4AG BT with CP High comp piston.. compression 10?

[mafia_staff]

Good day everybody, Recently install CP high comp piston 82mm and it mention compression 12. After the installation and free run I feel something wrong with my engine before mod. Then I try to check the compression by gauge. It shows 10. I ask the mechanic at my installation workshop and they said thats the piston compression design.. Hmm but Im not satisfied. Try to drag test with a few of my friends, and lose.. Am I conned by the workshop? Do you think the mechanic know what he did?

Frustrated guy.. help!

 

[meg_omen]

correct compression?

i think its 2 different things, compression ratio and static compression...
sigh... need to learn more...

 

[bera]

i think for an accurate compression spec you need to measured using a vernier caliper...the formula for calculating it is available here...i pening already looking at the formula and symbols...

Compression ratio - Wikipedia, the free encyclopedia

using compression gauge is by right not the correct way to measure CR accurately...

 

[D7zul]

this is more simple & understandable

Engine compression ratio cc - YouTube

---------- Post added at 09:37 AM ---------- 6 hour anti-bump limit - Previous post was at 09:14 AM ----------

usually, high compression piston looks like this.. its stuck up..

http://www.opfietse.com/mr-racing-static/zuiger.jpg


and low compression piston looks like this.. its dished..

http://www.enjukuracing.com/product_images/v/710/wiseco-piston__23639_zoom.jpg

 

[cuscostrutbrace]

Compression ratio is called static compression,compression test using compression tester gauge is called dynamic compression.Dynamic compression is affected by a few factors and we cant compare compression ratios to dynamic compression directly.

 

[mafia_staff]

So, do you think my mechanic doing the right thing to my engine? feel like being cheated!!!

 

[D7zul]

So, do you think my mechanic doing the right thing to my engine? feel like being cheated!!!

how do ur piston looks like ? stuck up or dished? or flat like a stock piston?

the best way to modify ur car is to do a dyno test before & after the mods..

only that way u can see an increase/decrease in power..

u also can feel the power.. but it depends on how sensitive your feeling is

from my little knowledge about tuning cars.. high comp piston need to use with high cam duration.. only then u can make more power..

just my 2 cents

 

[lkeong88]

Since you changed piston and rebored, did you run in the rings first?

---------- Post added at 01:39 PM ---------- 6 hour anti-bump limit - Previous post was at 01:33 PM ----------

Also did they do honing?

 

[pwhyze]

You need a before and after to compare figures. Still have the old pistons?

 

[meg_omen]

Compression ratio is called static compression,compression test using compression tester gauge is called dynamic compression.Dynamic compression is affected by a few factors and we cant compare compression ratios to dynamic compression directly.

thanks bro...
i've learned a new thing today...

 

[^pomen_GTR^]

yep...the one using gauge is dynamic...not really related to static compression....

perhaps u need to check your bore and ring gap....as well as camshaft pulley adjustment

 

[mafia_staff]

I know the different between high comp piston and low comp piston. Mine is high comp piston and as you know it expensive (hmm feel like pour the money into drain already). In order to make powerful engine, good in torque I need a high compression.. the key word for NA power is HIGH COMPRESSION the original compression suppose around 10.5 and now the compression is 10 (hmm I think even I plug in TURBO I can play boost 1 bar without detonate the engine)... high comp piston with high camshhaft? hmm I think it will bent your valve.. (just my 2 cent, Im also newbie) the engine already running in, piston ring CHECK, after the adjustment of campulley the best compression is 10.. I think either the mechanic use too thick of metal gasket or he do not shave the head, hhmm let say by 2mm? I wish to get 12 or higher than that my engine compression..

 

[mADmAN]

the original compression suppose around 10.5 and now the compression is 10

r u sure ur measurement is correct way to do it? go ask some workshops on how to measure ur current compression ratio and dont be surprised if they tell u they need to use water to get a proper and accurate compression...

also theres the dynamic and static compression thing too


now heres the most important thing... after the high compression pistons.. did u get ur car PROPERLY TUNED? with compression increase dont be surprised ur ignition timing chow...coz thats wat happened to me

before with VAFC and stock B20 bottom got 185whp n 18.8kgmm ... after install high comp pistons... and tuned with VAFC got 186whp n 20kgmm...VAFC no ignition tuning... just a/f ratio...n everytime i go dyno the tuner will say my car engine is very rough... coz the graph is like earthquake graph...

then i got Crome which has a/f and ignition tuning... same setup...just change tuning hardware only... 200whp and 22kgmm. n a much smoother graph too.

if u havent gotten it properly tuned... do it.. then come back n see if theres anything to complain or not...

also, one more thing my sifoo has mentioned before...basically to make proper use of high comp... should get high cams

 

[mafia_staff]

So, what should I do now? open the head back? Is it 10 or 10.5 is normal for NA engine? Hmm had enough money to pour already..

 

[mADmAN]

So, what should I do now? open the head back? Is it 10 or 10.5 is normal for NA engine? Hmm had enough money to pour already..

normal NA engine compression may be different from 1 engine to another...

wat u should do now, is get ur car PROPERLY TUNED. maybe aftermarket management like e-manage with ignition harness or something like that. if got more money then haltech.....n get it PROPERLY TUNED.

i do recommend going onto a dyno to check ur power and a/f first.... n see take a good look at the graph... after that do the management n tuning then u can do a proper comparison.

u have to remember that some mods are not simply a standalone mod... like air filter or exhaust... some mods require supporting mods.. such as high cams require adjustable cam pulleys and tuning. or a dramatic increase in compression requires proper tuning or increase in displacement will require bigger fuel injectors etc etc

the key word for ANY engine has always been tuning.

 

[^pomen_GTR^]

how thick the head gasket? stock gasket? metal gasket more than 1mm??

*do agree that tuning was the most important aspect of high compression....

i forgot which svt or blacktop got knock sensor...it auto retard the ignition if sense knocking so making low power overall to save the engine

 

[mafia_staff]

Currently running on Adaptronic ecu.. dyno test 138 something horsepower.. AFR is Ok.. Hmm either the TUNER is no good or the mechanic is no good

 

[lkeong88]

So your tuner is Kegani? lol

 

[hon_cs]

hmm the dyno result really on the low side base on your current setup. my previous ride in stock form already achieved that. i've heard from my formen last time adaptronic is a bit tricky if the tuner not good enough.

 

[Acoustic]

hmm feel like pour the money into drain already

I feel for you man, but don't worry, and don't give up yet, read more, what's said above are so many and so true, I won't repeat, but give 3 examples to elaborate.

Point 1 - >>>it's a total package
Point 2 - >>>adjustable length control arm (backside of the FF)
OK, you've invested WELL, just hasn't team-it-up well, hence NOT-LOST. read more !!!

Point 3 (final) - >>>HIFI subwoofer
OK OK bad example.

Replace with this example, sure good one. Sensitivity(efficiency) not enough, DIY plug in a second magnet at the backside :) xi xi xi, Sens. up 3dB immediately, lucky :), but then Qts changed, Bl changed, then the suspension Vas also changed, but (what has magnet got anything to do with suspension), cannot be leh, oh yes, but it does ..... so what was a good match with the box become out-of-tune with the box.

OK OK enough, I go sleep. Don't scold me.