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Discussion Starter · #1 ·
I am curently having my block sleeved...Was thinking about JE 10.5:1, since I have K-Pro (currently 12PSI map)...Not sure what I might boost after 3 bar map...I here 10.5:1 is harder to tune, is this true? Does it matter with K-Pro? What is the max on JE 9:1 and 10.5:1 pistons? Just looking for max HP at 12PSI, for now :)

Thanks for any advice...
 

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what i dont understand is why you would get your block sleeved and then only run 12 psi. with 9:1 your car will be very sluggish without boost. you will get more power at 12 psi with the 10.5:1 pistons, but if you decide to up the boost later with the 10.5:1 pistons you will need to run lots of fuel. I see you have 750 injectors, so that should be no problem. i would say not to go with the 9 pistons. where are you in texas?
 

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Modeman said:
I am curently having my block sleeved...Was thinking about JE 10.5:1, since I have K-Pro (currently 12PSI map)...Not sure what I might boost after 3 bar map...I here 10.5:1 is harder to tune, is this true? Does it matter with K-Pro? What is the max on JE 9:1 and 10.5:1 pistons? Just looking for max HP at 12PSI, for now :)

Thanks for any advice...
Unless you are someday planning on running 30 PSI, you should consider the 10.5:1... It shouldn't be any more difficult to tune, but you will make more power. You wil also be happier with your car's off boost characteristics.

See ya,
JMS
 

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Discussion Starter · #4 ·
Yes, Texas...I would like to boost higher, however K-Pro only maps to 12PSI...29PSI on way...Plus daily driver, sleeves should give me more piece of mind...What PSI would be reasonable with 10.5:1?

JMShipp2, you are the Honda Tech with all the experience, yes?
 

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Discussion Starter · #5 ·
types03 said:
where are you in texas?
Sorry, Abilene...tune in Dallas...Bit daft this afternoon :p
 

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9:1 compression would be the safest way to go if you want to boost high. Even Porsche runs a mild compression in the 911 turbo just to be safe, and their crankcase was developed turbo-specific.

If you have high octane gasoline all the time, then running a higher compression would be ok. But you will still have to deal with the tremendous amount of heat that's being generated.
 

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Modeman said:
Yes, Texas...I would like to boost higher, however K-Pro only maps to 12PSI...29PSI on way...Plus daily driver, sleeves should give me more piece of mind...What PSI would be reasonable with 10.5:1?

JMShipp2, you are the Honda Tech with all the experience, yes?

With 10:5:1 I wouldn't go higher than 15 psi on pump gas, even that could be dangerous. With race gas you could up the boost a bit more. 10:5:1 running 18-20 psi on race gas, that would be sick power (still might go boom tho). You have a sleeved block so that makes it a bit safer, but that's not gonna stop you from melting a piston. I wish someone would make 9:5:1 pistons for our car. I don't want to have to go all the way down to 9:1.
 

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So will the 9:0:1 pistons from JE will be an overkill for someone just wanting to boost 15-18 psi daily?? should the 10:5:1 be better?
 

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zulusTypeS said:
So will the 9:0:1 pistons from JE will be an overkill for someone just wanting to boost 15-18 psi daily?? should the 10:5:1 be better?

No, 9:1 would be the right way to go for a daily driver at that psi... 15 psi would be the max on pump gas running 10:5:1 IMHO. Race gas like c16 allows you to run higher boost levels because it decreases detonation because it burns slower. With race gas you could probably go up to 18psi or so on a 10:5:1 motor, but that shit is expensive ($9+ per gallon in CT). I would say 12psi would be relatively safe for a 10:5:1 motor.
 

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zulusTypeS said:
So will the 9:0:1 pistons from JE will be an overkill for someone just wanting to boost 15-18 psi daily?? should the 10:5:1 be better?

You do not need to lower your CR to 9.0:1, this is old school logic... Vehicles with CR's this low have very poor throttle response and off boost drivability. Since this is a daily driver, these things are going to matter to you.

With proper tuning, (since you are a K-Pro user, this may be achieved) you can run the 10.5:1 pistons and be just fine all the way up to about 18 lbs. on Sunoco 94 octane. I know several people out there who are running 18 lbs. and higher on stock B16's, and do not need to run race fuel. They just have very carefully tuned cars.

I personally ran 18 lbs. all day long with my Si on it's stock B16 and put almost 28,000 miles on the engine under boost, before it was stolen.

Do a little research, and you will find that the shape and design of the pistons can often play more of a role in preventing detonation than CR can. In fact "squish volume" or the area around the rim of the combustion chamber can play one of the biggest roles in preventing detonation. A Honda’s combustion chamber is designed to push the air charge toward the center of the piston as it achieves top dead center. This design aides in eliminating spent gases and keeping charge turbulences high. A poorly designed 8:1 piston will often actually ping worse than a well designed 11:1 piston. One company that recognizes this effect on combustion is Endyn.

Take a look at the Roller Wave Pistons: Endyn's roller wave pistons

Unfortunately, there is no current offering in this line for the K motors, but I would bet we will see them soon.

Also, Cam Angles will play largely on detonation, because the amount of Cam overlap affects both effective CR and the amount of spent gases allowed to re-enter the intake cycle. Once again, another huge advantage to K-Pro.

Now, if you get yourself an electronic boost controller, you can install the higher CR pistons, and run lower boost levels while you run around town and may not have access to good fuel, and the days you feel like driving like an ass, pick up some race fuel, and turn it up!!!

You will have a blast.

If you would like more detail on the science behind all of this, let me know.

Just remember, OEMs often use lower CR to compensate for the generic ECU tunes they use and to effect vehicle emissions. When you are at the point where you are in this game, performance and reliability is really what matters.. You killed your cars emissions rating long ago.

See ya,
JMS
 

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Discussion Starter · #11 ·
great info...I would love any additional detail, links, thoughts...

Thanks for the help!
 

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JMShipp2 said:
You do not need to lower your CR to 9.0:1, this is old school logic... Vehicles with CR's this low have very poor throttle response and off boost drivability. Since this is a daily driver, these things are going to matter to you.

With proper tuning, (since you are a K-Pro user, this may be achieved) you can run the 10.5:1 pistons and be just fine all the way up to about 18 lbs. on Sunoco 94 octane. I know several people out there who are running 18 lbs. and higher on stock B16's, and do not need to run race fuel. They just have very carefully tuned cars.

I personally ran 18 lbs. all day long with my Si on it's stock B16 and put almost 28,000 miles on the engine under boost, before it was stolen.

Do a little research, and you will find that the shape and design of the pistons can often play more of a role in preventing detonation than CR can. In fact "squish volume" or the area around the rim of the combustion chamber can play one of the biggest roles in preventing detonation. A Honda’s combustion chamber is designed to push the air charge toward the center of the piston as it achieves top dead center. This design aides in eliminating spent gases and keeping charge turbulences high. A poorly designed 8:1 piston will often actually ping worse than a well designed 11:1 piston. One company that recognizes this effect on combustion is Endyn.

Take a look at the Roller Wave Pistons: Endyn's roller wave pistons

Unfortunately, there is no current offering in this line for the K motors, but I would bet we will see them soon.

Also, Cam Angles will play largely on detonation, because the amount of Cam overlap affects both effective CR and the amount of spent gases allowed to re-enter the intake cycle. Once again, another huge advantage to K-Pro.

Now, if you get yourself an electronic boost controller, you can install the higher CR pistons, and run lower boost levels while you run around town and may not have access to good fuel, and the days you feel like driving like an ass, pick up some race fuel, and turn it up!!!

You will have a blast.

If you would like more detail on the science behind all of this, let me know.

Just remember, OEMs often use lower CR to compensate for the generic ECU tunes they use and to effect vehicle emissions. When you are at the point where you are in this game, performance and reliability is really what matters.. You killed your cars emissions rating long ago.

See ya,
JMS

Don't you think 18psi on a 10:5:1 motor is pushing the envelope?? I agree that these pistons will offer superior driveability. I just don't know about running 18psi daily on pump gas (even 94, which most of the country can't get anymore). But I still think that if you wanted to run 18psi daily, a lower CR should be used. Granted the k-series motor has proven, thus far, that it can handle the demands of a turbo or sc application, and there is even one car that was managing 14psi daily on stock internals, but I would want to see more extensive testing done with 10:5:1 before I ran 18psi daily. However, your alternative, which you would run lower boost for daily driving and then crank up the boost using a boost controller and race gas, I agree with completely. As a matter of fact this is the route I have been contemplating since JE released the 10:5:1 pistons. I also plan on switching over to hondata so that the car can be properly tuned (I'm with you there for sure). I've read many of your posts, and i just don't understand why people don't understand the importance of cam and ignition timing, and that tuning is so much more than a safe a/f ratio.
 

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Discussion Starter · #13 ·
At this point I just want to be safe...I will leave the records to XCELL...I drive like a old man, most days, never over 3k rpm in any gear...This just got out of hand when I lost a piston ring on stock...Hondata tuned it ok...334whp @ 8PSI before the ring went...was sure 8PSI would be fine...Shop expect 370-380 @ 12PSI...I hear at around 400, Axel and other issues come in to play? What kind of times would you get on street tires (quaife LSD installed now)...??? Goal was kinda to run with SS or Vet...???
 

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Modeman said:
At this point I just want to be safe...I will leave the records to XCELL...I drive like a old man, most days, never over 3k rpm in any gear...This just got out of hand when I lost a piston ring on stock...Hondata tuned it ok...334whp @ 8PSI before the ring went...was sure 8PSI would be fine...Shop expect 370-380 @ 12PSI...I hear at around 400, Axel and other issues come in to play? What kind of times would you get on street tires (quaife LSD installed now)...??? Goal was kinda to run with SS or Vet...???
With 370-380 whp on street tires you would probably pull low 13's high 12's with a ridiculous mph (116 or better). From a roll you should own an ss or a vet unless it's pretty modded... From a dig you should be able to reel them in. Its so much fun chasing down a V8 and passing them like they were standing still.
 

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Discussion Starter · #15 ·
TRICKY912 said:
With 370-380 whp on street tires you would probably pull low 13's high 12's with a ridiculous mph (116 or better). From a roll you should own an ss or a vet unless it's pretty modded... From a dig you should be able to reel them in. Its so much fun chasing down a V8 and passing them like they were standing still.
This should be interesting anyway, still have not adjusted to 265whp...how do you stop your wheel spin? What do you launch at? I see most "feather" out the clutch, however, views on launch rpm are all over the place?

BTW...Thanks for all this info... :thumbsup:
 

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Modeman said:
This should be interesting anyway, still have not adjusted to 265whp...how do you stop your wheel spin? What do you launch at? I see most "feather" out the clutch, however, views on launch rpm are all over the place?

BTW...Thanks for all this info... :thumbsup:
No problem man... You can't stop wheelspin in a fwd car that makes power with out slicks and some suspension tweeking. I launch at about 4k and slip the clutch pretty hard, you have to controll the wheelspin with the throtle. Its ok to spin as long as you are going somewhere, once you start to get wheel-hop, bang second, the car should hook fairly well without much spin... then you're on your way. I haven't mastered this yet, but my cousin, is awsome at lauching fwd cars. He pulled a 2.1 60 the 1st time he drove my car, with crappy tires and without lowering the tire pressure. He used to beat awd cars out of the hole with bfg drag radials when he had his gst. He was pulling 1.8 60's in a fwd car without slicks. Thats incredible.
 

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The lower the static compression the easier the tune. However, low end torque suffers if static compression ratio is too low.

The 10.5:1 would be a far cry tuning wise from tuning the 11.0:1 CR slugs in the stock bottom end. Trust me...it would be a great advantage to lower static compression the mere .5 . If you planed on staying mild with the boost pressures, say 12-18psi you would have a monster. The tune would be critical, but no more critical than it is running the Greddy kit at 8psi with stock bottom end. It's already a ignition timing dance to get everything perfect. 10.5:1 would be a good move if you were cool with staying mild...and your part throttle charactaristics would be very nice.

Plan on running more boost than stated above? 9.0:1 is the only way. With sleeves and 9.0:1 static CR, you will be able to run a lot of boost 25+psi (provided good forged connecting rods were installed). Not to mention you will be able to run ALOT of ignition timing, which will allow for lots of on boost power.

Tune for 100+octane with either set-up and you will be able to make some really serious numbers.

Here is a good calculation for you:

Static Compression + boost pressure = effective compression.

Stock K20A2 bottom end:
If you are running 10 PSI of boost at an altitude of 0 feet. Your motor's static compression is 11.0 :1. At this boost level and altitude your effective compression ratio is -18.48 :1, and without altitude correction your compression ratio would be 18.48 :1.

K20A2 with 10.5:1 static compression pistons:
you would have to run 11.1psi to acheive the same effective compression as the 11.0:1 static CR engine @10psi.

K20A2 with 9.0:1 static compression pistons:
You would have to run 15.4psi to acheive the same effective CR as the 11.0:1 static CR engine @10psi.


Remember that the lower the static compression, the more ignition timing can be advanced...the detonation threshold is much higher with the lower static CR's than with the high static CR. High static CR causes high cylinder temps and pressures just by static compression alone. This makes it harder for ignition timing to be introduced due to the low detonation threshold of the high static compression engine.

Just thought i would offer this info up. This is a hard decision i am about to make myself, next month. :)
 

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Also, you have to remember that Effective Compression Ratios only tell half the story. The other half is decided by things like combustion chamber charactaristics, turbine size and piston design, ect.......

Say if you ran 9.0:1 pistons at 15.4psi. You would be able to make a considerable amount of power over the 11.0:1 pistons at 10psi even though they have the same effective CR. The reason being is the ability to run alot more ignition timing. So, peak WHP would see great gains, but low end torque and part throttle conditions would suffer greatly.
 

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running 10.5:1 compression is fine at 18 psi on pump gas. it is all about tuning and having enough fuel. the hondata and the aem that are coming out have the abilities to do such a thing. i just would not trust the black magic for that though. i run 14 psi on a stock motor and have been four over four months daily with no problems at all
 

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Modeman said:
This should be interesting anyway, still have not adjusted to 265whp...how do you stop your wheel spin? What do you launch at? I see most "feather" out the clutch, however, views on launch rpm are all over the place?

BTW...Thanks for all this info... :thumbsup:

BTW, if your car still looks like the sig picture, I realy like it!!! It looks very "plain" but that is good, It makes an exciting sleeper... The only thing I would suggest you consider doing, is adding SwainTech's stealth coating to your intercooler. Not only would it hide that monster box in the front of your car, it will actually increase the item's efficiency ratings.

See ya,
JMS
 
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