Evil Aviator

Dang, would that beat my twin GT55s? From reading teh ntrnet I know that twins spool faster than any single, period, but nobody ever said anything about twins vs. quindecuples. I wish I knew more about turbos.

Well of course I don't know anything about turbo setups. For example, I wasn't even aware that there was a GTR RX-7, but now I know better thanks to you. Also, when I wrote the post that you quoted, I was not aware that twins always spool faster than any single, period. Since reading this informative thread, I now know better, and that is why I am going to put twin GT55s on my car. No need to be a hater just because I am learning.

Monkman33

iTrader: (28)

twins running independently will perform very well due to one major factor: EBP


Caveat: They have to be sized properly for your application.


If you don't know, research Howard Coleman's threads, and stop thread crapping if you don't know what you are talking about. The reason running 2 turbos on a 2 rotor is pretty obvious if you ask me. very efficient exhaust path from one exhaust port to one turbo. No collector, less bends... etc...

However, sequential twins and efficiency do not go hand in hand. We are talking strictly parallel-independent turbos.

gracer7-rx7

iTrader: (16)

What he said.



Go ahead and look at HC's setup. no offense to howard, but the numbers aren't as spectacular as you make it sound. Spool doesn't seem any faster than a properly setup 500R or 42R for example and power potential thus far hasn't been all that much higher at around 500 HP at 20 PSI of boost.

https://www.rx7club.com/single-turbo-rx-7s-23/15-000-miles-twin-t04s-daily-driver-450719/page3/

Just b/c you have 2 of them doesn't mean you make any more HP or that spool is any quicker. You are still working with the same amount of air generated by the 2 rotor motor except now you are trying to spin 2 turbos instead of one.

FearNoPiston

iTrader: (17)

His goal was to get heat out of the rotary faster and it worked.

scathcart

Would you mind explaining this "pretty obvious" to the engineer and the aerospace analyst why doubling the turbocharger parasytic losses results in a more efficient set-up?
I love how "read someone's opinion on how great his car runs" has become synonymous with performing actual research.

bc_fd3s

iTrader: (2)

Well I don't have experience with twins on a rotary but the basic idea is the exact same. The RB26 is the best engine to compare the rotary to as well since it is a 2.6L which most people consider to be the piston equivalent as a 13b.

Not ALL twins spool faster. Two SMALLER twins will spool faster than one LARGER turbo. If you think two GT55's are going to spool fast you're out of your mind.

amunoz3

iTrader: (2)

what i had said was meaning in general......... and was regarding to small twins because of course.... two big gt55 would be ridiculous. It was meant for 2 smaller turbos compared to one big one.......... I have never disrespected you so do not disrespect me, if its something you do not get just pm me.

amunoz3

iTrader: (2)

as for those asking for numbers that it produces thats fine just keep in mind im trying to blow up the auto stock tranny then we will be going for high numbers.

hondahater

iTrader: (2)

See what you guys are missing is that these big twin setups are probably made for drag racing where spool time really doesn't matter when you have a 2step to spool those things up on the line.

Diamond Geeza

I think you missed Evil Aviator's point...he is referring to turbo setups which will flow similar output. A new billet t67 is capable of putting over 800rwhp to the ground on a 6cyl. Where would your GT2860 pair have maxxed out?
The twin vs. single argument has been raging forever, and I really dont know which is better for spool to be honest. The idea that with twins you are overcoming twice the parasitic losses makes sense to me though. Both approaches have been proven to make great power, but comparing dissimilar sized setups is not accurate at all. Also a T67 should be back on power almost instantly between shifts with a 6 cyl motor being driven properly.

Jeezus

iTrader: (4)

I would assume with this set up, equal length manifolds are not needed?

t-von

iTrader: (8)

Dude Evil was being sarcastic do to all the nonsense that's being spread around on this thread.

Trots*88TII-AE*

iTrader: (11)

I'm still trying to wrap my mind around this. Even in theory, using sound engineering logic; all things equal (including manifold design) how can two smaller turbos, each with half the exhaust velocity and heat of a single, each suffering from parasitic losses in the bearings, with larger combined rotating masses and neither taking advantage of the pulsing effect of a two rotor, spool faster than a single turbo putting out the same flow?

Vierte

iTrader: (2)

Engineering logic is nothing more then an educated guess... ususally a very well educated guess but still it only gets you so far. Thats why one very important step in the design process is testing and analysis.

One thing, your assuming that the moment of inertia of a large turbo is less then that of two smaller radius turbos. If I remember correctly doesnt the moment of inertia increase with the square of the radius? If so then smaller radius turbos could very well be a quicker accelerating option.

Did you think about pipe flow losses? There are inherent losses when a pipe flows a fluid into a pipe of a different diameter, like a collector. The losses are a function of the ratio of of pipe diameters. A larger change in diameter causes a large flow loss.

What about when one rotor is pumping the working fluid out of the exhuast ports and the other rotor exhaust port just opens releasing higher pressure combustion gases? That pulse from the exhaust opening could raise the pressure insided a merged manifold and result in greater pumping losses on the other rotor.

Its really easy to make assumptions and approximations but there is only one way to get results.

fdracer

uh, you do realize that you had to get rid of your twins to switch to this setup, right?

ronbros3

I dont know where turbo technology is going,,BUT last week at the SEMA show Garrett had a all new design turbo,,GET THIS,, TWO COMPRESSOR WHEELS IN A SINGLE TURBO, ON ONE SHAFT.

claim its better than twins, and better than variable vane turbs for spool up,and flow!

Vierte

iTrader: (2)

just look at it as more of an .... upgrade!

Monkman33

iTrader: (28)

wow. READ MY POST.

I am talking strictly EBP. Exhaust Back Pressure. Eliminating points of restriction that hold in HEAT. The enemy to a RELIABLE rotary engine.

Holy hell people. Has the reading comprehension of the general populous really gotten to the point where they see one friggin' word and automatically assume whatever the hell they want to? Do I need to specify the TOPIC of a post at the beginning or end of EVERY sentence?

Then, when you take into consideration the single "Caveat" that I so kindly included in my post.... you'll see that I made perfect sense. Oh, and I have more than just Howard Coleman to go off of, I use him as a reference on this board due to easily being able to find his threads. I was not talking about any other type of efficiency except for EBP.

But wait, there's more. You claim that having two turbos is twice the parasitic loss (I pretty much agree with you to a point)... etc. But what about the losses in collectors and merging gas flows? Are you going to prove the entire theory wrong with a variable rate flow analysis taking into consideration the differences in temperature at different load levels and the convergence factor in a collected manifold? I think not. Properly sized and plumbed parallel twins will probably be more efficient overall than a single (sized exactly equivocally for total flow rates) in both spool (worst case equally), and in heat retention to the engine.

amunoz3

iTrader: (2)

custom made from Turblown Performance great custom work.

apexFD

Some of you guys need to pursue mechanical engineering.

=Benjamin

Evil Aviator

Oh, so you are saying that there is no difference in the amount of exhaust manifold tubing between a V engine and an inline engine with respect to feeding a single turbo? Obviously I don't know much about turbos, but I would have thought that a V engine would not efficiently power a single turbo due to the massive amount of exhaust tubing requred for both cylinder banks to feed the turbo, while an inline design like the 13B could feed a single with almost no tubing if necessary. Silly me for thinking that, lol.

Hey, if you are implying that amunoz3 is out of his mind, then you need to stop disrespecting him and take it to PM like he said. I have been on the Honda forums for a very long time, and I can tell you that the whole point of internet threads is for people to post cool ideas so that everybody can tell them how great they are, and not for people like you to ask questions or engage in a technical discussion about the topic.

I searched "Garrett" and "two compressor wheels" on teh ntrnet and found this Garrett TPE331 engine thingie. It says it was produced in 1963, which must be a typo since the idea is brand new. Maybe they meant to say it would be produced in 2063?
http://en.wikipedia.org/wiki/File:Turboprop_cutaway.jpg

13B-RX3

iTrader: (2)

Vierte

iTrader: (2)

That's funny. But if that's an attempt to be an E-bully, you fail.

dpf22

I will be finishing a custom twin turbo setup this winter. The turbos have within 30cfm of a 3076r compressor's maximum flow (still over 400hp on a rotary) and the turbine area is just larger than a p-trim t04. The combined a/r will be .96 between the two turbos.
I'm no engineer, there has been a lot of assumptions and "guestimation" with this setup. I am having the manifold custom made by a pro (whom I will not mention out of respect) and the system is based around a very fast spooling methodology. Small primary diameter, length around 18". Downpipe size is chosen for scavenging effects at mid rpm, not maximum power. This will be an ssm autox car (has been for a few years now) and I am trying to maximize powerband between 3000-7500rpm without the added heat of a restrictive hot side on a large(ish) compressor. I will post up a dyno chart when all is said and done, but it won't be for a few months at the rate I'm going. If it doesn't work well enough, I'll sell the setup and try something different. I'm all for out of the box thinking, its what makes some of the big boys so memorable. Following trends never made anyone great....

fdracer

the rb26 is an inline 6 engine.