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How does a twin-turbo set-up work?

13K views 30 replies 19 participants last post by  Ducman69 
#1 ·
Old topic, but I did a search and didn't find the answers I was looking for I've read the entire post over at club-si about turbos. I've also searched at How things work.com

I removed the battery from the engine bay and that created a ton of room in there....anyways, I have the Kaminari front bumper and am thinking that I could have the intakes pointing down towards the openings in the bumper if I took the fog lights out. So intakes are no problem....Now, I already have one turbo in there where the cat used to be, so that's one turbo down. There is a ton of space where the battery used to be, so I know that another turbo would fit there....but here's where the questions come in.

(1) The MITS TEO4H I have i've been told spools up very quickly; therefore, this would take care of the low end boost, but for another turbo for top speed boost, What size turbo do I need?
(2) How do I get this larger turbo to kick in only at a certain higher rpm range?
(3) Does the intake for the second turbo only suck in air when it is spooling.....at the higher rpms?
(4) What happens to the first turbo and intake when I'm in the higher rpms?
(5) How will the piping work with running the turbos through an intercooler? Will I need 2 intercoolers?
(6) How does the throttle body work with 2 turbos running into it? Do I need 2 throttle bodies, and if so, how do I do that?
(7) Will I need some kind of gate or something that blocks the intake air from the turbo/intake not being used at the moment and then releases it to the atmosphere via BOV??
(8) How much crazy ass HP could I expect from a set-up like this?

I know that there are some twin turbo cars out there, I'm just very curious to find out how their twin turbos work.
 
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#2 ·
I dont know if this will help but read up on alot of info about the 2JE-GTZ twin turbo Supra Engine and the VG30DETT 300ZX twin turbo engine...


I know it might sound stupid but look at a Chilton book of these two cars..It might tell you how each one is constructed and how the two turbos go into one throttle body and how the fuel system is set up.....

If I am wrong..somebody set me right


btw, I know those engines are V6's but at least it gives you some idea of how it might work on a V4
 
#4 ·
<blockquote><font size="1" face="Verdana, Arial">quote:</font><hr>Originally posted by icemanZX3:
btw, I know those engines are V6's but at least it gives you some idea of how it might work on a V4<hr></blockquote>

V4???? You been smoking that crack again?? LAst time I checked, we had an INLINE 4??


But yeah, I am trying to figure out how this works as well. The 91 MR2 was a Twin Turbo one as well. I will look for info right now!
 
#5 ·
<blockquote><font size="1" face="Verdana, Arial">quote:</font><hr>Originally posted by Jays2000ZX3:


V4???? You been smoking that crack again?? LAst time I checked, we had an INLINE 4??


<hr></blockquote>

Yeah well it was short for 4-cylinder..im just lazy!!!
 
#6 ·
I'm useless... but the lazy way is I-4 (I, V, L, W refer to cylinder configurations... V and L are generally used interchangably although I really think of L-engines as being 90o and V being anything less than that).

BTW, since you don't seem to plan to merge your intake pipes at some point, how are you going to control two MAFs?

One question regarding twin turbos is what you want to do with them. Do you want two small ones in parallel (not sure what the advantage would be) or two sequential ones? Most importantly, what are your goals and what do you hope to achieve?
 
#7 ·
<blockquote><font size="1" face="Verdana, Arial">quote:</font><hr>Originally posted by Ducman69:
BTW, since you don't seem to plan to merge your intake pipes at some point, how are you going to control two MAFs?

One question regarding twin turbos is what you want to do with them. Do you want two small ones in parallel (not sure what the advantage would be) or two sequential ones? Most importantly, what are your goals and what do you hope to achieve?
<hr></blockquote>

I don't know if I will need 2 throttle bodies or not. I know if both intakes/turbos put air into the same throttle body, then they are going to have to be merged somewhere. I just don't know how you control which intake/turbo is on at what rpm and so forth.

I should have been more clear, or perhaps you didn't read the whole thread, DUCKY???


I want to keep the turbo I have now, it's a smaller one MITS TEO4H which will spool up fast enough for me, but for serious HP up in the higher rpms, I want a second huge mofo turbo. I really don't know what my goals are as of yet, I was thinking that I wanted upwards of 400HP at the wheels, but I still haven't made my mind up.

rotten EGZ, I got your blown engine right here!
, no really I do...


[ 02-18-2002: Message edited by: RoRo ]</p>
 
#8 ·
No don’t take this as law, but you might want to check out the Audi S4 guys. I think the S4’s have a bi-turbo setup; one is a small turbo for quick spool time and a bigger one for the high end of the engine. I think on the Supras one turbos air goes into the second and into the intercooler and right into the engine. Well I’m hope I’m right with some info here.
 
#10 ·
<blockquote><font size="1" face="Verdana, Arial">quote:</font><hr> I thought you needed to have a V configuration. <hr></blockquote>

what about the rotory motors, the rx-7 had a twin turbo. i see alot of cars that dump the twin set up for one large turbo for the big power.
 
#11 ·
Generally yeah... otherwise you'd only have two cylinders per turbo (1,3 and 2,4). So I'm not sure how two small turbos parallel turbos would be better than one large turbo.

Roro, I was reading, but you were talking about TBs and I was talking about MAFs. Just pointing out another issue. I don't know either, so I'm of little help.
I've only skimmed over an RX7s setup before.
 
#14 ·
There are two ways to do twin turbo. Sequential or parrallell. Parallell is where there are two independent turbos like one on each side of a v6.

Sequential is two in a row. Basically one starts while letting some go to the 2nd turbo and some out of the exhaust. The "pre-spools" the 2nd turbo. Then it appears that a complex arrangement of vaccum lines, switches and solenoids work with the ECU to operate valves to direct air toward the 2nd turbo.

http://homepage.ntlworld.com/peter.betts/supra/TechTips/turbos.htm

Here is something I was thinking about though. What if you had a really small turbo with a moderately large turbo that hung off of it's wastegate. Am I stupid for thinking that would work?
 
#13 ·
Actually if you open the hood of a supra they run an I-6 configuration not a V-6, and the mr-2 didn't have twin turbo it had twin entry turbo. Single turbo, two air intakes. I had a freind with a 90 mr-2 with a 92 j-spec turbo engine.

Rodney what do you plan on doing with two turbos, if you want big power that spools quickly, I know a kid with an Integra and a T4 drag turbo, he says there is little to know lag with that big of a turbo. Maybe you can do that instead of twin turbo.

[ 02-18-2002: Message edited by: focus---R ]</p>
 
#15 ·
Ideally this is a great idea. Have a small resposive turbo up to RPM X, then pre-spool the big whopper turbo and switch over once it is wound up for crazy ass top end power. Reality has shown us that the gains of these systems are marginal (Supra sequential vs. single upgrade) and the complexity and reliablity are problems (RX-7). For that kind of money and power levels a better solution can be found. I would investigate the larger aerocharger turbo or a Garrett GT ball bearing turbo would offer outstanding transient response with crazy-ass top end power.
 
#16 ·
Maybe I misunderstood, but from the little I did read, I was under the impression that both turbos are being spooled together always.

One small turbo and one large turbo. The small turbo will spin up fast to produce boost, but will have a flow limit and set to a certain boost level (this is probably where the complicated vacuum line part comes in to play). The second large turbo is spooling at the same time as the first one, but it would be a giant T4 capable of 350hp by itself that isn't reaching its max boost until nearly redline.

Thats all.
 
#17 ·
Just a side note, the Audi S4 uses two small same sized turbos that spool up fast than just one big one. I'm not exactly sure on why this would be the case, but I know the results are extremely impressive. Boost threshold is under 2K and lag is un-noticeable [by me anyways]. Also peak torque at 1850-3600 RPM!
 
#18 ·
First of all the 91 MR2 Turbo has a single turbo charger that has a dual entry at the turbine section. I should know, I own a 91 MR2 Turbo!!!-Jays2000ZX3-

Second, I think a lot of you guys need to understand how turbos work. In order to set up a twin turbo on a Inline 4 cylinder, you need to have small enough turbos that will spin off two exhaust ports from our 4 cylinder. The other turbo of course would run off the remaining two. Such a turbo would probably be something like a T2. Not a T25, but a T2! After you did all the math and used all of your experience to find out what turbine and compressor trims to use on our zetec, then you would have to find a way to mount them. Most likely you would have cylinders 1 and 3 run one turbo while 2 and 4 running the other. So you would have to create a manifold for them. Also, you need to create an exhaust outlet from each individual turbo, and have them merge together. Same with the Intake portion after each turbo's compressor. Have them merge before the throttle body.
And finally you would worry about the oil lines and cooling, just like any other turbo, but set up for two of them. This would be nice if you can get two small Aerochargers and not create these lines, but they are prohibitedly expensive.

Creating a sequential twin turbo set-up would be very difficult because you would have to create a way to basically shut one turbo off from creating boost and having another bigger turbo go on for higher boost pressures. Not an easy job at all. I seen different ways from vacuum techniques, to having clutches to change the turbo. You need some engineering experience, if you know what I mean.
 
#19 ·
<blockquote><font size="1" face="Verdana, Arial">quote:</font><hr>Originally posted by spankenstein:
Sequential is two in a row. Basically one starts while letting some go to the 2nd turbo and some out of the exhaust. The "pre-spools" the 2nd turbo. Then it appears that a complex arrangement of vaccum lines, switches and solenoids work with the ECU to operate valves to direct air toward the 2nd turbo.

http://homepage.ntlworld.com/peter.betts/supra/TechTips/turbos.htm

<hr></blockquote>

Wow, thanks everyone for the responses. That link there is some good reading material.

focus---R I would be interested to get some information on that T4 drag turbo. I wonder what your friend's idea of little to no turbo lag is?

Ducky no, you read right, that's exactly what I was talking about.

everyone I know that one huge ass turbo would net me more HP and all, but I don't want that huge ass turbo lag time waiting for the turbo to spool. I really don't want to go the route of a supercharger either.

Somebody mentioned something about 2 intakes going into 1 turbo??? What are the benefits/drawbacks to this kind of set-up?
 
#20 ·
Thank you sooo much focus---R and Frios.....

I hate to see bad information given about engines...especially the "beloved" and not to mention "coveted" Toyota Turbo's.....Supra having a v-6.....evryone knows all sporty 6 cyl. are in a straight line......Geesh anyone ever heard of a 911? And the Mr.2 well, she did have a single turbo here and they even used to be Supercharged in the late 80's and very early 90's.......


Oh and as far as I know all Supra hp hungry people goto a large single turbo...same with the small 300ZX turbo's...

[ 02-19-2002: Message edited by: Sir_Gawain ]</p>
 
#21 ·
I just got home and saw this thread...Man why did you have to say twin sequential turbos!!!!
Now I can see it in my head.


Use a log style manifold like I designed for my setup and on the bottom turbo flange put a 2" wastegate style flap valve actuated by a solinoid controlled by a pressure switch. On the driver side of the manifold put another flap valve on a pipe running to the BIG turbo. That valve could just have a fairly heavy spring to hold it shut while the little turbo does it's thing. Run the exhaust from the little turbo into the pipe leading to the BIG turbo to help it spool...pant...pant..drool..pant.


Sorry everyone I thing I'm having a flash back from the 70's or something....(shakes head, splashes cold water in face) I'm feeling better now.


How about using n2o to help spool a large turbo?
 
#22 ·
Please correct me if im wrong but i heard that twin turbo setups for 4cyl engines are pointless. Something about not having enough exhaust energy to turn the impellers to create sufficient amount of boost. Ive only seen things get as crazy as a turbo and supercharger setup on a 4cyl car (the Meguirs integra).
I dunno.... just my thoughts
 
#24 ·
<blockquote><font size="1" face="Verdana, Arial">quote:</font><hr>Originally posted by P-51:
What's the point, really?

Tom's single turbo setup is not too laggy, and will make all the power the Zetec can handle. What more do you really want?
<hr></blockquote>

Well being under a budget is what I'm really trying to do here. I already have the Gude turbo which is the MITS TEO4H turbo, so I really don't want to have to buy tom's turbo if I don't have to. That's why I was thinking if I have to buy another turbo, it might as well be bigger than this one and I could also use this turbo. Just random thoughts...
 
#25 ·
The 911 isn't a inline engine either... its flat (clyinders are pointing away from one another).

Would the problem with two turbos simply mounted inline and spooling together be the pressure exerted from the first turbos compressor side on the 2nd turbos compressor side when you combined them at some point? I hadn't thought of that before. Otherwise you could simply plumb from the outlet of the first turbos exhaust to the inlent on the 2nd turbos exhaust and combine the intake piping. The rpm of the 1st turbo would be controlled via the wastegate which would dump exhaust back towards the 2nd turbo.
 
#26 ·
Uh... doing a twin turbo setup would cost A LOT more than buying Tom's setup.

And the only reason for doing it would be to make MASSIVE power. Like 400-500, in which case you're gonna have to rebuild your engine and that alone will cost WAY more than Tom's setup.

I really think you should think about what your goals are.

If your goals are 200fwhp, you're there.

If you want 300fwhp, the cheapest way is with Tom's setup. $5000

If you want 400fwhp, the cheapest way is Tom's setup with a built motor. $10,000

500fwhp would require a huge turbo, or twin setup, with a built motor. $15,000
 
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