Jump to content
SAU Community

Recommended Posts

Well thats not quite true. If you take just the short block, and replace the crank, rods, and pistons, you would still need to fit the GTR oil pump and water pump which are both different to the RB25 parts.

Up top, although the combustion chambers, ports, and valve sizes are the same, and the GTR head has no power advantage. But everything is totally different except maybe the cam drive sprocket on the exhaust cam, and the timing belt and idlers.

The RB26 has heavy duty parts throughout, and although a lot of things look the same, and fit, they are actually quite different.

DJ-L3ThAL, I don't quite know what your getting at??? (according to my thread name)???????

There is almost NOTHING even close to being the same between a R33 RB25det engine and a R32/33 RB26dett.

The blocks are different, The oil pumps are different, the heads are totally different, different port shape, different bolt pattern for inlet and exhaust manifolds, one has VCT the other does not, so I can't see why, being "my thread name" I should lie to skwertle and tell him there's NO difference????????

If he's talking about just a short block then he's going to need to get a block from a 4wd stagia, oil pump from a RB26dett etc etc.

Then, I think the head bolts are a different size so the block would still be different....Rob

I think the point here is that the two engines ARE totally different, but all the differences have to do with long term durability under extreme operating (endurance racing) conditions rather than actual power potential.

Yes the blocks are different. The difference is the GTR block has different oil pan rails for the 4WD sump, and an additional oil drain hole for the second turbo. There is no reason why an RB25 block would not be just as good, unless you wanted to run 4WD, then you might have a bit of a problem. All the moving parts interchange perfectly, and there is no strength difference.

The oil pump has a slightly larger displacement and runs dual springs in the pressure relief valve on the GTR. The only advantage of the larger pump is at idle, when you have a second turbo. A GTR road car may spend a considerable time idling, and the lower oil pressure might cause the oil light to come on if a smaller pump was fitted. At anything above idle, the relief valve will be open, and there will be full oil pressure. I am not sure why the GTR has dual springs in the pressure relief valve, but the only reason I can think of is reliability. The cost of the extra spring is SFA, so if there was a technical reason why it was better, all Skyline engines would probably have dual concentric springs fitted.

For flat out racing, a smaller displacement oil pump would work fine. It is only the road cars that really need the big pump !

The GTR water pump has a different impeller, but is otherwise identical. This is to allow higher sustained engine speeds without cavitating the pump. For anything but sustained racing conditions the RB25 pump will work fine, including drag racing. But if you are planning to hold full throttle for over a minute at 9,000RPM plus, the GTR pump is definitely the one to have.

I could go on about larger head bolts (10mm/12mm), sodium cooled exhaust valves, and solid tappet camshafts, but you get the general idea.

The manifold bolt patterns are very slightly different, but only so you can get a spanner onto the nuts with the two different manifold shapes. The port shapes sizes and locations are identical.

The power potential of the RB25 with identical external bolt ons (manifolds + turbos) would be the same. But for long distance endurance racing the RB26 would be going long after the RB25 died.

There is no doubt that he RB26 is a far better engine, but if you actually need all that stuff to drive around at less than 100Kmh is doubtful.

Have a look at the RB26dett head on the left and then have a look at the RB25det head on the right, DON'T LOOK THE SAME TO ME????????? Ports are totally different, manifold bolt pattern is totally different etc etc. But maybe I'm wrong I've only got about 20 heads here to compare IN THE FLESH, Check your heads and take a Photo and let me have a look.......Rob

SUMO look at the first post mate, 2.6 is the capacity of the engine, and I think he was refering to making a RB25det into a 2.6 liter by using a RB26 crank pistons and rods and he wanted to know if there was any other differences, and there sure are!!

You could make a RB26det with a RB25det block with RB26 crank,rods and pistons and use a RB25det top end and it would be a RB26. Just not a real RB26dett.............Thats what he was getting at.

Those ports look the same to me, allowing for the fact that the GTR head has had the valves removed which effects the lighting conditions.

Also the viewing angle is different. There is a difference around where the injector sprays, but the actual port and valve sizes are identical.

Its an interesting picture to be sure. I have an RB25 head and an RB26 inlet manifold here, and when I find time, intend to make up an adapter plate. Some of the studs line up, and so do the ports, but an adapter plate is still quite a bit of work. This has been done many times before by others and is well worth the trouble.

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


  • 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...