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Is the stock B18C1(new motor) compression 170 or 270psi? It says 270 psi in the Haynes book, but it doesnt make sense since all the other motors(the LS, and civic motors) have about 180psi, but have the same servicible limit at 130psi. My teacher also said that its impossible to have that kind of compression in a gasoline engine.

I've searched, 170psi seems low compared to people, but what my teacher says makes sense. If a B18C1 motor has a stock compression of 270psi, and a stock civic motor(sorry dont kno the engine code) has about 170psi, how could both have the same servicible limit of 130psi.

Is this a misprint in the Haynes book?
 

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no, not a misprint.

my car made over 250psi on the compression test during break in.

10:1 static CR, and well engineered sealing characteristics, make for a high-squeeze motor.

this ain't your dad's muscle-car v8.
 

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10:1 compression ratio on unleaded pump gas! Be careful there, sonny! Sorry, I'll stop talking like I'm from smallblock country.

Just for good measure, the B18B's spec is 199 psi.
 

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my 2000 GSR tested in at 243-240-241-240 or something like that. 270 would be incredible.

now dynamic compression is different. Dynamic compression on a GSR is supposed to be 175. My understanding is that dynamic compression is the average compression the engine goes through on a single stroke. Perhaps someone could elaborate more?
 

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I have a JDM B18C1, I put nothing but premium in it because we have sh*tty gas over here. I regularly put Lucas injector cleaner ever other fill-up, just to keep things clean. I don't really notice that much of a problem with the american gas. What are the octane levels in Japan?
 

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10.6:1 will run on premium gas fine.

people run 12+:1 on pump gas all the time.
 

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So to measure Static compression and dynamic compression, there are different ways? what are the different ways?
 

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Sounds like a very knowledgeable teacher you have there.
 

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that article doesn't explain what he just asked. The article explains dynamic compression as seen by an engine with extreme overlap on the upstoke. there is more to the definition of dynamic compression.

up, cause i'd like to know.

and btw, 270psi is way high. I'll have to check my manual, but if honda says 9.2:1=199psi in the chamber i dont see how an increase of 8% in static compression will bump it another 70psi/35%.
 

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the amount of CR you have to run is not exclusively dependent on what octane pump gas is available. it depends on combustion chamber shape and surface area, mixture motion/flow quality from the IM and headporting, and fuel tuning.

dynamic CR IS related to what was in the article: it depends on the reference denominator of the ratio equation. the denominator is larger during certain points ABDC since you include the head intake ports' & manifolds' runners volume effects with the valves partially open in the reference denominator volume. At these moments, the dynamic CR is at it's lowest during compression (where the detonation risk is at it's greatest).
 

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Weird how C-Speed racing says the optimal B18C compression should be around 200psi.
 

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well they must certainly know more than the people that engineered the motor


just goes to show all the misinformation there is on the web.
 
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