DOHC head and compression

FlashBlueRS · 11/18/2006, 02:42 PM

I was curious about the compression ratio with the new head on my car, so I crunched some numbers and found something very interesting. The head increases the stock 9.5:1 CR to about 10.2:1, maybe slightly more. A .7 jump is pretty good without touching the pistons. This worked out great for me, but FI guys will need to take this into consideration when doing the head swap.

buckethead · 11/18/2006, 03:24 PM

Great to know. eRep for you.

Dman88 · 11/18/2006, 05:07 PM

how much did it cost you?

DNS-EN · 11/18/2006, 05:17 PM

I'll let you know the exact cc of the head next week.

FTG · 11/20/2006, 07:30 AM

isnt the stock compression 9.0.....

FlashBlueRS · 11/20/2006, 09:38 AM

Just double checked it in the service manual, it's 9.5.

FTG · 11/20/2006, 05:52 PM

is it possible that there are different compression ratings for different years??? i wouldn't think so as long as it was still the 4g64

I am going to check the manual when i get home but here are 4 websites that say its 9.0

http://www.internetautoguide.com/car...788/index.html

http://www.automotive.com/2002/101/m...ons/index.html

http://www.automobilemag.com/am/2002...fications.html

http://www.automallusa.net/2002/mits...fications.html

the official website isn't working but that says 9 too...

i dont know anyone done a compression test to know exactly

FlashBlueRS · 11/20/2006, 07:56 PM

I'm just reading what the official mitsubishi service manual says. Doesn't matter anyway. The stock compression isn't even used when determining the compression with the DOHC head. The final compression ratio with the head swap is still in the 10.2 range.

mozart4898 · 11/20/2006, 08:02 PM

I think the reason that FTG is as concerned as he is, is because he's having his N/A 4 cylinder build done with 9.6:1 compression ratio pistons. While the difference between 9.0 and 9.6 isn't all that much, it is more than the difference between 9.5 and 9.6.

FlashBlueRS · 11/20/2006, 08:17 PM

I understand. I'm familiar with his thread. But, further discusion of that needs to be done in there.

mozart4898 · 11/20/2006, 08:24 PM

Yes, agreed. I have to say myself though too I was surprised to hear that the stock compression is 9.5. The raised compression from the head swap sounds like a nice thing for those who have done it on a N/A car...but yeah, that's a possible issue for those with FI.

Damn, I wish such a swap was possible on the V6.

00TampaBlueGS · 11/21/2006, 07:34 AM

An interesting side-effect of the head swap, to be sure!
Thanks for the info, flash. I'd like to hear your input on the thread I just created: http://www.club3g.com/forum/3g-eclipse-rs-gs-specific/78215-tampablues-eclipsed-evo-project-phase-1-dohc-research-post1868864.html

.... I plan to do the head swap about a year from now, and I'm logging my research.
I'd love for you guys to contribute... particularly the apparent "pioneer", DNS-EN. I'm sure PharmEcis and many others on here have tons of knowledge and trivia they could add, too...

DNS-EN · 11/22/2006, 10:32 AM

The kia dohc has a 56cc chamber. I'll have some pics of my head later today.

DNS-EN · 11/22/2006, 05:04 PM

The head swap actually lowers compression from 9.5:1 to 8.5:1 the stock head chamber size on the sohc is 47cc the kia dohc is 56cc

FlashBlueRS · 11/24/2006, 12:07 AM

I left piston height constant between the eclipse and optima motors when I calculated compression. This skewed my results because they are different. Once DNS gets the exact chamber size of the sohc motor, we will know for sure.

goosey2099 · 01/04/2007, 08:08 AM

Hey did anyone figure this out for shure??

malachi · 01/04/2007, 03:14 PM

the 4g64 has a 9.0 to 1

the 4g69 has ths 9.5 to1

is there a way to gauge the compression?

DNS-EN · 01/04/2007, 04:24 PM

Quote:

Originally Posted by goosey2099

Hey did anyone figure this out for shure??

goosey2099 · 01/04/2007, 06:24 PM

yeah, whats the actual compression with the kia head?

malachi · 01/04/2007, 09:03 PM

well lets figure it out, we know the CC of each head, kia, eclipse, and evo, all we need is the volume when the piston is at the bottom, anyone know this?

DNS-EN · 01/05/2007, 12:04 AM

Quote:

Originally Posted by malachi

well lets figure it out, we know the CC of each head, kia, eclipse, and evo, all we need is the volume when the piston is at the bottom, anyone know this?

I already posted the figures not my problem if you don't like the answer.

malachi · 01/05/2007, 05:28 PM

Quote:

Originally Posted by DNS-EN

I already posted the figures not my problem if you don't like the answer.

well then post up some numbers, and equations, and where you got your information from.

PS the sky is green, you dont like it tuff. prove your answer.

DNS-EN · 01/05/2007, 06:57 PM

Quote:

Originally Posted by malachi

well then post up some numbers, and equations, and where you got your information from.

PS the sky is green, you dont like it tuff. prove your answer.

Ok just be a lazy asshole and you will never know. I already gave you the only piece of information that is not readily available. The equation looked like this.

(syringe + oil) * plexiglass/w small hole drilled in top = actual cc of head

DNS-EN · 01/05/2007, 06:59 PM

Quote:

Originally Posted by DNS-EN

Ok just be a lazy asshole and you will never know. I already gave you the only piece of information that is not readily available. The equation looked like this.
(syringe + oil) * plexiglass/w small hole drilled in top = actual cc of head

BTW I don't have to prove my answer your the only one saying I'm wrong you prove yours I really don't give a shit.

malachi · 01/05/2007, 07:38 PM

Quote:

Originally Posted by DNS-EN

Ok just be a lazy asshole and you will never know. I already gave you the only piece of information that is not readily available. The equation looked like this.

(syringe + oil) * plexiglass/w small hole drilled in top = actual cc of head

BTW I don't have to prove my answer your the only one saying I'm wrong you prove yours I really don't give a shit.

REALLY! and what answer would i be proving right? I did not say you were wrong! i want you to prove the compression RATIO, weither its 9 to 1, 9.5 to 1, 9.6 to 1, 10 to 1.

and i am not an asshole, i am an engineer, and i have to prove all the time, why i say something is the way it is. i am just asking you to show your work on how you got the ratio's

malachi · 01/05/2007, 07:40 PM

Quote:

Originally Posted by DNS-EN

Quote:

Originally Posted by malachi

well lets figure it out, we know the CC of each head, kia, eclipse, and evo, all we need is the volume when the piston is at the bottom, anyone know this?

I already posted the figures not my problem if you don't like the answer.

as you can see, i said we know the CC of each head. i want to know the volume of each chamber so we can use that number and the CC's to get the compression ratio, which is what some one was asking for.

FlashBlueRS · 01/05/2007, 07:43 PM

I wouldn't tell anyone you are an engineer when you can't do this simple problem solving. Critical thinking is very important as an engineer.

All the specs you need are in the service manuals. Everything besides the size of the dish in the piston. Which is where i made my mistake because the pistons are different. Then you need to know how to find the volume of a cylinder. Middle school math.

malachi · 01/05/2007, 08:02 PM

well my good budy, i do not have a service manual. i bought the car used, and also had no floor matts

also did you see my question about that ECU?

FlashBlueRS · 01/05/2007, 08:15 PM

well pal, no cars come with the service manual. It is stickied in the general discussion forum. You are on your own with the your floor mat problem though.

DNS-EN · 01/05/2007, 09:11 PM

Quote:

Originally Posted by malachi

well my good budy, i do not have a service manual. i bought the car used, and also had no floor matts

also did you see my question about that ECU?

Well Mr. Cocknozzle do a search for compression ratio calculators like the rest of us nonengineers.

malachi · 01/06/2007, 10:13 AM

why are you snapping at me man?

Quote:

Originally Posted by goosey2099

yeah, whats the actual compression with the kia head?

this guy wantted to know the actual compression with the kia head, i was just trying to help him out.

and if anyone knows why i am cocknozzled, please let me know, it happend in my forum where i did weight redux. i did nothing to get it.

4g64tpsssst · 01/06/2007, 11:13 AM

i think its because your a cocknozzle just a crazy guess tho

NAPALM · 01/06/2007, 12:02 PM

Why is everyone so hung up on compression ratio?

PharmEcis · 01/06/2007, 02:49 PM

Volume of the cylinder would be 2.4 / 4 right? heh

XwP1ayawX · 01/06/2007, 03:06 PM

Quote:

Originally Posted by NAPALM

Why is everyone so hung up on compression ratio?

Really... who gives a fuck

Bolt it on and fucking tune it. It's the increased volumetric efficiency (Russ

) we're looking for here people

NAPALM · 01/06/2007, 04:07 PM

Quote:

Originally Posted by PharmEcis

Volume of the cylinder would be 2.4 / 4 right? heh

Yep, 600cc.

PharmEcis · 01/06/2007, 04:17 PM

Quote:

Originally Posted by NAPALM

Yep, 600cc.

I was trying to give the other guy his middle school math lesson.

NAPALM · 01/06/2007, 04:22 PM

Quote:

Originally Posted by PharmEcis

I was trying to give the other guy his middle school math lesson.

heh...Im just waiting for someone to get lost in my response due to the highly complex Liters to Cubic cm conversion.

PharmEcis · 01/06/2007, 04:23 PM

Quote:

Originally Posted by NAPALM

heh...Im just waiting for someone to get lost in my response due to the highly complex Liters to Cubic cm conversion.

Yes, so complex it needs nothing done.

NAPALM · 01/06/2007, 04:27 PM

Quote:

Originally Posted by PharmEcis

Yes, so complex it needs nothing done.

Shit, I had to bust out my Ti69234859156 to figure it out.

zeeshan · 02/02/2007, 05:30 AM

you can't figure out compression ratio exactly without using a burette, varsol, and actually measuring it.

as far as i recall the FSM has a mistake in it. it says 9.0:1 and 9.5:1 in a different page which me and napalm clearly showed a while ago.

flashbluers: you're running the stock pistons with the evo head? how'd you get them to clear?

dns-en: so i guess the evo head is quite different from the kia head if the head volume is 56cc? we measured the evo head at a stock 43cc and 41.5cc after we surfaced the head

FlashBlueRS · 02/02/2007, 06:22 AM

Quote:

Originally Posted by xull1x

flashbluers: you're running the stock pistons with the evo head? how'd you get them to clear?

I'm using the kia head

zeeshan · 02/02/2007, 06:25 AM

ah nice, cause there was less than 0.020" clearance on the intake valve when we did a valve to piston clearance with my dished ross pistons for the 4g64 that had no valve pockets in them. so i don't understand how people are running stock pistons with the evo head

FlashBlueRS · 02/02/2007, 06:35 AM

So far, I don't think anyone has bolted an evo head to a stock block.

malachi · 02/02/2007, 09:53 AM

Quote:

Originally Posted by xull1x

ah nice, cause there was less than 0.020" clearance on the intake valve when we did a valve to piston clearance with my dished ross pistons for the 4g64 that had no valve pockets in them. so i don't understand how people are running stock pistons with the evo head

HOLY SHIT!!!! THATS WHAT I AM DOING.

dam, why did i not see this before.

zeeshan · 02/02/2007, 05:33 PM

be careful, i would really suggest you measure the valve to piston clearance on both intake and exhaust valves -- super crucial

chokeX · 02/02/2007, 07:43 PM

Quote:

Originally Posted by NAPALM

Yep, 600cc.

I may be totally wrong, and i haven't really followed the thread but isnt 2.4 the displacement of the engine? not neccessarily the volume of all the cylinders. so if you're using that fact to calculate compressioin guess again

NAPALM · 02/02/2007, 08:21 PM

Quote:

Originally Posted by chokeX

I may be totally wrong, and i haven't really followed the thread but isnt 2.4 the displacement of the engine? not neccessarily the volume of all the cylinders. so if you're using that fact to calculate compressioin guess again

Im not exactly sure what you're trying to say, but it sounds like you may have your brain in the gutter(again).

I never said anything about calculating c/r becuase its kinda pointless beyond a very quick, and rough guesstimate.
But anyway. Yes, Ive always known the 2.4Liters as the volume of the assembled motor, from the top of the piston at BDC to the blocks deck multiplied times four. Which would be exactly the measurement you would need to estimate the c/r.

chokeX · 02/02/2007, 08:39 PM

i was just mentioning that because someone asked about the volume of the cylinders which is different from their displacement.

DNS-EN · 02/03/2007, 02:30 AM

Quote:

Originally Posted by xull1x

you can't figure out compression ratio exactly without using a burette, varsol, and actually measuring it.

as far as i recall the FSM has a mistake in it. it says 9.0:1 and 9.5:1 in a different page which me and napalm clearly showed a while ago.

flashbluers: you're running the stock pistons with the evo head? how'd you get them to clear?

dns-en: so i guess the evo head is quite different from the kia head if the head volume is 56cc? we measured the evo head at a stock 43cc and 41.5cc after we surfaced the head

Yeah the chamber is alot bigger on the kia head and should flow more air especially since I have 272 cams and 1mm oversized valves Also my pistons came in today Ross banodized 8.5:1 the're black dished pistons with the valve reliefs already cut into the pistons.

XwP1ayawX · 02/03/2007, 10:57 AM

Quote:

Originally Posted by malachi

HOLY SHIT!!!! THATS WHAT I AM DOING.

dam, why did i not see this before.

SLAM! Buh bye motor

Anybody know if the cp's give enough clearance?

mysticj · 08/22/2007, 07:56 AM

TDC=Swept Volume(same as BDC) divide by Compression ratio minus 1:

TDC=Swept Volume/(Compression Ratio-1)

Swept volume equals (bore^2)*stroke*(0.7854)]
So swept volume for the 4G64/G4JS is 587.656cc

Since the kia optima has a compression of 10.0:1===>
TDC=587.656/(10.0-1)
=65.295cc

The kia head cc is 56cc so subtract that number from the TDC:
65.295cc-56cc=9.295cc

Now the trick part: gasket volume.
Gasket volume is the same for measuring a volume for a cylinder object:
volume=(pi)*height*(radius^2)

So if 86.5mm=8.65cm/2=4.325cm for radius and height is the gasket thickness. Assuming the gasket thickness is 0.042" is 1.0668mm or 0.10668cm. Volume for the gasket for one cylinder is 6.269cc

Subtract the gasket volume from the remaining TDC:
9.295cc-6.269=3.026cc, assuming the piston to deck height is near or at 0mm.

Since this is a positive number, it indicate that the pistons are dished.

So if anyone considering swapping the optima pistons, the compression ratios are:

4G64 w/SOHC: 11.44:1
4G64 w/Evo DOHC: 12.24:1

And compression ratios with the stock pistons(9.0:1CR):
4G64 w/Kia DOHC: 8.5:1 (Correction: 8.1)
4G64 w/Evo DOHC: 10.0:1(Correction: 9.5)

4g64t · 08/22/2007, 08:18 PM

are the optima pistons really dished i was told they were flat with valve reliefs cut in

Ken · 08/22/2007, 09:35 PM

I still have the bottom end of the optima engine I bought for my DOHC build, so I will double check tomorrow. If anyones interested in the pistons send me a pm.

4g64t · 08/22/2007, 10:00 PM

i have a hyundai sonata engine i got my head off of and the pistons are flat with tiny reliefs cut in

mysticj · 08/22/2007, 10:31 PM

-3 dished piston pretty much look flat

4g64t · 08/23/2007, 12:24 AM

Quote:

So if anyone considering swapping the optima pistons, the compression ratios are:

4G64 w/SOHC: 11.44:1
4G64 w/Evo DOHC: 12.24:1

And compression ratios with the stock pistons(9.0:1CR):
4G64 w/Kia DOHC: 8.5:1
4G64 w/Evo DOHC: 10.0:1

Mysticj i was reading through your first post again and what about optima pistons with the optima head? or was this part "4G64 w/SOHC: 11.44:1" a typo? and meant to be 64 w/kia DOHC?

mysticj · 08/23/2007, 05:26 PM

Yes, the 64 w/kia DOHC...kia pistons with kia head is the same as a stock kia: 10:1cr.

The 4G64 with Optima(G4JS) pistons with the stock 4G64 SOHC head should yield compression around 11.44:1.
The 4G64 with the same kia pistons with an Evo head should yield compression around 12+.

I hope I clear that up from you about swapping the optima pistons into a 4G64.

btw...the cams for the sonata(don't know about the optima) starts off 'okay' and later become shitty...the99-2000 G4JS sonata is 252 intake/262 exhaust with 9.5mm lift on both cams; the 2001-03 has the same intake cam but exhaust has 244 exhaust with 9mm lift and the 2004-05 has 248 intake/exhaust.

I know the jdm evo 8(unsure about the usdm) cams are 260 intake/256 exhaust with 10mm intake and 9.5mm exhaust lift.

4g64t · 08/26/2007, 02:03 PM

isnt the 99-00 a different engine the 3rd gen cars are 01-05 for the optima and sonata

mysticj · 08/26/2007, 07:59 PM

Quote:

Originally Posted by 4g64t

isnt the 99-00 a different engine the 3rd gen cars are 01-05 for the optima and sonata

99-2005 hyundai sonata
00-2005 kia optima

99-2000 sonatas were the year the G4JS was first introduce.

11/18/2006, 02:42 PM	#1 (permalink)
FlashBlueRS Zero Resistance, LLC Join Date: Jan 2003 Location: Charlotte, NC Vehicle: 02 DOHC Eclipse RS Posts: 1,877	DOHC head and compression I was curious about the compression ratio with the new head on my car, so I crunched some numbers and found something very interesting. The head increases the stock 9.5:1 CR to about 10.2:1, maybe slightly more. A .7 jump is pretty good without touching the pistons. This worked out great for me, but FI guys will need to take this into consideration when doing the head swap.

11/18/2006, 03:24 PM	#2 (permalink)
buckethead KD0FIZ Join Date: May 2003 Location: Overland Park, KS Vehicle: '01 GS & '95 GS-T Posts: 1,487	Great to know. eRep for you. __________________ - Doug 2001 Eclipse GS HOBOWARS! EFC Mitsubishi-Forums Evolution M Missouri Mitsubishi

11/18/2006, 05:17 PM	#4 (permalink)
DNS-EN 1st 4cyl DOHC 3G Join Date: Mar 2005 Location: Charlotte Vehicle: SPYDER GS TURBO Posts: 1,434	I'll let you know the exact cc of the head next week. __________________ 2003 eclipse gs spyder @ 15psi evo 8 Turbo 9.8 hotside FMIC fic 550 Injectors 3" downpipe Rear disc conversion Evo carbon fiber hood Innovate LM1 Wideband ECUFLASH Progrmmed E-01 Boost controller/Programmer Manual Trans Swap prothane motor mount kit Tein S Tech Springs Kyb AGX struts

11/21/2006, 07:34 AM	#12 (permalink)
00TampaBlueGS imiTatum Join Date: Mar 2006 Location: Denver, CO Vehicle: 2000 Eclipse GS 5-spd. Posts: 4,367	An interesting side-effect of the head swap, to be sure! Thanks for the info, flash. I'd like to hear your input on the thread I just created: http://www.club3g.com/forum/3g-eclipse-rs-gs-specific/78215-tampablues-eclipsed-evo-project-phase-1-dohc-research-post1868864.html .... I plan to do the head swap about a year from now, and I'm logging my research. I'd love for you guys to contribute... particularly the apparent "pioneer", DNS-EN. I'm sure PharmEcis and many others on here have tons of knowledge and trivia they could add, too... __________________ My Ride, gradually evolving... My ambitious "Eclipsed(EVO)" plans for my GS: PHASE 1 -DOHC research__(n00bish fumblings) First documented AWD 3G_(local inspiration) messing w/ Evo 8 gear____(turbo options) See where I'm going with this? ...right back into debt.

11/22/2006, 10:32 AM	#13 (permalink)
DNS-EN 1st 4cyl DOHC 3G Join Date: Mar 2005 Location: Charlotte Vehicle: SPYDER GS TURBO Posts: 1,434	The kia dohc has a 56cc chamber. I'll have some pics of my head later today. __________________ 2003 eclipse gs spyder @ 15psi evo 8 Turbo 9.8 hotside FMIC fic 550 Injectors 3" downpipe Rear disc conversion Evo carbon fiber hood Innovate LM1 Wideband ECUFLASH Progrmmed E-01 Boost controller/Programmer Manual Trans Swap prothane motor mount kit Tein S Tech Springs Kyb AGX struts

11/18/2006, 05:07 PM	#3 (permalink)
Dman88 Senior Member Join Date: Jun 2006 Location: NY Vehicle: 2001 eclipse GT Posts: 547	how much did it cost you?

11/20/2006, 07:30 AM	#5 (permalink)
FTG Cocknozzle Cocknozzle Join Date: May 2005 Location: West Chester PA Vehicle: 02 Eclipse Gs Posts: 291	isnt the stock compression 9.0.....

11/20/2006, 09:38 AM	#6 (permalink)
FlashBlueRS Zero Resistance, LLC Join Date: Jan 2003 Location: Charlotte, NC Vehicle: 02 DOHC Eclipse RS Posts: 1,877	Just double checked it in the service manual, it's 9.5.

11/20/2006, 05:52 PM	#7 (permalink)
FTG Cocknozzle Cocknozzle Join Date: May 2005 Location: West Chester PA Vehicle: 02 Eclipse Gs Posts: 291	is it possible that there are different compression ratings for different years??? i wouldn't think so as long as it was still the 4g64 I am going to check the manual when i get home but here are 4 websites that say its 9.0 http://www.internetautoguide.com/car...788/index.html http://www.automotive.com/2002/101/m...ons/index.html http://www.automobilemag.com/am/2002...fications.html http://www.automallusa.net/2002/mits...fications.html the official website isn't working but that says 9 too... i dont know anyone done a compression test to know exactly

11/20/2006, 07:56 PM	#8 (permalink)
FlashBlueRS Zero Resistance, LLC Join Date: Jan 2003 Location: Charlotte, NC Vehicle: 02 DOHC Eclipse RS Posts: 1,877	I'm just reading what the official mitsubishi service manual says. Doesn't matter anyway. The stock compression isn't even used when determining the compression with the DOHC head. The final compression ratio with the head swap is still in the 10.2 range.

11/20/2006, 08:02 PM	#9 (permalink)
mozart4898 back to the 3G... Join Date: Mar 2005 Location: Woodville, OH Vehicle: 2001 Eclipse Spyder GT Posts: 1,654	I think the reason that FTG is as concerned as he is, is because he's having his N/A 4 cylinder build done with 9.6:1 compression ratio pistons. While the difference between 9.0 and 9.6 isn't all that much, it is more than the difference between 9.5 and 9.6.

11/20/2006, 08:17 PM	#10 (permalink)
FlashBlueRS Zero Resistance, LLC Join Date: Jan 2003 Location: Charlotte, NC Vehicle: 02 DOHC Eclipse RS Posts: 1,877	I understand. I'm familiar with his thread. But, further discusion of that needs to be done in there.

11/20/2006, 08:24 PM	#11 (permalink)
mozart4898 back to the 3G... Join Date: Mar 2005 Location: Woodville, OH Vehicle: 2001 Eclipse Spyder GT Posts: 1,654	Yes, agreed. I have to say myself though too I was surprised to hear that the stock compression is 9.5. The raised compression from the head swap sounds like a nice thing for those who have done it on a N/A car...but yeah, that's a possible issue for those with FI. Damn, I wish such a swap was possible on the V6.

11/22/2006, 05:04 PM	#14 (permalink)
DNS-EN 1st 4cyl DOHC 3G Join Date: Mar 2005 Location: Charlotte Vehicle: SPYDER GS TURBO Posts: 1,434	The head swap actually lowers compression from 9.5:1 to 8.5:1 the stock head chamber size on the sohc is 47cc the kia dohc is 56cc __________________ 2003 eclipse gs spyder @ 15psi evo 8 Turbo 9.8 hotside FMIC fic 550 Injectors 3" downpipe Rear disc conversion Evo carbon fiber hood Innovate LM1 Wideband ECUFLASH Progrmmed E-01 Boost controller/Programmer Manual Trans Swap prothane motor mount kit Tein S Tech Springs Kyb AGX struts

11/24/2006, 12:07 AM	#15 (permalink)
FlashBlueRS Zero Resistance, LLC Join Date: Jan 2003 Location: Charlotte, NC Vehicle: 02 DOHC Eclipse RS Posts: 1,877	I left piston height constant between the eclipse and optima motors when I calculated compression. This skewed my results because they are different. Once DNS gets the exact chamber size of the sohc motor, we will know for sure.

01/04/2007, 08:08 AM	#16 (permalink)
goosey2099 4G64 5SPD/TURBO Join Date: Aug 2005 Location: NY Vehicle: 2001 Galant Posts: 366	Hey did anyone figure this out for shure?? __________________ 4G64 5 SPEED MY 5 SPEED - MY TURBO BUILD - MY CARPUTER - MY CAR

01/04/2007, 03:14 PM	#17 (permalink)
malachi Senior Member Join Date: May 2004 Location: Louisiana Vehicle: 2000 RS Posts: 1,742	the 4g64 has a 9.0 to 1 the 4g69 has ths 9.5 to1 is there a way to gauge the compression? __________________ stock RS. 16.1 in 1/4 mile car on diet, but still stock = 15.58 2006 FASTEST ECLIPSE RS/GS STOCK 2006 FASTEST ECLIPSE RS/GS N/A 2008 NEW RECORD, RS/GS N/A = 15.2 2009 DOHC + 10psi = 14.0 @ 101.89 MPH 2009 DOHC + 15psi = 13.3 @ 108 MPH

01/04/2007, 06:24 PM	#19 (permalink)
goosey2099 4G64 5SPD/TURBO Join Date: Aug 2005 Location: NY Vehicle: 2001 Galant Posts: 366	yeah, whats the actual compression with the kia head? __________________ 4G64 5 SPEED MY 5 SPEED - MY TURBO BUILD - MY CARPUTER - MY CAR

01/04/2007, 09:03 PM	#20 (permalink)
malachi Senior Member Join Date: May 2004 Location: Louisiana Vehicle: 2000 RS Posts: 1,742	well lets figure it out, we know the CC of each head, kia, eclipse, and evo, all we need is the volume when the piston is at the bottom, anyone know this? __________________ stock RS. 16.1 in 1/4 mile car on diet, but still stock = 15.58 2006 FASTEST ECLIPSE RS/GS STOCK 2006 FASTEST ECLIPSE RS/GS N/A 2008 NEW RECORD, RS/GS N/A = 15.2 2009 DOHC + 10psi = 14.0 @ 101.89 MPH 2009 DOHC + 15psi = 13.3 @ 108 MPH

01/05/2007, 07:43 PM	#27 (permalink)
FlashBlueRS Zero Resistance, LLC Join Date: Jan 2003 Location: Charlotte, NC Vehicle: 02 DOHC Eclipse RS Posts: 1,877	I wouldn't tell anyone you are an engineer when you can't do this simple problem solving. Critical thinking is very important as an engineer. All the specs you need are in the service manuals. Everything besides the size of the dish in the piston. Which is where i made my mistake because the pistons are different. Then you need to know how to find the volume of a cylinder. Middle school math.

01/05/2007, 08:02 PM	#28 (permalink)
malachi Senior Member Join Date: May 2004 Location: Louisiana Vehicle: 2000 RS Posts: 1,742	well my good budy, i do not have a service manual. i bought the car used, and also had no floor matts also did you see my question about that ECU? __________________ stock RS. 16.1 in 1/4 mile car on diet, but still stock = 15.58 2006 FASTEST ECLIPSE RS/GS STOCK 2006 FASTEST ECLIPSE RS/GS N/A 2008 NEW RECORD, RS/GS N/A = 15.2 2009 DOHC + 10psi = 14.0 @ 101.89 MPH 2009 DOHC + 15psi = 13.3 @ 108 MPH

01/05/2007, 08:15 PM	#29 (permalink)
FlashBlueRS Zero Resistance, LLC Join Date: Jan 2003 Location: Charlotte, NC Vehicle: 02 DOHC Eclipse RS Posts: 1,877	well pal, no cars come with the service manual. It is stickied in the general discussion forum. You are on your own with the your floor mat problem though.

01/06/2007, 11:13 AM	#32 (permalink)
4g64tpsssst ASSHOLE! Join Date: Aug 2006 Location: parksley, va Vehicle: 2002 eclipse rs turbo Posts: 479	i think its because your a cocknozzle just a crazy guess tho __________________ http://www.myspace.com/mustangfreak1983

01/06/2007, 12:02 PM	#33 (permalink)
NAPALM OMFG Join Date: May 2003 Location: Southern California Vehicle: Cars Posts: 6,602	Why is everyone so hung up on compression ratio? __________________ Restore The Republic - Home Page Of The Freedom Movement The Federal Reserve is Engineering the Economic Collapse "Something Big is Happening" - Ron Paul America - From Freedom To Fascism The Web of Debt

01/06/2007, 02:49 PM	#34 (permalink)
PharmEcis Resident Asshole Join Date: Sep 2004 Location: Silver Spring, MD Vehicle: 2g stratus 2g eclipse Posts: 4,699	Volume of the cylinder would be 2.4 / 4 right? heh __________________ 01 Stratus R/T Turbo www.2gstratus.org www.ucsperformance.com 240.271.0280 2007 NASA TTR National Champions! 2008 Redline Time Attack Summit Point Unlimited FWD 3rd Place! FIRST PNP AEM EMS! FIRST 3.8L 6G75 MIVEC SWAP IN THE WORLD! I sell custom turbo kits for the 3G. If you are serious about a turbo kit, call the number above.

02/02/2007, 05:30 AM	#41 (permalink)
zeeshan turbo? unf unf! Join Date: May 2004 Location: Milton, ON, Canada Vehicle: rs-t 2003 Posts: 1,955	you can't figure out compression ratio exactly without using a burette, varsol, and actually measuring it. as far as i recall the FSM has a mistake in it. it says 9.0:1 and 9.5:1 in a different page which me and napalm clearly showed a while ago. flashbluers: you're running the stock pistons with the evo head? how'd you get them to clear? dns-en: so i guess the evo head is quite different from the kia head if the head volume is 56cc? we measured the evo head at a stock 43cc and 41.5cc after we surfaced the head __________________ 2005 -- 326whp/339wtq 50 trim, stock motor 13.61 @ 108mph 2006 -- 400whp/400wtq 50 trim, built sohc 12.98 @ 114.7mph 2007 -- gt3582r w/ stock motor, 12.84 @ 116.55mph 2008 -- built 4g64 w/ evo 8 head, gt3582r 2009 -- 3g back to stock (daily driver) + 93 fd rx7 gt35r project

02/02/2007, 06:25 AM	#43 (permalink)
zeeshan turbo? unf unf! Join Date: May 2004 Location: Milton, ON, Canada Vehicle: rs-t 2003 Posts: 1,955	ah nice, cause there was less than 0.020" clearance on the intake valve when we did a valve to piston clearance with my dished ross pistons for the 4g64 that had no valve pockets in them. so i don't understand how people are running stock pistons with the evo head __________________ 2005 -- 326whp/339wtq 50 trim, stock motor 13.61 @ 108mph 2006 -- 400whp/400wtq 50 trim, built sohc 12.98 @ 114.7mph 2007 -- gt3582r w/ stock motor, 12.84 @ 116.55mph 2008 -- built 4g64 w/ evo 8 head, gt3582r 2009 -- 3g back to stock (daily driver) + 93 fd rx7 gt35r project

02/02/2007, 06:35 AM	#44 (permalink)
FlashBlueRS Zero Resistance, LLC Join Date: Jan 2003 Location: Charlotte, NC Vehicle: 02 DOHC Eclipse RS Posts: 1,877	So far, I don't think anyone has bolted an evo head to a stock block.

02/02/2007, 05:33 PM	#46 (permalink)
zeeshan turbo? unf unf! Join Date: May 2004 Location: Milton, ON, Canada Vehicle: rs-t 2003 Posts: 1,955	be careful, i would really suggest you measure the valve to piston clearance on both intake and exhaust valves -- super crucial __________________ 2005 -- 326whp/339wtq 50 trim, stock motor 13.61 @ 108mph 2006 -- 400whp/400wtq 50 trim, built sohc 12.98 @ 114.7mph 2007 -- gt3582r w/ stock motor, 12.84 @ 116.55mph 2008 -- built 4g64 w/ evo 8 head, gt3582r 2009 -- 3g back to stock (daily driver) + 93 fd rx7 gt35r project

02/02/2007, 08:39 PM	#49 (permalink)
chokeX Member Join Date: Mar 2006 Posts: 76	i was just mentioning that because someone asked about the volume of the cylinders which is different from their displacement.

08/22/2007, 07:56 AM	#52 (permalink)
mysticj Senior Member Join Date: Aug 2007 Location: Charlotte, NC Vehicle: Galant GS Posts: 128	TDC=Swept Volume(same as BDC) divide by Compression ratio minus 1: TDC=Swept Volume/(Compression Ratio-1) Swept volume equals (bore^2)stroke(0.7854)] So swept volume for the 4G64/G4JS is 587.656cc Since the kia optima has a compression of 10.0:1===> TDC=587.656/(10.0-1) =65.295cc The kia head cc is 56cc so subtract that number from the TDC: 65.295cc-56cc=9.295cc Now the trick part: gasket volume. Gasket volume is the same for measuring a volume for a cylinder object: volume=(pi)height(radius^2) So if 86.5mm=8.65cm/2=4.325cm for radius and height is the gasket thickness. Assuming the gasket thickness is 0.042" is 1.0668mm or 0.10668cm. Volume for the gasket for one cylinder is 6.269cc Subtract the gasket volume from the remaining TDC: 9.295cc-6.269=3.026cc, assuming the piston to deck height is near or at 0mm. Since this is a positive number, it indicate that the pistons are dished. So if anyone considering swapping the optima pistons, the compression ratios are: 4G64 w/SOHC: 11.44:1 4G64 w/Evo DOHC: 12.24:1 And compression ratios with the stock pistons(9.0:1CR): 4G64 w/Kia DOHC: 8.5:1 (Correction: 8.1) 4G64 w/Evo DOHC: 10.0:1(Correction: 9.5) Last edited by mysticj; 06/17/2008 at 07:30 PM.

08/22/2007, 08:18 PM	#53 (permalink)
4g64t Senior Member Join Date: Jul 2004 Posts: 487	are the optima pistons really dished i was told they were flat with valve reliefs cut in __________________ Brandon - Fully Built 64/63 Galant

08/22/2007, 09:35 PM	#54 (permalink)
Ken Shocker Lite Join Date: Dec 2006 Location: Erie PA Vehicle: 03' Eclipse GS Posts: 1,031	I still have the bottom end of the optima engine I bought for my DOHC build, so I will double check tomorrow. If anyones interested in the pistons send me a pm.

08/22/2007, 10:00 PM	#55 (permalink)
4g64t Senior Member Join Date: Jul 2004 Posts: 487	i have a hyundai sonata engine i got my head off of and the pistons are flat with tiny reliefs cut in __________________ Brandon - Fully Built 64/63 Galant

08/22/2007, 10:31 PM	#56 (permalink)
mysticj Senior Member Join Date: Aug 2007 Location: Charlotte, NC Vehicle: Galant GS Posts: 128	-3 dished piston pretty much look flat