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RB30 Head Gasket thickness for more boost

VL_Turbo
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VL_Turbo Contributor

VL_Turbo

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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.

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Piggaz
Piggaz

What’s the limit of boost at 9.0:1? Very curious to know.

FiXtUrE
FiXtUrE

From my understanding you can achieve about 5 - 10 psi with 9:1 - 9:5:1 comp safely before it goes pop.. before you think this wack boost levels, you have to consider the turbo, dump back exhaust, fmi

FiXtUrE
FiXtUrE

Regardless to fuel it’s the boost/comp pressure that will determine if it gos pop or not.

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GTSBoy Grand Master

GTSBoy

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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.

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VL_Turbo Contributor

VL_Turbo

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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. 

👍

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Ben C34 Grand Master

Ben C34

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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.

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Ben C34 Grand Master

Ben C34

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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.

 

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VL_Turbo Contributor

VL_Turbo

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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 ?👍

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VL_Turbo Contributor

VL_Turbo

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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.

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