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Std Rb20 Head Gasket Thickness?

Roy

By Roy,
in Engines & Forced Induction

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Roy Grand Master

Roy

Posted
Posted

Is it 1mm? I have had a look around and all the people that make them only make 1mm and up. So does that mean if i want some cheap compression my only option is to machine the head?

I have had a look around and cant find the cc of the RB20 head, i am guessing i cannot machine enough of the head to get compression up to around 8.5:1? I just want to cheaply bump up the compression i can...and give that i can get an RB20 head for $50 want to have a go at porting a head myself (I am after all the Butcher of Southbank)

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Swiper the Fox Grand Master

Swiper the Fox

Posted
Posted
Is it 1mm? I have had a look around and all the people that make them only make 1mm and up. So does that mean if i want some cheap compression my only option is to machine the head?

I have had a look around and cant find the cc of the RB20 head, i am guessing i cannot machine enough of the head to get compression up to around 8.5:1? I just want to cheaply bump up the compression i can...and give that i can get an RB20 head for $50 want to have a go at porting a head myself (I am after all the Butcher of Bangalore)

fixed

yes Roy they are 1mm

you could get a copper gasket made that would be thinner than 1mm

The Dan Grand Master

The Dan

Posted
Posted
Is it 1mm? I have had a look around and all the people that make them only make 1mm and up. So does that mean if i want some cheap compression my only option is to machine the head?

I have had a look around and cant find the cc of the RB20 head, i am guessing i cannot machine enough of the head to get compression up to around 8.5:1? I just want to cheaply bump up the compression i can...and give that i can get an RB20 head for $50 want to have a go at porting a head myself (I am after all the Butcher of Southbank)

Isn't the standard compression 8.5:1? It's been a while since I worked that one out but I was fairly sure it was.

The Dan Grand Master

The Dan

Posted
Posted

Type (see below) RB20DET Twin cam, in-line 6, Turbocharged

Displacement 1998 cc

Compression Ratio 8.5:1

Max. Power; kW/bhp 160/214 @ 6400 rpm

Max. Torque; Nm/ft-lbs 263/194 @ 3200 rpm

Bore x Stroke; mm 78 x 69.7

Redline 7600 rpm

Fuel Injection Nissan EGI (ECCS)

Roy Grand Master

Roy

Posted
  • Author
Posted

Head porting costs money, also, typically porting slows velocity so hurts low-mid rpm but helps high rpm flow. ??? Yes, No?

..not what comes to mind when wanting more torqe and response to spin a turbo up...ditto longer duration cams.

But i am all ears if you have actual before / after figures and a place that knows the right thing to do to a head. I am considering buying a cheap used head and just cleaning it up with knife edging etc...but no real porting.

I am happy to spend the money but dont want to be the guy paying for the experiment and piss poor results or backwards step. :D

...Just dawned on me that yes the RB20 is 8.5:1 a its half a point behind the RB25 at 9.0:1 so completely stuffed that up. :bunny:

The Dan Grand Master

The Dan

Posted
Posted
Head porting costs money, also, typically porting slows velocity so hurts low-mid rpm but helps high rpm flow. ??? Yes, No?

..not what comes to mind when wanting more torqe and response to spin a turbo up...ditto longer duration cams.

But i am all ears if you have actual before / after figures and a place that knows the right thing to do to a head. I am considering buying a cheap used head and just cleaning it up with knife edging etc...but no real porting.

I am happy to spend the money but dont want to be the guy paying for the experiment and piss poor results or backwards step. :D

...Just dawned on me that yes the RB20 is 8.5:1 a its half a point behind the RB25 at 9.0:1 so completely stuffed that up. :bunny:

Slows velocity but increases flow. Your engine is an air pump, the more air you can get in and out, the better. It improves both response and overall power potential. There is, of course, the possibility of porting too much and going backwards, but you have to take out an incredible amount to do this.

With camshafts, an increase in lift only is required for better response. That, and possibly some cam timing changes. A set of custom grind cams or even a set of GTR cams will do nicely. Time them with a set of gears and do a slight clean up of the cylinder head and you will get massive results.

The Dan Grand Master

The Dan

Posted
Posted

Increasing compression by making the head gasket thinner is extremely poor practice. Using copper gaskets to do this is even worse and as far as expensive goes...o ringing your block and getting the copper gasket made would be the same cost as getting a head port.

If you want to talk to the king of porting, ring Marty White - 0733917533

Roy Grand Master

Roy

Posted
  • Author
Posted

Well before i waste Marty's time...are we talking about $800-$1500-$2000 for a head re-co and clean up/porting of head, inlet and exhaust? The idea is for me to give it a go myself, but if the dollars are not too ludicrous and the confidence is high that it will net tangible results then happt to do it

Hear what you are saying about air pump. But its the gas velocity at low-mid rpm that gives you cylinder filling which gives good combustion and good torque and the improved gas velocty spins the turbine with more torque sooner. I am happy enough with the 260rwkws, more would be great, but what i want is to fatten it up and make the same power easier. I just need a tad more grunt in 3rd gear at 4,000rpm . 30rwkw improvement at that point to make the same (give or take) peak power is what i need.

The Dan Grand Master

The Dan

Posted
Posted
Well before i waste Marty's time...are we talking about $800-$1500-$2000 for a head re-co and clean up/porting of head, inlet and exhaust? The idea is for me to give it a go myself, but if the dollars are not too ludicrous and the confidence is high that it will net tangible results then happt to do it

Hear what you are saying about air pump. But its the gas velocity at low-mid rpm that gives you cylinder filling which gives good combustion and good torque and the improved gas velocty spins the turbine with more torque sooner. I am happy enough with the 260rwkws, more would be great, but what i want is to fatten it up and make the same power easier. I just need a tad more grunt in 3rd gear at 4,000rpm . 30rwkw improvement at that point to make the same (give or take) peak power is what i need.

Basic head porting with 15% improvements will set you back around $800. Your best bet is to talk to Marty. Tell him everything you have said there and get his opinion. No one on this forum can argue he is probably the best in the industry. I do porting myself but whenever it comes to major re-construction I take them to him.

Roy Grand Master

Roy

Posted
  • Author
Posted

Meh...cost too much money and it may end up in the long run over time costing me more money but there is fun in tinkering and getting improvements on small spends. Without experimentation we would all be driving RB20s with high 253s or RB25s with GCG Hi-Flows ;)

  • 3 months later...
benz_200t Rookie

benz_200t

Posted
Posted (edited)

it freaked me out too.......

i am also thinking the same thing....

making the RB20s' compression slightly higher.

thus making driveability off boost better of the higher comp ratio.

**looking for RB20 head**

Edited by benz_200t

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