[OpenFlash]

Originally Posted by Tonyturbo42

Actually you are missing the point, a large turbo might be more efficient up top because of greater flow but the twins are going to give you a broader power range every time. Why do you think the factory installs twins? Cause its fun to spend extra money putting two of something where one will do? No drivability is the answer. And for you to say smaller turbos "Need alcohol" to fight detonation shows me you read more form posts than you actually know. I have been building turbos and turbo systems for more than 20 years, our business has been for close to 40. Properly sized twins and a good intercooler will keep IAT temps in check and a quality tune has more to do with detonation than your choice of twins or a single. To say smaller turbos "Need alcohol to fight the detonation" shows your really do not understand the concepts you are discussing. I am not saying you do not have some experience. But that statement is fundamentally flawed. I am not really sure why you even jumped in here. I simply stated both are great options and the single is a better choice for someone wanting max power and somehow you still wanted to put in your .02 cents about a subject you need to do some more research on. Not everyone on these forums is a kid trying to bolt upgrades onto the first car he has ever had with a turbo.

The knock prone nature of the currently available upgraded twins at higher boost/power pressures comes from the much higher exhaust back-pressures they operate at. And as far as turbo performance goes, back-pressure is evil. It leads to many bad things including exhaust gas reversion which is bad for VE and really bad for in-cylinder combustion temperatures. The unfortunately high back-pressure levels are thanks to the OEM exhaust housings which are used for direct bolt-on compatibility to the downpipes and OEM exhaust manifold. It has very little to do with compressor inefficiencies as small to moderate differences adiabatic behavior can be compensated/negated by the cooling effects of intercoolers and/or methanol.

The only way to offer twin turbos that perform similarly to a single turbo, as you will see, is to have them run non-OEM exhaust housings. Which means using a new manifold and a new downpipe/wastegate configuration. And you will find that under-hood real-estate is going to be an issue when trying to fit larger frame twin turbos. Unless you can bend the laws of space and time (or relocated the engine mount and modify the frame rail), that is going to be impossible.

You will also have to use non-OEM induction plumbing which will post somewhat of a packaging dilemma since you will have to either route them in front and behind the engine or get all bendy and keep them on the hotside. Both solutions are better than using the stock induction pipes. But both are inferior to a straight, short-tubed intake.

Lastly, all other things equal, a single turbo will always offer better compressor and turbine efficiency than two smaller turbos. Even if they were using the same aero/material as the single turbo. This is because compressor and turbine efficiency is largely dependent clearance between the wheel and the housing which is limited by machining technique. So two smaller turbos will have the same nominal clearance as a larger single. But their relative clearance (relative to the wheel diameter) is greater which means generally lower efficiency.

Hope that helps
-shiv

[jippii ensio]

Originally Posted by Tonyturbo42

Actually you are missing the point, a large turbo might be more efficient up top because of greater flow but the twins are going to give you a broader power range every time. Why do you think the factory installs twins? Cause its fun to spend extra money putting two of something where one will do? No drivability is the answer. And for you to say smaller turbos "Need alcohol" to fight detonation shows me you read more form posts than you actually know. I have been building turbos and turbo systems for more than 20 years, our business has been for close to 40. Properly sized twins and a good intercooler will keep IAT temps in check and a quality tune has more to do with detonation than your choice of twins or a single. To say smaller turbos "Need alcohol to fight the detonation" shows your really do not understand the concepts you are discussing. I am not saying you do not have some experience. But that statement is fundamentally flawed. I am not really sure why you even jumped in here. I simply stated both are great options and the single is a better choice for someone wanting max power and somehow you still wanted to put in your .02 cents about a subject you need to do some more research on. Not everyone on these forums is a kid trying to bolt upgrades onto the first car he has ever had with a turbo.

Tony, you are mixing concepts. I have RBs myself and enjoy the wide power band that you are talking about and the peak power is enough for me. Do you know, that actually the low moment of inertia achieved by using small twins with tiny A/Rs is the main reason for the power band starting early and for that reason being wide?

Yes, I do know why BMW decided having twins and later changed for twin scroll single N55, do you?

You are moving from the subject to talk about "properly sized twins", what ever that means. Let's stick to the RBs, since that is what you referred to when saying Shiv's figures were somehow misleading. You see, "properly sized" could mean double the size of one single for someone, if you understand the exaggeration.

If you are claiming that you can push stock frame twins further than 520WHP with "a good intercooler" alone, I have to disagree. The boost pressure needed would be so high that the IATs cannot be kept reasonable with any intercooler. Since the back pressure becomes high, the pressure drop of the intercooler becomes very important in addition to the cooling efficiency. What kind of pressure drops and efficiency percentages you were thinking of when you talked about "a good intercooler"? Also, what boost pressure you were thinking of for the twins? What compressor maps were you looking at? You were thinking of upgrading the MAP sensor and in which way are you going to manage the DME in case of non-stock TMAP.

You started questioning the dyno figures Shiv stated because you have probably not been searching or looking for the actual dyno graphs. He referred to the need for higher octane to reach the figures in question with the stock frame twins and that relates to the vastly increased backpressure and also turbo efficiency dropping at the higher revs at the peak power. You could start studying by looking at the compressor maps of the said options. You could give us your professional opinion on the achievable power figures after you have studied the compressor maps and evaluated the level of the backpressure. I believe you know the static and dynamic CRs of N54?

Are you claiming the stock frame turbos, with stock CR pistons and stock cams, don't need high octane to reach 520WHP? If yes, you could either demonstrate that by showing us a dyno of it, or calculate it for us having all the info available. We are basing our arguments on several dynos that would imply the power figures being flow and octane limited with the stock frame turbos.

[enrita]

hehe funny

[Rob@RBTurbo]

Great post above by the Shivmeister. Well put.

[OpenFlash]

Originally Posted by RobBeck

Great post above by the Shivmeister. Well put.

Lol thanks Rob

[enrita]

Originally Posted by benzy89

Unless GIAC will make a custom tune for your upgradded turbos (which they might already), you'd prob be better off with COBB, JB4 or PROcede

they have NO tune for upgraded turbos but i am aware they will fix one for LOBA's turbos which are hybrids clipped turbine.

[dicostal]

Originally Posted by enrita

they have NO tune for upgraded turbos but i am aware they will fix one for LOBA's turbos which are hybrids clipped turbine.

Ciao Enrita, that is good to hear that I will have options in the future
it would suck if I had to get a completely new tune on top of the turbos.

Thanks - Luigi

[Tony@vargasturbotech]

Originally Posted by shiv@vishnu

The knock prone nature of the currently available upgraded twins at higher boost/power pressures comes from the much higher exhaust back-pressures they operate at. And as far as turbo performance goes, back-pressure is evil. It leads to many bad things including exhaust gas reversion which is bad for VE and really bad for in-cylinder combustion temperatures. The unfortunately high back-pressure levels are thanks to the OEM exhaust housings which are used for direct bolt-on compatibility to the downpipes and OEM exhaust manifold. It has very little to do with compressor inefficiencies as small to moderate differences adiabatic behavior can be compensated/negated by the cooling effects of intercoolers and/or methanol.

The only way to offer twin turbos that perform similarly to a single turbo, as you will see, is to have them run non-OEM exhaust housings. Which means using a new manifold and a new downpipe/wastegate configuration. And you will find that under-hood real-estate is going to be an issue when trying to fit larger frame twin turbos. Unless you can bend the laws of space and time (or relocated the engine mount and modify the frame rail), that is going to be impossible.

You will also have to use non-OEM induction plumbing which will post somewhat of a packaging dilemma since you will have to either route them in front and behind the engine or get all bendy and keep them on the hotside. Both solutions are better than using the stock induction pipes. But both are inferior to a straight, short-tubed intake.

Lastly, all other things equal, a single turbo will always offer better compressor and turbine efficiency than two smaller turbos. Even if they were using the same aero/material as the single turbo. This is because compressor and turbine efficiency is largely dependent clearance between the wheel and the housing which is limited by machining technique. So two smaller turbos will have the same nominal clearance as a larger single. But their relative clearance (relative to the wheel diameter) is greater which means generally lower efficiency.

Hope that helps
-shiv

Shiv, Thanks for the post I know you 100% know your stuff, Rob Beck obviously offers a quality product and seems like an awesome guy. The other people speaking on the matter I cannot say for sure. I wrote a lengthy reply and then decided there is no point to continue this debate. I would rather just talk like adults who both own businesses in the performance industry and share information. I offer my apology if you felt I was downing your knowledge or your system. Not the case at all.

[Tony@vargasturbotech]

Originally Posted by jippii ensio

Tony, you are mixing concepts. I have RBs myself and enjoy the wide power band that you are talking about and the peak power is enough for me. Do you know, that actually the low moment of inertia achieved by using small twins with tiny A/Rs is the main reason for the power band starting early and for that reason being wide?

Yes, I do know why BMW decided having twins and later changed for twin scroll single N55, do you?

You are moving from the subject to talk about "properly sized twins", what ever that means. Let's stick to the RBs, since that is what you referred to when saying Shiv's figures were somehow misleading. You see, "properly sized" could mean double the size of one single for someone, if you understand the exaggeration.

If you are claiming that you can push stock frame twins further than 520WHP with "a good intercooler" alone, I have to disagree. - WHERE DID I WRITE YOU CAN PUSH THESE TURBOS PAST 520 HP?? You like to listen to yourself type I think. We get it you are SOOO SMART. How many turbo systems have you built in your lifetime?The boost pressure needed would be so high that the IATs cannot be kept reasonable with any intercooler. Since the back pressure becomes high, the pressure drop of the intercooler becomes very important in addition to the cooling efficiency. What kind of pressure drops and efficiency percentages you were thinking of when you talked about "a good intercooler"? Also, what boost pressure you were thinking of for the twins? What compressor maps were you looking at? You were thinking of upgrading the MAP sensor and in which way are you going to manage the DME in case of non-stock TMAP.

You started questioning the dyno figures Shiv stated because you have probably not been searching or looking for the actual dyno graphs. - What? please show me where I question anything except some wording He referred to the need for higher octane to reach the figures in question with the stock frame twins and that relates to the vastly increased backpressure and also turbo efficiency dropping at the higher revs at the peak power. You could start studying by looking at the compressor maps of the said options. You could give us your professional opinion on the achievable power figures after you have studied the compressor maps and evaluated the level of the backpressure. I believe you know the static and dynamic CRs of N54?

Are you claiming the stock frame turbos, with stock CR pistons and stock cams, don't need high octane to reach 520WHP? - UM huh? Please show me where I said this If yes, you could either demonstrate that by showing us a dyno of it, or calculate it for us having all the info available. We are basing our arguments on several dynos that would imply the power figures being flow and octane limited with the stock frame turbos.

DUDE, all I have to say is you are delusional, I did not ask ANY of the above things you are claiming. I had a question about some wording and that was very clear. If you read the whole post I also made it clear both options are great just depends on your needs and goals. Next time you want to start spouting off about how much you know. Make sure you are actually addressing someone who first off knows less than you and secondly who actually made reference to anything you are talking about. With this I am bowing out of this convo. I have re-read over my first post and I can see how the first line could be taken wrong. My point was saying you have to run race gas and meth to safely run twins up to the 500 HP level was what I felt was misleading I could have stated it better. I actually have to get off the computer and go build some turbos which is my business. You can go back to your desk job. Thanks

[Tony@vargasturbotech]

Originally Posted by SIKH335

That's very interesting! So you are gathering opinions from N54 owners on what turbo set up is currently considered the best in order to create your own twin turbo option. Good luck I would be interested to see what you come up with, since the only two designs currently are a Hybrid twin or the Single. I will say this the single I am running today is very drivable, not to say there is no lag what so ever but if I'm in DS which I mainly drive in the spool up is incredibly fast on the 62mm option. Now DS keeps me above 2500rpm, as opposed to Drive which will shift to 6th at a 45-50mph cruze dropping rpm to around 2000rpm where lag is present.

Honestly my goal was just to join the community and learn what the N54 owners like and possibly dislike about the current products and just talk to some people. I think I need to listen more and talk less. No use getting into pissing matches with anyone. Cheers

[ATP]

Originally Posted by Tonyturbo42

Honestly my goal was just to join the community and learn what the N54 owners like and possibly dislike about the current products and just talk to some people. I think I need to listen more and talk less. No use getting into pissing matches with anyone. Cheers

You just need to conduct this conversation in the correct forum...

[Tony@vargasturbotech]

Originally Posted by ATP

You just need to conduct this conversation in the correct forum...

Huh? This was a conversation about the different options for aftermarket turbo upgrades for the N54. The Title of this forum is N54 Turbo engine / Drivetrain/ Exhaust modifications. Maybe you can let me know what the correct forum for this convo would be then. Thanks

[OpenFlash]

Originally Posted by Tonyturbo42

Shiv, Thanks for the post I know you 100% know your stuff, Rob Beck obviously offers a quality product and seems like an awesome guy. The other people speaking on the matter I cannot say for sure. I wrote a lengthy reply and then decided there is no point to continue this debate. I would rather just talk like adults who both own businesses in the performance industry and share information. I offer my apology if you felt I was downing your knowledge or your system. Not the case at all.

No apology necessary. It's always good to talk turbo tech with others in the industry.

[lamia2super]

just wanted to add that their is "supposedly" a little more gain left to be had with our hybrid twin upgrades, but single will always make more power

[Rob@RBTurbo]

There could always be a little more eeked out, but diminishing returns vs. cost has to always be considered.

[turb0mik3]

GIAC offered to tune my car if I purchased the RB turbos. I decided that a super good suspension setup was more beneficial than any twin/single upgrade would be; sad people don't realize that but ok, haha.

However I am still searching for a good compromise between RBs and shiv's option. Gintani's turbo upgrade is coming up quickly and ER already offered to build me an upgrade; just gotta find someone to tune it, LOL.

[benzy89]

Originally Posted by turb0mike

However I am still searching for a good compromise between RBs and shiv's option. Gintani's turbo upgrade is coming up quickly and ER already offered to build me an upgrade; just gotta find someone to tune it, LOL.

Gintani's getting in on the N54 game?? VAC said awhile ago that they were putting some R&D into a legit turbo upgrade too

[themyst]

Funny stuff. If price and warranty status weren't common denominators, i would go the single turbo route each and every time on this platform.

[turb0mik3]

Originally Posted by benzy89

Gintani's getting in on the N54 game?? VAC said awhile ago that they were putting some R&D into a legit turbo upgrade too

VAC has some internal upgrades that are very interesting. When I do upgrade my engine, internals will come first.

Originally Posted by themyst

Funny stuff. If price and warranty status weren't common denominators, i would go the single turbo route each and every time on this platform.

Agreed, single is the way to go, just need various options for different applications.

[nation]

http://www.youtube.com/watch?v=*****...eature=related

should be interesting.

[benzy89]

Originally Posted by turb0mike

VAC has some internal upgrades that are very interesting. When I do upgrade my engine, internals will come first.

I know they're doing their own Performance Cylinder Head Upgrade & they also have the CP Pistons, Carillro Rods + VAC Rod Bearings, but is there anything else they've got cooking?

[EDM92]

I don't care how great the single turbo might be, $10k is highway robbery. Seriously, ten thousand dollars for a turbo, manifold, downpipe, tune, and meth kit? The same in the Mitsubishi Evo world goes for no more than $5k.