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Blakeo

Are RBs worth building reliability wise


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2 hours ago, BK said:

Dunno what you're on about as there are upgraded H pattern gearsets for the stock case which will handle 600hp all day and have been for years.

The stock gearset will only take so much, so if you break it, you upgrade it. No decent driveline solution is ever cheap mate.

Sorry, I meant budget wise. There are good options from PPG, but your looking at $10k+ And generally dogbox's like in this case don't last a long time on the street. 

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You can get an OS Giken gearset at a fair price these days, sure you might have to wait.

You can also get syncro box's from others. 

Built without the frills you are well under 10k for any of the above.

I agree dog is not street due to service life, you can drive it on street but you can't do LOTS of driving.

I almost went PAR due to the ratio's on OS/PPG but ended finding an R34 getrag.

 

Big power = Big driveline and $$

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22 hours ago, Unzipped Composites said:

Yeh I dunno, keep in mind that what Nismo were doing with the cars and what Gibson were doing with the cars was quite different.

It's well known the Australian GTR's were making more power than the Nismo GTR's, Australia had the strongest Group A series in the world and they needed the power to compete. Nismo were making bank selling 500hp engines to private racers, and they owned the Japan Group A series. So for them developing the car further just meant spending more money, and they were already winning so why do it.

Here the Nismo-spec cars wouldn't have won, Gibson had to push them further and develop the cars more, and Nismo were too expensive so they were only a small part of that. Gibson were developing a lot of parts themselves as well as getting stuff locally and from America etc. But Nismo and Nissan still supported that development, and they developed the stronger blocks for them etc. The motors weren't getting completely rebuilt after every race, reliability was an important consideration for them and they had an obscene budget to do it.

You also have to wonder if they were capping power at 650 because that was the limit of the engine or because of other factors, ie. Old school turbo tech, old school ECU's, old school dyno tech, tyre restrictions meaning the old school tyre tech couldn't get it to the ground, terrible aero also making it difficult to drive any faster, etc. Is it a case of they pushed the engine as hard as it could go, or is it they pushed the entire package to the limit of what would make a fast Group A car? We know Skaife said they were horrific cars to drive, would having 800hp with bigger, laggier turbos have made them faster or slower?

So it's sort of difficult to say what power they were 'engineered' to handle vs what power they were developed to handle for Group A racing vs what power they can handle after 30 years of aftermarket development, etc. 

In this video at 1:45 Skaife mentions that the engines ran 1.8 or 1.9 bar and roughly 650-700 hp for max attack, probably qualifying. For the actual race 1.2 or 1.3 bar, roughly 600 hp: 

Modern technology helps but at the end of the day people have mentioned that the RB26 starts flexing in ways that are not conducive for longevity around the 700-800 crank hp mark even with a dry sump to 100% fix any oiling concerns. You can use block braces and all that fun stuff to keep pushing the limits but strictly speaking about what Nissan engineers designed the RB26 block to do it sounds a lot like 600 hp for group A with a 1.2x safety factor to me, with additional derate depending upon how long you want to go between rebuilds. To me 600 hp is a lot, especially from a dinky little 2.6-2.8L engine but you might not agree. Even with 2.8L that would be on par with stuff like the A45S AMG which has the highest specific output engine in a production car today.

 

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dumb question how did the old Group A get 600hp out of 1.2-1.3 bar and a 2.6?
17psi to 18psi and 440kw at the crank at 7600 rpm?

Did they do it with the race gas, porting and cams, or? 

Eg the A45S with 2.0 gets 415bhp (so about same specific power per litre) but needs 30psi.

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600 hp at the crank, so 500ish at the wheels. Very doable with 18-20psi. 

 

This is mostly about the 4wd system but does show engine dyno work

 

 

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