Jump to content
SAU Community

Recommended Posts

  • Replies 47
  • Created
  • Last Reply

Top Posters In This Topic

Top Posters In This Topic

Never heard of this company Grex, and it seems to me that 2.7 is done more by bore than stroke (cant rember stock rb26 bore).

From a recent discussion on another forum i understood that a 2.7 wont give that much extra power really, but if you are doing it to keep safe then it would be good.

but grex..... hope they are not releates to MotoRex in the usa

That price is just for the pistons, doesnt include the conrods or crankshaft that come in the higher priced ($10,000+) kits.

And yes, Grex is Greddy is Trust etc. They are the same company, but technically they are different.

is it worth the price tag

http://turbulence.com.au/shop/product_info...products_id=135

i thoguht they would be more expensive then that, can anyone confirm if the kit is any good

MrChams is running the Trust 2.7 kit in his R32

I sure am... there are different kits from what I understand.

The kit that I have is 87.5mm GREX pistons and GREX H pattern rods.

The larger 2.7ltr piston kit helps my Greddy T78 spool up quicker.

Due to the cost of after market cranks, I am running a standard crank that has been shot penned and cryogenically treated (dunno what the hell that is but hey...)

The standard cranks are pretty strong. Before my rebuild this crank held 720hp with no signs of breaking. Not sure what there limit is.

I'm still running in the engine. Once I have it tuned I'll let you all know how I went for power.

The kit on the link above is just the over sized 87mm piston kit.

MrChams is running the Trust 2.7 kit in his R32

This is not the stroker kit.

The piston size makes it 2.7ltr.

My pistons are 87.5mm not 86.5mm. Typo

If you check out this link, you can calculate the displacement

http://www.benedict.esu7.org/sblock/ccfrm.html

It's something like this (don't quote me on it)

Bore radius squared x pi x stroke x no. of cyl = Total cubic displacement

How do you get the extra stroke necessary for 2.7L from a standard crank and 86.5mm pistons? :confused:
I sure am... there are different kits from what I understand.

The kit that I have is 87.5mm GREX pistons and GREX H pattern rods.

The larger 2.7ltr piston kit helps my Greddy T78 spool up quicker.

 

I'm still running in the engine. Once I have it tuned I'll let you all know how I went for power.

how much difference? Just outta interest.

And running in an engine? Thats over-rated in this day and age

Ahhh okay...

Std bore & stroke (86x73.7) = 2568cc (juuuuuust enough to claim 2.6 Litres :P)

87.5mm bore & std stroke = 2659cc (also juuuuuuuuuuust enough to claim 2.7 Litres :))

Did you do these internal upgrades by themselves? Could you really tell the effects of extra 100cc capacity? Or did you do other things like camshafts, cam gears, etc etc at the same time?

The stoke on the trust piston is 75.7mm and the piston size is 87.5.

http://www.benedict.esu7.org/sblock/ccfrm.html

Regarding the mods etc,

It's not just the pistons that has given the improvement but extensive head work.

The head work included modifying the bowl shape, different angles on the valves and valve chamber, valve guide modified, cam area opened for bigger cams and the obvious port enlargement.

I am currently running the standard cams with adjustable cam gears.

Bigger cams will be fitted soon once I decide what size to get.

Yes, I did notice the difference. The engine does feel like it has more down low torque but I can't say till we tune it on the dyno.

Ahhh okay...

Std bore & stroke (86x73.7) = 2568cc (juuuuuust enough to claim 2.6 Litres :P)

87.5mm bore & std stroke = 2659cc (also juuuuuuuuuuust enough to claim 2.7 Litres :))

Did you do these internal upgrades by themselves? Could you really tell the effects of extra 100cc capacity? Or did you do other things like camshafts, cam gears, etc etc at the same time?

I don't agree with not running in an engine.

My mechanic use to work for Nissan Japan.

They did test on how to run in RB engines. He told me that the best result was when they ran the engine up to 4,000rpm for the 1st 1,500km then oil change then up to 5,000rpm to 5,000km.

He told me the bore was perfect after such a run in.

The test also involved using mineral based oil in some engines and full-synthetic in other engines.

The full-synthetic oil run engines came out much better.

how much difference? Just outta interest.

And running in an engine? Thats over-rated in this day and age

The price is very high just for Greddy pistons.

You should be able to get the pistons for approx $2500 and the rods for approx the same, $2500...

damn, when i saw the pic and the price i already got the credit card out, but for pistons only hm doesnt seem worth it,
The stoke on the trust piston is 75.7mm and the piston size is 87.5.

http://www.benedict.esu7.org/sblock/ccfrm.html

How exactly do you increase stroke by 2mm with a piston upgrade on standard crank? :confused:

And I don't need a web calculator, I remember my Year 7 volumetric formulas :Oops: Probably the first time I've used them since high school :)

They did test on how to run in RB engines. He told me that the best result was when they ran the engine up to 4,000rpm for the 1st 1,500km then oil change then up to 5,000rpm to 5,000km.

 

He told me the bore was perfect after such a run in.

The test also involved using mineral based oil in some engines and full-synthetic in other engines.

The full-synthetic oil run engines came out much better.

5000km run-in??? That would take most people 6 months to complete. You really think that's a feasible run-in time?

What engine parts could POSSIBLY need 5000kms bedding in time??? :uhh:

No comment on the full-synthetic running in oil use... People have different ideas on that one, but the vast majority believe that mineral oil for the first 1000kms or so is still the best way to go.

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

    • What an awesome idea to fit the facelift Lamborghini Diablo headlights. They are a perfect fit!
    • An update regarding the registration with the DVLA I sent off the paperwork the day after I collected the car from the port, two weeks later it was all returned with a letter explaining they have rejected the application. This was because the cheque was £20 short for the road tax (I used a price list I found online). Nevermind it is what it is, it was sent back to them the following day with a new cheque. Fast forward another 2 weeks or so, I called them for an update to be told it had been rejected. Yesterday (16th September) I received the documents back along with another letter, this time it was because I didn't put an X in one box on the V750 (personalised number plate certificate), which declared that I had the rights to the personalised number plate. Why this wasn't mentioned in the first rejection letter, I don't know, but it could have saved this headache. The documents were sent back today, so fingers crossed third times a charm and it'll FINALLY be registered on the road just in time for the bad weather (woohoo!) To cheer myself up I lowered the front 25mm, was sick of seeing it sit like a monster truck. No idea how much clearance I'll have getting on and off the driveway, I'll worry about that when I can actually drive it
    • You're going to miss not worrying about rust in the strut towers like the Skyline shitboxes out there
    • A few little updates that weren't filmed due to not taking long to do or not interesting enough for their own video. My new K&N Air Filter arrived, I went with an RU-4180 which matched the dimensions of the universal cone filter the car originally had.  The battery had gone flat, while that was charging I tidied up the spaghetti wiring at the bulk head and down the sides of the engine Next job was to swap the stereo The Kenwood harness had the female ISO plugs cut off and the male ISO plugs cut off the adaptor loom and joined with bullet connectors. I ordered in a repair loom through work and re-did it all. New Kenwood unit installed (Android Auto, DAB, Bluetooth, Reverse Camera) The bonnet/hood gas struts have been poor since collecting the car. I couldn't find any suitable replacements locally so took a chance on a pair from AliExpress.  The originals don't use a retaining clip to secure the cup onto the ball fixture, would explain why I struggled for 10-15mins trying to pry off the cups. The ball fixtures unscrew using a 12mm spanner, new ones are the same size. Sadly no photo of them fitted, you're not missing much lol The dished Momo steering wheel got replaced with my Momo Tuner, turns out I ordered counter sunk bolts for the horn trim ring (like they normally are for the steering wheel) instead of allen cap (flat seat)  A terrible photo of a Quaife style gear shift knob I've had stashed in my tool box for many years after purchasing the incorrect thread size (I can see a pattern emerging with ordering incorrect parts...) Also threw in a cup holder and a (empty) Boss Coffee can, because why not  
    • GT-R clearly the better choice! The 300 is certainly not insaly fast but has a decent amount of poke. Does a nice little drift around the corners with a decent amount of throttle. It's VERY predictable in a slide too.  Feels so progressive! People probably presume there's a 25 year old driving it based on my behaviour this week! 🤣
×
×
  • Create New...