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Discussion Starter #1
I searched for this but didn't find it.

It is probably different for every motor and depending on other mods but:

How much increase in horsepower will a motor see from (X) amount increase in compression?
 
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I searched for this but didn't find it.

It is probably different for every motor and depending on other mods but:

How much increase in horsepower will a motor see from (X) amount increase in compression?


what kind of compression are we talking about static compression or dynamic compression?
 

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Discussion Starter #3
For Example: From this compression calculator http://www.knology.net/~jediklc/D.htm

the stock A6 has a ratio of 9.1:1
An A6 with different pistons and headgasket has a ratio of 11.7:1

What would be the increase in horsepower?
 

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Brokedick Millionaire
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the only thing that comes to mind was rulle of thumb 3-4% gain in hp AND tq per full point of compression increase.

9.2 to 13.7 compression.......

I'm at 130 whp, that would put me at 148 whp (dynojet) and ported head should bump me to 155-160 whp, it not more!!!!!!!!

My goal of 145-150 whp D15 is not out of line........
 

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Brokedick Millionaire
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torque wins races, hp wins benchraces
 

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Discussion Starter #7
the only thing that comes to mind was rulle of thumb 3-4% gain in hp AND tq per full point of compression increase.

9.2 to 13.7 compression.......

I'm at 130 whp, that would put me at 148 whp (dynojet) and ported head should bump me to 155-160 whp, it not more!!!!!!!!

My goal of 145-150 whp D15 is not out of line........
Alright thanks. I couldn't find this infor anywhere, and didn't know if it was a dumb question.

Is 13.7:1 safe for everyday driving?
 

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Brokedick Millionaire
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Wanna bet?????

Just have to be VERY careful with the tuning......
 

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According to most of the big name tuners, running much over 12:1 on a street engine has diminishing returns. You have to pull so much timing to run pump gas that you'd make the same power with lower compression.
 

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D-series Janitor
Front Engine Dragste
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According to most of the big name tuners, running much over 12:1 on a street engine has diminishing returns. You have to pull so much timing to run pump gas that you'd make the same power with lower compression.
Not quite. Static Compression is like 30% of the equation, if someone tells you just by static compression if you can run pump gas, they probably either don't know what they are talking about or don't feel like taking the time out to know all the parameters first.

Dynamic compression is the actual measure of pressure within the cylinder, only this can tell you if you are within reason to run pump gas.

Valve event timing has a heck of a lot more to do with pressure than static compression does.
 

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Feel free to take it up with them. I suspect they're the top tuners in the nation for a pretty good reason. :)

edit:
I wasn't going to say anything else because I know what's going to happen, but whatever. Check out the WD-40 shoot out. You'll notice that not one of those professionals is building an engine with more than 11.5:1 static compression, so they can run on Cali 91 octane. Dynamic compression is most certainly the best measure of a running engine and valve timing events can most certainly change that. Going by prevailing logic you can 17:1 static as long as your cam is big enough to keep your dymanic under 9.5:1. In reality, this isn't true. You'll have to pull a significant amount of timing to make the engine run properly on pump gas. This is one of the many reasons why high compression race engines don't use the same gas that we use.
 

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I been runing 13:1 cr for almost year. With a crappy tune on pump gas.

When my rods and pistons get here, I'll be runing 14:1 on race gas and a crappy tune.
 

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Black Dynamite
1991 HONDA Civic
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the only thing that comes to mind was rulle of thumb 3-4% gain in hp AND tq per full point of compression increase.

9.2 to 13.7 compression.......

I'm at 130 whp, that would put me at 148 whp (dynojet) and ported head should bump me to 155-160 whp, it not more!!!!!!!!

My goal of 145-150 whp D15 is not out of line........

gohead mr. bone
 

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Brokedick Millionaire
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According to most of the big name tuners, running much over 12:1 on a street engine has diminishing returns. You have to pull so much timing to run pump gas that you'd make the same power with lower compression.
screw the tuners, talk to the engine builders..........

Have you read who won the lastest Engine Masters build-off?????

http://www.popularhotrodding.com/enginemasters/challenge/2006/0610em_challenge_results_friday/

Wanna guess who's been helping me?????

Next week Tony's moving his shop to St. Leon, IN......needed more room.
 

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screw the tuners, talk to the engine builders..........

Have you read who won the lastest Engine Masters build-off?????

http://www.popularhotrodding.com/enginemasters/challenge/2006/0610em_challenge_results_friday/

Wanna guess who's been helping me?????

Next week Tony's moving his shop to St. Leon, IN......needed more room.
I prefer to stay with Honda engine builders and tuners. It amazing who you can talk to on Honda-Tech.

Rage Racing/Whitfield Tuning
Church's Tuning
RLZ Engineering
Rocket Motorsport
Don Flores
etc.

Seriously, hit the All-Motor forum over there and start asking those guys what they think of high compression in anything other than a race engine. They'll all tell you to run less than 12:1 and get a quality port and polish...for a street engine.
 
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