Jump to content
SAU Community

[Rb26] Which Compression Ratio With 1.3Mm Head Gasket?

Behind Horizon
 Share

Recommended Posts

Behind Horizon Collaborator

Behind Horizon

Posted
Posted (edited)

Hello,

I intend using a 1.3mm metal head gasket with CP 86.5mm 8.5:1 pistons in my RB26.

Can you let me know which compression ratio I will have with a standard non skimmed head?

All the compression ratio calculators are asking for data which I couldn't find, hence me asking here.

Just want to make sure that the compression ratio won't drop too much as I already bought the head gasket but not the CP pistons.

Would you therefore recommend running 9.0:1 pistons or 8.5:1? Installed GT2860-5 turbos already.

Thanks!

Edited by Behind Horizon
KiwiRS4T Grand Master

KiwiRS4T

Posted
Posted

Piston selection is going to make more difference than your choice of head gasket - why would you not be using the higher compression pistons?. Should have bought the pistons before choosing head gasket. Presumably you can return the head gasket if it is not suitable. What compression ratio do you want and what fuel will you be using?

Behind Horizon Collaborator

Behind Horizon

Posted
  • Author
Posted (edited)

The cometic head gasket I have came together with a RB26 complete engine gasket kit from which I used already half of the gaskets.

Hence I can't return the head gasket and would like to use it.

CP piston data SC7310:

Bore (in): 3.406 in.
Bore (mm): 86.500mm
Piston Style: Dome, with no valve reliefs
Piston Material: Forged aluminum
Compression Distance (in): 1.193 in.
Piston Head Volume (cc): -16.20cc

Check the attachment for other data.

I couldn't find data for the deck height so I assume it must be close to original with these pistons as their compression ratio is 8.5:1?

post-38112-0-93146900-1376831239_thumb.jpg

Edited by Behind Horizon
KiwiRS4T Grand Master

KiwiRS4T

Posted
Posted

Still think you're complicating things unnecessarily. If there is nothing strange about your build you would expect 8.5:1 pistons to give you a CR of 8.5:1 and 9.0:1 would give you 9.0:1.

In fact there may well be a small variance but I defy anyone to calculate it - you will have to measure it when the pistons are installed.

Shoujiki Proficient

Shoujiki

Posted
Posted (edited)

^ I looked it up, and most people that actually real world tested it said 63 +/- 1.5cc.

But for the sake of calculation, using 70cc spits out 8.02:1. Again with 0mm deck clearance.

Edited by Shoujiki

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

    • joshuaho96
      R32 GTR EV? The leaf of the Godzilla's!

      By joshuaho96 · Posted

      Somehow Vertimass/Oak Ridge National Labs has figured out a catalyst that can convert ethanol into C9-C10 hydrocarbons in basically a single step without ending up with a bunch of ethylene or similar waste products: https://patents.google.com/patent/WO2023224867A1/en I still don't think anything like this will keep us from needing to transition to EVs regardless along with all kinds of other electrification, but things like this will go a long way towards alleviating the problem of how to electrify things like planes. Renewable diesel is seemingly an easier problem as well, Chevron is already running refineries for the stuff and the primary feedstock is tallow and other waste fats from agriculture.
    • RB2533
      UniClutch

      By RB2533 · Posted

      Ok so I have sorted everything with my uniclutch and  i can offer up a bit of feedback and some things that might help others.    I found problems with factory damper line. Weird shit and had trouble with peddle adjustment    I used this https://au.gktech.com/products/r33-gts-t-skyline-braided-clutch-line?_pos=2&_sid=22b01b9b9&_ss=r Also when adjusting peddle leave a bit of play. You can get into a over stroke condition easy.. Make sure you can push the slave forward after adjusting to confirm fluid can return to master then you will need to pump it up heaps…..not sure why but that’s how it is.    last thing the splined adapter is machined perfectly. If your input shaft is old like mine was I would put a bit of valve grinding paste on it and stroke it like a 15 year old. Just to give it a tad more clearance and to better match it to the spline.    reason is on a near flat shift I have had situation where the peddle returns a millisecond after you lift from the clutch. No slip or anything but I reckon this is due to tolerance on the spline being way tighter than stock clutch and binding for a sec. I think this will go away but also my spline was old. Box is old so I guess I should have checked better. It’s a super neat fit.    it feels light as and holds awesome without any noise    
    • Duncan
      Rv37 400r questions

      By Duncan · Posted

      My Fuga Hybrid is JDM, 2014 model but very similar to the V37 from the looks of things..same platform just physically larger and very comfortab;e
    • elir32
      Rv37 400r questions

      By elir32 · Posted

      Was that Australia Delivered Duncan? Does it have siren etc?   I used to have remote start on an old 32 two decades ago, it was a cool feature. I used to wake up early in winter for work. Start it and by the time i was out the door a few minutes later the engine was warmed up and the heaters had the car toasty. It was great.    I don’t mine the ambience lighting.  I drive a western star and it has footwell lights and ambient lighting and it’s great! From the pics of seen of them installed in a skyline I think it’s a nice touch 
    • Duncan
      Rv37 400r questions

      By Duncan · Posted

      re the security system, my Fuga/Q70 has the factory option where the puddle lights in the mirrors turn on when the prox key is detected, it was clearly dealer fitted and has a switch in the lower dash to disable it....it didn't have remote start but TBH I don't really miss that, I had it in the Stagea originally but never used it....we don't often have to warm the car up in the snow before we get in for Australia. And the Fuga also has the illuminated footwells, sounds like a useless feature but I actually quite like the indirect light within the car, it was a nice addition
×
×
  • Create New...