Jump to content
SAU Community

Head Gasket thickness for Rb26

shoey

By shoey,
in Engines & Forced Induction

 Share

Recommended Posts

shoey Contributor

shoey

Posted
Posted

Hello

I have had my bottom end rebuilt in my GTR and installed Arias pistons that stick out of the block by 8thou. What thickness head gasket would I need to buy to keep the standard GTR comp ratio? I am guessing that 8thou is approx .2mm?

What is a standard GTR head gasket thickness?

Cheers.

Link to comment
Share on other sites
  • 3 weeks later...
shoey Contributor

shoey

Posted
  • Author
Posted

I have a couple of questions then:

1. I had brought a 1.8mm metal head gasket, can anyone guess at what my resulting compression ratio would be? I am guessing that it would be the same as using a 1.6mm gasket on a standard motor?

2. What would be the compression ration if I ran a standard head gasket (1.2mm) with the pistons protruding 8thou?

Just trying to work out the best combination for running R34 N1 turbos on the motor.

Thanks.

Link to comment
Share on other sites
shoey Contributor

shoey

Posted
  • Author
Posted

I will try to rephrase the question:

What is the standard compression ration for a GTR?

How much does this move for a .2mm gasket thickness increase? ie, does it move from 8.5 to 8.9?

Any help appreciated.

Link to comment
Share on other sites
ylwgtr2 Grand Master

ylwgtr2

Posted
Posted

you can work out the headgasket volume but you need the diametre of the hole....for the pistons drop them say 10mm down the bore(measure with a dial indicator)then CC it....work out what the volume of 10mm with your bore size then deduct it from the reading and that will give you a minus figure....then do the head then work it all out from there

Link to comment
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
 Share
Go to topic listing


  • Similar Content

  • Latest Posts

    • Lithium
      Boost level and torque curve

      By Lithium · Posted

      There is a LOT of stuff that can be done, it all depends on how much time and money you want to spend on doing in.  Not all ECUs will be able to do it, and the more control you need the more time and knowledge needs to be put into making it work.  If you're willing to spend the time and money and have the right hardware and skills involved there's a lot that can be done. 
    • thx78
      Boost level and torque curve

      By thx78 · Posted

      I am impressed with all this level of adjustment. I didn't expect all this possibility
    • Lithium
      Boost level and torque curve

      By Lithium · Posted

      Correct.  In the case of the 500kw dyno plot I showed you the car actually runs two boost control solenoids for boost control and a 5psi wastegate spring.  It allows me to control how much boost pressure is applied to both sides of the wastegate valve at any point and fairly accurately control boost target as a result. I've tuned it so that it's able to target anywhere from 5psi to 25psi depending on what's needed.  The target tables I've set up in that car are Gear vs RPM, so every gear has potential for a different boost (and torque) curve.   First and second gear have quite low boost targets, third gear actually has different target boost all the way through the rpm range as it's a stock RB25 gearbox - the boost targets have been chosen to maintain a peak of 600nm (what the owner has set as the maximum torque he's happy with putting through the stock 3rd gear) but it carries that to the rev limiter.   The boost curve to achieve that is something of a ramp up, then hold, then ramp up again and the power curve looks more like a flat line haha.  
    • thx78
      Boost level and torque curve

      By thx78 · Posted

      so you can decrease or increase the boost depending on the diet as you wish?     by acting on the wastegate?
    • Lithium
      Boost level and torque curve

      By Lithium · Posted

      That's torque and power, it's all from a single run.  The boost curve is "held back" from it's peak target in the 3500rpm to 5000rpm range from memory, so it ramps hard to something like 18psi then climbs more progressively to 23psi nearer 5000rpm.   It makes the torque (and power) ramp more "natural" and less hard on parts and traction, it doesn't feel artificially held back.   
×
×
  • Create New...