need help asap

[Aproductions]

I am in the middle of the build on my 99 eclipse and ran into a problem...

the headgasket.

The machine shop who is doing the build said since they decked the block and head, my 9:1 pistons come out to about 9.6:1.

Now I will be running a MLS headgasket and I can get rid of this high comp by running a thicker gasket.

THE PISTONS DO MY PROTRUDE OUT THE HEAD AT ALL...so is it bad to get the thicker gasket?


The gasket would be between .070-.075 thick.

 

[PWR4HIM]

Well, do you know what the new compression ratio will be with the thicker gasket? 9.6:1 IMO is a little higher than I would build a turbo motor unless I was planning on running race gas. somewhere between 8.5-9:1 would be where I would want it.

If the thicker gasket is a quality piece and it will allow you to run in the 8.5-9 range I would go for it. It will allow you to run a higher boost with pump gas safer than the 9.6:1, and less likely to detonate.

Just my 2 cents. I wouldn't feel as warm as fuzzy at night if I was running fairly high boost on pump gas and 9.6:1.

 

[JStrateger]

I'm not very experienced in this department but I would just try to get the compression ratio back to standard value. If the machine shop is doing the work, they should know what to do. After all, you're paying them to build your engine because they have the knowledge and experience to do it correctly.

I would tell them to advise me on what parts I need to get the engine back to the correct compression ratio, then fetch the parts for them. If it be a thicker gasket, so be it.

Also, something to note and to bring up to them, I believe the compression ratio from a factory 4G63 is 7.8-1 for 1G 6-bolts or 8.5-1 for 2G 7-bolts.

 

[KevinMCMXXCIX]

x2 with your post!
Good luck with it and keep us posted

 

[LiquidX]

How did they come to the conclusion of it becoming 9.6:1?

 

[motormilitia]

I would say that the difference made by a head surfacing is negligable. You can still feel it but I wouldn't change my build because of it. Not sure that thier # is 100% correct either.

 

[Aproductions]

they measured the CC's in the head and whatever else they had to do.

The pistons are 9:1, also they took off of the head and block and with a .052 MLS gasket it will will around 9.6:1....I think they said I got the wrong 9:1 pistons.

anyways with a .075 gasket I will be at 8.6:1 and with a .070 gasket I will be around 8.8:1.

 

[motormilitia]

What pistons do you have?

 

[Aproductions]

I have the manley 9:1 platinum series from strictly import motorsports

 

[motormilitia]

You gonna stick with the Holeset on this motor? I would just run it with the MLS gasket. There is more of a chance to blow a thick head gasket than break a piston, etc IMHO. If you're really worried about it turn down the boost a couple psi and still get better response and spool-up.

 

[Aproductions]

9.6:1 is alot.

I don't get how I will blow a MLS gasket though even though it would be thicker like .070.

 

[thetalonator]

9.6:1 is alot.

I don't get how I will blow a MLS gasket though even though it would be thicker like .070.

^^ lots of knock (detonation)

what head gasket did they use when measuring the comp ratio? i had my block decked and head milled had no problems but, im also only runing 8.5:1 pistions. i have friends that have boosted hondas with a 10:1 comp ratio with no problems. u just have to be a little more percise on your tune. id suggest running a little less boost and e85.

 

[90tsiPA]

I wouldn't worry about it too much. As long as the piston to valve clearance is good and the tune is good you shouldn't have any problems. It's all in the tune.

 

[motormilitia]

I would just run it with the MLS gasket.

There is more of a chance to blow a thick head gasket

Thicker gasket = more area exposed to pressure of the clyinder between the head and block

 

[Aproductions]

I thought since it is multi layered steel, and not composite that it shouldn't really matter.

it shouldnt matter if there is 1 layer or 5 layers.