Jump to content
SAU Community

Recommended Posts

Does anyone know any cost effective ways to increase the capacity of the FJ20 . A fellow I know bored and stroked one to 2400cc's years ago for a group G 1600 . This was very expensive at $1200 to weld and offset grind the crank plus god knows what for its Cosworth pistons and rings . This was an NA motor along the lines of the 240RS engine . I once considered using a block spacer plate and liners but costs go out the window . Does anyone make oversize pistons for the FJ20 ? If so what are the results like .

Also FJ20's are bloody heavy lumps . Some of you seem to be using RB's in R30's , how does the weight compare . I like the look of the RB24 conversion but not sure what youd pay for GTR crank/rods let alone the Tomei pistons . I need more cubes and less weight - any ideas ?

Link to comment
https://www.sau.com.au/forums/topic/47617-how-to-stretch-an-fj20/
Share on other sites

For those of you who have not seen FJ24 style pistons , the gudgeon pin is far higher up the skirt and the ring lands close to the pistons crown . Not the ideal thing for a turbo piston wich should have thick strong ring lands . As mentioned above my plan was to use a spacer plate and liners to get the increased stroke with std or at least conventional pistons . From a cost point of view big bore pistons are more practical . I would rather use a factory style cast piston for a road car and not have the rattles and bore clearence dramas that forged pistons have .

For those of you who have not seen FJ24 style pistons , the gudgeon pin is far higher up the skirt and the ring lands close to the pistons crown . Not the ideal thing for a turbo piston wich should have thick strong ring lands . As mentioned above my plan was to use a spacer plate and liners to get the increased stroke with std or at least conventional pistons . From a cost point of view big bore pistons are more practical . I would rather use a factory style cast piston for a road car and not have the rattles and bore clearence dramas that forged pistons have .

Im using Arias pistons(80thou over) and are availible from Rocket industries.Forged pistons nowadays(mine anyway) dont rattle cold because of higher silica content,hence some factory built motors can now use them.

Driving my car never ever leaves me wanting for more capacity....

I'd like to know the details about the Aries +2.5mm or 80 thou over pistons . What cost and what compression ratio , how much more torque . Its a lot of expense for 100 cc's more .

Just for the record I'm not spending lots of bucks . All the goodies ie Autronic , GT28RS , R200 LSD Bilsteins etc are bits I gutted from the Bluebird .

Chow A .

I'd like to know the details about the Aries +2.5mm or 80 thou over pistons . What cost and what compression ratio , how much more torque . Its a lot of expense for 100 cc's more .

Just for the record I'm not spending lots of bucks . All the goodies ie Autronic , GT28RS , R200 LSD Bilsteins etc are bits I gutted from the Bluebird .  

Chow  A .

I didnt fit the pistons to gain 100cc,it was to gain stronger pistons.As for torque,not many would test the increase from the piston size increase alone,because the boost is usually wound after fitment.The FJ is a torque animal with people fitting RB25 gearboxes behind them.

Yeah sorry I was thinking 100 thou and 2.5mm ! It looks like I'll have to call Rocket about the Aries ones . I would be game to bore the FJ20 block to 93mm with a bit of sonic testing . These blocks have really thick cores , its just a shame that its a little short on deck height . Does anybody know off hand what size Rex pistons are and gudgeon pin diameter ?

just a thought......dont american 180sx's(240sx) use a ca24 or ka24 or something? i dont know the series of engine but it is definately a 2.4 litre.....try nissansilvia.com they would know....maybe the crank will fit fj's?

just a thought......dont american 180sx's(240sx) use a ca24 or ka24 or something? i dont know the series of engine but it is definately a 2.4 litre.....try nissansilvia.com they would know....maybe the crank will fit fj's?

From what I know,they are not compatable.The Nissan Z24 (pathfinder,etc)cranks are spose to be similar,but that's getting away from the cheap end of the scale to do.

lol Gold! Pure gold! :)

I also use 80thou over pistons,which I bought "off the shelf" for my FJ. And Disco,what's so bad about a little noise for 10 min while forgies warm up anyway?

:confused:

Ask your bores that and see what they say in response!!!

Boof,I took your advise,and my bore's reply was as follows:

"what's your problem? We're still round.....We like it rough!!! MORE...GIVE US MORE!!!!!!!"

:):D;)

I duely appolijised to my precious bores,and prominsed never to doubt them again ;)

Hahaha smart ass :) What i was trying to say is the whole rattling of the forgies around in the bores can't really be that good for them can it?? Or has the whole fact that there is increased amounts of silica being used now meant that the cold piston to bore tolerances can be decreased meaning less piston rattle when cold????

I was just talking to the fellow who had an FJ24 made up . It was rallyd at std capacity then 92mm and finally 93mm . The pistons were made from Cosworth forgings and used Subaru rings . Cosworth pistons usually have thinner walls than most which makes them lighter and expand less when warmed up .

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


  • Similar Content

  • Latest Posts

    • Seat of the pants assessment of the new intake: The car is way less "doughy" when hitting the loud pedal, especially off idle when stopped or in traffic, I did use a cheapo lazer thermal thingo to measure the temp around where the pod filter got its air, it was between 55 - 60°C, in saying this the car was shut off and not moving, so the OEM intake pipe was not supplying any fresh air to where the pod was when the car was at least moving A weird bonus was induction noise on the throttle in the cabin increased a bit,  I was worried that I was actually going to lose some of that induction noise I love so much, outside though, when I got the daughter to do a WOT drive by pass for me, the induction noise has increased alot when on the throttle, not quite ITB doort, but well up there I'm extremely happy with the results and have been exploring the country roads in the region  As for house mods: 1.New front fence is up and is awesome, it really upgraded how the joint looks from the street, and the added security is nice 2. Electricians have replace some interior lights, and with more lighting in the garage, a few new motion detecting lights out the front above the garage, front room, and at the front door, which I have already found heaps helpful coming and going, also now has fancy pants CCTV all round the house The only hold point for power though is the solar and batteries due to supply issues, although this will happen over the next few weeks 3. I have done a heap of landscaping out the front and I'm almost ready to do a new small retaining wall with some nice blocks to replace the brick and cemented in rocks around the raised garden beds cemented in river stone "was the fashion at the time" the house was built. I currently have a pallet of retaining wall blocks and 2 bulka bags of 20mm blue metal to replace the wood chip that is in the raised garden beds around the house 4. I now have 3 big raised garden beds for out the back to grow some vegetables, about 70cm high, 200cm long and 100cm wide 5. My 2 compost bins are already pretty full with brown, green and kitchen waste from the landscaping I'vedone so far, but they will probably take a few months to break down, so anything else that gets chopped, trimmed, and kitchen waste will just start filling the base of the raised garden beds to about 30cm before I start throwing 40cm of good compost, and stuff, for the vegetables to grow in, I'll need a few ton of compost and soil, but the local supplier can sent me bulka bags of the stuff Basically the logs, wood chips and a few strategically placed rocks for drainage, will give the beds some good organic materials down low to break down over time, and they will hold moisture during the warmer months to save the water in my big arse water tank if we don't get alot of rain So, all in all, the car and house mods are going well, and I'm really enjoying being retired, I sleep in too 0700 and slowly plod around inside until I feel like actually doing anything, and only work in the yard for as long as want, which has actually been alot over the last few weeks,  although when you look at it, it seems that not a huge amount of work has been done,  until I look at the before I started the work pics Happy days and good times indeed 
    • hahaha yeah. Plan is to get side skirts and probably just rear pods. But going to do them one-by-one. I've got a set that I really like from RHDJapen, but that one isn't shipped to AU. So need to find someone who can get it for me
    • Here's an idea, answer the questions I asked you as they are trying to work out WHY the LSD will be binding up in a straight line.
    • You haven't driven many modern cars then have you? Most of them have sfa steering feel with their stupid electric bullshit steering systems.
×
×
  • Create New...