Build of Australia's FASTEST PATROL ...Potentially, Using RB26DETT Goodness :)

The standard gearing of hi range in GQ is much lower than the rb was ever designed to push so I dont really see you having a problem at all.
Add reduction gears as you have, and you should find the hp and torque is something only a select few of us get to play with.
I really think you should not get to carried away with big hp engine as this mtr is going to surprise you.
little things like larger injectors fitted can be tuned for lower power but give you the option of turning the wick up if you retune without the extra expense of buying another set of injectors.
Go for reliable power, the GQ's gearing will take care of the rest.
You have me wishing I had the spare cash to do this my self, but I dont think my better half wants to be setting any speed records towing a trailer lol.
cheers

Ok so what I can gather is these are the gear ratios:
1st gear | Low range ratio | Diff ratio | Final Drive ratio
What I started with: 4.556:1 | 2.02:1 | 3.900:1 | 21.955:1
What I ended with: 4.556:1 | 2.02:1 | 4.625:1 | 37.940:1
What the GTR has: 3.830:1 | N/A | 3.600:1 | 3.550:1

So if this info is correct, even with the massive wheel size difference I should still be ahead with a lower final drive ratio than what the RB26 was intended to be driven with. Am I wrong in saying that there is about 34 revolutions difference at the axle in the final drive between the GTR and Patrol? or am I looking at this the wrong way? would it also help with the RB26 having a wider band in the rev range than the TB42?

This is the Surge Tank I'll be running with Twin Bosch 044 fuel pumps, capable of pumping 260L/h at 3bar or 43psi and 600hp each, probably crank HP. I'll need a FPR to hold them back while they are powering the TB42, I'll probably only power one of them until the RB26 goes in. Get Pirtek or Enzed to make me up some braided fuel lines to prevent rub through.

4:30am and to tired to crunch numbers, I know diff ratio for R32 is 4.11 so gearing is different to your specs, but that's not important.
What is, your low ratio of Gq will have rb spinning way sooner than it was originally designed to.
add cams, mod timing, play with fuel maps.
You will be a happy chappy, so far as power goes.
maybe not so with the fuel bill !!.

I'll dig up dyno chart if ya like give you an idea on torque for around 300 kW atw, wont be relevant , but gives you something to chew on.

I'm so keen to see how it turns out, The way I see it is even if it's a failure I can always pull the motor and all the goodies I have for the RB26 and put them into a Silvia or Skyline and sell it, use that money for build a big turbo diesel like every other sheep (No offense to people who have big turbo diesels, just not my thing). Win Win situation.

Their are a few options in the gq standard diffs as well.
Like 3.9 4.1 4.3 4.6

Quote:

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Originally Posted by MudSlut

I'm so keen to see how it turns out, The way I see it is even if it's a failure I can always pull the motor and all the goodies I have for the RB26 and put them into a Silvia or Skyline and sell it, use that money for build a big turbo diesel like every other sheep (No offense to people who have big turbo diesels, just not my thing). Win Win situation.

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just remember that a big td will set you aside the best part of 20k+ if you start with an N/A 4.2

And then some if your really keen. The good thing about a high power TD42 is they are generally still pretty reliable and are making good power in the 3rd of the rev range an RB26 would. There is a bloke up here in QLD who was running around 36 psi through a TD making in the area of 300hp and did this for 2 years unopened.

Quote:

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Originally Posted by DC-Auto

if you want drive-ability you really need torque, for offroad climbing, you have to have low end torque. what is your budget for the build? to get power, you need more efficient turbo/s at high boost, which means bigger. to get torque you need larger engine displacement (stroking). you can get torque with power from small engines, there are 2 ways to do this, twin charge (supercharger & turbocharger), and compound turbo's (small turbo spooling a larger turbo, like heaths GU).

how much power and how much torque are you aiming for?

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Rb's are full of torque. The square bore and stroke and iron block on the RB26 with solid lifters can handle and make better use of more boost than any 4.2.

Cause' the RB26 is <relatively> small, chargers on this motor can rob more power from the inertia of the spool when compared to larger capacity motors. Particularly when compared to taking power to spool a turbo or 2 from the exhaust gases, rahter than engine Kw's.

Same as the 'compound turbo's' you refer to or what is commonly known as sequential turbos, like the RX7's. Sequential turbo's are inefficient on the small application of the RB26, just as they are on the high flowing rotor's of the RX7's. This is why the first modification most people do is to replace the sequential turbos on the RX7's, because they are the main bottleneck for big power.

The RB26's can handle the boost, big boost. It can just be a dark art of getting as much boost in there as possible with minimal cost to power that is being made, that's why charger's and sequential turbo arrangements are not suited to the RBees. A good set of parallel N1's, or even better twin Disco Potatoes with a .46 housing will dominate any modified 4.2l that is running with any mods anywhere, anytime...

There is a big difference between sequential and compund turbo setups.