Dual Turbo's?
 

I was thinking to myself that dual turbo's would be really neat and technically challenging to make work right. The question is, would they be benefitial to performance. You know how the outside pistons fire together and the inside pistons fire together; well, at least in out 4 bangers? I was thinking of routing the exhaust from the outside pistons into one turbo and the exhaust from the inside pistons into the other turbo. This would increase efficiency since the exhaust gases wouldn't bounce into each other with the pulsing of the engine.

Anyway, I have several questions...

1. Would I need separate wastegates?
2. Would I not get an increase in efficiency if I routed the charge pipes from the two turbo's into one charge pipe that leads into the throttle bofy?
3. Would cross-routing give me any gains? Routing the outside pistons exhaust gases that drive the turbo into the inside pistons intake ports and vice versa. Of course, having two throttle bodies would be necessary. Let's not take this into account though when thinking of any increases.
4. How do the pressures add up? If both turbo's give me 8psi, then do I have 16psi? Probably not. However... Both turbo's can now be smaller to give me that 16psi and therefore they will spool up quicker, right?

I think this would be a very unique thing to do and if there are any performance gains then I might do it. it would be pretty challenging too. any opinions or suggestions are welcome.

I for one am not "turbo-wise" ...but the only twin turbos I see are on 6cyl. engines and above. I've only seen twin-turbos on V8s where each of the two exhaust manifolds gets a turbo.

Correct me if I'm wrong, but a turbo runs off of exhaust gasses. Wouldn't putting a two turbos on a single manifold engine cut each turbo's capable PSI in half?

*takes out a rubber band* Streeeeeeeeeeeeeeeeetch...:tdown:

Edit: But it will be fun while ya got it! :)

i don't even think we can fit a dual turbo set up in our civics

Can a GSR have a dual turbo setup?

yeah. ive always though that twin turbs were for v-6s and up

Who said it had to be a V-6? The Skyline and the Supra have many twin turbo setups in the past.

The turbos will have to be really small. You will benefit from a quick spool(you can get that from a single small turbo) or if you want more power, go for a bigger turbo. You will only need one wastegate and BOV(both turbos run into one intake manifold). For people that have taken thermodynamics, you know the sizing of the turbos only changes the different effects you want in performance and not change in maximum horsepower. Twin-turbos are thermal efficient with engines above 3.0 L(reason why the HKS TT RB26DETT is bored and stroked out to 3.2 L - would that make it a RB32DETT?

since it's 3 in the morning, i'm not sure if you're being sarcastic about your question at the end.

well, if you're not, technically yes that would be correct. the number is the displacement in liters
RB26=2.6L
B18=1.8L
us D17=1.7L

do u mean twin turbos are thermally efficient with engines that have a displacement of 3L and above?

cuz if u say only above 3L, you are implying that the tt mkiv is not efficient since displacement out of factory is 3.0L.......[IMG]i/expressions/beer_yum.gif[/IMG][IMG]i/expressions/beer_yum.gif[/IMG]

edit: i forgot to mention, i agree that there will be only one blow-off valve since both turbos would connect eventually from one pipe to the intake manifold, but shouldn't there be 2 wastegates or would they be connected in such a way that both stem from one pipe leading to the header and that pipe is where the only wastegate would be located?

Um, what Supra or Skyline isn't a 6cyl?

there is a 4cyl. supra that i think has maybe the same corolla motor that is used for rally. it's in gt3 too and it is the engine that we see in the intro although i have no idea why they didn't keep the 2jz in there; maybe corolla motor w/ bigger turbo means overall less weight due to less displacement compared to the 2jz.....[IMG]i/expressions/face-icon-small-confused.gif[/IMG]

Have you thought about sequential turbos like on an RX-7 or some of the STi Subarus in Japan? The Subaru's are 4 bangers and it works, I don't know if you could fit it though.



Supras and Skylines have Straight (Inline) Six engines in them, not V's

Yes, this is possible:

You would need:
1. Custom manifold to fit 2 turbos.
2. 2 waste gates
3. 1 B.O.V.
4. 1 smaller intercooler to make up for the turbo lag instead of big one.
5. 1 throttle body (only 1 needed)
6. Custom charge piping into a y into the intercooler then one pipe going from intercooler to throttle body.
7. Custom downpipes (routes first turbos waste gate blow off and exhaust into second turbo)
8. 2 intake filters
9. Downpipe off of second turbo
10. Bigger injectors and upgraded fuel system
11. Custom exhaust
12. A few beers and lot of time.

Twin turbos are usually setup in a small turbo and a big turbo. You have a small turbo that spools very quickly (1,000 to 3,500 RPM) and helps spool a bigger turbo (4,000 to redline) for top end speed and power.
There will be turbo lag on these motors and even the RSX motor. You could only run low boost even with internals, not because of the power but because not enough exhaust gas to spool the turbos. It is a hell of an idea. I think it would be awsome, although it is a show item not performance on our motor. You couldn't use 2 of the same size turbos, because there would be super turbo lag for one if they were big turbos and if they were smaller there would be no high rpm power. This is all I can think of right now. If anymore questions just ask.

EDIT: Power to you grey.

Is there even a turbo or supercharger out for our 2k1. I really want a supercharger.

NUMBERoneHONDA: Yeah, I thought about that a little later. Getting a smaller turbo and a larger turbo. The smaller one would spool up at lower rpm's and the larger one would spool up at higher rpm's. Then they would combine their compressed air before the throttle body. Plus the wastegate of the smaller turbo would activate at the maximum rating of the smaller turbo and vent it's exhaust gases into the larger turbo. Yes! Thank you...

It would be more complex and a little more costly, but I would have more boost at lower rpm's than with a single turbo setup. Fitting all of that in the space betwean the block and the radiator fans would be a challenge, but I think it would be worth it. Not only for show either ('cause I don't go to shows), I'm looking for a performance gain out of this.

The piping for the smaller turbo would be smaller than the piping for the larger turbo. Including the intake filters, the downpipes, the wastegates, everything. I kinda don't understand why there's only one BOV since the pressure in the charge piping will be greater than the maximum psi rating of the smaller turbo... Oh well, I'll read about it.

You are a monster [IMG]i/expressions/face-icon-small-smile.gif[/IMG]

This is what it's all about, people. Who cares about shows? It's all about beating the next guy on the track, and having fun building your own car.

Who cares if you can wax your car all pretty? THIS is what the tuner scene is all about!

Good job man, I hope this project comes through! [IMG]i/expressions/beer_yum.gif[/IMG]
:tup:

if it's for performance a sequential setup would work...to correct you on something 2 pistons do not fire at the same 2 go up..one is pushing out exhaust gasses, one is compressing air..only 1 fires at a time.

For a sequentiel turbo setup to really work your engine would have to able to take alot of boost. Somethig like a GT25 turbo or even smaller to get you through the lower rpm power band. untill you can develop enough exhaust gasses to actually spin a nice big turbo. It makes a car more streetable and still high boost capable. but from a 1.7 if your gonna build the internals and plan on running alot of boost your best off just getting a T3/4 Hypbrid in a t3 housing...it's a ball bearing turbo and spools up quick enough and can provide up to 25PSI boost on a 1.7 so it'd be more than you ever needed..

Unless you plan on running a HUGE turbo like a T66 which won't even start to spool untill your running 5500+ Rpms (where the sequential setup comes in) then you can run 40+ PSI boost...not that the engine would ever really handle it [IMG]i/expressions/face-icon-small-smile.gif[/IMG]

so then would the two turbo's combine into a sort of y-pipe from their respective compressor "sides" to the intake manifold....thus needing one blow-off valve?

"I kinda don't understand why there's only one BOV since the pressure in the charge piping will be greater than the maximum psi rating of the smaller turbo... Oh well, I'll read about it."-Grey

now that i've really read that, it makes sense.......?

and since the two turbo's would be connected to one exhaust manifold, then wouldn't just one wastegate be necessary? now i don't really see how two w.g.'s would be necessary...unless one would be needed for the smaller turbo since it will spool up quicker and need to release excess pressure sooner than the bigger one...?

now i'm not sure on quantity of either:_doh:

<---------- :_doh:



anyway. i like this idea Grey i think it should be thought out a little more but i thought about that a while back when HKS was being thrown around and then i trailed off so ive been doing some research on this particular subject so hit me up maybe we can discuss some of this

Sequential? You mean VNT turbo's? There's an explanation of it here: Click Me! I would use one if I could find one. This would probably be less hassle than dual turbo's and it would be just as good (if not better).

I'm not sure what you mean, but I was referring to this: Click Me! That is how our engines fire.

Yes, that is the way I see it.

You need two wastegates because you don't want to push the smaller turbo past it's limits. You want to use a smaller wastegate on the smaller turbo that activates at a certain boost level and sends the exhaust gases into the larger turbo. That way the smaller turbo can be pushed to it's limit and the larger turbo take over from there on out to produce even more boost.

http://static.howstuffworks.com/gif/engine-inline-4.gif

Grey,

when the 2 cwnter cylinders are going up, one is on it's compression stroke, one is on it's exhaust stroke blowing out exhaust gas.

the 2 outer one's ..1 is at the end of it's power stroke and about to releas exhaust gasses as it goes up..the other is at the bottom of it's intake stroke and is reay to compress the air

Ah, I getcha. Okay, that's the way it is...
Hmm... Yeah, so disregard what I was talking about in the first post.
I didn't take everything into consideration, so there might be no performance benefits of routing the charge pipes into certain intake ports. Although you never know, I have to think about it some more...

HKS ( or GReddy, i forget) tried a twin turbo set up with an ITR. Not only did it cost 2x the ammount of money and time to fabricate, the performance wasnt anywhere NEAR what was available with a properly tuned single turbo set up. Fact of the matter is, no matter how small those turbos are, 1.8l isnt pushing enough gas to use them efficently.

Hmm... Okay, screw it. I still might go with a VNT turbo though. That is if I can find one.
Dual turbo's would be interesting, but maybe not as nice as a VNT. I'll have to do some more research to find out for sure, but it seems that a single VNT turbo will yield better gains throughout the whole powerband than two different size turbo's.

Edit: K3wl little article... Click Me!

so then on a V6, 3 cylinders on one side are in each 3 different phases of the combustion cycle and the same goes for the remaining 3 cylinders?

also, as can be seen in mohawk's neat little video the 2 pistons on the inside are in unison (going down) while the two outer pistons are in unison (going up) how is the setup on a V6?

on a V6 it's different because you have 2 banks.. on a V-6 the pistons are offset..Instead of having one set of pistons at TDC at the same time as the others are at BDC you'll also have 2 more a Center

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Cheaper than buying a 200HP car[IMG]i/expressions/face-icon-small-cool.gif[/IMG][IMG]i/expressions/face-icon-small-cool.gif[/IMG]

pardon me for skipping the second page, but as i understand it, the benefit to twin turbo is not a separate turbo per pair of cylinders, its teh removal of the spool up time.

i was always taught that you can run 2 turbos in line, one little one and one big one, so you get the fast spool up time then the big big boost.

if physics and caraudio taught me anything, running an identical turbo per pair of pistons at 8 PSI each gives you 8 + 8 = 8 psi total [IMG]i/expressions/face-icon-small-wink.gif[/IMG] i would also assume that each turbo manifold would be working half as hard to maintain the same pressure.

as far as actual performance benefits, i dont think anyone in here has actually tried it, and tho we can bs for days/months/years about it, i think you may be the first to find out [IMG]i/expressions/face-icon-small-wink.gif[/IMG] maybe........

good luck tho!

http://www.howstuffworks.com/turbo.htm

If you want to get educated on turbos, i'd suggest "turbochargers" bu Hugh Macinnes.

as for the discussion...

a dual turbo setup would be alot better than the single turbo setup, except in terms of maintinance and tuning.




the twin turbos (TT's from now on) would spool faster as they would have a smaller moment of inertia since you would be using two SMALL trim turbos.

with two smaller, INDENTICAL turbo's on the car, it would be easier to pick a set that would run more effieciently while staying away from surging... (look into reading compressor maps.)

the TT setup could use ONE external wastegate... or TWO internal wastegates... you'd only need one intercooler, and one intake...

all that having been said... i have NO IDEA if you could fit the monster into the engine bay... but even if you could... it would be worthless unless you build the motor from the ground up so you can run high levels of boost... even going so far as to sleeve and o-ring your block and o-ring the head...


Using two different size turbo's would require an active diverting valve to control where gasses were going... it would need to flow air through the small turbo THEN INTO the large turbo at low engine speed, then bypass the small housing turbo at high speed and go directly into the large turbo... (read: "this is TOO MUCH work.")


For the tech-minded:

our engine is about 104 C.I.D.
at 6000 rpm's and at an assumed 80% volumetric efficiency, the volume flow is about 130 cubic feet per minute.

using that, plus the Pressure ratio (a calculation based on how much boost you WANT to run)... you consult the compressor maps for various turbos... if you can divide the volume flow by 2 and the boost pressure (ONE partt of the presure ratio) by two while keeping you ambient pressure (the otehr part..) the same, you can find a turbo that can be used in a TT setup.

ideally you want your turbo to run as efficiently as possible while staying FAR from the surge line... or the line on the map that tell you where the turbo will fail... normally turbos run with a 60-70% efficiency... if you could find a small turbo that flowed the right volume of air and ran at 70% (or better) efficency at the level of boost you wanted THOUGHOUT the powerband... (in otherwords not JUst the 130CFM's you get at 6000 rpms) then you would have a near zero-lag setup that could run high boost and make tons of power.

i'll fill up the gas tank of whoever does this first with 107 octane race gas, just to say "thanks" for stomping mustangs.