PDA

View Full Version : doubling up on head gastkets?



newaccorddriver
09-17-2006, 08:58 AM
so i was talking to elijah and some guy the other day, and they said that its possible to lower my compression ratio by doubling up on the head gaskets. im not sure if its actually safe as i dont want to blow up a motor i spent $1500 on rebuilding, any opinions?

MessyHonda
09-17-2006, 09:35 AM
just get lower compression pistons. some one must have some

A20A1
09-17-2006, 09:47 AM
Are there ones ment to stack on top of each other? Or can you use the stock ones.

I know that too thick a gasket under the carb base can warp the carb. I'm pretty sure it has to do with the gasket construction/material though, not just that the gasket is thicker.

newaccorddriver
09-17-2006, 10:05 AM
i was gonna use the multi-layer steel ones and lower my compression slightly. elijah said its possible, but i have no clue

A18A
09-17-2006, 08:07 PM
ya i dont see why it wont work, you might have a leak with your coolant or oil though, but i dont see why it wont work.

newaccorddriver
09-17-2006, 08:40 PM
ya i dont see why it wont work, you might have a leak with your coolant or oil though, but i dont see why it wont work.


i hope your being sarcastic cause if theres an oil leak or a coolant leak, that would just outright piss me off

A20A1
09-18-2006, 01:41 AM
see there are gaskets out there that interlock... and are ment to stack.

A18A
09-18-2006, 01:44 AM
it still beats puying low compression pistons which would probably cost alot cause they most likely have to be custom. plus installing them.

i think if you tighten the bolts tighter it might seal better? i tightened my head down tighter than what is recommended by the manual cause my head was leaking oil and water, but yet again thats probably cause i have a warped head

A20A1
09-18-2006, 01:57 AM
don't overtighten, I would think that the tightness of the bolts need to allow for the heat expansion of the bolts and gasket and block and head... when everything is hot it will probably add that extra bit of sealing... but if you tighten it too much then there is no extra room for that expansion.

just a thought.

A18A
09-18-2006, 02:11 AM
and also never forget that if the head is off, nothing gets down the bolt holes, especially oil ;) i didnt tighten it like 432765 turns, prolly less then half a turn. no oil leaks now though :D just carb problem o.O

newaccorddriver
09-18-2006, 06:34 PM
so what kind of head gaskets are stackable? OEM ones?

smufguy
09-19-2006, 08:21 AM
u can get OEM or performance OEM spec ones and just stack them. its not gonna drop ur compression a lot, but enough to run safe numbers if that is what you are looking for. Me personally......... I would just lower my compression and run single Head Gasket.

bobafett
09-19-2006, 06:20 PM
cometic makes solid copper gaskets of different thicknesses. i dont know the stock thickness, but i have a .050 uncrushed gasket. they make .070 and other thicknesses too, you would have to call and check with them. :)

AccordEpicenter
09-19-2006, 07:39 PM
umm... exactly why would you want to LOWER compression? 9.3:1 is very boost friendly, as is 9.1:1

And i would NOT reccomend doubling up headgaskets

88Accord-DX
09-19-2006, 07:56 PM
And i would NOT reccomend doubling up headgaskets
The ONLY time I recommend using two headgaskets if you have a warped head & has been shaved to eleminate warpage past the .004 limit ..... (cause there is no money for a new one)

newaccorddriver
09-19-2006, 08:26 PM
umm... exactly why would you want to LOWER compression? 9.3:1 is very boost friendly, as is 9.1:1

And i would NOT reccomend doubling up headgaskets


i guess if 9.3 is boost friendly, then ill probably try and get a thicker head gasket and not double up.

bobafett
09-20-2006, 06:17 AM
*sniff sniff* :(

lol i am running 8.4:1.... NA power, BEGONE! but its all for the cause. i wouldnt probably run 20-30psi on stock compression since i have never tuned before and wouldnt trust myself.

AccordEpicenter
09-20-2006, 08:22 AM
on the built motor im running a stock profile piston, so i should be at around stock compression. There are guys running around with turbo S2000s on stock internals making 600+ hp, and those are 11:1 compression! The problem with boosting cars 10:1 compression and higher is that tuning becomes more critical as does your fuel octane. I agree with sean that lowering the CR is counter productive because you make considerably less power per PSI, so if you left the compression stock, at 13 psi, it might take you 15-17psi to replicate the same power if you lowered it to 8:1... Ive hit as much as 17 psi on my stock engine on pump gas with a conservative tune and the pistons looked fresh when i pulled them, no broken ringlands, even on 13psi all the time. So its a waste to lower your compression if you want to boost, spend your time and money on managemant and a good tune

bobafett
09-20-2006, 10:03 AM
yeah the lower the compression, the more room for error you have on the tune, but the less power you will make per psi, and the less power you will have off boost. you do definetly give up a lot.

if/when i get another motor in the accord a few years down the road, i will be much more comfortable with tuning, and i will probably try a higher compression, like 9:1 or 9.5:1.

jason is right, with a reasonably good tune, 9.3:1 is totally safe. just make sure you keep your tune in check.

rjudgey
10-17-2006, 11:37 PM
You can get copper gaskets made from a thicker material to lower CR or thinner to raise CR, the company i know makes the gaskets and supply's chamber rings to seal them effectively for long term use, but you also need to use a special copper spray to seal the block and the head onto the copper to stop the coolant and oil from mixing with each other. Also the engine needs to be preferably a freash build with a skimmed head and deck so that the copper gasket has best chance of sealing. working on the combusiton chambers will help reduce CR ratio too, unshorusing the valves and cleaning up machine marks, and polishing will help lower, as well as reducing the valve size heads and recutting the seats helps the valve seat further up into the port creating more space in the chamber, matching the chamber walls to the bore size will really help with detonation and help reduce CR ratio especially if you have a bigger bore, and also don't forget that using A20A1 pistons will lower your CR ratio as they have a big dish sealed pwoer ones also have a big dish in them and seem pretty sturdy for cheap pistons. with chamber mods and A20A1 pistons you should be able to get around 8.5:1 without any major expense.

AccordEpicenter
10-18-2006, 07:50 PM
why would you ever want to go that low. Lower CR hurts off boost driveability and turbo response

bobafett
10-19-2006, 08:04 AM
hey i dont know about the east coast, but on the west coast they piss in our gas and call it premium.

smufguy
10-19-2006, 09:11 AM
8.5 is not that bad of a compression ratio. I mean the stock 1st gen DSM came with a 7.8CR and still managed a 14s pass on their AWD setups and the second gens with an 8.5CR. One of the kids from school had a 3000GT VR-4TT with an 8.0CR on his street car. Yeah the response might suck, but if power is what they are aiming for, then thats the best option they have. You know this Jason :tongue: ;)

2oodoor
10-19-2006, 09:29 AM
The ONLY time I recommend using two headgaskets if you have a warped head & has been shaved to eleminate warpage past the .004 limit ..... (cause there is no money for a new one)
Oh shit dude Im in trouble cuz mine is shave .015, I have not put a lot of warm up cycles on it yet maybe I will sell this POS soon, its giving me too many headaches well not really I just dont have time for the bitch this car puts me through even though I still love her... sounds omg familiar

NewAccordDriver, I think bobafet has your best answer, it has to be race engine gaskets you stack if your gonna last, Ive seen them for chevys and fords to lower compresssion for squirting and supercharging, mainley nitrousmotors use metal gaskets from what I seen but I aint seen it all there ya go....

2oodoor
10-19-2006, 09:39 AM
You can get copper gaskets made from a thicker material to lower CR or thinner to raise CR, the company i know makes the gaskets and supply's chamber rings to seal them effectively for long term use, but you also need to use a special copper spray to seal the block and the head onto the copper to stop the coolant and oil from mixing with each other. Also the engine needs to be preferably a freash build with a skimmed head and deck so that the copper gasket has best chance of sealing. working on the combusiton chambers will help reduce CR ratio too, unshorusing the valves and cleaning up machine marks, and polishing will help lower, as well as reducing the valve size heads and recutting the seats helps the valve seat further up into the port creating more space in the chamber, matching the chamber walls to the bore size will really help with detonation and help reduce CR ratio especially if you have a bigger bore, and also don't forget that using A20A1 pistons will lower your CR ratio as they have a big dish sealed pwoer ones also have a big dish in them and seem pretty sturdy for cheap pistons. with chamber mods and A20A1 pistons you should be able to get around 8.5:1 without any major expense.

rjudgey
Hey ... I dont see you posting much but you definatley nailed part of that question. I forgot about the copper formagasket spray , its been a long time since iI have used it or even seen it. I saw a guy cheep out one day and use some aluminum spray paint to do that.

newaccorddriver
10-19-2006, 03:05 PM
rjudgey
Hey ... I dont see you posting much but you definatley nailed part of that question. I forgot about the copper formagasket spray , its been a long time since iI have used it or even seen it. I saw a guy cheep out one day and use some aluminum spray paint to do that.


everybody i talked to says OEM gasket with a copper spray and ARP head studs should be fine. sure... ill stick to that with ARP head studs, but when asked where i can get the copper spray(i tried every auto store i go to), they have no clue where i can go... any suggestions for a canadian shop?

88Accord-DX
10-19-2006, 03:29 PM
Oh shit dude Im in trouble cuz mine is shave .015, I have not put a lot of warm up cycles on it yet maybe I will sell this POS soon, its giving me too many headaches well not really I just dont have time for the bitch this car puts me through even though I still love her... sounds omg familiar

That was a general rule I go by at work for 4 cylinder motors. The warpage limit on these Accord heads is actually .002 - .008 in (.05mm - .2 mm) Anything past that would require replacement of the head.

Looks like your well over the limit.

Edit- I have seen gasket shims to restore aluminum head warpage after being resurfaced.

2oodoor
10-20-2006, 03:32 PM
That was a general rule I go by at work for 4 cylinder motors. The warpage limit on these Accord heads is actually .002 - .008 in (.05mm - .2 mm) Anything past that would require replacement of the head.
Looks like your well over the limit.
Edit- I have seen gasket shims to restore aluminum head warpage after being resurfaced. I have been thru a lot in the past months so I may have my info messed up, I have to go back on my own post to see, I think I mentioned it back then what he cut off.
I beleive that what the guy said he cut off to get it streight, time will tell. I am almost to the point of buttoning up this car, make it pretty and sell it. I have not had the car a year, and others here have had thiers for years. If I had enclosed garage I could hide it and not worry about tag and ins. untill I finish , insurance is getting too expensive.
Newaccorddriver, ive seen the copper spray at Autozone, or you might try some old school parts stores if you have any, also maybe try a good plumbing supply place, or just use aluminum spray paint?, I may have seen it in summit catalog a while back too??? I dunno aluminum bumper paint seemed to do the same thing for that guy. I have not tryed it myself.
I favor the idea of studs in the block too.....

AccordEpicenter
10-22-2006, 04:58 PM
everybody i talked to says OEM gasket with a copper spray and ARP head studs should be fine. sure... ill stick to that with ARP head studs, but when asked where i can get the copper spray(i tried every auto store i go to), they have no clue where i can go... any suggestions for a canadian shop?

i agree with this reccomendation