single or twin turbo for RB26

[GTS-t VSPEC]

I have to agree with Simon that that power figure seems extremely high for a pair of 2530's, but that's not the point of this thread.

The choice between single or twin is simply based on your preference of how much and what sort of power you'd like to make. If your chasing a street drivable setup then I think twin low-mounts work fine:D

[JAGR33]

two.06L - Is there any chance you can show us a dyno sheet in non shootout mode, running the same setup as the graph above???? Just want to see the difference in power figures of the two....

Cheers

[Guest two.06l]

two.06L - Is there any chance you can show us a dyno sheet in non shootout mode, running the same setup as the graph above???? Just want to see the difference in power figures of the two....

Cheers

There is no non shootout mode graph....this was in a dyno comp at Powercruise. there would be no difference anyway if dyno is set-up right. eg barometric pressure, air temp etc

[Guest two.06l]

I have to agree with Simon that that power figure seems extremely high for a pair of 2530's, but that's not the point of this thread.

As far as we know its the third most powerful 2530 powered GTR in the world....and the worlds highest figure recorded under strict competition conditions!

[Guest two.06l]

OK so hang on is that 466 rwkw's ?? If so then your making 624rwhp. Now. Someone please explain how you get that sort of horsepower out of 2530's when even 2540's would struggle to get anywhere near that.

Actually it is 627rwhp...2rismo and Bu5ter were present at the runs...no funny business going on just one tough, well sorted GTR!! . 3 years of hard work has gone into this combo....you cant just bolt on a set of HKS turbos and expect this kind of power. It does 131MPH down the quarter too...and who said 2530s lack top end!!

[dangerous_daveo]

There is one point we all miss here. We all are assuming manufactors make cars to be there best / fastest / most effecient.  

Manufacturers dont make the best car the possibly can,  they make cars that SELL and make money ......

Doesn't TWIN Turbo sound cool to the marketing  department ?

Above that I dont truly know the answer to which is better. I just thought it nice to show some real world examples up for thought

Doesnt sound as good as X car has 50hp more than Z car... X car will sell more because more power is what people want, twin turbos dont mean willy if your sitting behind car X. If its about selling cars that is.

One engine that comes to mind is an RB30DET done by JH Hill, boost came on at 2000rpm (this is using Gibson motorsport twins, not sure of specs) by 4500 it had 400rwhp, and thats as far as they got, it started spinning too much to tune it. That was about 4 years ago, the car is mental.

And how can you say that a single bb turbo is better than two bb turbos? If both have a proper set up?

[JAGR33]

There is no non shootout mode graph....this was in a dyno comp at Powercruise. there would be no difference anyway if dyno is set-up right. eg barometric pressure, air temp etc

There is no differenece between shoutout and non shoutoot????

I've got graphs from both modes, got 360 kws in shootout (6 - not 8), and 335kws in non shootout mode....

Doesn't shootout mode allow for corrections????

[Gts-t]

There is no differenece between shoutout and non shoutoot????

I've got graphs from both modes, got 360 kws in shootout (6 - not 8), and 335kws in non shootout mode....

Doesn't shootout mode allow for corrections????

What did the all the GT500 skylines run? oh thats right twins!

[R31Nismoid]

Did you care to notice the signature on the graph...it was in competition, so the run was performed under competition rules (not mine) Also there is not enough loading on the dyno in shoot6 for high powered vehicles...i.e. too much wheelspin in shoot6...all dyno comps use shoot8...i.e. everybody has the same dyno loading.

i couldnt care less if there is a signature on it or not.

If others can run thier cars in shoot_6 then so can everyone else.

i'll be everyone elses figures were a tad different using shoot_8 also

not denying the number, hell... shootout was designed to make things equatable. Pity it doesnt work as the correction isnt accurate and reads false

(yes i have seen it tested back to back on my car how the correction works to give a nice bump to the kw reading)

[R31Nismoid]

There is no differenece between shoutout and non shoutoot????

I've got graphs from both modes, got 360 kws in shootout (6 - not 8), and 335kws in non shootout mode....

Doesn't shootout mode allow for corrections????

Yes there is.

Go talk to benno Jack

My car had a 20rwkw difference... running non-shootout and then using shoot_8

got the print outs in my car to back it up

[NXTIME]

When comparing one single to twins, you should ensure that you retain as close a power rating as possible between the two set ups to keep the comparison in perspective. For example there is little point in comparing a 1000HP single to an 800HP pair of twins.

[R32-GTS]

With 627rwhp you'd be expecting more like 140mph than 131. Just my opinion. And no matter what u do the rb26 , cams , porting etc etc 627rwhp is still a hard figure to believe outta 2530's as thats nearly 800hp at the engine.

[NXTIME]

I seriously doubt that there would be 170-odd HP drivetrain loss. More like 50-70HP. Where is SK?

[pnblight]

With 627rwhp you'd be expecting more like 140mph than 131. Just my opinion. And no matter what u do the rb26 , cams , porting etc etc 627rwhp is still a hard figure to believe outta 2530's as thats nearly 800hp at the engine.

where on earth did you guess that from

ants 680rwhp only made 142mph

so you think 53 less hp = 2mph

lewah 597rwhp ran 132mph

dirtgarage 626rwhp ran 130mph

so when you compare to some real facts and runs it looks pretty much on the mark.

but simone with all that track time running your gtr who would know better than you ,OPPS forgot i dont believe your has even seen the tarmac. Shed racing expert

[R31Nismoid]

this is great debate.

dont draw it down to having sly sAfrican Americans are each other.

everyone is passionate and full credit. Just everyone debate the issue, not the persons

[R32-GTS]

where on earth did you guess that from  

ants 680rwhp only made 142mph

so you think 53 less hp = 2mph

lewah 597rwhp ran 132mph

dirtgarage 626rwhp ran 130mph

so when you compare to some real facts and runs it looks pretty much on the mark.

but simone with all that track time running your gtr who would know better than you ,OPPS forgot i dont believe your has even seen the tarmac. Shed racing expert

Well Petie Pie .. i've been racing at plex alot longer then you believe it or not. Maybe not in this car but 2 other cars. And if its making 50rwhp less than ants you think thats gonna make it 10mph slower ?? I dont think so., Get a clue. Really. Oh and please, learn to spell.

[180bfj20det]

this is great debate.

dont draw it down to having sly sAfrican Americans are each other.

everyone is passionate and full credit. Just everyone debate the issue, not the persons

I agree.

Back onto the topic. I have read little about fluid dynamics but enough to come to the conclusion that it IS ideal for one turbo per exhaust port. That said, then it would seem twin turbos would definately be better than one. However, there is a big difference between ideal and reality. The fact is you can mimick your gas flow to pulse as if there were only one exhaust port by properly designing an exhaust manifold – ie equal length with runners collecting as close as possible to the collector. Maybe 6 turbos are ideal but they’re certainly not economically or geometrically viable but even then, then latter has not been proven and back to back tested has it??

I am not insulting or disagreeing with nissan or any other manufacturer so please don’t knock on this door. But on the topic of large financial groups, lets say the nissan R and D is far from being minor and as such we would expect their decision to have been a good one. I would be wrong to disagree with it with the huge success of the GTR. However, there is far more money going to formula 1 R and D and in the 80s they didn’t go 6 turbos did they?? Why wouldn’t they if it is theoretically inherently better? The answer is simple, because it isn’t. They used 2 turbos only because it is better for a Vee setup.

From another manufacturer’s point of view, Subaru: The new liberty has dropped the old twin turbo setup for a new single setup that outperforms the twin turbo setup in both torque and power throughout every rev range. That is something to ponder upon. That said you can argue that the old liberty B4setup was sequential which is far different to the non-sequential setup of the GTR.

If you were to compare a twin setup to a single which both have the same combined output (ie where 2turbos hp = single turbo hp) using excellent turbos such as the garrett BB, then you would see very little difference and from what I have seen it would tend to favor the single setup. Compare the BB nismo N1s (approx 600hp) to a single 600hp GT30 and see what differences you get.

Someone was asking before in the gists of “why then are kits manufactured as twins”? Well its simple: marketing, and that’s all. The fact is a buyer is more attracted to buying something that will bolt on and look standard than something that does not. This fact is confirmed by most kits for the RB25s or 20s being single rather than twin. Ok some kits don’t bolt on and are so because they make large HP but the idea here is that one turbo couldn’t possibly make that HP….though now there is with the GT42. You only need to twin turbo if you want more than 1000hp.

But think to yourself, if two is really better than one based on fluid dynamics than all 4 cylinder turbos would have two turbos or more and 6s would have 3 or more, 80s F1s would have used more than 2 turbos on their 6 and subaru would have just dropped the concept of sequential turbos for just plain non-sequential turbos and lastly, Garrett themselves would manufacture turbos for marketing for twin turbo use or multi turbo use.

From what I see, the differences are really quite minimal. But to say that twin is better than single is wrong if you are arguing on the basis of engine turbo response. This is only the case ideally. If you disagree with me, argue with respect and if you don’t I will not hesistate in reporting you. :kick:

Oh yeah, my single 600hp GT30 powered FJ20 is more responsive than my brother’s twin turbo GTR and mine has far more agreesive cam timing and duration.

Happy arguments!

[williamsf1]

Jeeeezzzzzz Paul I hope it wasn't you refering to Stace below! :O

now where is the humour gone???? :wassup: :wassup:

:flamed:

AND has a set of low-mount twins!!!

Try getting a power curve like that with a single!!!!

oh and twins rock! high mounts for girls, and low mounts for boys....

[JAGR33]

Yes there is.

Go talk to benno Jack

My car had a 20rwkw difference... running non-shootout and then using shoot_8  

got the print outs in my car to back it up

Yeah Ash, I've got dyno sheets of the two different modes aswell, that's why I find it bizzar how two.60L said that shootout and non-shootout should have no difference.....

Hence why I asked to see a dyno sheet in non-shootout mode!!!!! Through my calculations shootout reads about 10% more, bringing the figure close to 420rwkws, which sounds much more realistic.....

[Mik]

where on earth did you guess that from  

ants 680rwhp only made 142mph

so you think 53 less hp = 2mph

lewah 597rwhp ran 132mph

dirtgarage 626rwhp ran 130mph

You really need to consider the mass differences too. All else being equal, a weight saving of say 100kgs will make a hige difference to the trap speed. (like having maybe 8% more power)

I remember seeing somewhere that the Mines BNR34 runs low 130mph traps, and is rated at alot less than 600rwhp. And that is in a heavy body.