Jump to content
SAU Community

Wiseco Forged Pistons

B0oStEr

By B0oStEr,
in Engines & Forced Induction

 Share

Recommended Posts

B0oStEr Mentor

B0oStEr

Posted
Posted

I need pistons for an rb25 buildup using rb26 crank and rods.

I've been looking at some used rb26 wiseco forgies but have found out that wiseco spec their compression ratio at 7.9:1 or 8.25:1 if you deck the max off the block.

I was hoping to keep comp. at 8.5 for off boost response.

Dome volume is listed as 14cc compared to ACL of 16cc for 8.5 CR

Wiseco list the rb26 chamber volume as 70cc and I thought it was less than this.

Can anyone who has used wiseco pistons in their rb26 please comment on CR?

Link to comment
https://www.sau.com.au/forums/topic/123425-wiseco-forged-pistons/
Share on other sites
proengines Rising Star

proengines

Posted
Posted
Checking up seems to indicate rb25de and rb26 heads both have chamber volume around 63cc.

Where does that leave Wisecos CR specs when they list volume as 70cc?

Strangely enough, very close. I've used heaps of Wiseco's in RB26's and they run the same size dome as a standard piston. I've run them up to 9:1 with a 1.2mm head gasket, the piston flats .005" out of the block and milling the head to suit. I wouldn't put too much faith in the catalogue.

For RB25's though, they have supplied us 2 different pistons, one is very similar to the factory piston dome wise and the other only runs a 1.5mm or so dome which doesn knock out some compression that you can make up for milling the head. Either way they are a top quality piston, most now come skirt coated as well which is an extra $200 or so worth for free.

I used a set of Mahle Motorsport pistons in the last 26 I did, nothing compares to them for quality and design, they are completely different to any piston that I've seen for a 26 before. They are a proper slipper skirt, very short pins, very short skirts, "graflon" coated skirts, 1mm steel top ring, Mahles new design locks and are nice and light. They do require some modification of the cooling squirter but are well worth the effort. They are twice the price of a lot of other forged pistons but you do get what you pay for.

B0oStEr Mentor

B0oStEr

Posted
  • Author
Posted

I went to two local engine builders and both tried to sell me 'mahle' pistons.

The second guy pulled one out of a box and I said that looks very similar to an ACL piston.

He said it is but it's made by mahle.

I've heard the companies are related but do mahle make the forged pistons for ACL?

It's obviously not the same as the Mahle pistons you used.

proengines Rising Star

proengines

Posted
Posted
I went to two local engine builders and both tried to sell me 'mahle' pistons.

The second guy pulled one out of a box and I said that looks very similar to an ACL piston.

He said it is but it's made by mahle.

I've heard the companies are related but do mahle make the forged pistons for ACL?

It's obviously not the same as the Mahle pistons you used.

ACL piston products is owned by Mahle. The ACL race series pistons in the yellow boxes are made by Ross for ACL and are a nice piston. The Mahle pistons for the RB26 are new, I used one of the first sets and they are made by Mahle in the US, Mahle is a German company but Mahle Motorspot pistons are made in the US.

I've got some photos of them here that I can upload if you like.

proengines Rising Star

proengines

Posted
Posted

Some pics are hopefully attached. Because the pistons are a slipper skirt design, the strut that runs from the pin boss out to the skirt interferes with the squirter in its normal location. It's just a matter of rotating the squirter slightly to clear the piston. They are making a running change on the pistons and machining a small relief in the skirt to clear the squirter once it's moved. These are one of the first sets they have made so it was a little R&D as we went.

ACL/Mahle give fantastic support, I spoke to Paul in Sydney about the squirters one afternoon at almost 5PM and by 8AM the next morning I got an email through from Mahle in the US agreeing with what to do with the squirters and they had made a running change to the design to suit.

post-8303-1151234576.jpg

post-8303-1151234629.jpg

  • 2 weeks later...

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

    • GTSBoy
      New kid on the block

      By GTSBoy · Posted

      The wiring diagram for the R33 RB25 is freely available, and is essentially the same same as most other RBs (just with differences as to which pin # does which job). To get the ECU to power up, you just need to provide power to the ECCS relay, and have the other power feeds that come in from the top left of the wiring diagram (wrt the ECU) that give perma power to the fuel pump relay, the ECU itself, etc etc, all connected. When you put power on all these it will just come to life. It's pretty clear from the diagram what needs to happen. Just follow the lines from the 12V + supply stuff in the top left over towards the ECU. I've even posted snips of such diagrams (not for vanilla 25, I think for Neo and 26) to various threads here in the last few months, talking about what it takes to get the fuel pump and FPCM up and going. Search these up and they will help get you started on doing the same with the vanilla 25 diagram. Hell, for all I know, I've done the same with that one in years past and have forgotten.
    • Duncan
      New kid on the block

      By Duncan · Posted

      Yep...so unless someone posts up the answer you will need to probe from the ECU connector to the dash plug with a multi meter in continuity mode to trace the wires.  Note the ECU has multiple - and + (and across different key settings - Battery, IGN and Start) and most likely the power is fed from the connector(s) that is normally near the left hand headlight.
    • Songo
      New kid on the block

      By Songo · Posted

      Thanks Duncan, I am actually just trying to get the Rb turning and running with the RB25DET S2 original loom itself  I am just trying to get it going outside the body and not thinking about the S15 or trying to match anything to the S15 loom at all I am only trying to see if anyone has done this and what pin they found to be the ignition trigger and ECU+/- on the dash connector, that's about it. Thanks  
    • iain_ST44GA
      M35 VQ25DET starter motor

      By iain_ST44GA · Posted

      Hi Guys, Does anyone know any aftermarket part numbers for a starter motor to suit the VQ25DET? I can find lots of alternative part number for the VQ35DE, which I assume would fit, but there is a lot of conflicting information out there. Thanks..
    • Murray_Calavera
      R33 GTR running -9 with no tune

      By Murray_Calavera · Posted

      I don't understand how this hasn't boiled down to - Upgrade the turbo when you have everything required. ECU, injectors, fuel pump, turbo, etc. Do it all at once.  If you don't have everything required, just enjoy the car as it is and keep saving up your pennies. 
×
×
  • Create New...