[ewendc2r]

rofl -- jeesus. I thought Arithmetic simply meant maths based.

Learn something every day. Without any figures to point to this is useless, but if you lost 10% power between top of threshold and bottom of threshold surely that is significant? I understand the point above -- That power loss may not be as much as most poeple would think for a given compression drop..

On the same page now? lol.