rb25det & rb26dett why convert to singel turbo?

[deep in silvia]

I just wanted to know why GTR (RB26dett) guys convert to a single turbo set up. If they are going to do that, then why not save the money a get the GTS (RB25det).

Also..... I have the Rb25det and want to know my disadvantages against a rb26dett converted to single. Yes im talking about the motor in a 240.

thanks to anyone that can help

[drift freaq]

RB26 was designed from the ground up as hardcore race type engine. Reason some convert is to put a huge turbo on for high horsepower, high boost, when they are not concerned as much with the bottom end power. Nissan used a twin turbo setup so as to get a real fast, lag free spool, with a good amount of power stock. The Turbos were small because of this and become inefficent at higher boost levels.
The RB25 vs the 26 is like I stated above. The 25 while being capable of high horsepower numbers is not as built stock as the 26. Think of it in terms of the 25 being a engine that Nissan built to put in several cars and the 26 being a single purpose engine. I.E. extreme high performance AWD supercar engine that was race ready and could be taken racing straight out of the box.
In that respect a RB26 will cost more to purchase and install. Converting it to single turbo does make the install process easier.
It is also heavier due to the fact of the transfer case oil pan. While you can weld plates on either side it does make the engine heavier than the 25. Hence why a lot of us opt to put in the 25. Plus the 25 is a cheaper engine to obtain as well.
I think in addressing what the 26 is I addressed your question about the disadvantages in a overall fashion. :D
Also if you had a RB26 in your car why wouuld you step backwards. The 26 is an absolutely sick engine.

P.S. posting from Chicago :D

[S14DB]

You want to be a dyno whore.

[irritatedmax]

drift freaq made good points about the turbo setups. for drift, you want the low end power and less lag and the reverse for drag. i just wanted to add if you are doing the 26 swap and want switch to rear wheel drive, it is popular to mate up the 25 rwd transmission to the 26, thus you get the best of both worlds. the 25 is an awesome engine, after all it was good enough to be in the skyline.

[deep in silvia]

RB26 was designed from the ground up as hardcore race type engine. Reason some convert is to put a huge turbo on for high horsepower, high boost, when they are not concerned as much with the bottom end power. Nissan used a twin turbo setup so as to get a real fast, lag free spool, with a good amount of power stock. The Turbos were small because of this and become inefficent at higher boost levels.
The RB25 vs the 26 is like I stated above. The 25 while being capable of high horsepower numbers is not as built stock as the 26. Think of it in terms of the 25 being a engine that Nissan built to put in several cars and the 26 being a single purpose engine. I.E. extreme high performance AWD supercar engine that was race ready and could be taken racing straight out of the box.
In that respect a RB26 will cost more to purchase and install. Converting it to single turbo does make the install process easier.
It is also heavier due to the fact of the transfer case oil pan. While you can weld plates on either side it does make the engine heavier than the 25. Hence why a lot of us opt to put in the 25. Plus the 25 is a cheaper engine to obtain as well.
I think in addressing what the 26 is I addressed your question about the disadvantages in a overall fashion. :D
Also if you had a RB26 in your car why wouuld you step backwards. The 26 is an absolutely sick engine.

P.S. posting from Chicago :D

thank you drift freaq

you answered my question right on.

[420sx]

my buddy got rb26 in his sil80 and almost ready to roll, few more things to finish up. im trying to talk him out of going single turbo. i told him to do dual t28

[TheWolf]

btw the tranny syncros on rb25 trannies are the same part as z32 so one would wonder if you could do a bellhousing swap and not worry about blowing up hard to find expensive jdm trannies.

[kuramaya]

Very Common over here...two of my Friends with GTR's have done the swap and both run T88's Here is one of my Local Friends car, He works at the shop I get all my parts from..Single T88, RB27..
http://i23.photobucket.com/albums/b382/kurumaya/IMG_2749.jpg

[kuramaya]

my buddy got rb26 in his sil80 and almost ready to roll, few more things to finish up. im trying to talk him out of going single turbo. i told him to do dual t28

I say Twin 2530's for Drift or 2871's for power

[Angel]

A properly chosen single can spool just as fast if not faster than twins for a given hp level. This has been proven many times over, take a look at the 2jz's. On top of that the setup will be lighter, cheaper,more reliable and easier to troubleshoot as you only have one of everything and vastly simplified piping.

[turbo_lover]

A big single turbo is the way to go if you want to make REAL power. Twin turbos aren't as efficient. But as street cars go { like the red GT-R street car} , i would go with single. The majority of people do go big single depending on displacement. Big single turbo will give you more HP also than 2 turbos.

[S14DB]

More PEAK hp. Twins should make a wider HP band. I have seen 600hp twins pwn 900hp singles. It depends on where and how you want to make your power.


Would it be cheaper, more effective to mount a 26 head on a 25 block rather than swap in a 25 oil pan and trans on a 26?

[slownslurious]

Yeah but most of the really (and I mean REALLY) fast drag GTRs I've seen retain twins... the veilside car, the sumo power one, that other super fast one down in AUS...

I'm not sure why... It takes some serious power to get 8 second timeslips (like 1200 hp+ I'm guessing) so maybe twins work better at that power level (not streetable).

[drift freaq]

More PEAK hp. Twins should make a wider HP band. I have seen 600hp twins pwn 900hp singles. It depends on where and how you want to make your power.


Would it be cheaper, more effective to mount a 26 head on a 25 block rather than swap in a 25 oil pan and trans on a 26?

hmmmmm, never heard anybody discussing doing that one. Its a valid question but there could be some block differences. Of course it is easier to swap a tranny and a oil pan vs a head . :D hehehehehhehehehe
Your engine is already out of the car to start with since your doing a conversion.
As far as Turbo setups go , it really is a matter of some opinion, on the setups of High HP cars running duals and High HP cars running Single .
Though on average, like I originally stated, answering the thread starters question, my statement stands. There is always exceptions in areas like this, does not mean they are wise or efficient . People like to do things different ways just to be different as well.

[wootwoot]

http://users.tpg.com.au/cobra30/twincam.htm

Nice RB hybrid..