Rb26 or rb30???

[r32-25t]

42 minutes ago, Old man 32 GTR said:

Yeah I hear you, this is my car now, even with the 68/70, it’s on when you roll the throttle, rpm doesn’t really matter. As a street car, it’s probably as good as you’d want, but because I’m a little weird I think ‘As a GTR’ where do I want it? 
shouldnt a GTR have lag, isn’t that part of the driving experience, lol
If I do this, it won’t be one engine out and one in, it will be engine bay respray, blast and coat subframe, replace bonnet, re wire engine bay. I will bring the bay up to a standard I want it. It presents well now, but It’s no where near finished to a level I’m happy with. 
But thanks for the the input, I appreciate peoples opinions on this, helps to give perspective and give me an idea what to expect if I move forward with this. 

This is my plan now that my engine needs to come out 

[Old man 32 GTR]

31 minutes ago, WantGTR said:

26 block here. if i had my time again id go 30. you live and you learn.

Hi bro, how you been? How’s the car? 
I might have an rb 30 for sale soon! Lol 

 

[Old man 32 GTR]

23 minutes ago, Stixbnr32 said:

Its something that was in my mind when i built my car.   GTR's meant to be twin turbo and 2.6L.

And have HICAS and ITB’s etc, for me it’s a juggling match, I want to build the car and retain as many ‘factory’ features as I can, but I want 500kw so there will obviously need to be some sacrifices made. 
Off topic, but another area of the car that’s  got my head spinning is brakes, mine is currently fitted with V-spec brembo’s. I like this as they were a factory fitted item, but I’m so tempted to put the new Alpha Amega brembo kit that someone posted here. 
Interior, I have recaros fitted currently but have purchased genuine R32 seats, the interior will be getting a full makeover and I’ll be going back to factory colours but use more modern/ better quality materials. 

[Predator1]

3 minutes ago, Old man 32 GTR said:

And have HICAS and ITB’s etc, for me it’s a juggling match, I want to build the car and retain as many ‘factory’ features as I can, but I want 500kw so there will obviously need to be some sacrifices made. 
Off topic, but another area of the car that’s  got my head spinning is brakes, mine is currently fitted with V-spec brembo’s. I like this as they were a factory fitted item, but I’m so tempted to put the new Alpha Amega brembo kit that someone posted here. 
Interior, I have recaros fitted currently but have purchased genuine R32 seats, the interior will be getting a full makeover and I’ll be going back to factory colours but use more modern/ better quality materials. 

I think I can relate. I'm in the same boat. My original plan was 2.8, but here we are. I had to ditch the clutch booster to make my GReddy plenum fit :(. The only 'stock' feature I've ditched is HICAS, still keeping AC/ABS etc.

Re Brakes - Look up BrakesDirect - They did me an AWESOME deal for a pretty dam good price. 6pot fronts and 4pot rears.. 378mm fronts and 355mm rears. They brakes are fkn HUGE.

[joshuaho96]

doublepost

Edited December 8, 2020 by joshuaho96

[joshuaho96]

1 hour ago, Stixbnr32 said:

Its something that was in my mind when i built my car.   GTR's meant to be twin turbo and 2.6L.

If i had my time over again (was 7 years ago) and i was 29 and naïve i would have gone single turbo and 2.8L at least.

Is 2.8L stroker on the RB26 really a wise move to go for in a rebuild? I get the impression that the RB26 was already a stroker motor from the factory and was originally intended to be a 2.4L. 2.8L would cause the conrod/stroke ratio to get even more unfavorable.

I'm currently planning out an RB26 build and this issue has made me go back and forth on whether a stroker kit is really wise. 

[Old man 32 GTR]

6 minutes ago, joshuaho96 said:

Is 2.8L stroker on the RB26 really a wise move to go for in a rebuild? I get the impression that the RB26 was already a stroker motor from the factory and was originally intended to be a 2.4L. 2.8L would cause the conrod/stroke ratio to get even more unfavorable.

I'm currently planning out an RB26 build and this issue has made me go back and forth on whether a stroker kit is really wise. 

Depend on what stroker kit you use 

[joshuaho96]

10 minutes ago, Old man 32 GTR said:

Depend on what stroker kit you use 

Stroker kits are either 119.5mm or 121.5mm, but the stroke in both cases increase to 77.7mm. So you're picking between a 1.56 rod ratio or 1.54 rod ratio. Either way it's on par with the B18 used in the Integra Type R, which seems to be pretty close to the edge of what is considered safe. The longer conrod length kits use a different piston design to get everything to work. Anyways, my plan has always been to target low power and focus on balance. I expect with the HKS GT3-SS turbos I selected it will already nose over well before 7000 RPM even with 2.6L displacement.

Edited December 8, 2020 by joshuaho96

[BK]

46 minutes ago, joshuaho96 said:

2.8L would cause the conrod/stroke ratio to get even more unfavorable

You come up with some weird shit. Of course stroker kits are a wise choice. Are you saying a square bore / stroke like say 86 x 86mm would be even more unfavorable ? I think we know what the real world answer is here as quite a few good performing engines are exactly this.

For the record, I too went the RB26 block in the 121.5mm rod length Nitto 2.8

[joshuaho96]

12 minutes ago, BK said:

You come up with some weird shit. Of course stroker kits are a wise choice. Are you saying a square bore / stroke like say 86 x 86mm would be even more unfavorable ? I think we know what the real world answer is here as quite a few good performing engines are exactly this.

For the record, I too went the RB26 block in the 121.5mm rod length Nitto 2.8

Yes, if you're going to go past a 2.8L stroker on an RB26 block it definitely makes sense to go to an RB30 bottom end instead, which has a much longer 152.7mm conrod. Even with a 3.4L, 94mm stroker kit on an RB30 you're still at 1.62 rod ratio which is roughly what the RB26 is at stock.

More cubes is better for performance no doubt, my concern is that going to a 2.8L stroker on the RB26 means you might increase piston side pressure to unfavorable levels, and that going to a 121.5mm rod means you compromise the piston design. Shorter compression height means there's less room for the piston rings, either the top ring gets closer to the crown, the oil control rings get closer to the piston pin bore, or the rings have less spacing. 

Personally, I'm really hoping the turbo I selected is small enough to not require agonizing over this issue any further. 

[BK]

The rings are definitely thinner on the Nitto 2.8, with top ring at 1.0mm and second ring at 1.2mm with the custom JE pistons. For comparison, most other RB pistons like CP use 1.2mm top and second 1.5mm rings.

For your situation, the turbos your going to run don't really need a stroker. But would it be better with bigger than 2.6 capacity with them ? Yes, absolutely it would.

[joshuaho96]

1 hour ago, BK said:

The rings are definitely thinner on the Nitto 2.8, with top ring at 1.0mm and second ring at 1.2mm with the custom JE pistons. For comparison, most other RB pistons like CP use 1.2mm top and second 1.5mm rings.

For your situation, the turbos your going to run don't really need a stroker. But would it be better with bigger than 2.6 capacity with them ? Yes, absolutely it would.

I was under the impression that if a turbo is already choking the engine above a certain RPM, additional displacement would just shift the power curve down some amount of RPM. Is this not the case?

[burn4005]

6 hours ago, Predator1 said:

I think I can relate. I'm in the same boat. My original plan was 2.8, but here we are. I had to ditch the clutch booster to make my GReddy plenum fit :(. The only 'stock' feature I've ditched is HICAS, still keeping AC/ABS etc.

Re Brakes - Look up BrakesDirect - They did me an AWESOME deal for a pretty dam good price. 6pot fronts and 4pot rears.. 378mm fronts and 355mm rears. They brakes are fkn HUGE.

Alcons?

[Piggaz]

5 hours ago, joshuaho96 said:

Yes, if you're going to go past a 2.8L stroker on an RB26 block it definitely makes sense to go to an RB30 bottom end instead, which has a much longer 152.7mm conrod. Even with a 3.4L, 94mm stroker kit on an RB30 you're still at 1.62 rod ratio which is roughly what the RB26 is at stock.

More cubes is better for performance no doubt, my concern is that going to a 2.8L stroker on the RB26 means you might increase piston side pressure to unfavorable levels, and that going to a 121.5mm rod means you compromise the piston design. Shorter compression height means there's less room for the piston rings, either the top ring gets closer to the crown, the oil control rings get closer to the piston pin bore, or the rings have less spacing. 

Personally, I'm really hoping the turbo I selected is small enough to not require agonizing over this issue any further. 

Have you driven a decent 2.8/stroker RB? Building a 2.6 is a waste of time. Less text book, more get in and drive it.

Having had a Tomei 2.8 in my car for 15 years, if someone said that I HAD to run a 2.6, I would sell the car. They couldn’t pull a skin off a custard. It’s made out like the rings are worn in 2,000 kms and it needs a rebuild. Realistically, it would have spun a bearing or the car would have been sold on by the time it needs to be “serviced”, especially with turd twins which you won’t be revving north of 8000 rpm with.

There are positives AND negatives for every RS ratio.

[joshuaho96]

2 minutes ago, Piggaz said:

Have you driven a decent 2.8? Building a 2.6 is a waste of time. Less text book, more get in and drive it.

Having had a Tomei 2.8 in my car for 15 years, if someone said that I HAD to run a 2.6, I would sell the car. They couldn’t pull a skin off a custard.

There are positives AND negatives for every RS ratio.

No, but I'd rather not spend 5000 USD on a stroker kit only to discover that the engine peaks in power undesirably early. -5s are too small for 2.6L, but the GT3-SS is so small that it has trouble holding boost out to 7000 RPM even with 2.6L. I have a feeling that if you stroke it out to 2.8L it's going to be even worse in that regard.

[Piggaz]

1 hour ago, joshuaho96 said:

No, but I'd rather not spend 5000 USD on a stroker kit only to discover that the engine peaks in power undesirably early. -5s are too small for 2.6L, but the GT3-SS is so small that it has trouble holding boost out to 7000 RPM even with 2.6L. I have a feeling that if you stroke it out to 2.8L it's going to be even worse in that regard.

-5’s are too BIG for a 2.6. My god they’re a heap of shit to drive on a 2.6. Again, have you driven that setup? You’d be pumped to the moon and back by a euro hatchback.

I wouldn’t piss on those new journal bearing shitheaps from HKS. Waste of time.

You may be only looking at where they “fall off”... but how they drive and how the come on is chalk and cheese.

The GTR is a big, heavy heap of shit with tall gearing with the 5 speed and can’t be helped by any “smarts” in the engine bay (like VCT). It’s a small stroke, low comp donk with a dumb head. It needs all the help it can get to push around that pork!

It’s ok, I own one, have had for 15 years. But to own one with a 2.6 is a no go for the above reasons.

[Robzilla32]

Sweet jesus, here we go again...

[Shyboy]

“The truth hurts but silence kills”

Mark Twain

[Old man 32 GTR]

4 hours ago, Piggaz said:

-5’s are too BIG for a 2.6. My god they’re a heap of shit to drive on a 2.6. Again, have you driven that setup? You’d be pumped to the moon and back by a euro hatchback.

I wouldn’t piss on those new journal bearing shitheaps from HKS. Waste of time.

You may be only looking at where they “fall off”... but how they drive and how the come on is chalk and cheese.

The GTR is a big, heavy heap of shit with tall gearing with the 5 speed and can’t be helped by any “smarts” in the engine bay (like VCT). It’s a small stroke, low comp donk with a dumb head. It needs all the help it can get to push around that pork!

It’s ok, I own one, have had for 15 years. But to own one with a 2.6 is a no go for the above reasons.

So what about 2.7? 

[r32-25t]

I know of car that’s a 2.8 with a 6870 with a 1.15ts rear on it and he’s claiming he’s all in at 4,100. So Even with the smaller engine it’s sounds like it’s not going to be a pig but you won’t be riding the wave or torque you are able to currently