I am reposting this with an appropriate title so it generates more attention.

Before all you flamers start, yes i am car literate, i've been reading these boards for a while so i've seen many people's "custom kit" ideas blow away in a few days and i've seen some people with bad ass kits. i am actually a good welder and can work with metal and other things pretty well. This is an idea that has been floating around in my head for a few days now. I have thought this up on the SOLE PURPOSE of being unique. I don't want to hear all of you people bitching about how a single turbo is better etc. My goal here is to create a turbo setup that is either:
A)twin turbo
or
B)Sequential
In that order. My goal is the build a manifold(YES I KNOW WHAT IT TAKES AND NO I WILL PROBABLY NOT MAKE IT!!!!!!) that supports two small turbos, what do you guys think would be a good pair for our car? t25's?14b's?t28? i was thinkin 25's but a 14b also can be upgraded easily and it was easier to find a used one for cheap on ebay. And as far as hood capacity i've asked a question somewhere else in this forum about hood clearance. I want to know if the posibility of two TB's is possible. the only problems i can see is the idle being fuct up by having two iac's to control...but even if you spliced the iac signal wire to accomadate two tb's, there is still more airflow than with 1 tb. will the iac's be able to compensate for this electronically? the way i want to mount the dual tb's is to take my intake mani, chop off the left side of it. not any of the runners but just enough that i can buy another manifold, chop off the same size piece of the tb flange and weld it on the other side. i'd have to move the map sensor and other things i'm sure but i am thinkin it won't be too hard. another question is what is the mani made of? can it be welded to with any strength? and as far as tb's go, if a tb will work upside down then i don't think i'll have a problem using it. I'll just have to reroute the throttle cable and extend it so that i can wrap the wire around the tb on the left a couple times, then over to the right tb... like this: __0_/---0
yet again another bad example. but you get the idea. it just needs to be wound around the first 0 once or twice so that whent he 0 on the right is pulled it twists the left 0 the opposite direction, which is actually the correct way because its upside down...get it? back to the manifold. i think that in order to get the twin turbo's to fit in the space provided, i'll have to move some of the enginebay stuff around. like the radiator hose, and maybe some stuff by the left side of the bumper(facing it).the manifold will be built with two parts. obviously one part for the 1 and 2 cyl. and one for the 3,4. the flanges will both be moved away from eachother a inch or two to create more room between the turbos. this is where my idea comes in. will turbos work upside down? i saw that wheat king guy had his turbo on the stock manifold upside down... because the turbo ont he left will be completely upside down, and the flanges will be welded on at an angle so the turbos are in a V shape... this way, both the turbine housings will be next to eachother and the compressors will be on the outsides. making piping easier and btw this idea is non-IC'd. the advantage of this would be, the heat wouldn't be gong by the air pipes and the DP would be much easier to make. what do you guys think so far? the main problem with this is clearance. the turbo on the left will have the pipe that leads to the tb on the left go over the cam gears. or in that little space between the strut tower and the cam gears(save a half inch or so) I'm not sure, but how big does the piping have to be? 3" or so? the piping on the right is self explanitory. this would feature twin BOV's and no IC's. maybe another version, or when i feel like hacking out my engine bay to accomodate room. as far as money, i am going to college!!!!! but i only need to make 3500 this summer to have college completely paid off. (i got a bunch of financial aid(grants)and am taking out a small loan) the idea is i'll be working in salt lake city all summer long doing some roofing work(sealing up roofs with this epoxy shiat).like all the parenthesis? so I'll make around 8-9g's this summer.if i make 8 g's, that leaves me with 4500 to do this... think i can do it? another problem, i'm not very familiar with the fuel side of this. i'm not sure how a MBC controls boost very well, so would it be able to control two turbos?
I'll get to my sequential idea later...

Im not gonna flame you, but this topic has already been discussed. I mean if you were to actually construct a twin-turbo system, I would love to see it and you would get a lot of recognition as probably being one of the few (if not only) twin turbo DSMs out there. However, there are things to consider.

What would be the point of actually having twin turbos? Our cars have a 2.0 liter engine. You would probably have to use t-25, maybe 14b's at the most. Assuming that you put each turbo on 2 cylinders, the exhaust velocity simply would not be adequate enough to actually spin the turbos fast enough to make it worth while. On a 2G turbo, a t-25 spools at about 3000rpm, when runing on all 4 cylinders. Imagine providing only half of that exhaust velocity to a turbo. Youd be spooling those t-25s at a much higher RPM. And lets even say that you overcame that problem, youd still have to run only a minimal 3-4psi of boost on each turbo (unless you had a rebuilt engine). Assuming that t-25 makes about 350cfm at peak efficiency, youd only be pushing maybe 150-200cfm per turbo. Our engines simply arent large enough to facilitate twin turbos. Larger displacement engines (such as 3kgt vr-4 and supras use 3.0L engines) create a much higher exhaust volume, which is enough to spin two small turbos on that car. Ask yourself, why do so many supra/3kgt/other twinturbo cars actually get rid of thier twin turbos and upgrade to a single turbo? Because you can never make the amount of power a large single turbo can produce by having two smaller turbos.

Now about the sequential turbo setup. Actually, this topic had been discussed alot before by my local DSM club. In the end it was decided that again, its basically pointless. On a sequential turbo setup I would assume that you would use a smaller turbo first, followed by a larger turbo (or vice versa) so that you can gain the advantage of fast spool up followed by large power. Again, take into consideration exhaust volume and velocity. A turbo slows down the exhaust gasses as they travel through the turbo. By the time the exhaust passes through the first turbo and enters the second turbo, it is going slow. At that speed, it probably wont spin the second turbo to peak efficiency, once again lowering the CFM that turbo puts out. It would also probably mean that the second turbo would start spooling at a rediculously high RPM.

Basically, in my opinion, its not worth to actually attempt to twin turbo our car. Imagine that you can actually achieve to push 200cfm out of each turbo @ 4psi of boost each. Whats the point? You might as well as get a single 14b and make 400cfm from that! Or get a 16g. Or a big 16g. Or a 20g. And on and on and on. In my opinion, creating a twin turbo setup with two MAP sensors and two throttle bodies and two intake manifold and all that stuff would cost way more than 4500$. Plus the hassle of actually assembling everything together only to realize a year down the road that you want to run more boost from larger turbos but you cant would probably make this project pointless. Stick to what everyone else has done. For 4500$ you can have a rebuilt engine along with a large turbo pushing 15-20 psi. That would create MUCH more power than twin t-25s, trust me.

Hope this helps in some way.

Well said^^

Nick
97RS

actually, i'm quite aware of that. but thanks for the input in case i didn't. The primary reason for having twin or sequential setup would because I intend to make my car a show car.... and like ppl say, how many tt eclipse's are there? that would definately put me out in front with the judges wouldn't you say? and yes, i'm also considering going single turbo with one of alains manifolds with a t3 and getting some 8.6 ta ones and doing lots of crap like removing the balance shafts, etc and going all out performance... what happened to the 3.0l aluminum block? i got the money for it now! again, thanks for the input and yes i'v read tons of other posts about twin turbo on asog and dsmtuners as well... and i envey them, they must have learned tons of things doing that, and are obviously owners of one of a kind vehicles. another reason for doing it was because i wanted a project...i wanted to accomplish somethin if you know what i mean. it was one of those lust things that i might go through with. i don't care if i can't boost much, its sorta the same trade off people make with a spyder. they are dogs, but they look good. anyone want to add to that? and you know those electronic valves that can turn your exhaust into a dump straight pipe with the push of a button, somehow a rpm signal could trigger a copuld of those to rerout the exhaust gasses around that first turbo into the second.... now that would be useful. and it wouldn't be driving the first turbo
.... dunno how it would spool tho....LOL!

and seriously Collente, what do you think "^^ well said" does? nof offense but that was plain ghey. what you are doing is racking up your posts, and showing everyone that you know more shit than anyone else. like, you gave him your approval or your stamp of authenticity to what he said! spend your time "helping" other people please. did you not read the title? i don't see that useful in anyway. i'm not pissed at you or anything, i just find it how some people can be ignorant at times. -Peace
FAHZHA!!

Okay, no need to blame the other guy :) Im sure he was just agreeing with what I said. Now that you say you know that this is going to be a very hard and expensive project, heres what I can offer (in my best opinion) to help you go on your way.

I would advise against going with a twin turbo setup that would employ only 2 cylinders on each turbo. I would say go with a sequential turbo setup. First off, I would advise against going with the dual throttle body manifold setup. The fact that you would have to probably run two MAP sensors is enough for me to stay away from it. But even if you overcame that problem, the problem of air entering the intake manifold from two different directions at high pressures could lead to undesireable airflow. What I would suggest you do is actually get a manifold... then port the hell out of it. Try to get the widest possible pipe that you can. Also, consider porting the engine before the exhaust manifold. This would maximize the amount of exhaust volume and velocity, and thats your primary convern. As for turbos, your first turbo should be a VERY small one, even smaller then a t-25. I would go with something like an 11b. Once again, port the hell out of the exhaust side of the turbo. Your next turbo should be something bigger, but not too big. Id stay away from anything larger then a 14b. Again, port the exhaust side. You NEED to get as much exhaust veocity as possible.

Figure out a way to make a custom downpipe. Try to keep the diamater large enough that exhaust gasses can escape quickly, but not too big so that you dont see boost spikes. Have both of the compressor outlets join into one large IC pipe, which should run to an intercooler. Use a 1G DSM intercooler, and your choice of BOV. Then just figure out a way to run all the vacuum lines and figure out some sort of boost control, as well as oil feeds/dumps, and you should be set.

Good luck on your project, if you actually do undertake it please take pictures/videos along the way so we can all see what youre doing. Good luck :)

One quick comment on what neo said above. IF you want velocity higher, shouldn't you leave it as is (no porting).

B/c larger tubes = slower movement assuming everything else is constant. Volume (mass) will be the same, but velocity will drop. PV=nRT

Oops, I made a mistake :) Youre right. But from what I heard, you need to get as much exhaust out of the engine as possible to spin those two turbos.

You do. Actually I used the wrong equation above earlier as well. (should be fluid dynamics instead of ideal gas law...anyways).

With only 2 cylinders feeding each turbo, though, enlarging the ports would do more harm to your low end than the benefit you would get out of the top end imo.

I advised against 2 cylinders per turbo, i was thinking thats probably the worst setup. I was thinking the sequential setup might be the best bet.

If you don't care too much about power or driveablity and want it just for show quality...then this is a viable project. With some money and time, you can certainly fab up a twin turbo engine. Our engines will "run" with all kinds of crap done to them. I say "run" like that because you just want this for show. A daily driver should "run well".

My first step would be to visit the local university library. Find text books on internal combustion engines. With luck, you will find books just about turbocharging. I have a nice book called "Turbocharging and Supercharging". It was written in the 80's, but discusses many relevent topics (such as twin turbo setups).

Corbin

'95 ESI-T
HRC+FMIC+ETC...



Gimme fuel...Gimme fire...Gimme that which I desire

the turbo sits off center of the exhaus manifold. so you could try to put another spot for a turbo on the same position but opposite. like say put the turbo between 1 and 2 and the other between 3 and 4. then have both go straight to a front mount and maybe you could find a way to have one downpipe still. like between 2 and 3 the turbos share a downpipe somewhat. mainly the gturbos would be workgin off of 2 cylinders but they would not be blocked from only getting 2 cylinders. one downpipe makes exhaust easier and maybe have the turbos share a intecooler pipe or something. it could be possible, probabaly better to be done a a 2.2L or a 2.4L since you would have more exhaust flow. if i can draw a picture of what i mean ill post it, but im at school right now

great input! this is awesome. But i've done a lot of thinking and this is what i've come up with. IF, i still go the show only route, which is strictly for pleasure obviously, I would have to do lots of things like remove my power steering, ac to accomodate the second turbo. I think that if it is an all show no go car, the idea i had would be more of the way to go because it would have more of a symetrical and proffesional look to it. but as far as drivability and racing wise, the sequential is by far imho also the better way to go. Finding room to mount these things would be sorta difficult. I wouldn't want to remove the ac or power steering etc. so creating a manifold that would accomodate these needs would be rather difficult. The reason I am considering this, is because I'm going to be working this summer with an awesome paying job. my college is pretty much paid for already, and i'm still receiving scholarships still. so i'll have everything i make this summer basically to go into my car. }( :D
yeah yeah, don't beat me up. another possibility is to go single turbo with the afx 3.0l! i would have enough money to purchase that sucka, 2400 plus all the internals i'll need. that there would be a good start, and it would spool turbos much better with half again as much displacement. remember, i have not told anyone that i am going to do this, or go any route like this at all, because i just don't want anyone to say later, "what happened to that joker that said he was making a tt eclipse?". If you know what i mean, i've seen it happen too many times. I'll keep you guys filled in. by the end of the summer, i'll either have a pretty DARK silver eclipse with a body kit and miscellaneous sheet, or a turboed car with a built bottom end... oh, how hard to choose! I don't think i'll go with a kit. I want to save as much money as possible and want to have the expierience of doing it myself. It was pretty much the sole reason i wanted this car so bad. great input guys. thanks for not posting a bunch of crap, it really helped me exlplore the options here. keep the ideas comming if you got any!

Wont flame cause I posted it when I first joined the board cause I wanted to be different, like I used to be w/ my exhaust. I wanted 2 of everything.. 2 bumps on hood, exhaust and turbo's. Seq will definately work better but like people have posted it's hard to spool two turbo's w/ a 4 banger especially if the 4 banger doens't have much power to start off. Lots of BA 4-bangers w/ close to or over 200 HP so they would probably have an easier time, I would think w/ twins. Good luck w/ it if you decide to try it. i wish I tried it, even if its not as fast, as long as I didn't spend a crapload of $ on it, it would still be different and kool.
-Dave

>and doing lots of crap like removing the balance
>shafts, etc and going all out performance... what happened to

No balance shafts in our engine... it's the 4g63 guys that have balance shafts to remove.

>the 3.0l aluminum block? i got the money for it now! again,

I don't think Gary had enough interest to make them right now. You might want to give him a call and find out. I think that's about the only engine I would attempt a TT setup on, and I have quite a few 420a/turbo rebuilds under my belt now. Good luck with whatever you choose to do... I'd love to see a TT 2GNT!

hmm I seem to recall juan talking about a twin turbo 2GNT (or was it a GST?) a long time ago that he rode in at some kinda meet. So long as you get the plumbing right you could do it. and dual T25s should do it those spool like nothing they have no topend though. Those suckas spool at like 2k RPM or some rediculously low RPM. So if you can fit 14bs or a T25 and a 14b that'd be nice.

everything is crowded enough in there already with one turbo already O_0