I just want facts. I ALWAYS thought a single turbo was a better setup...all the fastest supras and GN's are a single setup...however the 2 fastest ls1's are twin...why is one better than the other? Somone help me. All my mechanic friends said they always throught a single one was better, and also dont have any first hand turbo experience, so im kinda at a loss. thanks in advance!

 

I went single to make my life easier to be honest. The logistics behind fabbing a custom twin turbo setup boggled my mind, especially since I had no prior experience. As far as which is better, my impression is that its a matter of preference. I prefer my single

 

Actually I think the two fastest LS1's as of today are #1-a single turbo, and #2-a twin turbo. Choose whatever you want, different strokes for different folks.

 

Some engines use two turbos of different sizes. The smaller one spins up to speed very quickly, reducing lag, while the bigger one takes over at higher engine speeds to provide more boost. Twin turbos are harder to set up and more expensive. I will be going with a single in my low compression 408

 

it really depends on how dedicated you are... and honestly I can't see you needing anymore then you could get out of a decent single setup. If you did want more then that you should have the know-how to understand a twin setup, see where I'm going? Whatever floats your boat dude mad power can be made either way.

 

so much for facts...

 

May be obvious but I think:
-twins require more plumbing
-twins harder to fit on late model cars where engine compartments are tight
-twins would suffer less lag potentially but I bet it's hard to make a single vs twins straight comparison
-singles can get pretty big

 

Zach, if your not talking about the obvious, as in it cost more for TT, and more plumbing and WTF you going to put it all....then what you are looking for is the performance aspect. Its seems like it is kind of preference. The TT guys will say TT is more efficient, less lag and makes the most power, and so will the singles. The only way I could argue is that for a single to make mondo power, there will be more lag by nature it takes a monster single to make monster power, where you could use TT, smaller so they should spool quicker. How much, well thats where you get into all the **** I am still figuring out, A/Rs, piping size, engine flow etc......

Basically, either way you win!

Good luck,

Charlie

 

Thanks john and cat3. Yeah i was just looking at the physics part of it. assume it was an engine test stand, all the room in the world. I can see all the obvious, but things arent what they seem, such as it takes two people that can lift 100 lbs to lift something 200 lbs, they could actually probably lift 150 together, but one person who can lift 200 lbs may not beable to lift the 200 lb item due to the size of it mabye, that kind of theory. i understand 2 would spool faster, because you can get 2 small ones, but will you make as much boost? and your spinning two smaller ones, which would make me THINK you could spin instead of an (just blurting out numbers) an 88mm turbo, you cant nesscarily spin TWO 44's due to the friction and inertia of getting TWO turbos to start spinning etc etc. THESE are the reasons i ask. I am not going to build a turbo motor tomorrow nor do i have the money, im just asking so when it comes up in a conversation, i can sound smrt! (yes smrt) If anyone has any other knowledge, its appreciated. Thanks!

 

i dont know how you guys get this in your heads...
with a TT you use 2 turbos that are half the size of the single you would need, BUT you have to split the exhaust in half so the difference in spool up would be naught. now, if you took ONE of those twins and used it as a single THEN spool up time would be much quicker but you wouldnt make alot of power.
the only real advantages are:
single: $$$ only need 1 turbo, wastegate, bov, etc.
twin: if you dont have anywhere to put a huge single you may have room to put 2 smaller ones in 2 different places.

 

this is exactly why i started this thread, to find out wtf is the truth. hahaha thanks everyone for all your input, but everyones facts still drown out everyone elses facts haha. perhaps i should go on amazon and get a book?

 

LOL. Someone could say or ask this same thing about your post.( " I don't know how you guys get this in your heads...")

You should watch what info you give also and who you get it from carefully. These guys probably got this info from someone similar to you that felt he was speaking fact, and then repeated it.

Everything is not as logical as it seems such as .... "with a TT you use 2 turbos that are half the size of the single you would need BUT YOU HAVE TO SPLIT THE EXHAUST IN HALF SO THE DIFFERENCE IN SPOOL UP WOULD BE NAUGHT". People seem to say that quite a bit, but it is not as simple as .... "you split the exhaust so each turbo only gets half the energy".
Certain undeniable laws of physics apply to many things that people think are just clear cut. It might seem to someone trying to reason to say the above about twins, but the real world and physics tell the real story. For instance look at Harlans car , I think he has 2 T66's that probably have the potential to make about 1450 - 1500 hp . Even with that HP potential, they probably spool faster on his engine than a single T88 that has only about 1250 hp potential would. Also many PROFESSIONAL, and people who REALLY KNOW, will tell you that twins do spool quicker for a given hp level.

Also , look at a quote from below which should basically answer the original question with some physics involved. Also, it is from PROFESSIONALS at INDUCTION MOTORSPORTS who also have real experience........................................ .................................................. ...........................

.....Frequently asked tech questions/topics:
Turbo choices: single or twins?




"Assuming that both setups are capable of the same amount of max power, what's better, two small turbos or one big turbo?"

Twin turbos will spool faster if the comparison is apples to apples. In other words, don't pair two 10-year-old junk yard turbos up against one brand new GT turbo and call it a fair shootout. If the twins and the single all share similar wheel technology (aerodynamics and materials) then the twins will out-spool the single. It's true that each of the twin turbos will only get half of the exhaust energy but the inertia (the resistance to a change in rpm) of the wheel is proportional to the 5th power of its diameter -- a wheel that is only 15% larger in diameter will have twice the inertia of the smaller wheel. So small changes in wheel diameter make huge changes in spool.
Second point, a single turbo is more efficient than twins because the tolerances inside the housings are roughly the same on all turbos, independent of the overall size. This means that 1/8" of clearance, for example, on a 15" housing amounts to a lower percentage of air gap (and a higher efficiency percentage) than 1/8" of clearance on a 6" housing.

Bottom line: once you get the things spooled, the single will produce more efficient boost, but the twins will make boost sooner."


It seems like there is not one that is Better, but which is better for YOU, how the car is set up , and how the car will be used. Is a bit quicker spool important? is a bit more effeicency or power more important? Of course you can still get good spool with a single, and awsome power with twins also, Up to a point , both can get the job done on a street car. It may just come down to what you can fit. A single T76 can give you full boost in the 3000's and make about 1000 hp and two smaller ones like T60' can make about 1000 hp, BOTH in a streetable combo that can even be daily driven. One may spool quicker, and one may be a bit more efficient up top, but they can both give you about 1000hp if that is what you want. It may come down to what fits. Maybe both will fit. So It just depends.

 

I know these boards , are to share information, and you get some VERY good information , but some is also very , VERY BAD, (FALSE). When you get information be carefull who it comes from. You will find that especially on this board, and others like it, you will get some straight up false information about Turbos . Lol . Just look at many of the turbo post on the whether it be here , the 'other board", or camaroz28.com. If you want to hear some funny stuff, start a post about Turbos or turbo Cams. LOL

Don't get me wrong, SOME people know there stuff. Read, post from, INTMD8 , Harlan, Wheel to Wheel, and guys who actually race and /or work with turbos , engines, for a living as well as many other sharp guys here that do it for a hobby, but who maybe learn from racers , pros , and experience, that have TRUE KNOWLEDGE. There is Alot of good knowledge on the net, but alot is False , and is just regirgitated trash, that someone heard , repeats, and keeps spreading from one self proclaimed guru to another. The cycle just keeps repeating, and false info continues to spread like rumors. Sometime people make mistakes giving info, but sometimes, people just don't know the truth (what they are talking about)

Again, watch what you believe, espcecially about turbos. LOL

There is some good factual information, you just have to get past the wrong stuff. If you ask a pro, racer, knowledgeable person, and they are in agreement, that is usually the answer. Often you will find they are often in agreement, (Except about gapless piston rings ) Although everyone is wrong sometimes, and sometimes even racers and engine builders don't agree. Usually those guys will give you the right info IF there is a CLEAR answer.
There are those on here that can point you in the right direction , and then there are those who remind me of the scripture in the Bible that talks about the Blind leading the blind.

 

rpm2800, bingo. THANK YOU. THATS exactly what i was looking for. I appreciate you taking the time to write all of that.

 

rpm2800. i do get most of my info from this site so i only know what i hear from the guys who do this for a living so if i say something thats not correct(and seem cocky about it) its not intentional .
now with that aside, i understand your explination of how with 2 small turbos you have more of the weight centered on the shaft as opposed to a large turbo with the fins extending farther. but does it really make that much of a difference in spool rpm as opposed to a comparably well setup/sized single? i was always under the impression that the impeller was one of the lightest parts of a turbo so even though you have more weight farther from the center of gravity, the weight of the impeller itself was almost insignificant.