compression ratio ??????

lexforlife · 11-19-2009, 05:32 AM

boostlogic , i need this question answered please

i currently am using your 2.5 mm hg for approx alittle over 2yrs. also used are arp headstuds ( i have a alum rad using a 19psi cap)

i think i might have a compromised head gasket.... under full 23psi sustained highway driving boost , my car tends to push some coolant into my overflow res and depending how long i have been driving on the hwy the overflow gets alittle to full so it spits some out of the overflow tube and ends up on my engine.

now heres the twist, i can drive locally for weeks on end , on and off short spurts (like 1/4 to 1/2 mile jaunts) and not really have much of any coolant pushed into res , i check my rad every few days and its full , i have done the test for hydro carbons in rad and we came up negative, compression test was around 155psi on every cyl on hot motor and over 160psi on cold motor..

whats your take on this scnerio , could i be getting very slight head lift under heavy sustained boost or is it possible the headgasket might be compromised near a water jacket whereby its pressurizing the cooling system

lastly , can boostlogic once and for all clear up the misnomer about what the expected compression ratio is using your 2.5mm hg on a ge setupand what the expected ratio would be using a 2mm hg

kamiraa · 11-19-2009, 08:54 AM

what fuel are you doing this 23 psi on? What ecu? you may be running to much timing for the boost your running and pushing the head up.

motor sounds healthy compression wise though.

lexforlife · 11-19-2009, 09:39 AM

Quote:

Originally Posted by kamiraa

what fuel are you doing this 23 psi on? What ecu? you may be running to much timing for the boost your running and pushing the head up.

motor sounds healthy compression wise though.

23psi on 93 oct on full aem tuned by alpha . tune is very safe although i do need to have a clean up tune done since taking care of boost leaks and stuff after the initial tune

egt's on full hwy pull stay around 1350f to 1400f tops so timing is not bad

suprareyrey · 11-19-2009, 10:19 AM

Where is your coolant reservoir located?

lexforlife · 11-19-2009, 12:20 PM

Quote:

Originally Posted by suprareyrey

Where is your coolant reservoir located?

My res is located up front mounted just above intercooler in stock location

racing fan · 11-19-2009, 05:32 PM

I replied to your PM sir.

lexforlife · 11-19-2009, 07:06 PM

Quote:

Originally Posted by racing fan

I replied to your PM sir.

thanks for the answer sir

i have some ttc cams to put in so i think i am going to try and retorque head and see .. it doesnt cost me to try for i do my own labor

if does not work i will order a new gasket from you okay

so when surface material is removed it actually raises compression

racing fan · 11-19-2009, 07:47 PM

Quote:

Originally Posted by lexforlife

so when surface material is removed it actually raises compression

Correct

Mark Conte · 11-20-2009, 09:19 AM

Quote:

Originally Posted by lexforlife

23psi on 93 oct on full aem tuned by alpha . tune is very safe although i do need to have a clean up tune done since taking care of boost leaks and stuff after the initial tune

egt's on full hwy pull stay around 1350f to 1400f tops so timing is not bad

Fixing boost leaks and doing highway pulls without any tuning in between can be dangerous...especially on pump fuel.

lexforlife · 11-20-2009, 10:14 AM

Quote:

Originally Posted by Mark Conte

Fixing boost leaks and doing highway pulls without any tuning in between can be dangerous...especially on pump fuel.

i hear ya but alpha has car tuned well and i have read him the settings and boost is very very safe in fact too safe , but a clean up tune will maximize the power potential .. a/f are rich in the high 10's and timing was set somewhat conservative from the start anyways

Mark Conte · 11-20-2009, 11:13 AM

What is "too safe" on 23psi and pump fuel out of curiousity?

lexforlife · 11-20-2009, 12:44 PM

Quote:

Originally Posted by Mark Conte

What is "too safe" on 23psi and pump fuel out of curiousity?

alpha knows and car has been running that way since oct 2008

maybe i need to take out the "too safe " verbiage and say running okay for now hows that

remember i am on that thick 2.5mm hg so i have run abit more boost to make the power

FrgMan251 · 11-23-2009, 03:28 PM

Are you using 1/2 inch headstuds or OEM size? I was going to upgrade to ARP head studs when I re-built my motor and head but, was told not to unless I was going to use L19's or 1/2 inch. Apperently the OEM size ARP's stretch and will cause the nuts to come loose over time.

lexforlife · 11-24-2009, 08:12 AM

Quote:

Originally Posted by FrgMan251

Are you using 1/2 inch headstuds or OEM size? I was going to upgrade to ARP head studs when I re-built my motor and head but, was told not to unless I was going to use L19's or 1/2 inch. Apperently the OEM size ARP's stretch and will cause the nuts to come loose over time.

standard headstuds , i am installing my cams sat so i am going to recheck trq values on the headstuds , i kinda hope 1 or 2 are loose so i dont have to replace for now until i am ready to swap in a gte shortblock

FrgMan251 · 11-24-2009, 02:04 PM

Yeah replacing a head gasket would suck. Good luck to you man.

11-19-2009, 05:32 AM	#1
lexforlife SupraForums Member Join Date: Oct 2003 Location: ft lauderdale Posts: 1,135	compression ratio ?????? boostlogic , i need this question answered please i currently am using your 2.5 mm hg for approx alittle over 2yrs. also used are arp headstuds ( i have a alum rad using a 19psi cap) i think i might have a compromised head gasket.... under full 23psi sustained highway driving boost , my car tends to push some coolant into my overflow res and depending how long i have been driving on the hwy the overflow gets alittle to full so it spits some out of the overflow tube and ends up on my engine. now heres the twist, i can drive locally for weeks on end , on and off short spurts (like 1/4 to 1/2 mile jaunts) and not really have much of any coolant pushed into res , i check my rad every few days and its full , i have done the test for hydro carbons in rad and we came up negative, compression test was around 155psi on every cyl on hot motor and over 160psi on cold motor.. whats your take on this scnerio , could i be getting very slight head lift under heavy sustained boost or is it possible the headgasket might be compromised near a water jacket whereby its pressurizing the cooling system lastly , can boostlogic once and for all clear up the misnomer about what the expected compression ratio is using your 2.5mm hg on a ge setupand what the expected ratio would be using a 2mm hg __________________ 1997 sc 300 NA-T black/custom tan int,AEM TUNED by Alpha 561@21psi pump 600@24psi vp103 mix auto couture body kit ,t67 dbb .81 a/r,TTC 268 cams,Brian crower springs/retainers,2.5mm boostlogic headgasket, boostlogic down pipe,boostlogic manifold,tial 44mm WG,r154 soarer 5sp,act stage 3 clutch, lsd 3.77 diff, tial 50mm blowoff,rc eng 750cc injectors,walbro intank , Bosch 044 inline,FSM Fuel rail,HKS DLI,mishimoto 3row rad,Megans coilover,daizen sways,&swiss 20x9/20x11,rotora 6piston frnt 4piston rear 355mm

11-19-2009, 05:32 PM	#6
racing fan SupraForums Manufacturer Join Date: Mar 2001 Location: Austin, Texas Posts: 3,261	I replied to your PM sir. __________________ -zohair jaffery http://www.boostlogic.com 11906-B Anderson Mill Rd Austin, TX 78731 512-371-9960 zohair@boostlogic.com

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11-19-2009, 08:54 AM	#2
kamiraa Engmaineer Join Date: Dec 2007 Location: Chicago / Houston Posts: 1,877	what fuel are you doing this 23 psi on? What ecu? you may be running to much timing for the boost your running and pushing the head up. motor sounds healthy compression wise though.

11-19-2009, 10:19 AM	#4
suprareyrey Finally finished Join Date: May 2005 Location: miami Age: 31 Posts: 1,564	Where is your coolant reservoir located?

11-20-2009, 11:13 AM	#11
Mark Conte First Team All-Galaxy Join Date: Jan 2002 Location: Florida Posts: 4,244	What is "too safe" on 23psi and pump fuel out of curiousity?

11-23-2009, 03:28 PM	#13
FrgMan251 SupraForums Member Join Date: Oct 2007 Location: San Diego Age: 27 Posts: 180	Are you using 1/2 inch headstuds or OEM size? I was going to upgrade to ARP head studs when I re-built my motor and head but, was told not to unless I was going to use L19's or 1/2 inch. Apperently the OEM size ARP's stretch and will cause the nuts to come loose over time.

11-24-2009, 02:04 PM	#15
FrgMan251 SupraForums Member Join Date: Oct 2007 Location: San Diego Age: 27 Posts: 180	Yeah replacing a head gasket would suck. Good luck to you man.