RB30 Head Gasket thickness for more boost

[VL_Turbo]

Hi All,
Have a VL NA converted to Turbo, after a thicker head gasket, looking into MLS cometic. 
They come in 1.29mm. 1.89mm and above 2.0mm thickness.

Planning to run hi boost (20psi) any advice would be great.

2.5mm thickness would drop it to nearly 8:4:1 or something like that?

Seems like 1.29mm is default choice for rebuilds?

Leaning towards 1.89mm thickness. What thickness do people mostly use?

Will keep it on 98 octane for now but will eventually go on E85

 

TIA.

[VL_Turbo]

Anyone?

[GTSBoy]

25 minutes ago, VL_Turbo said:

Anyone?

Really, after just half an hour?

There is no way that I would want an engine with only 8.4:1. What management are you using? Anything with good management for knock control should have no fear of running at least mid 9s.

[Dose Pipe Sutututu]

Don't lower the comp.

[Ben C34]

Put 2 gaskets on.

[trel]

Didn't you post the same question in another forum? 

Anyway have a look at the rb30 threads. Plenty of info. 

[VL_Turbo]

Have searched with not much luck. Will be running haltech. 
 

im leaning towards 1.89mm / 0.75 thou but wanted to know what everyone else normally does? 

[r32-25t]

Leave the factory 9:1 compression, this isn’t the 80s anymore! Everyone is raising compression now not lowering it 

[VL_Turbo]

I think I might go 1.29mm. TIA

[VL_Turbo]

Update, changing paths and now going with Nitto 1.1mm with (fire rings) head gasket as opposed to mls cometic 1.29mm gasket.

apparently nitto seals better and have stronger fire rings. 
cometic is good but would require copper spray and wet stone/knife sharpening the block as cometic are very sensitive and my leak compression if not done properly. 

👍

[Ben C34]

Good luck telling the difference between the two.

 

Also I seriously doubt the nitto gasket is any more forgiving than another mls gasket. They all need to have the sealing surfaces prepped  properly.

[VL_Turbo]

1 minute ago, Ben C34 said:

Good luck telling the difference between the two.

Meaning? My tuner prefers Nitto hence the change.

Edited March 11, 2023 by VL_Turbo

[Ben C34]

Cometic also recommend installing dry. Not sure why you think they need copper spray, or why the nitto can handle a bad deck surface.

 

 

Cometic make great gaskets. Nitto make great gaskets. That's what I mean.

For a slap together build no way is the head gasket going to be the actual root cause of any failure.

 

[robbo_rb180]

*next post- my engine is making a knocking sound

 

Any decent metal head gasket will do the job. Do Arp head studs and valve springs while the head is off.

Pending turbo sizing, fuel system and condition of engine, bottom end will be the biggest weak point.

[VL_Turbo]

Could someone please confirm what these two rubber seals are? Bought a timing belt and these two seals and lubricant came with it. Thanks 

[Duncan]

Cam front seals.

 

[Duncan]

And, since there are 2, that makes me wonder if you have the right timing belt kit. Are you converting to twin cam head, and if so are you adding a second idler?

[r32-25t]

Crank and cam seal 

[VL_Turbo]

No, single cam. Thanks kindly. I just put the tensioner back on and there is a little spring, so I just put that back in the grove and put the bolt back on?
 

Crank and cam gear seal seem the same ?👍

[VL_Turbo]

On 11/3/2023 at 5:45 PM, robbo_rb180 said:

*next post- my engine is making a knocking sound

 

Any decent metal head gasket will do the job. Do Arp head studs and valve springs while the head is off.

Pending turbo sizing, fuel system and condition of engine, bottom end will be the biggest weak point.

Bought some copper spray today. I also believe it's good to add copper spray for extra safety.