twin mitsu 2.5

[4cefedomni]

i'm trying to go twin mitsu's on my omni with 30-35 psi in my sights. Just curious what i will have to do to the wastegates to hold that much pressure. and if its not possible then how i could modify them to work with an external wastegate (i'm making my own header so it is a possibility). the reason i'm going with the mitsu turbos is that i have five of them and i got some rebuild kits for them for $100 each so these are the turbos i'm using please don't tell me i should go with a hybrid or something. thanks

[Ground Rat]

I'm kind of new at the TD thing, but isn't 30+psi way out of the mitsu's range? If you are getting 15psi a piece on those turbos, aren't you still at only 15psi, just more CFM? Also, how hard would it be to spool twins on a 4cyl? :confused:

[cordes]

You will probably kill those little things at that boost level, and toast your motor with scorching hot boost.

That being said, let me dig up the link to Carl's web site which details his TT mitsu shadow...

ETA: Link

http://66.78.24.116/index.htm

[4cefedomni]

i'm not sure myself i've never done it before but if one is good for 15psi then 2 should do 30 right? and the twin mitsu thing has been done once to my knowledge in a dodge shadow i believe it was Brian Slowes. If memory serves the lag wasn't that bad and it was capable of some high boost numbers. I hope mine will work well if not i build a new header and get a bigger turbo but right now thats out of my pricerange and i already have the turbos.

[Wink]

Look at the mitsy compressor maps. None of the TD04 or TD05 maps will go to 30+ psi. If they can't get to that pressure, then two won't be able to. They will just be able to flow twice the amount of flow per psi. That's all.

[cordes]

I posted the link.

15PSI from turbo1 +15PSI from turbo2 does not = 30PSI.

pressure does not work that way.

If your intake manifold is seeing 15PSI, that is what both turbos are putting out 15PSI. You will be flowing approximatly twice the air though.

You might want to take a look at the home made alky setup on carl's site too as that would go a long way in keeping your motor from becoming an ashtry maker.

ETA: Made the formula a little less confusing.

[Bardo]

thank god someone found it cause i was racking my brain looking for that link cause i wanted to do the same thing about 4 years ago and found out its not worth it

[turbovanman²]

I don't think its worth the hassle. Granted time is free but heck, for the effort, you could buy the proper turbo and not break a sweat. Carl went back to a single turbo I believe.

[4cefedomni]

well call me ignorant if you want but i have the parts to do it this way so this is how i'm going to do it if it works awesome if not then i need to try something else but i do think that 2 turbos will be able to reach higher boost than 1 turbo and there is also the awe factor of pulling up in a twin turbo car

[Ground Rat]

well call me ignorant if you want but i have the parts to do it this way so this is how i'm going to do it if it works awesome if not then i need to try something else but i do think that 2 turbos will be able to reach higher boost than 1 turbo and there is also the awe factor of pulling up in a twin turbo car
You won't get more boost w/ twins unless you run them in series, but you won't need to since you'll be moving about twice as much air at the same psi.

[WVRampage]

piggy back them like a deisel truck then 15 on one turbo then 15 more from the next. so the outlet of one goes to the inlet of the other,mount one turbo right under the other one on the dp then youd have twins with 30 psi. Even beter yet you could use lower boost and be well with in the limits of the mitsu. Same as above must have been posting at the same time.

[Ground Rat]

piggy back them like a deisel truck then 15 on one turbo then 15 more from the next. so the outlet of one goes to the inlet of the other,mount one turbo right under the other one on the dp then youd have twins with 30 psi. Even beter yet you could use lower boost and be well with in the limits of the mitsu. Same as above must have been posting at the same time.
http://img.photobucket.com/albums/v126/GroundRat/Animated/mswerd.gif I've seen up to three turbos on a diesel set up like that, the last was pushing 150psi. I've never seen it on a gas motor but don't see any reason why it wouldn't work. I don't think the same size turbos would be a good idea w/ that kind of setup though; the idea is to quickly spool a small turbo so it can quickly spool a larger turbo.

[Ondonti]

you can put one or 500 mitsus on your engine and it will never boost past 2.7 bar......unless you like getting pieces of turbo implanted in your face.

[TrrboJeep]

you can put one or 500 mitsus on your engine and it will never boost past 2.7 bar......unless you like getting pieces of turbo implanted in your face.
:nod: :nod: :nod:

It is great to create.. even God thinks so. That being said, you must realize that, as stated above, 2 turbo's each making 15psi of boost, will only net 15psi of boost pressure in your intake!

What others have found by creating exactly what you are going to try, is that

a.) the turbo lag associated with using 2 cylinders to spool a mitsu will be immense.
b.) the mitsu's will never be able to achieve 30+ psi of boost.
c.) although the "AWE" factor of twins may be there initially, after one race with someone cleaning your clock, it will quickly fade to something else.
d.) The best form of "AWE" occures in how your car performs, not how it looks.

If you truely want twins, you need to stage the turbos as stated above. Use one mitsu to spool a larger turbo. But, even that is not the ideal setup for a TD. But heck, since performance is not a concern, I'd say go for quads! You did say you had 5 mitsu's. Run 4 and you'll have one for a backup! If twins look impressive, think how jaws would drop when you popped your hood and folks saw 4 of them in there! :eek:

Don't hate us for saying this, we're only trying to help. You see, by doing this you will be reducing the performance of your car, and making it less fun to drive, all for the sake of some looks. It's kind of like the kids who wear their shorts/ pants down to their knees, they think it's cool, but the practicality of it defies the form and function it was designed for. You can no longer run, jump, sit, squat, and your constantly grabbing onto them with your hands to keep them from going all the way down to your ankles and exposing things!
We just don't want you exposing things that shouldn't be... thats all. :D

[Subliminal]

I think Carl went 12s, maybe even 11s with his tt setup, which wasn't much more than stock, if i remember right. I asked him a while back if he'd do it again, and he said probably not. He did it because he had the parts and it was free. He said the plumbing was a nightmare, though. And you have to have access to a welder to weld the manifold...

And Joel, I don't think he had any problems spooling the turbos, either. The rest of your points look pretty good, though.

d

[Wink]

... and there is also the awe factor of pulling up in a twin turbo car


That's the only reason I'm fabricating my custom manifolds for my V6. Most are adding a single turbo to them. Where I single myself out with having the only twin turbo project on the drawing boards at the moment.

I was told this and I'll pass it down to you.

Don't let others tell you something can't be done. If you have the ability to do something, then do it. If it works, then flaunt it. If it doesn't work, then learn by it. The only thing that you loose by trying is your hard earned work.


With this said, go out and prove everyone wrong and have fun with the project.


Now I get to play devil's advocate......

If you're planning on running the turbos in parrallel, then the setup has already been done and proven to work. However, it didn't work as well as hoped or the owner grew out of the setup and wanted higher boost. But, if you were to run them in series, like some of the deisel setups I've seen, then I don't see why you can't reach your goals. It will just take a lot of patiece to pull it off.

Good luck,

Wink

[turbovanman²]

Where not telling him NOT TO DO IT, just telling him its not worth the hassle and the fact that 2 turbos don't double the boost, and he will never hit 30 psi or more. If he wants to do it, knock himself out, :nod:

[Wink]

Where not telling him NOT TO DO IT, just telling him its not worth the hassle and the fact that 2 turbos don't double the boost, and he will never hit 30 psi or more. If he wants to do it, knock himself out, :nod:


I realized this. That's why I mentioned the sequential turbo setup. But, you have to admit, once someone gets something in their head, nothing short of finding out for themselves will make them understand.

I only posted that because of the "cool factor" he wants. But I totally agree that with two mitsu's in parrallel, he will not be able to attain that kind of boost, period. But I'd like to see someone try out a sequential twin set, just too see if it would work.

I do have one question about this, if anyone absolutely knows....

When you push compressed air into a compressor, will the pressure side of the maps increase exponentially with the pressure of the inlet? Or will that not matter, and you just won't see above the boost pressure that the maps show?

I just thought that if you pressurize an already pressurized mass of air, it would compound the pressures. Set me straight someone!!!! Please.


Wink

[TrrboJeep]

I asked him a while back if he'd do it again, and he said probably not.
That is one of the most often ask questions I hear, in regard to turbocharging my Wrangler... "if you had it to do all over again would you add the turbo, or just swap in a V8?"
I always reply with "I'd add the turbo" Why? Because everyone else does the swap. It's not unique, they're everywhere, and lots of people have them. I know of no one with an intercooled turbo setup on a 4 cyl. Wrangler!

So I guess, I'm the pot calling the kettle black! Live your dream... throw on the twins and run a safe amount of boost, so the mitsu's can live long and prosper! I wonder how much boost Carl ran on his setup?

Wink, your twin setup is a horse of a different color. On the V6 small twins actually have a performance edge on a low boost application. You'll spin them up quick and get some good low end grunt and low rpm boost. I think no one is working on that setup only because of the complexity of it, not because it is poor from a performance standpoint. I've been following the posts and pictures on your build up, and I think it's gonna be a sweet setup, with a lot of balls when its done!

If you choose to proceed with the twin mitsu's, be sure and post some pictures as you progress. We can't get enough of this crazy stuff around here! :eyebrows:

Oh and BTW, I got no clue on the pressurizing pressurized air??? :confused:

[4cefedomni]

that is correct thats why hooking turbos in series is called compound turbocharging. but what i don't get is if i have them in parrallel and now they are flowing twice as much air the engine can only take in so much the rest would build up hence more pressure. and the setup i plan on running is to have cyl 1,4 run independantly from 2,3 both on intake and exhaust side that would make it seem like a big turbo on a small engine and big turbos should be able to get high boost pressures. on the intake side i plan on having 2 throttle bodies feeding 2 cylinders each with an intake that looks similar to a header( like whats on a toyota vvti motor if you have seen one).

[TrrboJeep]

Wow, that's sounding more and more complicated... but interesting. Basically you'll be feeding 1.25 liters with a mitsu X 2. I'm not sure, but it seems like totally separating the intakes and exhausts would make for a motor that might run a bit rough (uneven)? How will you ensure each half is getting equal amounts of air/fuel, boost? I guess this means dual intercoolers?

If compression varies cyl to cyl that could effect the spool up, and hence your turbo's might not spool evenly. That would make for uneven power cyl to cyl. (2 cyl might see 11 psi, while the other two are at 12?) Just something to consider.

[4cefedomni]

a lot of you seem to be implying that i don't have alot of experience. that being said i don't, but i do have some my first full rebuild was a 1985 2.2 t1 that i did when i was 15 i am now 22 and since i built the engine in my first car i have been hooked on turbo dodges. the lebaron i had with the t1 would smoke mustangs on a regular basis, it had 23 psi of boost with alcohol injection. this time around i'm doing a custom calibration(3bar) with large injectors(somewhere about 93lb/hr accel makes them) to handle extra boost, so i wont turn my engine into an ashtray. i also happen to hate the ricer mentality and my car will not be all show i hope to have a 10 second omni that looks almost stock, after i whoop them then i might let them see why they lost.

[4cefedomni]

if i go the series route for turbos i do have the garret t3 from my old lebaron so i could still have one big and one small turbo. the engine is getting a full rebuild so compression should be even and the turbos are both rebuilt but i might still have to put in an equalization tube between intakes and use just one boost controller hooked up to both turbos. i havn't started welding it up yet so we will see.

[SpoolinGLH]

goodluck fitting all the tubes,turbos,intercooler,ect under the hood of an omni....unless your like russ and cut holes in the hood lol

[4cefedomni]

thats the plan but with a big cowl or something covering it. the turbos are going above the engine facing forward so i might try to use a scoop or something but i'm not worrying about that until the engine is completed and in then i will modify the hood. i might go fiberglass because my dad works with fiberglass all the time.

[Ground Rat]

One thing no one pointed out yet is that a single turbo will be more efficient. I hope you do go w/ some sort of crazy twin setup though, simply because of the cool factor. Crazy fabriction and experimentation is what hotrodding is all about. :nod:



When you push compressed air into a compressor, will the pressure side of the maps increase exponentially with the pressure of the inlet? Or will that not matter, and you just won't see above the boost pressure that the maps show?

That is an excellenct question! I have no idea so I'm off to the diesel boards to do some reading. :D

[cordes]

A staged turbo setup is most often used in high altitude aircraft, or wild deisel applications. I think that there is a very good reason that they are not used in a gas motor. Heat. The tiny mitsu will heat up the air significantly, and then the second one will heat it up much, much more. You would need one wild IC, and probably some sort of chemical IC system to bring the temps back down to some thing approaching normal for the mitsu.

If your goal is 10s, I think you are barking up the wrong tree with the twin mitsus. I don't think that they would flow enough air for that even in a perfect world. I have got to believe that stuffing all of that plumbing in the engine bay of an omni will be a one shot deal, and that swapping out turbos later would mean re-fabricating every thing.

Finally, even if you can make all this work, only the people on this thread will be in "awe" when they see your car. A Dodge Omni can do a lot of things, but inspiring awe in the average joe while sitting still is not one of them.

Good luck in your quest.

[Ondonti]

that is correct thats why hooking turbos in series is called compound turbocharging. but what i don't get is if i have them in parrallel and now they are flowing twice as much air the engine can only take in so much the rest would build up hence more pressure. and the setup i plan on running is to have cyl 1,4 run independantly from 2,3 both on intake and exhaust side that would make it seem like a big turbo on a small engine and big turbos should be able to get high boost pressures. on the intake side i plan on having 2 throttle bodies feeding 2 cylinders each with an intake that looks similar to a header( like whats on a toyota vvti motor if you have seen one).


You are missing the point.

The mitsu is physically incapable of making 30 psi boost. It will explode through the firewall into your face before that happens.

Compressor surge will be your new best friend, that or you overspin a turbine blade into your eyesocket.

[TurboMinivan]

The mitsu is physically incapable of making 30 psi boost. It will explode through the firewall into your face before that happens.

Did you not read that link? Brian Slowe regularly got 25+ psi out of his twin Mitsus.

-Dempsey

[Ondonti]

Did you not read that link? Brian Slowe regularly got 25+ psi out of his twin Mitsus.

-Dempsey
25 psi is in the range of the mitsu. I dont know what you are talking about. Their map goes up to 2.7 bar.

[4cefedomni]

ondonti find an online turbo calculator that has an option for twin turbos and fill it out i did i know these aren't that accurate however it said i should go with garret gt25 wth a .63 ar i pulled up the compressor map for that turbo and compared it to a teo4h they look almost identical and both only go to 2.7 bar. i filled out mine saying that i wanted to go to 35psi of boost at 7000rpm with a 2.5l. i realize that putting two 15psi sources together will only get me 15psii'm not retarded, however with two turbos to get that 15 psi at the same flow the shaft speeds would be much lower thus enabeling a high peak boost. it makes sense to me and i am also aware that a single large tubo would be a more efficient way of obtaining my goal, but that is not in my budget and i have several te04h turbos lying around.

[89acclaim]

He said it did 12.16 on street tires.

Daniel Merrill

[Ondonti]

Your biggest problem is there are very few small turbos that will push 35 psi. Thats probably the main reason why single turbo for that much boost on a small motor is the only affordable way to go.

If you have a bigger motor then your have more options for twins and high boost.

[4sfed4]

I am not expert and its been awhile since Ive thought about this stuff, but I believe that theoretically the maps will still be mostly accurate and usable.

Compressor maps are generally posted using a pressure ratio.

This is the ratio of pressure between the inlet and outlet of the turbo and is defined as--

Pressure Ratio = (Outlet pressure + inlet pressure) / inlet pressure

We usually just assume the inlet of the turbo is at ambient pressure.

So, the formula usually ends up being--

Pressure Ratio = (Outlet pressure + 14.7) / 14.7

The 14.7 is "normal" ambient pressure in psi at locations near sea level. The outlet pressure is "boost" pressure plus ambient pressure.

So, for a car running 15 psi boost, the pressure ratio comes out to just about 2.0, 20 psi boost is 2.36, 25 psi boost is 2.70 and 30 psi boost is about 3.04.

If there is a turbo feeding the inlet of a turbo with compressed air, the inlet pressure is no longer 14.7 psi. It might now be 29.7 psi if the turbo supplying the inlet air is running say 15 psi boost. (You have to add the boost pressure to ambient pressure.)

So, in the case of one turbo supplying 15 psi "boost" to the inlet of another turbo which is in turn "supplying" 30 psi "boost" to the engine---

Pressure Ratio = (outlet pressure + inlet pressure) / inlet pressure

Pressure Ratio = (44.7 + 29.7) / 29.7

Pressure Ratio = 2.51

So, in an euqally balanced 30 psi "boost" pressure sequential dual turbo arrangement, the first turbo (which is supplying 15 psi to the inlet of the second turbo) is running at a Pressure Ratio of 2.0, while the second turbo (which is receiving 15 psi "boost" from the first turbo and then supplying 30 psi "boost" to the intake manifold) is running at a Pressure Ratio of 2.51.

So, when one was looking at the compressor maps, they could probably get a general idea of how things would work.

But, the catch is that, although pressure can keep adding with series turbos, the flow is going to suffer as now the air must flow through not one but two turbos. One is essentially trading flow for pressure in using two small turbos in an effort to get more "boost".

Hopefully I didnt make any errors in my thoughts.











I
I do have one question about this, if anyone absolutely knows....

When you push compressed air into a compressor, will the pressure side of the maps increase exponentially with the pressure of the inlet? Or will that not matter, and you just won't see above the boost pressure that the maps show?

[Frank]

Here is the map for the mitsu....

http://squirrelpf.com/turbocalc/graph.php?company_id=2&family_id=4&product_id=1

[cordes]

Here is the map for the mitsu....

http://squirrelpf.com/turbocalc/graph.php?company_id=2&family_id=4&product_id=1


Those are going to be spun really hard to hit 30PSI.

[Ondonti]

Those are going to be spun really hard to hit 30PSI.aka why you will get pieces of turbine blade stuck in your face. :yuck:

[cordes]

aka why you will get pieces of turbine blade stuck in your face. :yuck:

Agreed. I should have put the winking smiley at the end of my last post.

[Aries_Turbo]

1. it was Carl Buchinder who made the car, not Brian Slowe.....

2. Carl made 30psi with the mitsus when he put vac on the wastegate cans.

[Frank]

I wonder how much that wastegate really moves on all of our applications. If you think about it, with 20psi of boost, you could typically have 40psi of backpressure in the exhaust. With the turbine housing the way it is, I could definently see why Carl would need vac to keep those things shut! :O


Frank

[4cefedomni]

i was thinking adding boost to the back of the wastegate can (dual port can) to hold them shut or add a external spring to do it. and as a previous poster pointed out you can trade boost for flow which is what i plan on doing two high pressure low flow turbos.

[4sfed4]

Those are going to be spun really hard to hit 30PSI.

From the looks of the map Frank posted it sure looks like it even if they are in series (and the PR on the second turbo is only 2.5).......and they still wont be moving much air.

[mock_glh]

2 turbos of any kind will have twice the exhaust flow that one has, even with the wastegates totally shut. You will make more power even at the same boost pressure you had with one. I picked up 3 mph in the 1/8 by going from 2-1/2 to 3" exhaust with the same turbo, same boost (20 psi). Upgraded from Super 60 to a T3/T4 and gained 4 more mph, still with 20 psi. Ultimate power is pretty much dictated by the flow capacity of the turbo. Pressure (boost psi) isn't everything. 2 turbos will run better than one.:amen:

[tryingbe]

I have tough enough time just to mount an FMIC with a/c stuff in a omni.

Can't even start to think about more pipings.